EGU General Assembly 2023  

As the global population expands, the demand for food, fuel and fiber rises steadily. Meeting these needs in a sustainable manner, without depleting natural resources or polluting the environment remains one of the greatest challenges of our time. What is more, anticipating changes in these systems as a result of climate change, and across a multitude of environmental and socioeconomic contexts adds yet even further complexity to this already convoluted issue. 

At the heart of this matter lies agricultural soils, and how management practices are used to modify and adapt their capacity to sequester carbon and provide nutrients and water to growing plants. While soils are notoriously heterogenous on their own, this is further enhanced by their role as an important environmental reservoir linking plants and residues to soil microbial communities and soil fauna, the atmosphere, and water. Understanding how management practices influence these interactive aspects of the soil environment is key to developing agricultural management systems in a sustainable, effective and site-specific manner.

In this presentation I will highlight how it is vital for future studies to consider a) how management practices will simultaneously impact a variety of different soil functions or services, not just one or two, in order to assess environmental tradeoffs within a given system, b) how these are impacted across different spatial scales, and c) the importance of developing management practices that are adapted to local, site-specific conditions. It is clear that the complexity of modifying agricultural systems to survive in a rapidly changing climate demands interdisciplinary approaches. It is thus my hope that this presentation will foster open discussion and meaningful collaborations to address such challenging societal questions.

How to cite: Garland, G.: Sustainable management of agricultural soils: Balancing multiple perspectives and tradeoffs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2801, https://doi.org/10.5194/egusphere-egu23-2801, 2023.

Introduction: Contamination causes undue risks to society, ecosystems, water and soil resources, and threatens the viability of many industries^1,2. As well as affecting soil, surface water and groundwater, air pollution has been recognised as one of the planet’s most challenging problems. This contamination of the living environment has been linked to 13.7 million deaths a year by the World Health Organisation, almost a quarter of all human fatalities https://www.who.int/data/gho/data/themes/public-health-and-environment). Even more concerning are the nonlethal side effects of global contamination, e.g. the decline in human IQ, the collapse of male fertility, the increase in child developmental and mental disorders etc. which, on a daily basis, adds millions of dollars to medical costs and indeed impacts the quality of human life. Describing contamination’s impact by deaths alone understates the problem. It is the lifelong disabilities and suffering of a growing percentage of the population which is also a core issue. There are hardly any measures in place to minimise these impacts other than some regulatory measures that rarely include all toxins in circulation around the planet.

The extent and severity of air pollution depends on many factors – including population, industrial activities, and measures in place to minimise contamination – and thus varies considerably among and within countries. Although more than $US$2 billion is spent annually to manage or remediate contaminated land and water bodies in Australia, limited funds have been allocated towards the management or remediation of air. Globally, environmental management costs exceed $US750 billion per annum with US $65 to $85 billion of this used for clean-up costs. However, these costs do not include the medical costs linked to many debilitating human health issues confronted in most if not all countries globally.

Globally, it is estimated that there are more than 10 million potentially contaminated sites. Despite growing awareness of the risks of exposure to contaminants, activities that contribute to contamination of our environment are on the increase in many countries as populations grow and industrialisation increases. One reason for this is a lack of adherence to regulatory policies, especially in developing countries, many of which are chronically under-resourced. What is needed are global protocols for restricting the use of toxic chemicals and a global 'contamination IPCC' to oversee and reduce universal contamination. Take a metaphor of IPCC that the climate talk and action has been much visible as a result of forming Intergovernmental Panel on Climate Change (IPCC) in 1988.

The proportion of contaminated sites that are successfully remediated is disconcertingly small. Uncertainties about the nature and extent of contamination can be a major constraint to sustainable development in both urban and rural areas, thereby increasing pressure on the use of limited uncontaminated land. Moreover, many techniques available for in situ or ex situ remediation are prohibitively expensive and thus poorly adopted.¹

Unlike point source contamination associated with industrial activities, diffuse pollution, such as that encountered in broadacre or agricultural farmlands, poses a different challenge. Although the risk of direct exposure from soil to person is low, the bioaccumulation of contaminants into crops and subsequent exposure via food consumption poses a major risk to humans and also damages local and international trade. Added to these are the inherent dangers of chemical mixtures, even from innocuous substances. The dangers of chemical mixtures are rarely considered by regulatory jurisdictions and indeed industries linked to contaminants. Also, the absence of information about the toxicity of new and existing chemicals further constrains management of environmental contamination.

Although generally present in low concentrations, diffuse contamination is often difficult and expensive to remediate because it can be spread over very large areas.

Exposure risks: The risks associated with exposure to contaminants vary considerably depending on the source and pollutant matrix. While 4 million deaths per year are linked to soil, water or food contamination, a recent World Health Organization report estimates air pollution poses a much higher risk than other forms of pollution, killing an estimated 6 million people every year. UK estimates suggest that air pollution will make 2.4 million people ill in England between now and 2035 and the healthcare and social costs of air pollution could reach US $23 billion by 2035.3 Air pollution is now seen as the invisible killer. Air pollution is caused almost entirely due to the use of fossil fuels and is expected to decline as they are phased out. Furthermore, environmental management is constrained by the highly leachable nature of soils in countries with sub-humid to humid tropical conditions (compared to soils in USA and Europe), and this limits application of technologies developed elsewhere. To make sound risk and remediation decisions, we need to refine the way we assess risks from contaminants. We need improved data and protocols that provide reliable prediction of exposures and the associated human/eco-impacts. We also need improved monitoring and assessment procedures and instrumentation for contaminants to deliver reliable, accurate data on contaminant presence and fate.

Clean up: The cost of clean-up continues to rise given the challenges of remediating both surface and subsurface contamination. Soil is now seen as a complex heterogeneous system that, once contaminated (especially when coupled with groundwater), is not easily remediated. Furthermore, drastic risk control (e.g. cleaning up sites to background concentrations or to the levels suitable for sensitive land use) is rarely technically or economically feasible. It is thus desirable to apply remedial approaches that reduce the risk of contamination while allowing the soil to remain on site. This approach to site remediation, which is gaining increasing acceptance, is commonly known as risk-based land management.

While clean-up is desirable it does not address and will never solve the overall contamination problem. It treats only one of the symptoms. What is needed is a global treaty to reduce Earth system contamination at source – i.e. to prevent pollution occurring in the first place by not releasing any more untested chemicals, maintaining a global inventory of what is released, and pinpointing major sources of toxicity (e.g. plastics in the home).

While the act of contaminating the environment may itself expend low energy and cost, the complex nature of contaminants – coupled with the heterogeneity of media in which contamination resides, risks and multiple receptors – means that the act of cleaning up is complex and cost- and energy-intensive. Given our planet’s large number of contaminated sites, the fragmented approach along national lines and the slow pace of remediation, it will take many generations to clean up the Earth, and we will never achieve the pristine conditions that existed prior to human civilisation.

Can we clean up the earth? This paper has provided an overview of the extent of global contamination, its risks and impacts, the challenges to remediation, and why a clean Earth is humanity’s next great challenge. The paper has also proposed that an international ‘contamination IPCC’ is necessary to meet this challenge. An international body of this type could champion a coordinated approach to the following issues.

Global issues that need to be considered:
(a)    The development of a comprehensive database and international chemical inventory and improved exposure pathway models that would assist with risk assessment of contaminated sites and air pollution.
(b)    The prioritisation of action for target contaminants/circumstances, especially for recalcitrant contaminants and mixtures in complex environments or where high risks are posed.
(c)    The development of specific remediation techniques relevant to region- or country-specific conditions, and demonstration of those techniques at national scale to encourage uptake.
(d)    The development of a database that provides the basis for a decision-support system on techniques for remediation or management of contaminated sites.
(e)    The availability of highly qualified environmental management and risk assessment graduates.
(f)    Environmental legislators with expertise in assessment and management of site contamination.
(g)    Trained professionals who can assist with the social implications of contaminants.
(h)    A global industry training program to raise industry awareness of the effects of global poisoning (which they ignore) and build a culture of stewardship for dangerous products.

Capacity building: Addressing the issues outlined above will also require a significant effort to build sufficient skilled capacity around the globe. There is strong demand for trained graduates with expertise in not only environmental management but also legal and social issues relating to contaminated soils.

Conclusion: The large number of contaminated sites together with increasing evidence of health effects from the consumption of foods grown on contaminated sites or farms with low level of contamination suggests that there would be considerable benefit in assembling a focussed group of international leaders in the field – through mechanisms such as the globalCARE™ initiative – to tackle these problems on a global scale. Members of this group should have skills to develop technology for (a) assessment of risks, and (b) management or remediation of degraded environments contaminated from both point and dispersed sources. A well-resourced international group such as this, together with a global treaty to reduce contamination at its source, may be able to reverse the trend and in time may well be able clean up the earth.

References

1.    Naidu, R. (2013). Recent Advances in Contaminated Site Remediation. Water, Air, and Soil Pollution. 224(12), 1705.
2.    Naidu, R. et al. (2021). Chemical pollution: A growing peril and potential catastrophic risk to humanity. Environment International. 156, 106616.
3.    Kass, D. (2018). Air pollution kills six million people every year: it's time for us to wake up to this grave threat. The Telegraph, 27 September 2018. www.telegraph.co.uk/news/2018/09/27/air-pollution-kills-six-million-people-every-year-time-us-wake/ 

How to cite: Naidu, R.: Can we clean up the earth?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17578, https://doi.org/10.5194/egusphere-egu23-17578, 2023.

Growth and death of microorganisms is central to the understanding of almost all global element cycles. To grow, heterotrophic microorganisms need to assimilate organic carbon, and to sustain a flux of readily available organic carbon, they need to depolymerize and deconstruct soil organic matter. When soil organisms die, their remnants become part of the soil organic matter. Thus, the processes that lead to both the decomposition and the accumulation of organic matter in terrestrial environments, are driven by the growth, activity and turnover of heterotrophic microbial communities in soil. Yet, little is known about how microbial growth, turnover, and activity is controlled in the current and in a future climate. In this lecture, I will share insights from a range of experiments that aimed at understanding the effects of soil warming, elevated CO_2, and drought, alone or in combination on microbial growth, turnover, and carbon use efficiency. I will draw on examples not only from my own work, but those of others, covering different levels of resolution, from the growth of microbial communities to that of individual bacterial taxa. I will argue that activity, growth, and turnover of microorganisms are the fundamental units of biogeochemical functioning in soils and that we need to move beyond the commonly reported metrices in soil ecology, and even beyond measuring rates of decomposition and mineralization themselves, if we are to understand the effects of climate changes on soil processes.

How to cite: Richter, A.: What controls carbon and nutrient cycling in soil? Microbial growth as the fundamental driver of soil biogeochemistry., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10907, https://doi.org/10.5194/egusphere-egu23-10907, 2023.

High urbanization rate and climate change are the main drivers of urban floods in developing countries. The increase in urban flooding incidents has become a significant threat to cities, which also result into considerable losses of life and the economy. Adapting to the risks of a changing climate and ill-effects of urbanization is imperative for national and local governments. This calls for a functionally and structurally resilient urban drainage infrastructure. Functional resilience is the coping capacity of system against external threats such as urbanization and climate change, whereas structural resilience is the resilience against internal failures such as blockage of inlets or sewers, structural damage of a pipe, bed load sediment deposition, asset aging/decay, and sewer collapse. This work aims to understand the impact of nature-based solutions on urban drainage resilience. Various researchers have identified Low Impact development (LID) practices as a potential solution to enhance drainage systems' resilience. LID can be defined as a land development and retrofit strategy that emphasizes the protection and use of distributed interventions to reduce the volume and rate of stormwater runoff from a developed landscape. In the present study, the green roofs and rain gardens are simulated in a part of Gurugram city of India using the Storm Water Management Model (SWMM) 5.2. Sensitivity analysis is conducted to overcome the problem of a lack of in-depth data to perform model calibration and validation. The simulations were carried out by developing various scenarios for functional and structural resilience assessment. The results indicate that if 25% of potential subcatchments are deployed with LIDs, functional resiliency of the system enhances by 25%, and structural resilience of vulnerable nodes decreases by 17%.  The study reveals that introduction of LIDs aids into enhancing the functional resilience of the system rather than structural resilience. This research provides evidence of LIDs' positive influence on the resilience performance of drainage systems. Overall, the study can help urban planners and drainage management engineers to develop understanding on LIDs role vis-à-vis city's resilience to urban flood problems.

How to cite: Mehta, O., Kansal, M. L., and Bisht, D. S.: Integrating Green and Grey Infrastructure for Resilience Enhancement of Conventional Urban Drainage System and its Evaluation through Modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-137, https://doi.org/10.5194/egusphere-egu23-137, 2023.

The increasingly frequent impacts of climate change in the Mediterranean region challenge the resilience and sustainability of the region's agroecosystems. In this context, Nature-based Solutions (NbS) emerge as a sustainable strategy to address climate change adaptation and mitigation. Extensive literature focuses on the analysis of NbS to address this problem, although no analysis discriminates against the individual and combined effect of NbS in agroecosystems. In this work, we capitalize on state-of-the-art results and present a random-effects meta-analysis of NbS. Our analysis focuses on a cohort of 80 NbS for agricultural land management, such as conservation tillage practices, soil-improving cropping systems, organic amendments and fertilizers, and landscape solutions. We used response ratios as effect sizes to determine the most suitable NbS for improving soil health. We built a database with field-scale data from 70 published case studies comparing NbS and conventional agricultural management practices in agroecosystems in 12 countries with a Mediterranean climate. Our analysis results from a literature selection of 988 scientific articles published from 2019 to 2022. We have analyzed the combined effect that NbS have on soil's ability to retain water, organic matter, and carbon and to reduce soil loss. To further understand the influence of abiotic factors, we also analyze the impact of precipitation, soil texture, and irrigation systems on the effects of NbS. These results shall contribute to leveraging climate change adaptation in Mediterranean agroecosystems, addressing land and water-related Sustainable Development Goals (SDGs).

How to cite: Rodrigues, M., Antunes Dias, L. F., and Carvalho Nunes, J. P.: The positive effect of Nature-based Solutions for achieving the Sustainable Development Goals in Mediterranean agroecosystems: a meta-analysis , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-569, https://doi.org/10.5194/egusphere-egu23-569, 2023.

Climate change is expected to affect the frequency, magnitude, and seasonality of several rainfall-related hazards, including flooding as one of the costliest hazards in Europe. Recent studies have shown that flood risk in Europe is both increasing and decreasing, with increases in most eastern and southern European countries, including Slovenia and Czechia. In addition, significant changes in the seasonal occurrence of floods have also been observed in Europe, thus challenging conventional approaches to flood risk management.

As natural hazards have major impacts on infrastructure, human lives, and habitats, and cause large social and economic damages, it is clear that adaptation measures aimed at both prevention and mitigation of impacts must be considered to cope with climate change. To deal with the changing occurrence and characteristics of floods, different types of measures need to be adopted, including green, blue, and grey measures or combinations of these. Although their application is currently emphasized, purely green or blue-green measures in some cases may not be insufficient to cope with predicted future climate hazards. Additionally, implementation of such measures often encounter resistance in planning departments and among decision makers due to institutional path dependency related to the history of utilizing grey infrastructure measures. This is especially the case for some Central-Eastern European countries. An alternative are hybrid solutions that combine parts of grey and green infrastructure, since these kinds of measures can reflect the variety of environmental conditions. However, not much attention has been given to the documentation and evaluation of hybrid infrastructure in comparison to purely green measures. Hence, there are still several open questions related to the implementation and functioning of solutions combining elements of green and grey measures, so called hybrid solutions.

The main objective of this contribution is to present the theoretical framework, research design and initial research steps of a newly launched international project focusing on: (i) enhancement of documentation and standardization related to hybrid solutions, (ii) development and testing of applicability and social acceptability of specific hybrid infrastructure in different environments and climate change scenarios, and (iii) environmental modelling and evaluation of effectiveness of different measures from the perspective of the flood risk management. Within the project, the effects of hybrid solutions on flood hazard and hydrological regime of the landscape will be modelled for selected small catchments in Slovenia and Czechia, but the standardization of hybrid solutions will enable to extrapolate our results beyond Central and Eastern Europe.  

Acknowledgment: The research was conducted within the project [Evaluation of hazard-mitigating hybrid infrastructure under climate change scenarios] co-granted by Slovenian Research Agency (J6-4628) and Czech Science Foundation (22-04520L). 

How to cite: Bezak, N., Šraj, M., Raška, P., Slavikova, L., and Jakubínský, J.: Towards implementation of hybrid solutions for flood risk management under climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-934, https://doi.org/10.5194/egusphere-egu23-934, 2023.

Recent disasters have demonstrated the challenges faced by our global society because of the increasing complexity of disasters caused by natural hazards. For example, a community hit by a natural hazard while still recovering from the impacts of an earlier hazard faces many different challenges than when it is hit by a single hazard that occurs in isolation. With growing awareness of this complexity and its impact on disaster risk, there has been a push, from scientists as well as international organizations such as the UNDRR, for disaster risk research to account for these complexities. This research has aimed to take an increasingly integrated approach, often bridging across individual hazard types to accomplish a more comprehensive understanding of overall risk.

Incorporating spatiotemporal dynamics of all risk components (i.e., hazards, exposure, and vulnerability) is key to accurately modelling compound and multi-hazard risk events. There is great potential to better capturedynamics between and within risk components by learning from common approaches and methods used in different research communities. For example, recent years have seen a growing attention for research into compound hazards and hazard drivers using methods such as storylines, agent-based models, and system dynamics, all novelties for this field of research. An important, less studied aspect is that of the dynamics of vulnerability. Many of these once-novel methods now applied in compound hazard research have the potential to improve modelling capabilities of other compound risk aspects, such as vulnerability dynamics. This talk will highlight recent developments in assessing the complexities of disaster risk and discuss potential opportunities to further advance our modelling capabilities through multidisciplinary exchanges.

How to cite: de Ruiter, M.: The challenges of risk dynamics and how to assess them, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1243, https://doi.org/10.5194/egusphere-egu23-1243, 2023.

In Mediterranean areas, rainfall is one of the main variables affecting the control of eco-geomorphological processes. Water erosion processes, sealing and degradation of soils, reduction of the amount of water available for vegetation, modification of hydrological regimes can be cited among the most remarkable. Thus, the modifications in climatic variables resulting from Global Change are having an impact on the Mediterranean eco-geomorphological system, especially issues associated with water risks. Specifically, a dual pattern can be observed: on the one hand, a notable increase in the recurrence of the number of torrential events and an increase in the risk of water erosion, and on the other hand, an increase in the intensity or frequency of droughts, determining productivity and ecological and economic values due to the reduction in the availability of water in the soil. In this context, the research has focused on a traditionally agricultural territory that is highly fragile to these processes, namely GIAHS (Globally Important Agricultural Heritage Systems) dedicated to the raisin production in the Axarquia (Malaga, Spain). The main objective has been to (i) assess the impact of the most important water risks and (ii) identify the main Nature-based Solutions (NbS) implemented as adaptive mechanisms that have been implemented to ensure food security and the sustainability of these areas. To achieve these objectives, the rainfall dynamics have been statistically analysed with the data downloaded from nine meteorological stations of the SAIH Hidrosur Network located in the region (1997-2021). In addition, a total of 60 soil samples have been collected and analysed for the estimation of soil water erosion rates, based on the RUSLE model, and for the evaluation of its hydrological dynamics in recent decades. Finally, the NbS identified in the study area have been qualitatively assessed and analysed from an ecosystemic and agricultural approach. The results show an increased water stress in this GIAHS area according to the projections published by the latest IPCC report for the Mediterranean region. A slight tendency to concentration and increased rainfall erosivity is detected, as well as a lower water availability in soil for crop phenology. Similarly, soil erosion rates show very high values, with slopes exceeding 250 t ha^-1 year^-1) However, agricultural practices and the different structures identified have been determinant in the control of these natural risks, being considered as sustainable adaptation strategies and conforming as NbS.

How to cite: Sillero-Medina, J. A. and Ruiz-Sinoga, J. D.: Nature-based solutions to address water threats in the Mediterranean region. A characterisation of the GIAHS area of Axarquia (Málaga, Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1521, https://doi.org/10.5194/egusphere-egu23-1521, 2023.

Abrupt sunlight reduction scenarios such as a nuclear winter, an asteroid impact or an eruption of a supervolcano would decimate agriculture as it is practised today. We therefore need resilient food sources for such an event. One promising candidate is seaweed, as it can grow quickly in a wide range of environmental conditions. To explore the feasibility of seaweed in a nuclear winter, we simulate the growth of seaweed on a global scale using an empirical model based on Gracilaria tikvahiae forced by nuclear winter climate simulations. We assess how quickly global seaweed production could be scaled to provide a significant fraction of global food demand. We find seaweed can be grown in tropical oceans, even in nuclear winter. The simulated growth is high enough to allow a scale up to an equivalent of 70 % of the global human caloric demand, while only using a small fraction of the global ocean area. The results also show that the growth of seaweed increases with the severity of the nuclear war, as more nutrients become available due to upwelling. This means that seaweed has the potential to be a viable resilient food source for abrupt sunlight reduction scenarios. 

How to cite: Jehn, F. U., Dingal, F. J., Mill, A., Ilin, E., Harrison, C., Roleda, M. Y., and Denkenberger, D.: Seaweed as a resilient food solution in nuclear winter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1871, https://doi.org/10.5194/egusphere-egu23-1871, 2023.

Climate change is projected to increase the aridity of semi-arid ecosystems, including Eurasian rangelands (EAR), which provide ecosystem services that support food supply and pastoralist lifestyles. Climate hazards are expected to become more frequent and intense, leading to the most significant risk to pastoralists and impacting their future sustainability. There is an urgent need for research-based interventions that can help herder communities adapt to future risks. However, rigorous impact assessments of climate change on pastoralism-based livelihoods considering region-specific socioeconomic changes in the Eurasian Drylands are relatively neglected research areas with limited knowledge. Thus, we assess the climate change risk to rangelands in Eurasia under regional grazing patterns and intensity across EAR spatial domain (34−56◦ N, 20−130◦ E: West Asia, Central Asia and East Asia) during 1971–2100. We conducted a grid-scale (0.5 °× 0.5°) probabilistic risk assessment of EAR in the context of climate change based on probability theory. Risk is quantified as the product of the probability of a hazardous drought and vulnerability of the ecosystem. The probability of hazardous drought is defined by the Standardized Precipitation–Evapotranspiration Index. Vulnerability is defined as the expected difference in key ecosystem variables between years with and without hazardous conditions. The ecosystem variables were productivity (aboveground biomass, net primary productivity, soil carbon, and leaf area index) and plant-available soil moisture in the root zone, simulated with a process-based ecosystem model ORCHIDEE-GM (Organizing Carbon and Hydrology in Dynamic Ecosystems-Grassland Management) validated with field observations of biomass and soil moisture. Climate data were based on gridded observations and projections of CMIP6 the Coupled Model Intercomparison Project Phase 6) using scenarios ssp1-2.6, ssp3-7.0, and ssp5-8.5. Historical land-use data were based on the number of province-based livestock during 1971–2019. The constant value of 2019 is used to simulate the future impact of grazing on EAR. The results revealed that EAR experienced more frequent hazardous droughts with rapid warming and slight drying during 1971−2020, aggravated by increasing grazing intensity, which resulted in a reduction in soil water availability and grassland productivity, particularly in northeastern areas. In the future, climate change will lead to increased droughts in the EAR under these three scenarios. These great drought hazards increase the risk of rangeland productivity in the EAR, particularly in the western and southern parts of Central and Eastern Asia.

How to cite: Nandintsetseg, B., Chang, J., and Sen, O. L.: Sustainability of Pastoralism: Climate Change Risk to Rangelands in Eurasia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2659, https://doi.org/10.5194/egusphere-egu23-2659, 2023.

As a vital element of public spaces, trees in urban settings are acclaimed to offer numerous social and environmental benefits, making them a quintessential nature-based solution for a more sustainable city. While carbon sequestration, air quality, and urban heat island mitigation benefits have long been acknowledged, less emphasis is directed to utilizing the hydrologic function of trees in terms of stormwater runoff reduction in the urban environment and this benefit is often underutilized. For urban areas with high proportions of impervious surfaces, increasing the percentage of tree canopy cover and green spaces is crucial in restoring the natural functioning of the ecosystem and water cycle. Within the framework of our ongoing research, we are investigating the positive impacts of trees (i.e., single tree elements, forests) as nature-based solutions on the urban water cycle using field measurements of rainfall partitioning, runoff, soil moisture, and infiltration from experimental catchments in the city of Ljubljana, Slovenia which started on August of 2021. Preliminary results revealed that open-grown birch (deciduous) and pine (coniferous) tree canopies intercepted a relative amount of gross rainfall with pine trees having a greater interception capacity. The following trees also modified the drop size distribution (e.g., drop number, diameter, fall velocity) of below-canopy rainfall before reaching the ground, thus attenuating the mean and maximum 10-minute rainfall intensities by 42-50% and 40-44%, respectively, depending on canopy phenoseasons. Such reduction in the intensity of rainfall has a significant effect on the peak water level of event runoff which could provide important information for understanding the runoff generation process. Moreover, this benefit with the root system of trees has a positive impact on the condition and structure of soils in urban areas promoting infiltration, preferential flow, and soil water recharge. In addition to this, tree canopies also dampen the average kinetic energies of rainfall to cause soil erosion by 34%. These initial findings suggest that the hydrological benefits of trees in the urban environment are adequate to warrant a further investigation into their potential to regulate the flow mechanisms of stormwater runoff and reduce urban pluvial flooding. Thus, it is also imperative to explore how the integration of trees interacts with other stormwater control measures and how this interaction could leverage their functions. This will deliver invaluable information to urban planners, landscape designers, stormwater management experts, and decision-makers on the need to expand the efforts of urban greening to address the associated adverse impacts of rapid urbanization and various environmental challenges.

Acknowledgments: Results are part of the CELSA project entitled “Interception experimentation and modelling for enhanced impact analysis of nature-based solution” and research programmes and projects P2-0180, J6-4629, and N2-0313 financed by the Slovenian Research Agency (ARRS).

How to cite: Alivio, M. B. and Bezak, N.: Role of trees as part of the nature-based solutions in cities and their effects on stormwater runoff generation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3140, https://doi.org/10.5194/egusphere-egu23-3140, 2023.

Studies on projected agricultural yields focus on end-of-century scenarios. Simulations from the Global Gridded Crop Model Intercomparison (GGCMI) Project phase 3b show conflicting results for global and regional changes of different crops by the end of the century. Here, we interrogate the same simulations, focusing on year-to-year variations of agricultural yields in the important staple crops maize, rice, soybean and wheat.

An ensemble of GGCMI models shows a larger agreement on the variations of crop yields than for the long-term trend. Year-to-year variations of projected crop yields become more pronounced over time, especially so for negative crop yield anomalies. As a result, the frequency of negative global crop yield extremes increases with global warming. We show that these negative yield extremes may occur for individual or multiple crops at the same time, and may originate from individual or multiple regions. North America dominates global maize and soybean yield extremes (57% and 44% of all significant global extremes, respectively), and South East Asia and South Asia are important for rice extremes (24% and 22%, respectively), while regional results are inconclusive for wheat. Multi-crop extremes occur most commonly for the combination of maize and soybean, and are dominated by the North America region. Based on these findings, we show that depending on the region and crop, persistent spring or summer drought, cold or heat can be associated with years of global and regional negative agricultural yield extremes.

Our results show how specific climatic boundary conditions can lead to year-to-year extremes in important staple crops, highlighting the potential to anticipate such events in the future.

How to cite: Borchert, L., Orlov, A., Jägermeyer, J., Müller, C., and Sillmann, J.: Negative year-to-year agricultural yield extremes projected to occur more frequently under global warming, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3378, https://doi.org/10.5194/egusphere-egu23-3378, 2023.

In light of the hysteresis and acceleration of the climate crisis, climate overshoot has only recently been acknowledged as inevitable. As the IPCC belatedly reports, current pledges are not even remotely on track to limit global warming to 1.5°C above pre-industrial levels (Anderson 2015, IPCC 2018). Further, no amount of future emissions reductions can suffice to avert climate overshoot. Hence, this presentation critically analyses the proposition that a climate change technofix – namely Negative Emission Technologies (NETs) – is the only potentially efficacious means to avert runaway climate change (Carton 2020, Reynolds 2015).

However, not only is the efficacy of NETs to reduce sufficient greenhouse gas concentrations highly dubious, but any such technofix requires gambling on a host of unknown unknowns – namely, the inexorable complexity of the Earth System, coupled with planetary-scale interventions in the crisis. Therein, this presentation explores the linkages between extreme climate and societal dynamics surrounding risk, offering a theoretical study from the fields of social sciences and humanities as to the non-linearity of cascades and feedbacks between the biosphere and society.

To do so, I put forth a critique of how normative ethics remains anchored in rigid positions of anachronistic risk aversion, given how any attempted climate technofix entails unprecedented realms of risk and uncertainty. Using the frameworks of the Environmental Humanities, and Science & Technology Studies, I critically engage with the risk ethics of imminent climate overshoot, in relation to the interventionist gambles proposed by NETs through Synthetic Biology and Climate Engineering. Given the scale of the unknown unknowns unleashed by the Anthropocene, I present gambling as the most apt analogy for both the absurdity (and denied imminence) of the existential predicament, as well as the sheer improbability that any technofix can be invented in a sufficiently short time and implemented on a sufficiently large scale.

Given the profound social, cultural and ethical dimensions that this entails, discussion will include an overview of outreach activities I have undertaken as a Chief Investigator at the Australian Research Council Centre for Excellence in Synthetic Biology, including the At Risk in the Climate Crisis symposium and podcast series that I co-produced in 2021-22. Overall, in the context of the rapidly diminishing prospect for any efficacious environmental action, the presentation contemplates the unthinkable questions that our current situation demands we ask, and perhaps even try to answer.

How to cite: Wodak, J.: The Non-Linearity of Cascades and Feedbacks Between The Biosphere and Society: Risk Ethics for a Climate Change Technofix, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3746, https://doi.org/10.5194/egusphere-egu23-3746, 2023.

Disaster risk reduction has become an increasingly prominent concern in urban planning due to recent catastrophic disasters such as the Great East Japan Earthquake in 2011. Building levees or relocating to higher ground are measures used to reduce the risk of tsunamis. However, if those measures are implemented too extensively, they may obstruct views of coastal water that benefit residents. Environments where residents can visually access the waterfront are crucial for promoting awareness of river and disaster risk reduction and repairing the way we interact with nature. However, in Japan, safety has frequently been prioritized by ignoring the views of coastal water that may be lost.

This study developed an optimal residential area model for analysing the trade-offs between safety from tsunamis and views of coastal water (hereafter, ocean views), which will be able to support detailed urban planning. The model comprises weighted multicriteria, that is, the total tsunami risk and ocean views with controlling optimal allocations of population. Here we optimized “Improved Potential Achievement (IPA).” This indicated the extent to which the respective optimal value achieved has been achieved against the value (improved potential) of the two objectives being optimized alone as a baseline. 

We used the viewshed analysis to quantify ocean views. The analysis used the elevation value of each cell of the digital elevation model (DEM) to determine the visibility of a particular point of the ocean from a specific residential mesh. Using the visibility between specific locations, we conceptualized the index of “the ocean view presence” and “the width of the ocean view”. The ocean view presence expresses how many locations in a particular residential mesh have an ocean view. Meanwhile, the width of the ocean view expresses whether people have a panoramic view of the open ocean or whether they can only see a small area of ocean. We quantified ocean views using these indices.

We applied the model to Kuroshio, a tsunami-prone area along the Nankai Trough in Japan and the optimal residential area is calculated for each 500-meter mesh. The results of the sensitivity analysis that changed the weight β (0<β<1) of the safety from tsunami criteria showed trade-offs in which the more safety from tsunami risk is weighted, the more the view of ocean water in the target area is reduced. If weight β is larger than 0.7, ocean views decreases steadily. This is a case study of a specific area and such results are not spatially consistent in all areas. However, similar trade-offs are likely to be obtained in areas with the ocean and mountains in close proximity. This analytical technique is likely to be useful in pre-disaster recovery planning that explores induction-encouraged residential areas that benefit safety from tsunamis and ocean views.

How to cite: Nakai, F., Uchiuzo, T., Okubo, K., and Hideshima, E.: Analysing Trade-Offs between Safety from Tsunamis Risk and Views of Ocean Water Using an Optimal Residential Area Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4088, https://doi.org/10.5194/egusphere-egu23-4088, 2023.

Environmental governance innovation, especially nature-based solutions (NbS), is gaining scholarly attention over the past years due to issues including urban expansion and climate change. Most existing studies of such innovation focus on national, provincial or single city level, while few explore the translocal interactions among urban agglomeration levels. This paper illustrates the process of emergence and adoption of environmental governance innovations in the context of NbS. Furthermore, this paper analyzes the contributing factors of the innovation processes with particular focus on the role of translocal governance networks that involves the center and local governments, urban agglomeration networks and non-governmental actors.

Event history analysis is used to understand the sources and processes of environmental innovation generation and adoption. Environmental innovation event history is established via obtaining policy documents published on government portals across the country and case reports published by mainstream media from 2011 to 2021. Then, we use the pooled regression model to explain the probability of innovation being generated or adopted to analyze the contributing factors of environmental governance innovation in urban agglomeration. Vertical, horizontal, internal and external interactions are measured and used to explain the processes with other explanatory variables including political factors, economic factors, and other socioeconomic covariates. The following results are expected. First, environmental governance innovations mostly originate from external factors, such as breakthrough of environmental technology and global environmental alliances, and are generated from both central and provincial government. Second, the probability of innovation adoption is positively correlated with interactions across and within urban agglomeration, and the frequencies of vertical, internal and external interactions, and significantly negatively correlated with horizontal interaction factors. Third, economic and educational factors are expected to have the most significant influence on the probability of innovation generation; among social factors, population density could be negatively correlated with the probability of innovation generation. The findings of this study can further optimize relationship between local actors and governance structure to promote environmental governance innovation.

How to cite: Shi, R. and Pan, H.: Governance Innovations for Nature-based Solutions from Translocal Networks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4262, https://doi.org/10.5194/egusphere-egu23-4262, 2023.

Sitting at the intersection of knowledge production and project implementation, our work as conservation finance project developers leverages economic and other benefits of environmental restoration to attract new and diverse funding sources for nature-based solutions (NBS). Our work supports project activities ranging from variable density thinning and prescribed burning to low-tech and process-based riparian restoration. In our experience, NBS presents a powerful, cost-effective opportunity to create scaled improvements in ecosystem function. However, funding NBS projects can be challenging, as some NBS outcomes are only achieved through large-scale landscape restoration, which is expensive, or are realized gradually over a period of time following restoration activities. Conservation finance is one tool that can catalyze meaningful NBS work at scale by providing the necessary upfront capital for projects while contracting funding commitments based on outcomes over time. Using several examples of successful NBS projects, we present a process-based, multiple-benefit framework to demonstrate how NBS can be leveraged to increase funds and enable financing. This framework is grounded in western U.S. forest management to address catastrophic wildfire, but can be applied in other regions and for other types of restoration activities. This approach addresses the logistical, governance, and sociocultural challenges we have encountered to leveraging NBS within a conservation finance framework. We also propose future avenues of research to help increase investment based on NBS. These include formalizing metrics for measuring and monitoring of different NBS activities, managing the uncertainty and expectations around outcomes of NBS projects, and incorporating the future impacts of climate change into NBS models and planning. By describing this work in a U.S. context, we hope to catalyze a discussion about how the needs and opportunities identified in our projects can inform work in Europe and vice versa.

How to cite: Maurer, T., Seipp, K., Elias, M., and Saksa, P.: A multiple-benefit framework for implementing nature-based solutions using conservation finance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4599, https://doi.org/10.5194/egusphere-egu23-4599, 2023.

Extreme climate events constitute a major risk to global food production. Among these, the extreme rainfall is often dismissed from historical analyses and future projections, whose impacts and mechanisms remain poorly understood. Here, we find that rice yield reductions due to extreme rainfall in China were comparable to those induced by extreme heat over the last two decades, reaching 7.6 ± 0.9% (one standard error) according to nationwide observations and 8.1 ± 1.1% according to the crop model incorporating the mechanisms revealed from manipulative experiments. Extreme rainfall reduces rice yield mainly by limiting nitrogen availability for tillering that lowers per-area effective panicles and by exerting physical disturbance on pollination that declines per-panicle filled grains. Considering these mechanisms, we projected ~8% additional yield reduction due to extreme rainfall under warmer climate by the end of the century. These findings demonstrate the critical importance to account for extreme rainfall in food security assessments, posing greater challenges to climate change adaptation.

How to cite: Jian, Y., Fu, J., Wang, X., and Zhou, F.: Extreme rainfall reduces one-twelfth of China’s rice yield, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4835, https://doi.org/10.5194/egusphere-egu23-4835, 2023.

Given observed and predicted increases in the frequency and intensity of many climate extremes, researchers have shown an increased interest in the climate extremes and their impacts on ecosystems because of the profound effects. However, most previous studies on the responses of ecosystems to climate extremes focus on droughts and summer heatwaves, and relatively little is known about the effects of other kinds of extremes, such as winter heatwaves, extreme wet periods, and cold waves.

In this study, we identify four types of extremes (two temperature (heatwaves and cold waves) and two precipitation ones (droughts and extreme wet periods)) and present 4 alternatives to identify compound extreme events. We demonstrate the relevance of the different types of year-round (compound) events for ecological studies by demonstrating their impact on the abundance of 34 UK butterfly species across each species' life stages (hibernation, egg, larval, pupal, and adult) over a 45-year period. We chose this example as these species are expected to respond rapidly to climates due to their ectothermic nature and short life cycles.

The results show that considering different types of year-round (compound) extreme events is relevant from an ecological point of view as at different stages, other extremes have more impact on the survival of individuals. For instance, statistics show that heatwaves and droughts during the pupal and adult stages appear beneficial for butterflies in England, with around 30% of univoltine species showing significant positive influences, whereas extreme wet periods during the pupal life stage cause negative population change for 26% of univoltine species. Our study demonstrates that considering different forms of extremes during all seasons of a year may bring interesting new insights for ecologists. However, we did not seek any eco(fysio)logical explanations of the obtained results.

How to cite: Shan, B., De Baets, B., and E.C. Verhoest, N.: Four alternative ways to identify compound climate extremes and their relevance to ecological impacts: a case study of UK butterflies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5001, https://doi.org/10.5194/egusphere-egu23-5001, 2023.

Widespread changes to climate-sensitive systems are placing increased demands on risk assessments as a key for managing climate risk, enabling adaptive responses and enhancing system resilience. Although the complex, uncertain and ambiguous nature of climate-sensitive systems has been long recognised, recent attention on concepts such as compounding and cascading risks, deep uncertainty and ‘bottom-up’ risk assessment frameworks have stressed the need to more explicitly confront the overarching theme of systemic complexity. Drawing on insights from the field of systems thinking, we provide a theoretical foundation for addressing systemic complexity when assessing climate risks. We first describe the sources of systemic complexity as they pertain to climate risk, and highlight the role of climate risk assessment as a formal sense-making device that enables learning and the organisation of knowledge of the interplay between the climate-sensitive system and its (climatological) environment. We then highlight boundary judgements as one of the core concerns of risk assessment, acting as a filter of both information and value judgements, and thereby creating islands of analytical and cognitive tractability in a complex, uncertain and ambiguous world. Yet boundary judgements necessarily result in partiality, leading to the need for boundary critique, which emphasises the need of multi-methodologies and second-order learning processes as part of standard risk assessment practice. We build these concepts into a framework that divides climate risk assessments into five distinct but interrelated concerns or ‘problematics’ that collectively can be used as a starting point for managing systemic complexity in the assessment of climate risk. 

How to cite: Zscheischler, J. and Westra, S.: Accounting for systemic complexity in the assessment of climate risk, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5017, https://doi.org/10.5194/egusphere-egu23-5017, 2023.

The H2020 project PHUSICOS designs and implements NBS for DRR at demonstrator case sites in rural areas of Norway, Italy, and in the French and Spanish Pyrenees. This presentation covers four locations in the Pyrenees, where NBS to reduce risk from snow avalanches, rockfall and debris flows are implemented. Snow avalanches from the steep slopes of the Capet Forest threaten the French village of Barèges. The NBS here consist of afforestation in the release areas. 5000 trees have been planted in groups of 30-50, protected behind wooden tripods, which also act as protection structures until the trees are large enough to stabilize the snowpack. Rockfall poses a severe hazard at two locations along the important road A-136 / RD-934 between France and Spain. At St. Elena, Spain, the rocks are released by erosion of a slope in a thick till deposit. The implemented NBS consists of vegetated terraces, built up by a dry masonry wall and gabions constructed from wood and filled with the local till. At the location in Artouste, France, rockfalls in the steep slope are released from exposed ledges and from loose blocks in the till surface. The measures here consist of wooden stabilising and retaining structures for each individual ledge or block. These solutions are also tested at newly established laboratory and full-scale test facilities in Spain and France, respectively. The fourth location is near the Spanish village Erill-la-Vall, where debris flows from a >50m thick till deposit pose the threat. Several gullies feed the main debris flow path towards the village during periods of extreme precipitation. The implemented solution is a series of terraces, built up by local rocks and whole-log gabions in the lower parts of the gullies. These will prevent deepening of the erosional base and form increased rugosity in the debris flow paths. The site has been monitored during the last 15 years. In-situ borehole (piezometer) data shows two processes: a deep-seated (15-20 m) failure level, which reacts up to two weeks after a period of heavy rain, and shallow erosion, which reacts almost immediately as a direct response to heavy precipitation. The implemented NBS are primarily to mitigate against the latter process.

The NBS described here all have large upscaling potential, as there are numerous locations in the Pyrenees and elsewhere with similar problems. Terracing and afforestation for slope stabilization is not a new concept but is here re-vitalized in cooperation with stakeholders through Living-Lab processes. These processes have also helped overcoming challenges related to land ownership issues and permissions to operate, e.g., in national parks, which have caused implementation delays. Monitoring of the implemented measures, focused on both the resilience aspect and, not the least, the NBS' co-benefits will be important for building up an evidence-base for the functionality of NBS for DRR.

How to cite: Solheim, A., Vergès, D., Fabregas, S., Lespine, L., Räimät, C., Garcia, E., Oen, A., Kalsnes, B., and Capobianco, V.: NBS implemented in the Pyrenees during the PHUSICOS project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5754, https://doi.org/10.5194/egusphere-egu23-5754, 2023.

Emergent dynamic climate risks challenge conventional approaches for climate adaptation and disaster risk reduction. This situation demands new ways of addressing climate risks with integrated solutions. However, little attention has been paid to exploring methodological approaches for combining adaptation measures to reduce climate risks. Still, selecting the appropriate and effective combination of adaptation measures is a challenging task. This research results in a geospatial multi-criteria approach for developing ecosystem-based adaptation packages to face climate change effects and applies this innovative methodology to a case study area in the Puna region in Peru. We started with an in-depth literature analysis combined with a participatory process with local experts to identify and select locally valid adaptation measures for the specific context of the case study area. Building upon that, we developed the overall multi-criteria approach consisting of a matrix-based procedure to evaluate the applicability of relevant adaptation measures and their feasibility of being combined in adaptation packages. We then integrated the multi-criteria analysis into a Geographic Information System using a spatial analysis model to map suitable intervention areas. Next to the methodological innovation, we applied this multi-criteria approach in the case study area to generate a place-based adaptation package for addressing the risk of reduced water provision, with its respective potential intervention sites differentiated by adaptation measure. This methodological approach is novel and considered an affordable support tool that helps practitioners design more robust and effective adaptative interventions. Furthermore, this methodological approach involves shifting the perspective from activities focused on "single adaptations" to "multi-solution" strategic interventions that address climate risks more comprehensively, recognizing the dynamics and complexities of the social-ecological systems. We encourage researchers and practitioners to transfer the methodological approach to other contexts and, with that, accelerate the efficient and targeted implementation of nature-based solutions for climate resilience.

How to cite: Higuera Roa, O., Cotti, D., Aste, N., Bustillos-Ardaya, A., Schneiderbauer, S., Tourino-Soto, I., Roman-Dañobeytia, F., and Walz, Y.: Deriving targeted intervention packages for ecosystem-based adaptation: A geospatial multi-criteria approach for building climate resilience in the Puna region, Peru., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6712, https://doi.org/10.5194/egusphere-egu23-6712, 2023.

Rethinking cities in a more sustainable and integrated way is a key opportunity for successful climate change adaptation and mitigation. Nature-based solutions and green infrastructures can help to safeguard urban nature and biodiversity while providing multiple benefits to reduce climate risks and improving human well-being. Nature-based solutions help to mitigate flood risk by regulating storm-water runoff and peak-flow. This paper investigates the effects of nature-based solutions and green infrastructure networks on pluvial flood risk in Milan metropolitan area in terms of direct economic damage to buildings and population exposed. Results show that extended urban green networks can reduce pluvial flood damages (by up to 60%) and the population exposed (up to 50%). For all analysed rainfall intensities, damages to buildings and share of population exposed decrease as green area coverage increases, with slightly higher risk reduction for lower-intensity events. 25% of additional urban green coverage can halve the expected annual damage and reduce by 40% the expected annual population exposed. The applied methodological framework makes it possible to identify priority-action urban areas and hence inform decision-making processes as for where green solutions are most efficient.

How to cite: Staccione, A., Hrast Essenfelder, A., Bagli, S., and Mysiak, J.: Connected urban green spaces for pluvial flood risk reduction in the Metropolitan area of Milan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7906, https://doi.org/10.5194/egusphere-egu23-7906, 2023.

Forests in mountain regions provide an indispensable ecosystem service by protecting people and infrastructure against natural hazards. Thanks to this Nature-based Solution (NbS), costs of engineered technical protection measures can be reduced or even avoided. Numerous studies have proven the high effectiveness of forests in mitigating the negative impacts of natural hazards. However, open questions remain about the long-term and sustainable provision of protective service by mountain forests, which are expected to be increasingly affected by global change. Natural forest dynamics and disturbances can result in temporary or irreversible loss of protective effects of forests, potentially accelerated by climate change. At the same time, rising temperatures and more frequent and severe droughts will lead to shifts in tree species distribution and forest composition, which may in turn impact their protective effect depending on the type of natural hazard. Furthermore, socio-economic changes, such as land-use change or the expansion of settlements, may affect the protective function of forests. The uncertainties related to these changes pose great challenges for the quantification and sustainable management of this key ecosystem service in mountain areas. To improve our understanding of the various effects global change has on protective forests, we summarized current knowledge based on a quantitative review. We conducted a systematic literature search using predefined terms in different databases. We focused on forests in mountain regions protecting against gravitational hazards (i.e., snow avalanches, landslides, rockfall, torrential floods and debris flow). This resulted in 70 peer-reviewed articles, books or book chapters that we systematically assessed. Most studies focused on anthropogenic forest change (i.e., management, de-/afforestation), followed by natural disturbances, whereas climatically induced changes (e.g., clearly linked to drought or rising temperatures) were less often addressed in the literature. The analyzed studies mainly examined the protection against floods, followed by avalanches, landslides and rockfall. Preliminary results indicate that global change had a predominantly negative impact on the protective effect of forests in mountain areas. In a next step, the types of impacts and potential interacting and compound effects will be analyzed in more detail.

How to cite: Moos, C., Bottero, A., Stritih, A., and Teich, M.: Impact of global change on the protective effect of forests in mountain areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8181, https://doi.org/10.5194/egusphere-egu23-8181, 2023.

A consensus is emerging that restoring the fire-adapted forest ecology through nature-based solutions (NBS), such as prioritizing fire-resistant vegetation, promoting less fire-prone forests, enabling grazing by herbivores in areas facing land abandonment, prescribed burns, and restricted or risk-adapted development in wildlands, can reduce the risk of extreme wildfires. This paradigm shift away from fire suppression towards a fire loss-prevention strategy is urgently needed. The question is whether risk financing strategies, especially insurance, can untap the potential for promoting NBS, for example, by providing protection in case of damages from livestock grazing or prescribed burns, or by giving discounts to forest owners and homeowners that pursue ecological fire-prevention measures. Additionally, insurers can provide (parametric) policies that repair ecological damage, for example, for coral reefs after extreme storms, or policies that transfer the construction or liability risk of NBS. Since wildfire mitigation is to a large extent collective, another potential policy option to support NBS is community-based insurance strategies. This presentation will explore the opportunities and constraints for public and private insurers to support NBS for wildfire risk management. It reflects on-going research in three recently funded Horizon Europe projects: (Cross sector dialogue for wildfire risk management (FireLogue), Building a safe haven for climate extremes (The HuT), and Nature for insurance and insurance for nature (NATURANCE).

How to cite: Bayer, J., Bacciu, V., Plana, E., Sousa, L., Surminski, S., and Deubelli-Hwang, T.: Nature-based solutions for wildfire risk management: the role of insurance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9392, https://doi.org/10.5194/egusphere-egu23-9392, 2023.

Ecosystems and ecosystem services may contribute to reduction in disaster risk, sustainable development and climate change adaptation. The potential of Nature-based Solutions (NbS) is now recognized by major national policies and international framework agreements. However, to date there is limited scientific evidence about their economic viability and equity impacts. In this study we developed a global database of 406 observations from 87 peer-reviewed studies published between 2000 and 2020, completing economic evaluations of NbS for Ecosystem-based Climate Adaptation (EbA) and Ecosystem-based Disaster Risk Reduction (Eco-DRR). We examine available scientific knowledge on the economic viability and performance of NbS for Eco-DRR and EbA, both in terms of efficiency and equity. More than 40% of the studies analyze the role of coastal ecosystems, coral reefs, wetlands, and mangroves in attenuating disaster risk, with a special focus on floods, storms and erosion. Abundant are also studies examining forest ecosystems (30%), followed by urban (25%) and riparian ecosystems (23%). A smaller number of studies analyzes agro-ecosystems. The number of studies per region suggests that Europe, Asia, and North America are the regions where most Eco-DRR research was undertaken. Based on our results, 71% of studies found that the ecosystems studied were effective NbS in mitigating hazards. 24% of studies found that the ecosystems were occasionally effective in mitigating hazards. None of the studies found NbS ineffective in mitigating hazards. The ecosystems most frequently effective in mitigating hazards included mangroves (80%), forests (77%), and coastal ecosystems (73%). A subset of studies compared the efficacy and cost-effectiveness of NbS and engineering-based solutions in mitigating certain hazards (39%). Among these studies, 65% found that NbS are always more effective in attenuating hazards compared to engineering-based solutions, and 26% found that NbS are partially more effective. No study found that NbS are less effective than engineering-based solutions. 

How to cite: Vicarelli, M., Sudmeier-Rieux, K., Alsadadi, A., Kang, M., Leue, M., Schütze, S., Shrestha, A., Steciuk, E., Wasielewski, D., Mysiak, J., McAndrew, S., Marr, M., and Vance, M.: Economic benefits of ecosystem-based disaster risk reduction and ecosystem-based climate change adaptation: a global review, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9646, https://doi.org/10.5194/egusphere-egu23-9646, 2023.

The frequency, duration, and intensity of heat waves are expected to increase in the coming decades. This could lead to elevated heat stress and consequently an increase in excess mortality, caused by hyperthermia, dehydration, respiratory disease, cerebrovascular disease, or heat stroke. Public awareness of such impacts is key to mitigate heat-related consequences of hot temperatures. For example, the sentiment of heat-related media coverage can affect the perceived risk and the motivation of people to implement risk mitigation such as avoiding outside activities and ensuring sufficient water intake.  

In this study, we analyze the sentiment of temperature-related newspaper reports from multiple countries in an automated way. In particular, we investigate (i) how newspapers in different countries respond to hot temperatures in terms of the number of on-topic articles and their sentiment, and (ii) to what extent socioeconomic and climatic characteristics can explain differences between countries.
For this purpose, we employ data on minimum, mean, maximum, and apparent temperature from the ERA5 reanalysis. We obtain country-specific relationships between the sentiment of temperature-related newspaper articles and the respective temperatures. We hypothesize that these relationships differ, for example, between cold and warm countries, and that heat waves are generally perceived more positively in cold regions.

In summary, this work reveals the links between the sentiment of newspaper articles and hot temperatures across countries. Linking these results with observed heat-related health impacts can guide public health agencies, newspapers, and journalists in particular to ensure public awareness of the detrimental impacts of heat waves, which are expected to further aggravate in a warming world.

How to cite: Bogdanovich, E., Brenning, A., Guenther, L., Reichstein, M., Frank, D., Schäfer, M. S., Ruhrmann, G., and Orth, R.: Nice weather or burning heat? Sentiment analysis of temperature-related media reports., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12053, https://doi.org/10.5194/egusphere-egu23-12053, 2023.

The climatic cooling effects associated with large magnitude volcanic eruptions – the so-called ‘volcanic winter’ scenario – have long been identified as an extreme risk that may impact the continued flourishing of humanity. Such eruptions are relatively rare, but perhaps not as rare as we might think. A greater understanding of this mechanism and increased resolution of our geological records through the study of ice core records demonstrate that the recurrence of an eruption capable of this impact may be as frequent as 1 in 6 per century. These large magnitude volcanic eruptions (VEI 7 and above), could cause a global cooling event for up to a decade, if not longer, with more severe effects felt in the northern hemisphere, presenting a unique challenge for global food security.

Further, viewed through the lens of vulnerability, human society now closely intersects with regions of volcanic activity, potentially forging new pathways for volcanic eruptions to cause global disruption. Our research identified regions of intersection, or ‘pinch points’, where a compounding of global critical systems and infrastructure, such as submarine cables, global shipping lanes, and transportation networks, are proximal to regions of volcanic activity. These pinch points present locations in our interconnected world where volcanic eruptions may disrupt our systems, cascading us toward global catastrophe. With climate change increasing the frequency and intensity of volcanic eruptions globally and enhancing their impacts, more must be done to accelerate our preparedness for such events.

How to cite: Mani, L., Cassidy, M., Tzachor, A., and Cole, P.: Global societal vulnerability to volcanic eruptions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12929, https://doi.org/10.5194/egusphere-egu23-12929, 2023.

Extreme weather and climate events (EWCEs) have jeopardized crop yields globally. The evidenced increasing trends of EWCEs would amplify their impacts if they co-occurred. This would bring additional shocks to global food markets, and result in severe risks to food security. A systemical analysis of the risk of crop yield failure under EWCEs and their changes in a warming future is essential to guide adaptations adequately and ensure food security. In this study, we compared the relations between maize yield anomalies and 14 climatic indices over the growing season in the breadbasket (10 provinces) in China during 1981-2018 to identify the main EWCEs determining maize yield anomalies. We then compared the probabilities of crop yield failure under current climatic conditions and its projected changes under 1.5 and 2.0 ^oC global warming using 28 climate models from CMIP6. The result shows that the maize yield anomalies can be mainly explained by extreme temperate-related indices, despite the various indices for individual provinces. The probability of synchronous yield failure in 1981-2018 was below 7.5% when we randomly summed up seven maize provinces among ten. The probability may reach 2.45% and 7.73% on average under 1.5 and 2.0 ^oC global warming conditions for all ten provinces, respectively. The transferred risk of crop yield failure revealed that more current maize land would be outstripping its climate-safe space under warmer conditions. Our results highlighted the benefits of limiting global temperature rise within 1.5 ^oC. Furthermore, enhancing crop resistance to adverse climate situations through appropriate adaptations would be a promising solution to stabilize crop productivity.

How to cite: Liu, S. and Xiao, L.: Limit global warming to 1.5 oC will alleviate the synchronous failure of maize yield in China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13890, https://doi.org/10.5194/egusphere-egu23-13890, 2023.

Wooden pile dwellings (WPD) are an inexhaustible and precious source of information on landscape evolution and contingent cultural activities. There have been significant investigations on WPD submerged in Alpine areas, but important knowledge gaps are evident regarding Mediterranean volcanic and karstic lakes. The conservation of the latter archaeological remnants is endangered by the climatic change impacts and anthropogenic pressure, further exacerbated by the sensitive and circumscribed lake environments. Wood from pile dwellings is waterlogged, and its conservation mostly depends on the surrounding environment i.e. sediments and water quality. This project aims to study all the aspects of WPD in volcanic and karstic lakes through studies ranging from their potential exploitation, the investigation into their conservation and restoration, monitoring lake environment and forecasting scenarios through an aquarium reproducing the most significant abiotic conditions occurring in the lake. This last study will be achieved by means of an aquarium model. Three case studies have been selected in which agricultural practices influence climatic stress and pollution impact: Lake Banyoles in Spain and Lakes Bolsena and Mezzano in Italy. The foreseen investigations will employ an extraordinarily wide spectrum of skills and disciplines (palynology, dendrochronology, micromorphology, soil science and innovative tools like isotopic analysis). The characterization of wooden materials will involve gravimetric measurements, Fourier-transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry. Samples will derive from different sources to include immersed, reburied finds and restored wood, lake water and lake sediment samples. The main activities will be devoted to fields campaigns and unmanned aerial vehicle (UAV), high-resolution methods for monitoring environmental conditions (for example the installed probe will measure water lake temperature, pH and so on), capitalization of results (network of big data about lake sites), involvement of local actors and population on the historical, cultural and environmental value of WPDs to establish decision-making processes and to foster high-quality tourism.

How to cite: Tamantini, S., Sidoti, G., Antonelli, F., Galotta, G., Moscatelli, M. C., Kržišnik, D., Vinciguerra, V., Marabottini, R., Macro, N., and Romagnoli, M.: The WOODPDLAKE project. Lakes, wood and sediment: Natural and Cultural Heritage affected by climate changes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15116, https://doi.org/10.5194/egusphere-egu23-15116, 2023.

Climate change media coverage shapes climate-related societal and political debates and decisions [1, 2]. Yet it is unclear what drives media attention for climate change. More frequent and more intense weather extremes are a clear consequence of climate change and have a large impact on society. Extreme weather events might hence be an important factor for climate coverage. Here, we investigate whether weather extremes lead to more climate change coverage in the media. Further, we analyse how this changes over time and whether it differs between different types of extreme weather events such as heat waves or floods. Finally, we examine how the influence on climate coverage varies between weather extremes and other climate-related events such as climate protests, IPCC report publications and world climate summits.

To this end, we analyse approximately nine million articles from nine German newspapers over the last three decades (1991 - 2021). The selection of newspapers is diverse and includes regional and national media, daily and weekly publication rhythms, as well as various political leanings. Currently, the nine newspapers have a cumulative readership of more than 12 million people. Within all nine million articles, we identify approximately 57 000 climate-related articles, using a bag-of-word machine learning approach. Changes in the share of climate-related articles are evaluated against the background of the occurrence of weather extremes and other climate-related events, while controlling for potential confounders using fixed effects panel regressions. Information about extreme weather events are derived from the meteorological ERA5 reanalysis data as well as from the international disasters' database EM-DAT. In addition, we use data on activists’ protest, scientific publications and political climate-related conferences, derived from press releases of the corresponding organizations. 

Our study provides evidence that weather extremes increase climate change coverage. Separate analyses for the three decades (1991 - 2000, 2001 - 2010, 2011 - 2021) show that the influence of weather extremes on climate coverage increases over time. Differences in the influence on climate coverage are found for different weather extreme types. The influence of floods in Germany on climate coverage is about twice as large as that of heat waves. Comparing the effect of weather extremes with that of other climate-related events shows that the influence of social events on climate coverage is much stronger than the influence of weather extremes. We find evidence that protests exceed the influence of heat waves by a factor of four, and world climate summits even exceed the influence of heat waves by a factor of ten. These trends apply to all newspapers studied and are preserved under different controls and alternative climate coverage measures.

[1] Brulle, R. J., Carmichael, J. & Jenkins, J. C. Shifting public opinion on climate change: An empirical assessment of factors influencing concern over climate change in the U.S., 2002-2010. Climatic Change 114, 169–188 (2012).

[2] Sampei, Y. & Aoyagi-Usui, M. Mass-media coverage, its influence on public awareness of climate-change issues, and implications for Japan’s national campaign to reduce greenhouse gas emissions. Global Environmental Change 19, 203–212 (2009).

How to cite: Lochner, J. H., Stechemesser, A., and Wenz, L.: Effect of weather extremes on climate change media coverage - Evidence from 57 000 newspaper articles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16961, https://doi.org/10.5194/egusphere-egu23-16961, 2023.

As the global water cycle intensifies – with it’s increased variability projected to cause greater storm-events, more extensive flooding and more severe droughts – the obsolescence of current urban infrastructure is made clear, particularly in the face of an ever increasing urban population. To combat these challenges, concepts have been developed across the globe in order to better manage and utilize stormwater run-off; many leaning on the larger concept of green infrastructure, implementing solutions replicative of a more natural water cycle. The simplistic design, low capital costs and flexible application and incorporation into urban spaces has made bio-infiltration swales an excellent choice for urban planners and a center point of recent research. As the base of these systems, the soil substrate lends significantly to a swale’s services of dewatering, pollutant processing, biodiversity promotion and carbon accumulation. By combining urban mineral and organic wastes, we attempt to optimize the synergies between these services. In a microcosm incubation experiment, an extracted deep soil horizon was mixed with green waste compost to form a fertile constructed Technosol. Subsequently, biochars of varying feedstock and pyrolysis processing temperatures were added individually and in combination to determine their impact on water processing properties and nutrient availability. We hypothesized the combinations of biochars will create a structure that maximizes water-substrate interactions while also retaining a larger variety of pollutants due to their differences in chemical composition. The addition of biochar will also minimize run-off of nutrients introduced by the green waste compost, increasing their availability to potential vegetation.

How to cite: Porter, L., Bucka, F., Deeb, M., Paez-Curtidor, N., Egerer, M., and Kögel-Knabner, I.: Constructing multi-functional Technosols for storm-water management: mixing high-carbon organic amendments, a microcosm experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17016, https://doi.org/10.5194/egusphere-egu23-17016, 2023.

Global crises such as climate change and the COVID-19 pandemic do not affect cities uniformly. These crises converge in urban areas and often interact through their primary and secondary impacts with the vulnerability of urban populations. This paper investigates urban development dynamics and socio-environmental vulnerability in a megalopolis in the Global South, São Paulo (Brasil). Our goal is to assess the connections between urbanisation and risk exposure, a gap in vulnerability research when considering climate and health hazards. We implement an innovative mixed methods research design using thematic, hot spots, and survival analysis techniques. Two focus groups at the central and peripheral regions of the city provide qualitative data, while open data sets and COVID-19 case microdata (n= 1,948,601) support the quantitative methods. We find a complex system of relationships between urbanisation and risk exposure. Socioeconomic vulnerability characteristics of the population do not explain exposure entirely but significantly contribute to risk-prone location choices. Additionally, social vulnerability factors such as low income and social segregation are highly concentrated in São Paulo, coinciding with substantial COVID-19 fatality rates during 25 months of the pandemic. Finally, qualitative analysis helps us overcome the limitations of quantitative methods on the intraurban scale, indicating contrasting experiences of resilience and resistance during the health crisis. While the low-income group faced mental health and food security issues, the upper-middle-income sample took advantage of opportunities arising during the pandemic to improve work and well-being. We argue that these results demonstrate potential synergies for climate adaptation and health policies in combating socio-environmental vulnerability at the community scale. Environmental justice is thus paramount for global development agendas such as the Sustainable Development Goals, Sendai Framework, and the Paris Agreement.

How to cite: Pereira Santos, A., Lopez, M. R., and Scheffran, J.: Connecting COVID-19 and climate change in the anthropocene: evidence from urban vulnerability in São Paulo, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17315, https://doi.org/10.5194/egusphere-egu23-17315, 2023.

Small island states and jurisdictions face enormous sustainability challenges such as isolation from global markets, tenuous resource availability, heavy reliance on imports to meet basic needs, coastal squeeze, and reduced waste absorption capacity. At the same time, the adverse effects of global environmental change such as global warming, extreme events, and outbreaks of pandemics significantly hinder island economies’ progress towards sustainability, and consistently rank them high on various vulnerability indices. This talk introduces the concept of socio-metabolic risk, defined as systemic risk associated with the availability of critical resources, the integrity of material circulation, and the (in)equitable distribution of derived products and societal services in a socio-ecological system. Drawing on years of socio-metabolic research on islands, I will argue that specific configurations and combinations of material stocks and flows and their ‘resistance to change’ contribute to the system’s proliferation of socio-metabolic risk (SMR). For better or for worse, these influence the system’s ability to consistently and effectively deliver societal services necessary for human survival. Governing SMR would mean governing socio-metabolic flows, and easing resource requirements through green(-blue) infrastructure and nature-based solutions (NBS) to provide crucial societal services. Such interventions will need strategies to reconfigure resource-use patterns and associated services that are sustainable as well as socially equitable.

How to cite: Singh, S.: Socio-metabolic Risks and Tipping Points on Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17529, https://doi.org/10.5194/egusphere-egu23-17529, 2023.

The increasing involvement of citizens in scientific projects over the last decade is another critical factor that has encouraged Open and FAIR data. Citizen science is in fact one of the eight priorities of the European Open Science Agenda (2018), along with the establishment of the European Open Science Cloud (EOSC) enabling a federation of multidisciplinary research infrastructures.

Until now, citizen science projects and platforms, also known as Citizen Observatories (COs) in Europe, are yet to be considered among the research sector in the EOSC ecosystem. With the ambition of overcoming this challenge, the Cos4Cloud (Co-designed Citizen Observatories Services for the EOS-Cloud) project was the first ‘Enabling an operational, open and FAIR EOSC ecosystem (INFRAEOSC)’ project to include citizen science as a core part of research infrastructure.

Specifically, the Cos4Cloud aimed to integrate citizen science in the EOSC through co-designing innovative services to support widely used COs in biodiversity and environmental monitoring. To make COs interoperable, the services adopted internationally recognized standards such as SensorThings API and Darwin Core. As a result, over 30 interoperability experiments have been reported in various combinations among the new services and existing COs during the project period; some of which are now offered in the EOSC Marketplace following open and FAIR principles. The Cos4Colud has also demonstrated that the services combined with AI technologies and robust algorithms could improve COs by leveraging the data quality to the research grade.

We thus expect more resources and services derived from COs to be reused in the EOSC ecosystem, eventually enabling to establish its own thematic cluster for citizen science in the research infrastructure as well as facilitate the reuse of data by other researchers. We conclude with the key role of such diverse scientific communities enriched in the EOSC that may create a bridge among researchers, citizens and decision-makers.

 (This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no 863463.)

How to cite: Otsu, K. and Masó, J.: Open Science as the new normal, Citizen Science as the new component of research infrastructure, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-172, https://doi.org/10.5194/egusphere-egu23-172, 2023.

How to cite: de Baar, J. and Garcia-Marti, I.: Towards quantifying why, when and where to engage citizens to participate in weather observation networks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2655, https://doi.org/10.5194/egusphere-egu23-2655, 2023.

The Arctic is experiencing severe changes to its landscapes due to the thawing of permafrost influenced by the twofold increase of temperature across the Arctic due to global warming compared to the global average. This process, which affects the livelihoods of indigenous people, is also associated with the further release of greenhouse gases and also connected to ecological impacts on the arctic flora and fauna. These small-scale changes and disturbances to the land surface caused by permafrost thaw have been inadequately documented.

To better understand and monitor land surface changes, the project "UndercoverEisAgenten" is using a combination of local knowledge, satellite remote sensing, and data from unmanned aerial vehicles (UAVs) to study permafrost thaw impacts in Northwest Canada. The high-resolution UAV data will serve as a baseline for further analysis of optical and radar remote sensing time series data. The project aims to achieve two main goals: 1) to demonstrate the value of using unmanned aerial vehicle (UAV) data in remote regions of the global north, and 2) to involve young citizen scientists from schools in Canada and Germany in the process. By involving students in the project, the project aims to not only expand the use of remote sensing in these regions, but also provides educational opportunities for the participating students. By using UAVs and satellite imagery, the project aims to develop a comprehensive archive of observable surface features that indicate the degree of permafrost degradation. This will be accomplished through the use of automatic image enhancement techniques, as well as classical image processing approaches and machine learning-based classification methods. The data is being prepared to be shared and analyzed through a web-based crowd mapping application. The project aims to involve the students in independently acquiring data and developing their own scientific questions through the use of this application.

In September 2022, a first expedition was conducted in the Northwest Territories, Canada and UAV data was collected with the assistance of students from Moose Kerr School in Aklavik. The data consists of approximately 30,000 individual photos taken over an area of around 13 km². The expedition also provided an opportunity for the students to learn about the basics of data collection and the goals of the collaborative permafrost survey, which included the incorporation of local knowledge to address the questions of the local community.

By involving school students in the data acquisition, classification and evaluation process, the project also seeks to transfer knowledge and raise awareness about global warming, permafrost, and related regional and global challenges. Additionally, a connection through the shared research experience between students in Germany and Canada is established to enable the exchange of knowledge. The resulting scientific data will provide new insights into biophysical processes in Arctic regions and contribute to a better understanding of the state and change of permafrost in the Arctic. This project is funded by the German Federal Ministry of Education and Research and was initiated in 2021.

How to cite: Mueller, M. M., Thiel, C., Kaiser, S., Lenz, J., Langer, M., Lantuit, H., Marx, S., Fritz, O., and Zipf, A.: UndercoverEisAgenten - Monitoring Permafrost Thaw in the Arctic using Local Knowledge and UAVs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2698, https://doi.org/10.5194/egusphere-egu23-2698, 2023.

Roots are physical and chemical engineers of the subsurface that are sensitive to changes in climate, and whose power to reshape the subsurface differs with land cover. Roots create and destroy porosity through enmeshment of particles, lateral and vertical boring through regolith, and cleaving of rocks from parent material. Their ability to translocate water, exude sugars and acids, and take up solutes influences hydrologic connectivity, water residence times, carbon transport and transformation, microbial access to resources, and chemical equilibrium conditions. Analysis of land-cover datasets suggest that root depth distributions are changing globally, shallowing in agricultural environments and deepening with woody encroachment. Yet where, when, and how changes in root distributions alter water and carbon dynamics in the critical zone is not well known. Using data generated at environmental observatories across the U.S. Long-Term Ecological Research program, the Critical Zone Collaborative Network, National Ecological Observatory Network, and the Department of Energy Watershed Focus Areas in combination with the Pedogenic and Environmental Dataset (PEDS), we ask: How do roots shape regolith hydrology and carbon dynamics? 

A clear signal is emerging from grassland, forest, and agricultural sites across the U.S. that indicates changes in rooting dynamics have measurable and meaningful impacts on critical zone functions. Evidence shows that changes from forest to crop and back to forest impacts soil structure deep beneath the plow line in systematic ways. Losses of rooting abundance upon conversion of grasslands to agriculture affects the propensity of organic carbon to form and protect aggregates throughout the subsoil. Reduced fire frequency at tallgrass prairie sites in the Midwest have led to rapid woody expansion in recent decades. Where woody encroachment persists, coarse roots, smaller mean soil aggregate diameters, and more readily destabilized carbon pools proliferate. Encroachment of woody plants increases the infiltration of soil water rich in  CO₂ into deep rocks and enhances carbonate weathering as predicted by models. These woody plants rely on deeper water sources, draw soil moisture down to a greater degree at depth, and are likely responsible for reducing streamflow and changing the timing of groundwater contributions to the stream. At Rocky Mountains sites dominated by conifers and aspen, coarse- and fine-root abundances are elevated under aspen in the upper 75 cm of the soil profile compared to conifer sites. Elevated soil organic carbon, lower extractable organic carbon, lower C:N values and elevated enzyme activity indicate soil carbon under aspen is likely more stable as a result of more microbial processing. Finally, in a predominantly Douglas-fir forest in the Pacific Northwest, second-growth forests exhibit substantially fewer fine roots at depths <50 cm, which appears to exert control on nitrogen availability in this nutrient-limited system and thus potentially limits carbon stability as more extractable organic carbon is generated from second-growth forests at depth. Data from these sites demonstrate how alterations to rooting distributions change the physical structure and moisture status of soil, and may be linked to carbon stability as the proportion of fine and coarse roots dictate overall access to carbon pools.     

How to cite: Sullivan, P. L. and the SitS, FRES, and CZCN teams: How do roots restructure water and carbon dynamics in the critical zone?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4538, https://doi.org/10.5194/egusphere-egu23-4538, 2023.

As citizen science is becoming a widely accepted research approach across multiple disciplines, it is essential to explore methods for effective recruitment, involvement, and retention of participants for these programs. An effective recruitment strategy results in motivated and engaged contributors, longer-term participation, and better communication exchange.

In this research, we present two marketing approaches adapted from best practice in customer-facing fields in order to identify appropriate stakeholder groups for citizen science and keep motivation and retention of the participants high. Firstly, stakeholder analysis is a major tool within the frame of stakeholder management and includes the systematic identification of stakeholders and their relevance and influence on a project. Thus, efficiency of citizen science projects can be improved significantly by targeted identification and selection of participants and groups through stakeholder analysis, which are suited to generate the data needed to reach the project and research goals. Secondly, the value proposition canvas approach is based on business strategies to match products and services to the market or customer. The value proposition canvas can be adapted to scientific processes and the data generated can help citizen science groups to build a communication strategy that can clearly communicate the value of their message and shared goals to the participants.

The application of stakeholder analysis and value proposition canvas is demonstrated using the case study of the project "Next Generation City Climate Services Using Advanced Weather Models and Emerging Data Sources" (CityCLIM, a European Union Horizon 2020 funded project), where the focus is to develop next-generation City Climate Services based on advanced weather forecast models enhanced with data from emerging data sources such as Citizen Science approaches for urban climate monitoring. Before meetings with citizens in pilot cities, stakeholder groups involved in the CityCLIM project were examined and their profiles were analysed using the value proposition canvas. Lessons learned from the use of these tools for engagement with citizens in pilot cities will be presented. Findings also provide an approach that can be used by citizen science groups in environmental observation to strategically target participants and tailor key communication messages, towards the goal of a focused and sustained monitoring of environmental processes.

How to cite: Liang, C., Schütze, C., Ködel, U., Herrmann, T., Schmidt, F., Schütze, F., Schütze, S., and Dietrich, P.: Improving efficiency of citizen science projects by targeted activation of selected stakeholder groups, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7238, https://doi.org/10.5194/egusphere-egu23-7238, 2023.

The SeismoCitizen (SismoCitoyen) project presents and tests a new paradigm of collaborative monitoring of geohazards in urban and peri-urban environments. Seismological observations are obtained using a large number of low cost internet-connected equipment (Raspberry Shake seismic sensors and associated open access data). The breakthrough strategy of the project relies on the deployment of the sensors in residences or administrative buildings of non-seismologist voluntary citizens or authorities. The aim is to use those stations to densify the french permanent seismic network, and to improve the detection and location of seismic events, in particularly small ones. The volunteers take part in a sociological survey to estimate the impact of that participative project on their perception of science. Candidates are primarily chosen according to the seismic interest of their location and for some of them to represent the social variability of the population. 

Since the “Sismocitoyen” project was launched in 2018 by BCSF-Rénass and EOST (CNRS and Strasbourg University), sixty sensors have been deployed and are currently hosted by voluntary citizens in the region of the Upper Rhine Graben, in the area of Strasbourg, Mulhouse and alongside Vosges mountains. They were able to strongly improve our monitoring of the seismic events induced by a deep geothermal project close to Strasbourg where several events have been largely felt (2019-2022). The topic is becoming a major issue in the development of renewable energies that involve the subsurface as seismic hazards are of significant public concern and can have major socio-economic impacts. 

With the new PrESENCE ANR project (2022-2025) we focus on seismic hazards induced by deep geothermal operations in northern Alsace and their associated societal perception.  Seventy Raspberry Shake seismic stations are being deployed since the end of 2022 and installations will continue in 2023. We will use our previous experience to improve, refine and develop all aspects such as site selection, protection of privacy and confidentiality of volunteers data and information, station calibration before deployment, data transmission and protocol to minimize data losses, stations monitoring and data analysis.

During the project, interactions with the station hosts will be reinforced, in particular with convivial meetings (Stammtisch) to answer questions, present the use of the data and the results obtained.

How to cite: Turlure, M., Grunberg, M., Jund, H., Engels, F., Schlupp, A., Chavot, P., and Schmittbuhl, J.: PrESENCE : a participative citizen seismic network., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7615, https://doi.org/10.5194/egusphere-egu23-7615, 2023.

The ecohydrology of the Urban Critical Zone is characterised by strong heterogeneity and the entangling of hydrological and human time scales (Sivapalan & Blöschl, 2015). This not only poses a challenge to field measurements and the transfer of insights to other urban systems, but consequently limits the development of universal theoretical approaches for urban systems. In this contribution, we propose an interdisciplinary methodology to approach this challenge. Following the school of Darwinian hydrology (Harman & Troch, 2014), we hypothesise that analog to the co-evolution of natural systems, the history of a city and its neighbourhoods is a strong control on current ecohydrological patterns and processes. Thus, we argue that field measurements must be complemented by research into the historical evolution of the urban area to provide a full description and explanation of any observations made. While we need to be careful to avoid a too deterministic or simplistic view of history, research into the historical evolution of an urban area can strengthen explanation of current urban ecohydrological behaviour and potentially enable knowledge transfer and prediction capabilities in “ungauged” cities with similar historical development, as well as to help guide measurement campaigns. Hence, we search for historical and environmental patterns that correlate to provide a testable explanation of current ecohydrological function of urban space. Similar to the "uniqueness of place" in hydrology, every society and city has a unique history that is shaped by the complex interaction among culture, environment, and political events (Berking & Löw, 2008). Thus, we want to formulate a framework for determining similarities in historical development at relevant temporal scales. This requires a strictly interdisciplinary approach, because the application of historical sciences and the interpretation of results is non-trivial and should not be attempted separately. 
 
We discuss our current progress in developing such an interdisciplinary framework in a case study of the city of Braunschweig, Germany. Braunschweig has 250,000 inhabitants, a medieval city centre with Gründerzeit–era neighbourhoods surrounding it. The former fortifications of the city have been converted into urban green spaces during the 18th century. The Oker river that surrounds the medieval city centre has been heavily modified. The built areas of the city centre show very little green space with few trees, especially compared to the surrounding neighbourhoods, where we find a multitude of street trees, smaller green spaces scattered throughout, and large parks adjacent to the built-up area. This works as an example of how the policy regarding green spaces has changed over time. In this heterogeneous environment, we hunt for urban ecohydrological units. In particular, we are interested in whether similar historical development is an indicator of similar ecohydrological function in an urban context.

References
Berking, H. & Löw, M. (2008). Die Eigenlogik der Städte, Campus Verlag, Frankfurt, Germany.
Harman, C. & Troch, P. (2014), Hydrology & Earth System Science, 18, 417–433.
Sivapalan, M. & Blöschl, G. (2015), Water Resources Research, 51, 6988–7022.

How to cite: Gillefalk, M., Neumann, F., Bücker, M., and Özgen-Xian, I.: Darwinian approaches for the Urban Critical Zone — A case study in the city of Braunschweig, Lower Saxony, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7816, https://doi.org/10.5194/egusphere-egu23-7816, 2023.

Accurate precipitation measurements are essential for various applications such as determining the water balance of ecosystems and modelling soil-water fluxes in the earth critical zone. Gauge based point precipitation measurements are affected by wind, gauge design, and maintenance of the device. Ground-level gauges, like high precision weighing lysimeters, are less affected by environmental factors and thus provide more accurate data if well managed and the data are post-processed with filters. However, studies evaluating precipitation measuring methods with lysimeter references at multiple sites with high temporal resolution and detailed weather data are rare.

In the present study, high-precision weighing lysimeter precipitation data from four years of measurement with an hourly resolution were used as references to evaluate data from four different precipitation measurement methods at three sites under different climatic conditions. The methods were tipping bucket gauges (TB), weighing gauges (WG), acoustic sensors (AS), and laser disdrometers (LD). Different sites and climatic conditions were chosen to be able to draw conclusions as to whether deviations between the measurement and comparison data were environment-dependent or unit-specific. Methodically, the evaluation included correlation analyses, comparison of catch ratios, x-y scatter plots, and the application of correction schemes.

For the total period, all measurement methods recorded less precipitation than the lysimeters, with catch ratios between 33 to 92 % depending on the measuring method. Non-rainfall water inputs, like dew and fog, have been excluded for this study, therefore the measuring differences are attributed to the precipitation gauges. The bias of the hourly measurements varied between -0.69 to -0.01 mm h^-1 based on the measuring method and no site-specific influence on the data was detected. Correction algorithms reduced the bias and improved the catching ratios of hourly precipitation data with similar improvements at all sites for the same gauge models, thus one adequate correction scheme may be sufficient to be used for the same model under different climatic conditions and environments. The findings suggest that a correction of the data by empirical or mathematical models appears to be necessary to ensure the quality of the precipitation data and to reduce over- and underestimations, which is the prerequisite for environmental studies in the critical zone.

How to cite: Puetz, T., Schnepper, T., Gerke, H. H., Reichert, B., and Groh, J.: Evaluation and correction of precipitation data obtained with different measurement methods using data from precision lysimeter network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8059, https://doi.org/10.5194/egusphere-egu23-8059, 2023.

How to cite: Garcia-Marti, I. and Noteboom, J. W.: What does it mean to be a data researcher and platform facilitator of crowdsourced weather observations?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8411, https://doi.org/10.5194/egusphere-egu23-8411, 2023.

In the context of a double democratic and environmental crisis, participatory/collaborative action-research has multiplied in recent years with increased attention from institutions. Over the last ten years, many participatory research projects have taken up the democratic and environmental crises by proposing an emancipatory normative scheme to improve public participation and the effectiveness of environmental action.

Our paper presents the first results of a participatory science project, BREATHE, funded by the ANR. It aims to articulate two components : (1) a participatory measurement of fine particulate matter (PM) concentration (PM 10 - PM 2.5 - PM 1 - PM 0.1) and an identification of pollution sources) from passive filters (plants and sensors) and micro-sensors subject to standardization (2) a component of accompaniment and support of public policies based.

The project is based on a participatory science protocol (Chevalier and Buckles, 2009) based on participation engineering (Dosias-Perla et al., 2020). Our fieldwork covers three targets: (a) the incinerator (waste recovery center) - (b) a highways around a small town; (c) a street canyon, city of Montpellier, south of France. On the metrological level, the project aims at analyzing the implication and the effects of the Citizen Science device aiming at "co-constructing" at micro-scales a fine cartography of fine particles concentrations while discriminating the source and modeling the dispersion phenomena. On the political level, the project aims on the one hand to analyze the institutionalization process of the device and on the other hand to analyze its effects on the "co-production" of public policies and strategies through different regulatory frameworks (EPZ, PCAET, Mobility Plan, etc.).

We will also discuss the limits and contributions of this type of interdisciplinary and participatory approach aiming at acting on pollution with and for society. We will present current results and first analyses concerning the complex intertwining of technical and political issues related to air quality metrology, the importance and difficulties of standardizing measurement and of truly developing metrology at relevant scale levels when it comes to supporting public action and addressing health issues

How to cite: Dosias-Perla, D., Lefevre, M., and Camps, P.: Observing, measuring and tackling air pollution with citizens and elected officials: the case of public policy and technical democracy about particulates matter issue in Montpellier, France., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9605, https://doi.org/10.5194/egusphere-egu23-9605, 2023.

Along with the development of citizen science, more and more citizen science initiatives on soils are emerging. Soils are key components of ecosystems and from where 95% of our food originates. Because soils integrate multiple impacts of human activities, they are increasingly taken into account in public policies (agroecology, biodiversity, food, climate). This presentation will share the results of an online survey on agricultural soil citizen science across Europe. Most reported citizen science projects were at the national level (56%, n=40), limited in time (64.9%, n=40) because of funding (82.6%, n=23), with a budget less than 50.000 € (41.7%, n=36) and funded by a national research funding agency (47.2%, n=36). Regarding agricultural soil systems, half of citizen science projects studied urban or urban-countering gardening and 39% studied cropping systems, 29% fruit-vegetables and grassland systems, 18% arboriculture and vineyards. Over 57% of the reported projects have generated soil biodiversity data, 46% and 35% vegetation cover and soil organic carbon data, respectively. According to citizen science coordinators (n=33), the benefits for the scientists taking part in citizen science were ranging from publication of research outputs (69.7%) and learning opportunities (63.6%) to the potential to influence policy (45.5%). The reported benefits for the citizen scientists (n=33) ranged from learning opportunities (81.8%) and satisfaction through contributing to scientific evidence (72.7%) to publication of research outputs (24.2%). ‘Project very time consuming’ and ‘funding temporary’ were identified as the main research challenges for citizen science projects (n=31). ‘More staff resources’ was reported as the most important prerequisites for citizen science work followed by ‘more financial resources’ and ‘more recognition from academia for citizen science’ (n=28). This synthesis shows the state of the art in agricultural soil citizen science, but also the main lockers for citizen science development on soils.

How to cite: Gascuel-Odoux, C., Aldrian, U., Goetzinger, S., Masson, E., Miloczki, J., and Sandén, T.: A synthesis of the use of citizen science on soils and agroecosystems across Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9749, https://doi.org/10.5194/egusphere-egu23-9749, 2023.

Ghost forests and abandoned farms are stark indicators of ecological change along world coastlines, caused by sea level rise (SLR). These changes adversely affect terrestrial ecosystems and economies, but expanding coastal marshes resulting from SLR also provide crucial ecosystem services such as carbon sequestration and mediate material fluxes to the ocean. We introduce a US-NSF Critical Zone Network project designed to untangle the hydrological, ecological, geomorphological, and biogeochemical processes that are altering the functioning of the marsh-upland transition in the coastal critical zone. We have instrumented six sites in the mid-Atlantic region of the US, along the coastlines of the Atlantic Ocean, Delaware Bay, and Chesapeake Bay where marshes are rapidly encroaching into forests and farmland. We have installed field sensors to observe the effects of slow hydrologic change (i.e. SLR) and fast episodic events such as high tides and storm surges on water levels, land surface elevation, salinity, redox conditions, and sap flow. We are coupling these measurements to laboratory experiments and analyses, as well as modeling to elucidate drivers and feedbacks in these complex and highly transient critical zone systems.

How to cite: Michael, H., Pratt, D., Chin, Y.-P., Fagherazzi, S., Gedan, K., Kirwan, M., Seyfferth, A., Slater, L., Stephanie, S., and Tully, K.: Marsh migration in the coastal critical zone: Drivers and impacts of hydrological, biogeochemical, and ecological change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11150, https://doi.org/10.5194/egusphere-egu23-11150, 2023.

Recent IPCC reports claim carbon neutrality as the key strategy for climate mitigation, therefore compensating greenhouse gases’ emissions by carbon (С) sequestration become the core of climate mitigation measures taken by cities. Developing urban green infrastructures is considered an efficient measure for C sequestration and climate mitigation in cities. However, most of these solutions consider C sequestration in aboveground biomass and ignore the role of urban soil-C stocks. Urban soils’ contribution to C balance in urban ecosystems remains overlooked so far, but gets increasingly important with ongoing climate change. Urban soils are exposed to direct and indirect anthropogenic influences, they are very heterogeneous and dynamic. This variability is driven by both environmental (e.g., vegetation, geomorphology, and parent material) and social (e.g., decisions on maintenance and management) factors. Traditional soil surveys focus on the environmental factor and barely ignore the social drivers, that might be appropriate for natural or agricultural areas, but can hardly be implemented to study soil C stocks in cities.  In the Netherlands, urban areas cover at least 15% of the territory and are projected to expand with more than 1000 km² by 2040, however urban soils remain overlooked and sustainable urban development strategies are not supported by soil data. this study we aimed to explore the effect of natural and social factors on the spatial variability in soil C on Wageningen – a middle-size university town in the Netherlands.

Wageningen is a perfect case study to investigate factors influencing spatial variability of urban soil C. A long history and unique landscape diversity create conditions for high spatial variation in soil-forming factors. Based on the parent materials, the residential blocks outside the center can be subdivided into strata dominated by sandy and clayey soils. Urban expansion and building up new residential blocks, public and private green areas coincided with development and management of urban soils. A random stratified soil survey (n=56) allowed capturing the effect of parent materials, land cover and land-use history. The effect of the social factor was studied by expert interviews with the owners of the green areas (key plots, n=10), where detailed soil survey was done. Expert interviews included information on soil management as well as personal questions. In result, typical ‘portraits’ of landowners/ green-keepers were developed and related to soil C-stocks assessment. It was concluded that land-cover and land-use history/ historical zoning distinguished spatial patterns in soil C at the city level, whereas at the local scale social factors dominated. Moreover, local spatial variability distinguished by differences in maintenance/ management practices (e.g., minimal management in a student house in comparison to an intensive maintenance with irrigation and adding composts in a high-price cottage) was comparable or even higher than total variance at the city level.  This is an important message for urban planners and landscape designers, claiming that the social factors and personal decisions shall not be ignored in climate-resilient strategies and practices to develop and maintain urban green infrastructures.

How to cite: Vasenev, S., Vlaming, M., Breeman, J., Romzaykina, O., and Stoorvogel, J.: Environmental and social drivers behind spatial variability of soil carbon in urban green infrastructures of Wageningen, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11691, https://doi.org/10.5194/egusphere-egu23-11691, 2023.

In continental subsurface environments, biogeochemical reactions drive nutrient delivery, deep microbial life and mineral weathering, with crucial importance in the critical zone. Current models often simplify groundwater transport, using the residence time approach or hillslope models. However, increasing observations suggest that the nature, location and efficiency of reactions are strongly affected by groundwater 3D flow patterns, chemical gradients and subsurface heterogeneity. Here, we investigate how hydrological and geological structures control where and when biogeochemical reactions occur in the deep critical zone. For this purpose, our approach integrates long-term and widespread local observations in a catchment-scale framework and is based on data from two critical zone observatories of the French OZCAR national network. The first study took place in Guadeloupe (Obsera), where we integrated geophysical, hydrological and geochemical data in a reactive-hydrogeological model to simulate the 3D structure of groundwater flow paths and weathering. We found that the downstream evolution of the river chemistry is controlled by the pattern of hydrogeological circulations and by the depth of the weathering front. Furthermore, the calibrated 3D model allowed the delimitation of areas where weathering occurs and we showed that active weathering is restricted to catchment-areas where downward groundwater flows are deep. The second study focused on the dynamics of dissolved oxygen (DO) in a fractured aquifer at the Ploemeur catchment (Bretagne, France). Deep and intermittent inputs of DO in groundwater were observed, enabling the reaction of DO with dissolved Fe²⁺, in turn sustaining the development of deep microbial communities. In this study, we designed a simple model to simulate jointly the depth-distribution of DO and Fe²⁺ and to investigate the hydrological and geological factors controlling the DO depth-distribution. We found that the reducing capacity of the bedrock and the mean fluid transit time are the main parameters to explain and predict the depth of the oxic-anoxic transition in crystalline environments. In this presentation, we will provide new perspectives to observe and understand the origin of subsurface biogeochemical reactions and we will illustrate key processes that breakdown classical assumptions of reactive groundwater models.

How to cite: Bouchez, C., Osorio, I., Le Traon, C., and Le Borgne, T.: Groundwater flow patterns and subsurface heterogeneity drive critical zone geochemical reactions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12067, https://doi.org/10.5194/egusphere-egu23-12067, 2023.

The possibilities of citizen science-based approaches to environmental research and especially climate monitoring have recently expanded. This is among other things due to the availability of diverse measuring equipment at low costs, so that citizen science-based measuring missions can be implemented with a large number of participants. The advantages of high data density and spatial coverage are obvious. These advantages have been exploited for years by platforms such as www.awekas.at or www.weatherunderground.com and many others. With the help of mobile monitoring systems, the spatial coverage can now be extended even further. This means that the variability of climate values such as air temperature and relative humidity in cities can be investigated and more accurate forecasting models can be used.

A crucial aspect here is the reliability and comparability of the data collected with different devices. Therefore, we tested and compared within the EU project CityCLIM (www.cityclim.eu) different measurement equipment. Important characteristics of these devices are their low cost, ease of use and data access, data security and protection and the reliability of the measurement data. In the experiments presented here, 4 mobile systems were used: Meteotracker, senseBox, CHEAL5, PAM-AS520. All of these devices can determine air temperature, relative humidity, GPS-location and time and partly also particulate matter. In order to compare these systems, several measurement trips were made in the city of Leipzig in Saxony/Germany at different times of the year.

Surprisingly, there are considerable deviations between the devices in all measured values. This starts with the time and the GPS position. Here, there are sometimes shifts of several minutes and several metres. These errors could certainly be corrected with the help of calibration. However, this must also be practicable for the citizen scientist. In general, this example shows that quality control and backup of the data is necessary. In this sense, it is advantageous if there is a possibility to check the data live from the measurement operator or citizen. For this purpose, a direct upload of the data into the online portal/dashboard is very helpful. This direct data transfer also allows a simple and automated evaluation and storage of the large amounts of data.

Also the measurements of the air parameters show larger differences. Here, air flow at the sensor during the journey, protection from direct sunlight and the sensors used influence the measurement results. In any case, it is necessary to provide the users with detailed guidelines for the use of the sensors in order to increase the data quality. In summary, it turned out that the mobile measuring systems are suitable for citizen science-based climate observation with some limitations. Through the experiments, clear requirements for the devices could be worked out, which is helpful for the planning of future projects. The investigation of further devices and especially of quality control tools for the data are important next steps.

How to cite: Schmidt, F., Schütze, C., Ködel, U., Schütze, F., Liang, C., Schäfer, D., and Dietrich, P.: Comparison of Mobile Environmental Sensors for Citizen Science Based Climate Monitoring, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12542, https://doi.org/10.5194/egusphere-egu23-12542, 2023.

The development of citizen science is still at a very early stage in China. There are three primary reasons: 1. The government has strict data collection and sharing regulations. 2. There are very limited official leading groups, guidelines, and financial support on citizen science. 3. The public still lacks enthusiasm and basic training in citizen science. However, given the large population, increasing educational level of the society, and the help of new technologies, we can see a bright future for citizen science in China. We need to be prepared for that.

Hydro90 is a bottom-to-top established scientific community within the field of hydrology and earth science. It shares the latest academic research, broadcasts latest news, and organizes lectures, webinars, and workshops. It aims to enhance the communication among scholars, and between scholars and the public, especially among the young ages. It has been run for almost three years, with around 20,000 followers on the social media platform. However, we are still exploring how to promote citizen science in China. We want to share our recent experiences and efforts to overcome the current barriers in citizen science in the EGU. We are also looking forward to the great suggestions from European communities.

How to cite: Zhou, X., Wan, L., Lin, J., Shao, M., Feng, S., Zhang, B., Xu, Y., Li, Y., Liu, Y., Liu, M., Wang, L., and Tan, X.: Exploring practical citizen science in China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12615, https://doi.org/10.5194/egusphere-egu23-12615, 2023.

The depth of the Earth’s critical zone can be questionable especially in thousands meter deep sedimentary basins. Therefore, extension of the critical zone’s usually studied 10s of meters depth considering groundwater flow systems has critical importance. Growing demand for groundwater resources (water, geothermal energy), economic services of the groundwater flow related surface and subsurface processes and phenomena (e.g., groundwater dependent ecosystems, surface salinization), and the potential role of groundwater in the adaptation to and mitigation of the effects of human activities and climate change represent the significance and functions of groundwater flow systems in the critical zone.

Regarding the complexity of these flow systems, the primary goal could be the determination of their relative significance in the shallower parts of the critical zone. To this end, the present study proposes a methodology based on the hydrodynamic analysis of measured data to separate flow systems with different driving forces (topography, vertical compaction) and pore pressure regimes (normal or  close to hydrostatic, overpressured, underpressured). These characteristics define the renewability of groundwater resources, the near-surface conditions (e.g., distribution of nutrients, salts and heat, type of vegetation and soils, slope stability, etc.), and the exposure of flow systems to the effects of global and climate change.

As a case study, groundwater flow systems of the Great Hungarian Plain (Pannonian Basin, Hungary) were evaluated and characterized by analyzing about 5,800 measured hydraulic data (pre-production static water levels and static formation pressures) in hydraulic head vs. elevation and pressure vs. elevation profiles, tomographic maps, and hydraulic cross sections in combination with the geologic build-up and some surface phenomena (distribution of saline soils and vegetation). As a result, spatial extension and distinct functions in the critical zone were defined for three flow regimes, namely i) the near-surface topography-driven groundwater flow systems, ii) an underlying overpressured regime, and iii) the transition zone of i) and ii). For instance, outstanding significance of the upward flows of saline water from the transition zone was revealed in the generation of saline soils and vegetation.

The research was funded by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1-21-2022-00014 project.

How to cite: Czauner, B., Szkolnikovics-Simon, S., and Mádl-Szőnyi, J.: The influence of deep groundwater flow systems on the Earth’s critical zone , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12709, https://doi.org/10.5194/egusphere-egu23-12709, 2023.

Academia is more and more under the demand to create both scientific and societally relevant research with beneficial effects for society. There is a strong consensus that the engagement of non-academic actors in research activities is associated with greater societal relevance and usability of science for society. Involving non-academic actors within natural hazards and disaster risk research has seen a rise in popularity with the advent of participatory and transdisciplinary research approaches. Particularly in countries of the Global South, the participation, engagement, or involvement of non-academic actors in research on natural hazards and disaster risk is seen as promising strategy for solving data issues, raising awareness and generating knowledge. However, besides beneficial consequences, the participation, engagement, or involvement in scientific research may also have negative side-effects for non-academic actors (e.g., causing mistrust, anxiety, or research-fatigue). Against this background, the aim of the ImSE-R project is to assess how the participation, engagement, or involvement in scientific research on natural hazards and disaster risk may have consequences – ranging from intended impacts to unintended implications and negative side-effects for non-academic actors. This contribution presents the results of a systematic review of studies on hazards and disaster risk in the Himalayan region (2000-2022) to better understand how academic actors negotiate and manage research relationships with non-academic actors in the context of natural hazards and disaster risk research. The contribution derives insights on how non-academic actors were involved in natural hazard and disaster risk research activities (actively, passively); underlying motivations and goals of academic actors for involving non-academic actors in natural hazard and disaster risk research; and perceived impacts and implications of involving non-academic actors in research. The results of the review feed into the development of a conceptual framework on research impacts and implications in the context of natural hazard and disaster risk research.

How to cite: Posch, E.: Side-effects of doing research? Potential consequences of involving non-academic actors in natural hazard research, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14528, https://doi.org/10.5194/egusphere-egu23-14528, 2023.

The stable presence of humans in the Alps dates back to the Bronze Age and peaked in the mid-19th century, deeply shaping the landscape and allowing the co-evolution of numerous plant and animal species. Since the 1950s, socio-economic changes have led to the gradual depopulation of mountain areas, and the consequent abandonment of traditional agro-pastoral activities. The rupture of the long-established balance between man and nature has triggered a process of transition, further exacerbated and accelerated by climate change. The Belmont Forum project ABRESO (Abandonment and rebound: Societal views on landscape and land-use change and their impacts on water and soils) started in 2021 and aims at advancing the understanding of mitigation and adaptation strategies to environmental change, through an international partnership involving five countries (the United States, France, Italy, Japan and Taiwan). Italy contributes to the project with three case studies: Gran Paradiso National Park, Val Grande National Park and the Tesino highlands are investigated in the Italian Alps. Using an interdisciplinary approach, the project aims to study the impact of the abandonment of traditional activities on ecosystem services provisioning, such as biodiversity conservation and soil sustainability, as well as the actual perception of the ongoing environmental changes by different stakeholders and its subsequent integration into local land management practices and policies. The land use and land cover change occurring due to land abandonment can have profound implications in the critical zone (CZ), inducing changes in soil, vegetation, carbon fluxes and water resources. This project integrates the natural and social sciences approaches to study the evolution of ecosystems in response to these factors. More specifically, advanced techniques that integrate Earth Observation, biogeochemical analyses and socio-economic investigation are used in the Italian sites to understand in which extent geo-biophysical and social landscapes reciprocally interact. The environmental variables collected for ecosystem monitoring and to study and upscale the ongoing dynamics in the CZ include snow cover and phenology parameters, soil organic carbon, and land use change maps extracted from time series of satellite imagery, validated via in situ measurements. Then, the observed processes will be compared to the perception of different stakeholders (local population, policy makers, tourists, business keepers, etc.) to unveil new insights into the way land use change in the mountain areas influence and is influenced by the local land management practices and policies.

How to cite: Richiardi, C., Adamo, M., Scartazza, A., Sella, L., Baneschi, I., Botteghi, S., Brugnoli, E., Fuina, S., Gavrichkova, O., Maerker, M., Mattioni, M., Ragazzi, E., Rossi, V., Rota, F. S., Salvadori, M., Tarantino, C., Vicario, S., Zanetti, A., and Pennisi, M.: The impact of landscape and land use changes on the critical zone and society: the Belmont Forum ABRESO project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14567, https://doi.org/10.5194/egusphere-egu23-14567, 2023.

In the Tropics, disasters associated with natural hazards (intense convective rainfalls, floods, landslides) occur regularly. However, the general scarcity of reliable and accurate data collected on these events does not allow for a complete picture of their frequency and magnitude, thus hindering effective Disaster Risk Reduction (DRR). Such situation is observed in the Kivu region, in the eastern part of the DR Congo. Recurrent insecurity, long distances to travel, poor communication networks and the lack of financial resources to reach the affected areas are the main challenges faced by the Congolese Civil Protection in building a database that would allow for a better knowledge of these phenomena, in view of an appropriate disaster response and, in the long term, efficient DRR.

Based on this observation, a group of 20 citizen observers was set up to collect data on six different types of natural hazard disasters (floods, landslides, wind storms, hail storms, lightning, and earthquakes) using smartphone technology connected to an online platform. This new approach, based on citizen science, makes it possible to significantly improve the documenting and understanding of the spatial and temporal occurrence of these disasters that affect the provinces of North and South Kivu. Since the establishment of this network in December 2019, more than 700 events have been recorded.

If the data collected by this network of citizen observers constitute above all an unprecedented amount of information on the disasters occurring in such a tropical environment, they also allow for the compilation of a WebGIS and quarterly reports illustrated with maps and graphs, disseminated by Civil Protection to key DRR stakeholders active in the region, for a more tailored response, its planification, and, to some extent, the anticipation of such events. Scientists from universities and research centers in Bukavu and Goma are associated to that data collection and analysis. Moreover, citizen observers position themselves within their communities as key actors in raising awareness about disaster risks. However, although this type of approach has proven to be effective in the short term, the motivation on the long term of citizen observers, as volunteers, has been identified as a weakness to be addressed.

How to cite: Michellier, C., Mana Ngotuly, T., Maki Mateso, J.-C., Kambale Makundi, J., Bwishe, J.-M., Dewitte, O., and Kervyn, F.: Tracking natural hazard disasters in non-surveyed regions: the “citizen” observer network of the Kivu in DR Congo, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15940, https://doi.org/10.5194/egusphere-egu23-15940, 2023.

Processes linking lower and upper parts of the Critical Zone (CZ) are crucial for sustaining life on continents and ecosystem services provided by eco- or agro-systems. Rock weathering at depth is expected to be an essential source of nutrients and deep-rooted trees are believed to induce water and nutrient ‘lift’, benefiting the whole community. However, quantifying this nutrient lift remains a challenge linked on the one hand to the hidden nature of the roots and on the other hand to the complexity of the rhizosphere dynamics. The Nutrilift project aims at quantifying the role of deep critical zone in the supply of nutrients to eco- and agrosystems, based on the hypothesis that while in natural forests, deep-rooted species can derive part of their nutrient resources from increased mineral weathering at depth, the relative importance of this process in shallow-rooted agrosystems is much less - and agroforestry systems represent an intermediate situation. Conducted within the framework of the Indo-French Cell for Water Sciences (IRD - CNRS - INRAE - UPS - Indian Institute of Science, Bangalore, India), the project is based on long-term monitoring in the Mule Hole (diversified forest) and Berambadi (irrigated agriculture and agroforestry) watersheds of the M-TROPICS Observatory in Peninsular India. For this purpose, we study the vertical evolution of soil properties and associated pedological processes as a function of plant cover/land-use. Weathering processes and/or plant uptake will be studied in the vicinity of the roots using micro-characterization techniques, which will allow to calibrate combined hydro-geochemical models. The deep contribution to the nutrient budgets of each site will be quantified by intra-plant isotopic balances as well as by the identification of specific geochemical signatures to the deep contribution of the critical zone. An originality of the project is the observation of the deep critical zone (up to 10m) via instrumented pits with continuous pCO₂ and moisture measurements, scanners (root dynamics) imaging and pore water collection. The effects of future changes -associated with climate and land uses- on the dynamics of the deep critical zone will be explored from scenarios co-constructed with local stakeholders.

How to cite: Riotte, J. and the Nutrilift team: Deep roots versus pumps: comparison of deep nutrient removal in dry tropical eco- and agrosystems (ANR project Nutrilift), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17441, https://doi.org/10.5194/egusphere-egu23-17441, 2023.

While developed nations are assumed to provide high groundwater quality security, populations reliant on (typically rural, unregulated) private domestic groundwater wells are often uniquely vulnerable to supply contamination. The potential health ramifications of exposure to contaminated groundwater may be especially grave for immunosuppressed populations residing in service-deprived and climate-vulnerable areas, necessitating concerted government (educational) and household-level (behavioural) action. In response, a growing number of studies (spanning quantitative contamination risk assessments, policy strategies, communicative interventions and householder surveys) have emerged within the last several decades. To date, few investigations have sought to synthesise this literature and ascertain the potential generality of drivers of both private groundwater contamination and preventive responses in high-income countries.

The developed regions of the Republic of Ireland (ROI) and Ontario represent an appropriate point of comparison to establish research transferability. Both regions are characterised by high private groundwater reliance (> 10% of their respective populations), pervasive microbial groundwater contamination and significant associations between acute gastrointestinal illness (AGI) and private well use. Consumption of private well water contributes to approximately 4,800 annual cases of AGI in Ontario and as many as 80% of annual cases of verotoxigenic E.coli (VTEC) in the ROI. However, despite similarities, regional discrepancies exist with respect to policy landscapes (e.g., monetary requirements for private water quality testing) and contamination risk profiles (e.g., frequency of extreme weather event concurrence). In efforts to elucidate the potential implications of these phenomena, a scoping review of literature (1990-2022) in the ROI and Ontario outlining risk management measures to prevent private groundwater contamination in the was undertaken. The SPICE (Setting, Population/Phenomenon, Intervention, Setting, Perspective) methodology was utilised to inform literature search terms, with Scopus and Web of Science selected as primary databases for article searches. Following removal of duplicate studies and article screening, 92 articles (Canada = 70, ROI = 22) were retained for analysis.

Articles were predominantly comprised of quantitative contamination risk assessment studies (n = 68), with qualitative and quantitative questionnaire investigations (n = 16), interventions (n = 2) and policy studies (n = 6) noticeably less frequent. Quantitative risk assessments published after the year 2000 demonstrated an overwhelming focus on microbial supply contamination, identifying well type and proximity of agricultural activity as significant determinants of supply contamination. Survey studies in both regions also consistently highlighted gender, perceived confidence in maintaining supply and economic and convenience barriers as significant determinants of well user knowledge and behaviour. However, well users in Ontario demonstrated markedly higher rates of prior well testing (irrespective of adherence to regional guidelines), suggesting that incentivised (or free) well testing may lead to significant increases in uptake of well water quality testing. The paucity of identified intervention studies suggests that increased research investigating methods of well user outreach and groundwater risk communication will be necessary in the future to determine the broad efficacy of risk communication in developed nations.

How to cite: Mooney, S., O’Neill, E., and Hynds, P.: Top-down and bottom-up management of private groundwater contamination risk: A comparative scoping review of similarities, drivers and challenges in two developed regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17513, https://doi.org/10.5194/egusphere-egu23-17513, 2023.

Badlands are highly erosive landforms of dissected morphology, which can be found on soft rocks and unconsolidated sediments, with little or no vegetation, that are useless for agriculture. The erosion rates of these areas are high, causing important environmental and economic problems. For that reason, detecting the main conditioning factors that control badland occurrence and identifying susceptible areas is higly important to prevent soil erosion phenomena and their negative consequences.
This work attempts to assess badland susceptibility and their governing factors at a multi-scale level, using a random forest (RF) modelling approach. Previous RF-based research have demonstrated that RF modelling is a powerful tool for making predictions in the same spatial context and scale where the model has been trained. However, upscaling RF-modelling results to obtain accurate predictions in other, more extensive spatial contexts than that used for model training, remains an important challenge.
For that, the Upper Llobregat River Basin (ULRB, 504.8 km2) and Catalonia region (CAT, 32000 km2) have been selected as study areas. We have evaluated the viability of training a RF model for the analysis of badland suceptibility in the small spatial context of the ULRB, and further testing it to the more extensive spatial context of CAT. Revealing the most important factors that control badland distribution in the territory has been another goal in the present study. Eleven governing factors and two badland inventories developed for these study areas have been used for model training and testing. Model performance has been analyzed through validation tests and three different evaluation metrics: AUC, Kappa coefficient and accuracy. The outcomes of this work manifest that the two variables that have the most important relevance for badland occurrence are lithology and NDVI. In addition, our results showed that upscaling RF model results defined in the ULRB to the more extensive spatial context of CAT in order to predict badland occurrence, it’s possible but not ideal. Last, badland susceptibility maps of ULRB and Catalonia have been obtained with a very high accuracy (96% and 97% respectively), confirming the feasibility and uselfuness of RF approach for badland susceptibility assessment.

How to cite: Torra, O., Hürlimann, M., Puig-Polo, C., and Moreno-de las Heras, M.: Predicting badland occurrence in Catalonia by applying random forest techniques and a multi-scale approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-149, https://doi.org/10.5194/egusphere-egu23-149, 2023.

The models currently used to predict post-fire soil erosion risks are limited by high data demands and long computation times. An alternative is to map the potential hydrological and sediment connectivity using indices to express the general properties of the landscape under evaluation and map the possible connectivity between the different parts of a catchment.

In this study, we aim to answer the question: Do these alternative approaches identify post-fire sediment mobilization hotspots?  To achieve this, we assess the spatial variability distribution of the location of soil erosion hotspots using the Index of Connectivity (IC), Revised Universal Soil Loss Equation (RUSLE model) and the Sediment Export (SE) and compare it to the simulation results of a more complex Landscape Evolution Model (LAPSUS model). Additionally, we evaluate statistical measures of association between the four tools. Furthermore, IC, RUSLE model and SE are used due to their simplistic representation of erosion and ease of application, and the LAPSUS model is used as the best representation of erosion and sediment transport in the study area.

Our results show that the three tools (IC, RUSLE model and SE) tested in this study are suitable for identifying sediment mobilization hotspots, i.e., areas where the erosion rates are above the 90^th percentile, in recently burnt areas, and differences between their performance are minor. These findings can be considered for post-fire and water contamination risk management, especially for fast prioritization of areas needing emergency post-fire intervention.

How to cite: Parente, J., Nunes, J., Baartman, J., and Föllmi, D.: Testing simple approaches to map sediment mobilization hotspots after wildfires, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-261, https://doi.org/10.5194/egusphere-egu23-261, 2023.

Vegetative barriers have proven their effectiveness in controlling erosion and promoting other ecosystem services in agricultural areas. This has led to their conservation and promotion as landscape elements by the Common Agricultural Policy and other policy initiatives. However, predicting their efficiency in reducing hydrologic connectivity presents a large uncertainty (Gumiere et al., 2011).

This communication presents an analysis of trapping efficiency of sediment, runoff, and nutrients (P and N) by vegetative barriers aimed to provide a statistical approach to efficiency, based on a review of available studies, considering two climates: humid and arid/semi-arid (Muñoz et al, 2022). For this, different independent variables were grouped and identified to explore its influence: i) those defining the vegetative barrier dimension (width, slope of the plot, and area ratio buffer/plot) and ii) those related to experimental conditions (type of vegetation, soil protection of the non-buffered area, type of climate, type of experimental measurement and origin of the rainfall). A more detailed analysis was performed with the studies which reproduce similar situations to the ones occurring naturally (natural rainfall and paired plots).

In general, average trapping efficiencies for runoff and sediment are 40.1 and 62.6% and ranging between -81.0 to 99.9% and -109 to 100%, respectively. For nutrients, values of trapping efficiencies had an average of 44.9 and 38.4% for phosphorus and nitrogen, respectively. The lack of data and the large variability among and within the measurements from the studies considered in our review only allowed to detect slight trends and statistically significant differences in some cases for the different variables analysed.

In order to provide guidelines to farmers and technicians, a probabilistic model was developed for sediment trapping efficiency regarding the width of the vegetative barrier and the climatic region. The model showed that in 92% of the cases, a vegetative barrier will reduce erosion in humid climates while this trapping efficiency will be 100% in semi-arid/arid conditions. Grouping the vegetative barriers’ width in different intervals, it was observed that the maximum trapping efficiency is ~80 % for a width of 2.75 to 3-m in arid/semi-arid climate and 5 to 6-m in humid regions.

Acknowledgement: This work supported by the project PID2019-105793RB-I00 financed by the Spanish Ministry of Science and Innovation, and project TUdi, GA 101000224, of the European Union’s Horizon 2020 research and innovation programme

References

Gumiere, S. J., Le Bissonnais, Y., Raclot, D., & Cheviron, B. (2011). Vegetated filter effects on sedimentological connectivity of agricultural catchments in erosion modelling: A review. Earth Surface Processes and Landforms, 36(1), 3–19. https://doi.org/10.1002/esp.2042.

Muñoz, J. A., Guzmán G., Soriano M.A., & Gómez J. A. (2022). Trapping efficiency of vegetative barriers in agricultural landscapes. An operational model from a review of available information. Manuscript submitted for publication.

How to cite: Muñoz, J. A., Guzmán, G., Soriano, M. A., and Gómez, J. A.: Trapping efficiency of vegetative barriers in agricultural landscapes. An operational model from a review of available information, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-477, https://doi.org/10.5194/egusphere-egu23-477, 2023.

As part of the earth's dynamic systems, badland landscapes are chiefly generated by the interaction between bedrock weathering, climate seasonality, and the controversial contribution of the hillslope and fluvial erosion processes. Although contemporary definitions clearly point out that badland initiation is a function of overland-flow-dominated gully channels, gravitational processes-dominated mass movements, and subsurface processes-driven piping, the following related questions remain to be tackled regarding their topographic position in the landscape: (1) Are the badland landforms signature of hillslope or fluvial erosion domain? (2) How do climate and regional settings (i.e., macro landforms, homogenous or heterogenous lithologies, etc.) influence the topographic position of badlands? To address these questions, we have selected climatically distinct badlands from different continents where; digital elevation models are available: Utah and South Dakota (USA), Upper Llobregat and Murcia (Spain), Northern Apennines and Basilicata (Italy), Mediterranean and Plateau – Margin Transition Badlands (Turkey), and Southern Taiwan. The badland boundaries were visually inspected and manually digitized based on diagnostic morphologic indicators. We have utilized the slope and drainage area relationship by using a 5m digital terrain model to identify topographic thresholds at TopoToolbox, a MATLAB-based software for topographic analysis. Preliminary results show that most badland areas occupy a maximum of 10⁴ to 10⁵ m² contribution area in the landscapes. Although contribution areas relatively represent uniform thresholds in the sites, the local gradient (S), which is proportional to the contribution area, tends to be higher in the sub-humid mountainous badlands (Upper Llobregat, Northern Apennines) and wet tropical SW Taiwan than in semi-arid badlands (Basilicata, Murcia). We conclude that the topographic signature of badlands in the context of the sub-catchment scale may depict an appropriate instance of a transitional domain from a diffusive erosional process to a fluvial erosion process. Our findings may serve as a foundation for a better understanding of the classification and automatic detection of badland landscapes, also known as erosional hot spots.

This study has been produced benefiting from the 2232 International Fellowship for Outstanding Researchers Program of the Scientific and Technological Research Council of Turkey (TUBITAK) through grant 118C329 and TUBITAK 2214-A International Research Fellowship Programme.

How to cite: Avcioglu, A., Schwanghart, W., Görüm, T., Yetemen, Ö., Moreno-de las Heras, M., and Yang, C. J.: Topographic signature of badlands landscapes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-646, https://doi.org/10.5194/egusphere-egu23-646, 2023.

Soil erosion has always been a threat to the environment and agricultural practices throughout the world. For a country like India, where agriculture contributes primarily to its economy, it becomes a major problem. Identifying these vulnerable regions and planning for mitigation is crucial for sustainable soil resource management. For this, mapping or modeling soil erosion at a national scale is required to understand the variability of soil losses throughout the country. Performing field-based experiments to estimate soil losses over a large country is always expensive and tedious. Revised Soil Loss Equation (RUSLE), an empirical model, has been more prominent worldwide due to its simplicity and less forcing data requirements. In this study, average annual Potential Soil Erosion (PSE) was estimated over India using IRED (Indian Rainfall Erosivity Dataset), ISED (Indian Soil Erodibility Dataset), SRTM (Shuttle Radar Topographic Mission), DEM (Digital Elevation Model), and LULC (Land-use/Land-cover) obtained from NRSC (National Remote Sensing Institute) India. PSE was further analyzed using LULC categories and soil types to visualize the impact of soil erosion in each class. As erosion significantly affected agricultural activities, financial losses over the nation were also estimated, considering the severity of soil erosion. Further, Sediment Delivery Ratio (SDR) and Specific Sediment Yield (SSY) were also mapped over the national boundary to visualize the actual soil displacement at a grid scale of 250 m. Using the SSY map, the incoming sediment load to reservoirs/dams/lakes was also estimated considering its watershed areas. This study will be helpful for the experts in the field of sustainable soil resources management for planning mitigation measurements against soil losses in India.

Keywords: Soil Erosion, Sediment Yield, Sediment Delivery Ratio, India, RUSLE, LULC

How to cite: Raj, R., Saharia, M., and Chakma, S.: National Scale Soil Erosion and Sediment Yield Assessment over India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-883, https://doi.org/10.5194/egusphere-egu23-883, 2023.

A better understanding of soil erosion is not possible without including subsurface erosion. Soil piping may significantly contribute to the overall erosion problem in a given area and may therefore change the conditions and methods for controlling soil degradation. Therefore, there is an urgent need to identify regionally and globally sites where soil piping occurs which then may require a change of the strategies to control soil erosion. In this project, we are constructing the very first data-driven piping erosion susceptibility map of Europe. The crucial point is to identify piping-affected areas by mapping the soil piping-related features, i.e. pipe roof collapses (PCs) and pipe outlets in the European Union and the UK. Mapping is based on an in-depth literature review in combination with detailed mapping using Google Earth imagery, and LiDAR data (if available). The database currently consists of 6841 piping-related features (6171 PCs, and 670 outlets), among which the location of 88% features is certain (within a resolution of 25 m). Almost 28% (1889 features) were located based on detailed fieldwork, 25% (1726) were extracted from published papers, and 47% based on a detailed analysis of Google Earth imagery and LiDAR data (19% and 28%, respectively). This database is currently used to construct the very first data-driven piping erosion susceptibility map of Europe.

This research is part of the project “Building excellence in research of human-environmental systems with geospatial and Earth observation technologies” that received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 952327.

How to cite: Bernatek-Jakiel, A., Vanmaercke, M., Poesen, J., Biernacka, A., Borrelli, P., Derii, A., Hałys, J., Holden, J., Jakab, G., Panagos, P., Piątek, D., Regensburg, T. H., Rodzik, J., Nadal-Romero, E., Stolarczyk, M., Wacławczyk, P., and Zgłobicki, W.: A European database of soil piping-related features: a major step towards producing a piping erosion susceptibility map of Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1467, https://doi.org/10.5194/egusphere-egu23-1467, 2023.

Gullies and cliff erosion are significant indicators of land degradation. Knowledge of the spatial distribution and dimensions of these erosion features is needed to effectively quantify sediment budgets and to implement erosion mitigation measures. Expert delineation can help identify features at a local sale, however, mapping larger extents becomes time consuming. Object detection techniques based on aerial photographs and LiDAR elevation data can improve the automated delineation of such features. In this study, we tested a region-based convolutional neural network (Mask-RCNN) deep learning approach to identify gully and cliff features. 

An expert-based delineation of gully and cliff features was performed in the Wairoa catchment in Hawke’s Bay, New Zealand based on aerial photographs obtained between 2017 and 2020. These delineations served as reference data to create labelled chips for training deep learning models. Several terrain derivatives from the LiDAR digital elevation model (DEM), including slope, hillshade, slope length and steepness (LS) factor, and terrain ruggedness index, were computed. The terrain derivatives and spectral bands (R-G-B-NIR) from the aerial photographs were used to train deep learning models based on different band combinations. 

Despite achieving high accuracy (average precision score above 85%) during training, transferring the models to validation areas resulted in low detection rates, with a large number of false negatives. However, the correctly detected erosion features correspond very well to the reference data delineations, even achieving good results for the differentiation between gullies and cliffs. A closer inspection of the false positive features suggests that the reference data could be incomplete. Our study shows that deep learning has a high potential for automated gully and cliff mapping, but further improvement of the model transferability is needed. A combination of automated and expert-based delineation would potentially result in reliable and efficient erosion feature detection.

How to cite: Abad, L., Hölbling, D., Smith, H., Neverman, A., Betts, H., and Spiekermann, R.: Gully and cliff erosion feature detection in the Wairoa catchment in Hawke’s Bay, New Zealand, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1468, https://doi.org/10.5194/egusphere-egu23-1468, 2023.

Soil erosion is one of the most relevant environmental problems facing society today. Climate change has a direct impact on these processes through a feedback loop, especially in the Mediterranean region, where the situation is conceived as one of extreme fragility. The increase in extreme rainfall and temperature events, together with differential human land use, are leading to an intense degradation of Mediterranean soils. Therefore, it is essential to determine the levels of susceptibility of the landscape to erosion processes to create new strategies to improve the management of the land and reduce the potential risks that may exist. Specifically, this work has focused on the Guadalmedina watershed, in Malaga (Spain), which is characteristic of the current dynamics of the Mediterranean landscape. For this purpose, a soil quality index based on a multi-criteria analysis of different soil indicators (water, physical and organic) has been applied in this study, using a total of 132 soil samples measured in the laboratory. In addition, the results of this analysis have been contrasted with soil erosion values derived from the application of RUSLE model. From this process, those slopes and fields with the highest water erosion risk values have been identified at the most detailed scale. In general, the lowest soil erosion rates are found in those areas where soil quality indicators show optimal values. Furthermore, the results obtained indicate that organic soil indicators are decisive in the processes of water erosion in the Mediterranean area.

How to cite: González-Pérez, J., Sillero-Medina, J. A., Espinosa-Muñoz, J., and Ruiz-Sinoga, J. D.: Soil erosion susceptibility assessment in Mediterranean areas by means of soil quality. A test in the Guadalmedina watershed (Málaga,Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1523, https://doi.org/10.5194/egusphere-egu23-1523, 2023.

Soil erosion (SE) and saturated hydraulic conductivity (Ksat) are the essential indicators for land degradation and soil nutrient loss. Both processes are linked with each other as one can enhance the other resulting in positive feedback loops. The increase in soil erosion might block the macropores and reduce Ksat. In contrast, the reduction in Ksat triggers the runoff and increases soil erosion. However, modelling and predicting soil erosion, hydraulic properties are usually not adequately considered. We tried to link soil erosion directly with Ksat on a global scale. For this, we used global soil erosion and saturated hydraulic conductivity maps to yield combined soil risk classes. SE and Ksat maps were obtained from Borrelli et al. (2017) and Gupta et al. (2021), respectively. Each map was classified into six classes based on the previous studies. Moreover, both maps' classes were combined by creating six merged classes to develop the modified soil risk map. The modified soil risk map highlights regions with low Ksat and high SE. Furthermore, the final map was validated using continental and/or national sediment yield (SY) datasets. SY classes were compared with final risk classes to validate the accuracy of the map. The modified soil risk map showed higher accuracy compared to the SE map when compared with SY classes. This study demonstrates the first attempt to link soil erosion to soil hydraulic properties on large scales.

How to cite: Gupta, S., Borrelli, P., Panagos, P., and Alewell, C.: Modified global soil risk map using soil erosion and saturated hydraulic conductivity maps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1892, https://doi.org/10.5194/egusphere-egu23-1892, 2023.

Soil mobilization is particularly high in viticulture. In Austria and especially in Vienna, soil protection measures are frequently implemented, without the vintners knowing about the extent of erosion rates and where they can take additional measures in particular. However, new methods for erosion estimation with high accuracy and cost efficiency are expected to improve this situation. Of which one application will be presented in this study.

A relatively fast and low-cost possibility is the stock unearthing method (SUM), which provides a rough estimation of erosion, based on biomarkers but neglects the inter-row area. The improved ISUM is using additional measurement points in this area and therefore delivering more accurate erosion volumes. Additionally, the use of structure from motion (SfM) DEMs provided respectable results on small plots in vineyards. The combination of SUM and SfM allows the new ^airSUM approach to provide a significantly more precise estimation of annual erosion rates, making rendering interpolation techniques unnecessary. The resulting model represents the present relief and is able to reproduce visible runoff patterns. The use of ^airSUM enabled the detection of 32.7 m³ (avg. of ~83.9 t ha^-1 yr^-1) soil erosion on an area of 700 m² in a period of 8 years. Erosion hotspots could be modeled mainly in the wheel tracks with depths of up to 20.5 cm parallel to the slope and correspond excellently with field observations. This is partly due to the compaction of the surface, but mainly due to the preferential runoff and erosion. The identification of the erosion hot spots, runoff breaches and consequently runoff concentration allows the precise allocation of mitigation funds to reduce overland flow and erosion.

How to cite: Kanta, R. and Kraushaar, S.: airSUM - Structure from Motion supported Stock Unearthing Method: Erosion modeling in Viennese vineyards, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2355, https://doi.org/10.5194/egusphere-egu23-2355, 2023.

A few low-frequent but extreme rainfall events generate substantial erosion amounts and, as a result, land degradation negatively affects soil health and agricultural productivity. Determining rainfall erosivity (from small to extreme events) that drive soil erosion will improve our knowledge and understanding of extreme erosion processes and our ability to develop and adapt adequate soil protection strategies. This study aims to analyze rainfall erosivity characteristics across Austria‘s main agricultural production zones using long-term (from 27 to 82 years) with high-resolution (5-minutes) rainfall data from 27 rain gauges. Erosive rainfall characteristics such as rainfall amount, event duration, and the maximum 30-minute intensity were investigated, and typical rainfall types were assessed through a clustering approach based on the k-means algorithm. Results identified three dominant types (clusters) of erosive rainfalls across Austria's agricultural areas. Seasonal distribution analysis showed that the predominant erosive events, characterized by short duration and high intensities, occur during the summer months from June to August. In contrast, the long-duration and low rainfall-intensity events are evenly distributed throughout the year. The spatial distribution of rainfalls related to the largest rainfall erosivities showed a pronounced occurrence in the southeastern pre-alpine areas. Knowledge of the occurrence of erosive rainfall events in space and time eventually supports the implementation of locally adapted Soil Conservation (SC) practices in Austria.

How to cite: Vasquez, C., Klik, A., Stumpp, C., Strauß, P., Laaha, G., Özcelik, N. B., Georg, P., Dostal, T., Yin, S., and Strohmeier, S.: Erosive rainfall clustering across Austria's agricultural areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2588, https://doi.org/10.5194/egusphere-egu23-2588, 2023.

Land degradation affects the productivity of the land, but is also associated with a flux of greenhouse gases (GHGs) from soil and vegetation into the atmosphere. The large area of rangelands (35 million km², cover about 40% of earth’s surface) can contribute significantly to changes of atmospheric CO₂ concentrations following even a minor alteration of the rangeland soil C pool (Wang et al. 2002). Degradation of South African rangelands has been a concern for more than 100 years (Rowntree, 2013). The Karoo drylands, covering 30% of the land surface of South Africa, have experienced particular intense soil erosion and thus loss of topsoil C. To sustain the large number of animals, many small farm dams have been constructed mainly in the first half of the twentieth century. As a consequence of the soil erosion, they are now often silted-up and have breached (Boardman, 2014). The sediment deposited behind such small dams offers the possibility to reconstruct the loss soil C for the time peirod between construction and breaching of dams. Five dams were chosen to explore the possibility to use their sediment as an environmental archive for 20^th century rangeland soil Carbon loss. The specific aims of our study are to 1) find out whether distinct C profiles can be discerned in dam sediments; 2) identify whether these changes potentially reflect erosion and soil C loss in the dam catchments; and 3) to discuss whether the dam sediments can serve as an environmental archive to reconstruct soil-atmosphere interaction during recent decades. The initial survey of the dams involved the sampling of individual sediment strata and the analysis of their organic and nitrogen content, as well as the ¹³⁷Cs activity of selected samples to gain an insight into the time of deposition. Two dams showed a profile that indicates a loss of soil C during the first decreased after their construction, while the other dams showed no clear signal or even an increase of sediment C in the younger sediment. One dam showed no ¹³⁷Cs activity, indicating that it was filled with sediment very quickly after construction. These results illustrate that soil degradation and associated loss of soil C stocks can potentially be reconstructed based on the small dam sediments. However, the source of the sediment C has to be tested, as well as the individual land use and erosion history of each dam catchment. 

How to cite: Li, L., Krenz, J., and Kuhn, N. J.: The potential to reconstruct 20th century soil carbon erosion in rangelands from small reservoir sediments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3436, https://doi.org/10.5194/egusphere-egu23-3436, 2023.

During the last twenty years, Mayotte island (France, Comoros archipelago) has experienced an explosion of population (+80% between 2002 and 2021, taking the official population into account only) leading to a deforestation and a decline in traditional agricultural practices (mahorais garden) in favor of intensive food crop monocultures (e.g. banana, manioc…). These changes in land use are at the origin of an acceleration of erosion dynamics and an excessive transfer of sediments to water bodies downstream. In addition to land degradation, sediment transfers contribute to the filling of reservoirs devoted to supplying drinking water, to the deterioration of the lagoon and to a general loss of biodiversity.

The inertia, trajectory and the sources of this erosion remain poorly documented despite the acceleration of this land use evolution during the last 10 years. In this study, we propose a retro-observation of sedimentary fluxes and sources of sediment based on the analysis of sedimentary archives collected in one of the main reservoirs of the island (Dzoumogné reservoir, 22 ha) along with the development of a sediment tracing approach (associating radionuclide measurements, elemental geochemistry, organic matter and color analyses) in order to reconstruct the evolution of erosion rates and sources of since 2011.

The first results reveal the occurrence of two periods of erosion acceleration between 2013 and 2015, and then after 2019. The first increase (+140% of erosion rates, from 3.5 to 8.5 t ha^-1 yr^-1) occurred during a period of deforestation, which induced an opening of the landscape (e.g. creation of unpaved roads). The second acceleration phase took place during the most recent period of agriculture expansion associated with an intensification of agricultural practices (+115% of erosion rates, from 3 t ha^-1 yr^-1 in 2017 to 6.5 t ha^-1 yr^-1 in 2020). The sediment accumulated in the reservoir between 2011 and 2021mostly originated from subsurface sources (bank erosion, unpaved roads, gullied soils) and intensive cultivation (e.g., in 2021, 35% of sediment originated from unpaved roads, channel banks, landslides and 27% from intensive cultivation) while forests that are less exposed to erosion only supplied a limited contribution to sediment (<18%). As land use changes are expected to continue in the coming years, understanding the factors controlling the erosion dynamics and the supply of sediment sources are of prime importance in order to implement effective conservation measures and to protect the land and water resources.

How to cite: Foucher, A., Evrard, O., Rabiet, L., Cerdan, O., Landemaine, V., Vitter, M., and Desprats, J.-F.: Impact of rapid deforestation and conversion of traditional agricultural practices into food crop production on land and water degradation: a case study from Mayotte Island, Indian Ocean, France (2011-2022), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3537, https://doi.org/10.5194/egusphere-egu23-3537, 2023.

The Universal Soil Loss Equation (USLE) was initially developed to support the implementation of conservation measures to minimize soil loss by water erosion, i.e. sheet and rill erosion, on a local scale and in the context of agricultural land use. The approach was refined over decades and became the Revised Universal Soil Loss Equation (RUSLE).  At the same time the scope of applications has grown considerably. Due to its rather simple structure and relatively low demand for input data, it has been used for the assessment of soil loss from water erosion for ever growing spatial entities, i.e. regional scale catchments or whole countries. Recently this has been applied on a global scale in order to identify global hotspots of soil erosion. This coherent approach for a global comparison is most welcome against the background of the large number of country-specific assessments which are rather difficult to compare.

However, there are two issues of concern. First, one needs to remember that RUSLE-derived soil loss assessments do not account for gully erosion, which might not be linearly scaled with sheet and rill erosion. Furthermore, information on the uncertainties of RUSLE based erosion assessments are not frequently reported. This especially concerns the impact of specific combinations of varying unique input data on the results.

In this contribution we compare in high spatial resolution the results of two RUSLE-based soil loss by water erosion assessments conducted for six 100 by 100 km large study sites in South Africa. The first assessment was conducted about two decades ago and was based on the then available data covering the whole of South Africa. The second assessment is a revision, which includes the latest input data for rainfall erosivity, soil erodibility, the topographic factor as well as land cover and management. When compared, the results of the current soil loss estimates are an order of magnitude lower than the previous estimates. Does this difference represent a temporal trend or just the inherent uncertainties reflecting different input data and slightly different data processing? This is the question discussed in this contribution.

How to cite: Baade, J., Zoller, K., and Le Roux, J.: Soil loss by water erosion assessment uncertainties – experiences from South Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3578, https://doi.org/10.5194/egusphere-egu23-3578, 2023.

Global efforts to restore the world’s degraded croplands require knowledge on the degree and extent of accelerated soil organic carbon (SOC) loss induced by soil erosion. However, methods for assessing where and to what extent erosion takes place is still inadequate for precise detection of erosion hotspots at high spatial resolution.

In this study, we attempted to develop a spectra-based soil erosion mapping approach to pinpoint eroded hotspots in a typical catchment located in the black soil region of Northeast China as characterized by undulating landscapes. We built a ground-truth dataset consisting of three classes of soils representing Severe, Moderate, and Low erosion intensity because of their inter-class contrasts in estimated erosion rates from ¹³⁷Cs tracing. The spectral separability of different erosion classes was first tested by a combined principal component and linear discriminant analysis (PCA-LDA) against laboratory hyperspectral data and then validated against Sentinel-2 derived broadband spectra.

We will present results on the performance of the PCA-LDA model to classify soil erosion intensity classes based on laboratory and satellite-based soil spectra. We further identified distinctive spectral features representative of shifting soil albedo and biochemical composition due to erosion-induced SOC mobilization. A classification scheme comprising the spectral features was applied to the Sentinel-2 bare soil composite for pixel-wise soil erosion mapping, from which 15.9% of the catchment area was detected as erosion hotspots while the Moderate class occupied 65.4%.Our study highlights the potential of the spectral-based remote sensing approach for  better targeted cropland management to combat soil degradation.

How to cite: Qi, L. and Shi, P.: Detection of soil erosion hotspots with accelerated carbon losses in the black soil region of Northeast China as driven by Sentinel-2 multispectral remote sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4089, https://doi.org/10.5194/egusphere-egu23-4089, 2023.

In the Mediterranean area of southern Spain, a well-defined rainfall gradient is identified, ranging from 1.000-1.500 mm annual rainfall in the western sector to less than 150 mm in the extreme east. This fact implies a related impoverishment of ecosystem services, intensified by the impacts of current climate dynamics and leading to a degradation of soil-water-plant relationships and reflected in different indicator properties. In this respect, protected natural environments have a fundamental role to preserve and protect ecosystem services. Thus, the mitigation of the effects of climate change on them is a crucial challenge.  For this reason, this study has focused on the Cabo de Gata-Níjar Natural Park (UNESCO Global Geopark), located at the eastern end of the above-mentioned gradient, with territorial characteristics related to arid and semi-arid climatic conditions where the consequences of the current pluviometric pattern are emphasising the vulnerabilities of these areas. This research aims to (i) analyse the eco-geomorphological dynamics in last decades from a climatic and vegetation cover perspective and (ii) contrast this evolution with the soil quality situation, with emphasis on soil organic properties as determinants of the main degradation processes in the Mediterranean area. Methods used combine the statistical analysis of climatic variables based on data from the SAIH Hidrosur Network (1997-2022) with the use of spatial remote sensing techniques by applying vegetation indices in Sentinel-2 images. In addition, a total of 276 soil samples were collected and analysed to determine their physical, hydrological, and organic properties. On a preliminary way, the results show large differences between different landscape units. On the one hand, areas where abiotic factors control the current eco-geomorphological dynamics and where the aggressiveness of rainfall is causing important degradation processes, a reduction in the organic content of soils and, in general, a dynamic associated with rhexistasy, and on the other hand, areas where biotic factors are improving environmental conservation and the prevalence of biostasy processes.

How to cite: Espinosa-Muñoz, J., Sillero-Medina, J. A., and Ruiz-Sinoga, J. D.: Eco-geomorphological repercussions of recent climate dynamics on soil quality from Cabo de Gata-Níjar Natural Park (Almería, Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5030, https://doi.org/10.5194/egusphere-egu23-5030, 2023.

In the context of global soil degradation, biochar is being promoted as a potential solution to improve soil quality in addition to its carbon sequestration potential. Burying biochar in soils has been shown to affect soil physical properties, but the intensity of this effect depends, among others, on soil properties and application rates. Moreover, the long-term effects of biochar remain largely undocumented yet they are important to quantify given biochar’s persistency in soils. The objective of this study was therefore to determine the short-term and long-term effects of biochar on soil physical properties in function of soil texture and biochar application rates. For this purpose, experiments were conducted in Wallonia (southern Belgium) at two sites with different soil texture (silt loam and sandy loam). Both sites are characterized by the presence of former kiln sites that were used for studying the long-term (> 150 years) effect of hardwood biochar. In addition, fresh biochar produced from Picea abies at 500°C by GreenPoch SA was buried in subplots at both sites at rates of 1% and 2% in mass in the top 10 cm just before the spring sowing in 2021. Samples were collected on September 2021 in kiln sites, in fresh biochar (1 & 2%) subplots and in biochar-free reference plots, in triplicate. The measured soil physical properties were the bulk density, the water retention curve and the hydraulic conductivity curve.

Reference subplots were characterized by higher bulk density and lower saturated water content than biochar subplots. The presence of biochar increased the water content for pF < 1.5. These biochar effects were higher for the sandy loam compared to the silt loam and in the short-term compared to the long-term. The plant available water capacity increased with the presence of biochar on the sandy loam, but was unaffected on the silt loam. The hydraulic conductivity was slightly higher for pF < 1.5 in the biochar subplots compared to the reference subplots. On the silt loam, this effect was more visible for fresh biochar whereas on the sandy loam, this effect was higher in the kiln sites. Therefore, the study highlighted a positive effect of biochar in the short-term and in the long-term on soil physical properties for the range of soils and biochar application rates investigated here. Further research may be needed to confirm the observed trends over a wider range of soil types, biochar types and biochar application rates as well as to better understand the underlying mechanisms.

How to cite: Zanutel, M., Garré, S., and Bielders, C.: Short- and long-term changes in soil physical properties following biochar addition to soils with different textures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5160, https://doi.org/10.5194/egusphere-egu23-5160, 2023.

The splash phenomenon is one of the stages of water erosion, i.e. a process that causes soil degradation. The crux of splash is the detachment and displacement of soil particles due to the impact of raindrops. Another important aspect of the phenomenon is that a deformation called a crater is formed at the point of the impact. Research on craters helps to expand the knowledge of the splash phenomenon and may contribute to understanding its relationship with successive stages of water erosion. The quantities used to describe the deformation include static dimensions (e.g. depth or diameter of the crater) and dynamic quantities to describe the course of the deformation (e.g. the time for the crater to reach a stable shape). The small size of the craters and the high dynamics of their formation induce the use of accurate and advanced measurement methods.

The aim of the work is to present selected non-contact methods for measuring craters formed on soil after a drop impact.

The study was focused on photography, high-speed imaging, 3D surface modelling, and computed tomography (CT). The discussion of the methods includes a brief description of the measurements, the range of quantities that can be determined with the methods, and indication of their strengths and weaknesses. Knowledge of these issues allows making an informed choice of measurement methods when planning new experiments or projects, which may significantly affect the results that can be obtained.

References

Mazur, R.; Ryżak, M.; Sochan, A.; Beczek, M.; Polakowski, C.; Bieganowski, A. Soil Deformation after Water Drop Impact—A Review of the Measurement Methods. Sensors 2023, 23, 121. https://doi.org/10.3390/s23010121

This work was partially supported by the National Science Centre, Poland within the framework of project no. 2020/37/N/ST10/03363.

How to cite: Mazur, R., Beczek, M., Ryżak, M., Sochan, A., Polakowski, C., Gibała, K., and Bieganowski, A.: Non-contact methods for measuring craters formed on soil after a drop impact, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5433, https://doi.org/10.5194/egusphere-egu23-5433, 2023.

Soil erosion is one of the most recurrent environmental problems of public interest today. The western Mediterranean is an area sensitive to the effects of Climate Change, according to the latest IPCC Sixth Assessment Report, due to the proven increase in extreme events such as heat waves, extreme rainfall and droughts. Within this, the importance of competition in the territory between tourism and agriculture will be the result of radical changes in land use that are affecting the ecomorphological system to the point of making it even more susceptible due to the emergence and increase of high risks in the Mediterranean basins. Therefore, it will be essential to determine the levels of susceptibility of the basins under study with respect to erosive processes in order to create new mitigation measures to improve soil management and reduce these risks. Through this study we intend to analyze changes in land use and territorial susceptibility in several basins in southern Spain, in Malaga. The main objective is to determine the incidence and susceptibility of these basins and to analyse how they have been affected by land use changes through an observation of land use changes and the application of the RUSLE model. This project will look at the differences between two contrasting basins. One basin with steep slopes and the emergence of more sensitive crops, such as vineyards, which will increase the fragility of Mediterranean basins after torrential events, causing the appearance of a higher risk of erosion, while the other basin will be differentiated with the appearance of clearings that decrease the steep slopes together with changes to more competitive crops, such as subtropical crops. The results demonstrate the correlation between land use and torrential events in Mediterranean basins with respect to their susceptibility in their ecogeomorphological system.

How to cite: Triano-Cornejo, A., Pérez-González, M. E., and Ruiz-Sinoga, J. D.: Land use changes and spatial susceptibility in small Mediterranean basins, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5853, https://doi.org/10.5194/egusphere-egu23-5853, 2023.

In Switzerland, soil erosion by water is a challenge due to the complex topography. It is stipulated by law that a soil removal rate of 2 t/ha/yr (for soil depth < 70 cm) or 4 t/ha/yr (for soil depth > 70 cm) on arable land must not be exceeded as a long-term average. Furthermore, an impairment of soil fertility and of water bodies and near-natural habitats due to erosion should be avoided by all means.

In this study, we calculated the actual erosion risk on arable land of Switzerland for 2021 using newly available data sources on crops and tillage practices. The erosion risk was calculated with the Revised Universal Soil Loss Equation:

A = R∗K∗L∗S∗C∗P

With R = rainfall and surface runoff factor, K = soil erodibility factor, L = slope length factor,  S = slope gradient factor,  C = soil cover and cultivation factor, and P = erosion control factor.

The product of the factors R∗K∗L∗S represents the potential erosion risk. For the calculation, we used the available potential erosion risk map by Bircher et al. (2019).

To derive realistic C factors adapted to Swiss climate conditions, the following procedure was applied: average crop-specific C  factors for two geographical regions (valley, mountain) and three distinct tillage types (plough mulch, direct seeding) were deduced from data of the Swiss agri-environmental monitoring programme (SAEDN; Gilgen et al. 2023), which provides detailed management data on the field level of approximately 300 farms since 2009. The categorised C  factors were allocated to individual parcels using geo-referenced crop area polygons of the Swiss cantons as well as direct payment data from the Federal Office for Agriculture on crop-specific tillage types.

Since no data on the P factor was available, it was estimated using expert knowledge. Calculation was carried out on a 2x2m grid and summarised at municipality level.

Our calculations represent the best yet for Switzerland's actual erosion risk. However, a comparison with the erosion that has actually occurred, as carried out by Bircher et al. (2022), is still pending. The described method can be used in the future for monitoring that focuses on the environmental impact of farmers' management changes. A prerequisite for this is that sufficiently detailed data on farm management continues to be available.

References:

Bircher, P., Liniger, H.P., and Prasuhn, V. (2019): Aktualisierung und Optimierung der Erosionsrisikokarte (ERK2): Die neue ERK2 (2019) für das Ackerland der Schweiz: Schlussbericht. Bundesamt für Landwirtschaft, Bern 

Bircher, P., Liniger, H.P., and Prasuhn, V. (2022): Comparison of long-term field-measured and RUSLE-based modelled soil loss in Switzerland. Geoderma Regional, 31, e00595, https://doi.org/10.1016/j.geodrs.2022.e00595

Gilgen, A., Blaser, S., Schneuwly, J., Liebisch, F., and Merbold, L. (2023): The Swiss agri-environmental data network (SAEDN): Description and critical review of the dataset. Agricultural Systems, 205, 103576, https://doi.org/10.1016/j.agsy.2022.103576

How to cite: Gilgen, A., Blaser, S., Schneuwly, J., Hutchings, C., and Prasuhn, V.: Modelling Switzerland’s actual erosion risk on arable land, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6421, https://doi.org/10.5194/egusphere-egu23-6421, 2023.

Soil erosion is a result of detachment and transport of particles or small aggregates from the soil surface. Previous research has predominantly focused on studying the effects of either rainfall or wind on soil erosion processes as separate erosive agents. To date, there have been only few studies into the simultaneous effect of both agents operating at the same time on soil erosion and hydrological processes. In this research, the effect of wind velocities on the erosivity of rainfall was studied, comparing windless rain (WLR) and wind-driven rain (WDR) events when applied to a sandy loam soil. A moderate slope gradient of 11%, a simulated rainfall intensity of 90 mm hr^-1, a rainfall duration of 30 minutes and wind velocities up to 9 m s^-1 were used. The runoff, infiltrate and soil loss (including splash erosion measured at different heights) were compared between the different events and treatments. The soil surface roughness was measured before and after the rainfall event, using a hand-held laser scanner, to evaluate the effect of WLR and WDR on the surface morphology. The outcome of this study shows that, for the smooth surface under WDR, infiltrate volumes were less than under WLR and decreased with increasing wind velocity, while the runoff volumes increased under WDR compared with WLR. The rate of rainsplash erosion increased under the WDR event compared to the WLR event at all heights. The amount of splash-eroded particles decreased with height above the soil surface. We conclude that wind has an effect on the erosivity of rainfall; therefore, it should be considered in erosion studies.

Acknowledgments: This work was funded by OCP group, Morocco

How to cite: Bahddou, S., Otten, W., Whalley, R., Shin, H.-C., El Gharous, M., and Rickson, J.: Effect of wind-driven rain on runoff, infiltration and soil erosion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8245, https://doi.org/10.5194/egusphere-egu23-8245, 2023.

Mediterranean ecosystems are already under pressure from the combined impacts of direct human activities and anthropogenic climate change. In this highly human-managed region, land degradation and accelerated dryland expansion threaten the biological systems and the natural resources that sustain agriculture and forests [1]. The question of "what is the driving force of the changes," and specifically whether anthropogenic climate change or direct human management is to blame, is crucial. The attribution of these changes plays a key role in better managing the arid and semiarid Mediterranean agro-ecosystems, especially considering a different future climate. Here we examine the net effect of anthropogenic climate change-induced changes in the state of two significant land degradation factors, aridity and rainfall erosivity, across the Mediterranean.

We rely on a state-of-the-art counterfactual stationary climate dataset, a hypothetical climate in a world without climate change [2], to estimate impact indicators since the onset of industrial revolution (1900-2019). We compare results against aridity and rainfall erosivity calculated from observational (factual) climate data to examine historical imposed long-term changes attributed to human induced climate change. The difference between past impacts and counterfactual impacts is a proxy for a broad-scale concept facilitating a top down approach to define degradation and physical vulnerabilities of Mediterranean agro-ecosystems, in the frame of REACT4MED project. We further analyze scenarios of future climate change to unravel future trends. The information is further downscaled at pilot area level to support the co-development and analysis of local-scale indicators. Results will serve as a basis for the detection of potential future degradation trends used in the identification of potentially suitable areas in the Mediterranean for up or out-scaling of restoration measures beyond REACT4MED pilot areas.

[1] Daliakopoulos, N., et al. "Yield response of Mediterranean rangelands under a changing climate." Land Degradation & Development 28.7 (2017): 1962-1972.

[2] Mengel, M., et al. “ATTRICI v1.1 – counterfactual climate for impact attribution.” Geosci. Model Dev., 14, 5269–5284.

Acknowledgements: This work has received support from REACT4MED (GA 2122) PRIMA funded project, supported by Horizon 2020.

How to cite: Koutroulis, A., Grillakis, M., and Tsilimigkras, A.: Historical evolution and future storylines of degradation drivers in Mediterranean arid and semiarid agro-ecosystems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8611, https://doi.org/10.5194/egusphere-egu23-8611, 2023.

The crop cover-management (C-) factor in arable landscapes describes the soil erosion susceptibility associated with seasonally cultivated crops. Previous informatic and computational limitations have led many modelling studies to prescribe C-factor values and assume spatial and temporal stationarity. However, the multiple influencing factors ranging from parcel-scale crop cultivation and management to regional-scale rainfall regimes motivate new methods to capture this variation when identifying at-risk areas. Modern data systems (in this case: field parcel vector data, Sentinel-2 time series, rainfall erosivity time series networks, EU-scale land survey (LUCAS) and European regional statistical data) provide spatially and/or temporally dense information sources on which scalable model parametrisation frameworks can be built and updated. Here, we define a multi-component method to derive the C-factor by associating time series of canopy and residue surface cover from Sentinel-2 and climate-specific rainfall erosivity with Integrated Administration and Control System (IACS) field parcel data from European Union Member States. A standardised approach is emphasised to increase the future interoperability and inter-comparability of soil erosion modelling studies deploying the C-factor. Additionally, field parcel simulation units with associated crop declarations provide a new reference scale to link predictions of soil erosion risk with specific management decisions and declarations by farmers. After implementing the method on a homogenised subsample of 8600 field parcels covering available IACS data regions, several key findings are outlined: 1) time series information provides new opportunities to predict the time-criticality of erosion in specific crop cultivations, 2) the varying (a-)synchronicity between seasonal crop canopy cover and heavy rainstorms means that spatial variability is inherent within the C-factor across Europe, and 3) the addition of agricultural management practices (e.g. tillage practice descriptions) to open-access IACS repositories can facilitate more comprehensive evaluations of the C-factor and soil erosion risk in the future.

How to cite: Matthews, F., Panagos, P., Borrelli, P., and Verstraeten, G.: A crop phenology-based approach to quantify the C-factor at the field-parcel scale in Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8889, https://doi.org/10.5194/egusphere-egu23-8889, 2023.

Soil erosion by water is considered as one of the most serious processes degrading the soil functionality of arable soils around the globe. To assess the risk of water erosion at larger scales, the universal soil loss equation (USLE) and its derivates are commonly used for the implementation of policy instruments.

An important factor needed within (R)USLE model exercises is the K-factor, which reflects the natural erodibility of the topsoil. The spatial explicit determination of the K-factor is crucial to create reliable soil loss estimate maps. However, the accurate estimation of the K-factor at the regional level is challenging due to different existing calculation methods and as a variety of spatial data (e.g. soil texture fractions, rock fragments, soil organic matter) is needed. The latter severely limits the choice of available data, which differ in spatial resolution and information content of the required parameters. This leads to a high potential of uncertainty in the regional estimation of K-factors, but also of the soil erosion estimates at regional level.

Therefore, the aim of the study presented is to determine the spatial and quantitative accuracy of different soil data sets and calculation methods for estimating the K-factor for Germany. Furthermore, the influence of possible uncertainties on the estimation of soil erosion risk by combining all factors of the (R)USLE should be evaluated. Based on the aim of this study we modelled K-factors for three available harmonized German-wide datasets: I) LUCAS soil dataset of Europe), II) BÜK1000 and III) BÜK200 (soil overview maps for Germany) using the existing equations of A) Wischmeier and Smith (1978) and its extension of B) Auerswald et al. (2014) representing the original K-factor nomograph. For the validation of the three datasets, K-factors based on 2234 arable soil profiles across Germany from the Agricultural Soil Inventory (BZE_LW) with most detailed soil information were calculated.

The results reveal significant differences between calculation methods and data sets for the German-wide assessment of K-Factors. The LUCAS soil dataset overestimates average K-Factors of the BZE-LW by ~ +21 % (RMSE = 0.015, R² = 0.30), while BÜK200 underestimates K-Factors by ~ -30 % (RMSE = 0.016; R² = 0.34). In contrast the calculation method has a low impact on the average K-Factor estimation (~ 5 %) while the RMSE is comparable high with 0.012 (R² = 0.57).

The results imply that the choice of the calculation method and dataset at regional level is important and that detailed information on soil texture (e.g. very fine sand fraction) are crucial and strongly needed in order to improve the estimation of reliable K-Factors and soil erosion risk on regional-scales. 

How to cite: Saggau, P. and Steinhoff-Knopp, B.: Uncertainties in the regional estimation of Soil Erodibility. A German wide evaluation of the K-Factor comparing current datasets and calculation methods., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9045, https://doi.org/10.5194/egusphere-egu23-9045, 2023.

The (R)USLE and its many derivates are the most used models to estimate soil loss by water at regional scale. Within the (R)USLE the C-factor is used to assess the impact of crop and soil management on erosion. The exact, temporal and spatial explicit determination of the C-factor is crucial to create reliable maps on soil loss estimates, monitoring the impact of agricultural practices on soil erosion and evaluating the efficiency of policy instruments.

The derivation of accurate high-resolution C-factor data for larger regions remains a challenge, as a variety of spatio-temporal data (crops/crop rotation, tillage management, interannual variation of rainfall erosivity) is needed. Based on recent improvements in calculation methods and the availability of earth observation data, the C-factor can be estimated using agricultural statistics and parcel-based information on crop cultivation. Consequently, we developed two types of spatially explicit and regional C-factor datasets for Germany, mapping the impact of agricultural practice on soil erosion in a more reliable and spatially detailed way: i) harmonized mean C-factors for municipalities for 1999, 2003, 2007, 2010, 2016 and 2020, and ii) parcel-based C-factors for the period 2017-2020 based on crop type maps from satellite data.

In this contribution, we will present the implemented methods and will discuss the impact of the new detailed C-factor maps on soil loss estimates in a spatial resolution of 10 x 10 m for German cropland. The results show an increase in the C-factors for municipalities during the last two decades by 17 %. The parcel-based data reveals the C-factor ranges within the municipalities: While the mean C-factor for all parcels across Germany is 0.107 (conventional cropping; 2017-2020), the standard deviation within the municipalities ranges from 0 to 0.141 at a mean standard deviation of 0.045. This results in differences in erosion rates of up to 7 t / (ha • a), highlighting the importance of spatially explicit C-factor estimates.

How to cite: Steinhoff-Knopp, B. and Saggau, P.: The impact of new detailed (R)USLE-C-factor maps for Germany on soil loss estimates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9334, https://doi.org/10.5194/egusphere-egu23-9334, 2023.

A large effort has been devoted over the past century to assessing soil erosion using a variety of methods under a wide range of climatic conditions, soil types, land uses, topography, and others. Thus, we attempt to provide an analysis of national data of several soil erosion modeling and fingerprinting. The methodology adopted for this research is a review of scientific articles, conference papers and thesis on soil erosion, focusing more on categorization of the different soil erosion models and methods applied. Based on the statistical analysis provided by this review, the results are as follows: (i) Even though the threat of soil erosion is grave, the number of studies conducted to characterize and evaluate soil erosion in Morocco is limited. (ii) Studies on water erosion modeling are concentrated in the north of the country (Rif 32.89%, High Atlas 32.89%, Occidental Meseta 18.43% and Middle Atlas 10.53%). (iii) Water erosion models have been steadily developed and interfaced with GIS based approaches in recent decades. (iv) Although Morocco is geomorphologically and geologically varied (Rif, Middle and High Atlas, Mesetian and Saharan domain), several authors use soil erosion assessment models that ignore the unique characteristics of each study area and fail to adapt them to local conditions. (v) USLE (R) models have been widely used and modified over the past two decades and remain the most commonly used modeling tool today. (vi) The largest proportion of the erosion rate is concentrated in the Atlas and Rif mountains. (vii) Demonstration of a strong relationship between soil erosion rates with environmental factors and modeling conditions, and the lack of correlation with study area size and erosion rate. While the overall results show a relatively high variance, which cannot be explained by this combination of factors, it is partly related to the experimental conditions. This review is intended to support future soil erosion assessment and to facilitate the identification of priorities for soil erosion research in Morocco by supplying a state of the art for future targeted and comprehensive analyses to deal with the issue of soil erosion in Morocco.

Keywords: Soil water erosion models, Fingerprinting methods, Literature review, Morocco.

How to cite: Lamane, H., Mouhir, L., Moussadek, R., Baghdad, B., Briak, H., Zouahri, A., and El Bilali, A.: Statistical analysis of a systematic review on soil water erosion assessment in Morocco, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9800, https://doi.org/10.5194/egusphere-egu23-9800, 2023.

Soil erosion and associated land degradation, accelerated by anthropogenic activities, are serious worldwide environmental problems that can reduce crop productivity and cause on- and off-site damages resulting from sediment transport and deposition. A common feature of the agriculture-dominated landscape of the Prairie Pothole Region in western Canada is depressional wetlands (typically 10 to 20, small seasonal to permanent waterbodies per square kilometer).  These wetlandscapes are fragile agro-ecosystems that have been disturbed and impacted through human-induced soil erosion, receiving influxes of sediment and associated constituents (e.g., phosphorus, organic carbon and pesticides) from the surrounding local and regional sources (e.g., cultivated fields). The general objective of this study was to estimate the severity of soil loss and sedimentation rates, and sediment flux from surrounding cultivated fields into wetlands. The study area included two sub-watersheds in the Prairie Provinces of Manitoba and Alberta, within the Canadian portion of the Prairie Pothole Region. Soil and sediment cores were collected along multiple transects from the uppermost portion of each catchment to the central area of the wetland.  Transects were distributed within catchments to capture the variability resulting from the topographic complexity. The results of this study demonstrated high rates of soil loss in the upper slope and middle slope positions, and high rates of deposition in lower slope and foot slope positions of wetlandscapes. Furthermore, the areal average of transect data provided sediment delivery ratio estimates of 57% for Manitoba and 35% for Alberta, which indicates that a relatively high amount of the mobilized sediment was exported beyond the cultivated fields towards the wetlands, mostly deposited in riparian areas.

How to cite: Zarrinabadi, E. and Lobb, D. A.: Assessing soil erosion and sediment flux using 137Cs within topographically complex landscapes of Prairie Pothole Region of Canada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9841, https://doi.org/10.5194/egusphere-egu23-9841, 2023.

Gully erosion is regarded as one of the worst land degradation processes in the world. It is a complex geomorphic process resulting in on-site land degradation due to the removal of soil, and off-site land degradation, due to mobilised soil, pollutants, and pesticides adversely affecting soil and water resources. Climate change predictions show that the frequency of high-magnitude rainfall events will increase, thereby exacerbating the degradation impacts of gullying. By assessing long-term datasets (>30 years), the relationship between gully evolution and climate variability can be observed, providing potential insight into gully evolution under climate change. We aim to isolate climate as a driving factor by investigating three sites under similar land-use, environments transformed into conservation areas but exhibiting contrasting climates. The sites are in South Africa (SA), located in the arid Karoo, a Lowveld area with Savanna land cover and a humid Grassland region. A triangulation of methods was implemented, including i) digitising gully change from remotely sensed imagery spanning up to 78 years, ii) conducting field measurements, and iii) interviewing land managers. In the arid Karoo, gullies were discontinuous, forming successive chains waning into deposition zones, only to be reactivated again with an abrupt headcut downstream of the depositional area. Continuous gullies were found in the Grassland and Savanna regions. Remotely sensed image analysis shows a mean annual linear expansion along the main drainage line was the largest in the Savanna, 2.8 m, compared to 0.5 m and 0.4 m recorded in the Grassland and Karoo. However, the mean planimetric area changes of gullied extent were 6 and 8.4 times larger in the Grasslands compared to the Karoo and Savanna. Fieldwork confirmed active gully processes at all three sites, identifying active sub-surface processes, only found in the Grassland, as the leading cause for the morphological difference between the extensive Grassland gullies and the narrower linear gully features in the Savanna and Karoo. However, certain gully headcuts in the Karoo present as bulbous transforming into narrower downstream channels, most likely a result of being artificially enlarged from failed gabion installations at the headcut. During interviews with land managers, concerns about contemporary gully erosion were noted at all three sites, with the implementation of mitigation measures ongoing. There is consensus among the three methodologies, identifying that gully erosion remains stubbornly active, even after transforming to a conservation-orientated land-use. In the Karoo and Savanna, human influence and rainfall variability were attributed as causal factors of gullying, inherited from ill-placed farm roads and overgrazing, respectively. In the Grasslands, soil type is deemed the dominant driver of gullying, although animal tracks (specifically those from antelope) forming pathways for water after rainfall was contentious. Our analysis shows that gully erosion severity follows the climate gradient of SA. However, it remains difficult to completely isolate climate as a driver due to different inherent soil properties, geology, and slope. We expect an increase in gully erosion for all three sites under climate change predictions, although more pronounced in the Grassland region.

How to cite: Olivier, G., Van De Wiel, M. J., and De Clercq, W. P.: Historical evolution of gullies: Impact of climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10002, https://doi.org/10.5194/egusphere-egu23-10002, 2023.

With environmental protection becoming more and more important in recent years, the suitability of traditional regulation methods in rivers such as bank protection and river cutoff begins to be challenged. The regulation methods combined with ecology have become an important goal in natural rivers nowadays. In this research, a series of flume experiments were conducted to discuss the effect of bank erosion on vegetation roots between bare and vegetated banks.

The experimental parameters of flow discharge, water depth,  and channel slope are 0.014 , 9.5 cm, and 0.001, respectively. A kind of vegetation, Vigna radiate, is planted in cultivation boxes for 1 – 2 weeks and then moves into the channel as the vegetated banks. A laser scanner is set up on the flume channel to record the variation of initial and final topography. The results show that the erosion ratios of bare and vegetated banks are 40.24 % and 24.34 %, respectively. The root system of vegetation has a function of anti-erosion on river banks. In addition, we observe the exposed roots formed a protective layer along the flow direction on the bank over a period of time after beginning the experiment. The protective layer by roots helps the river bank resist water erosion and reduce the amount of erosion in the covered area.

How to cite: Chiang, Y.-C., Li, J.-F., and Chen, S.-C.: Effects of vegetation root on erosion degree under different arrangements of river banks., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11081, https://doi.org/10.5194/egusphere-egu23-11081, 2023.

Gully erosion is a damaging process not yet sufficiently understood and parameterized. Gully head topographic thresholds are empirical models used to predict the gully head formation. Such model have been used to investigate gully processes mostly in cropland, rangeland and forest. This study extends such modelling approach to badlands. Different badlands (eight sites) have been studied in the Mediterranean environment in Italy and Spain, characterized  by diversified climatic, lithological, and geological settings under different anthropogenic conditioning. Badlands have been characterized by their specific human history in addition to their geomorphological properties. Land use, as part of the human history, strongly affected many badland formation and development, through  extremely impacting land exploitation (usually overgrazing). The effect of geological and geo-morphological processes are usually particularly well visible. While the weakening effect of joints is confirmed, the different geological layer bedding orientation with respect to the slope aspect generates a different development of badland morphologies and different values of gully head thresholds values (as shown in two badlands sites on the same geological material and climate). The selection of Curve Number values, at the base of the introduction of land use into the gully head thresholds, has been more objectively defined in order to reduce arbitrariness in threshold application. The study additionally revises some of the physical basics behind the gully head threshold concept, requiring a description of the soil resistance in terms of frictional and cohesive components. This implies the explicit inclusion of rock fragment into the grain size distribution, which cannot be limited to fine grains. It results into an enriched threshold formulation that allows to describe the condition for gully head initiation and retreat as the result of the tradeoff between the frictional and cohesive components of the soil resistance forces. Eventually, the gully head threshold concept is confirmed and extended to include badlands.

How to cite: Rossi, M., Torri, D., De Geeter, S., Cremer, C., and Poesen, J.: Modelling gully head formation in badlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11902, https://doi.org/10.5194/egusphere-egu23-11902, 2023.

In 2015, during the 12^th Conference of the Parties (COP) a new overall vision objective of the United Nations Convention to Combat Desertification (UNCCD) and the Sustainable Development Goals (SDGs) for 2030 called “Achieving Land Degradation Neutrality (LDN)” was incorporated. NewLife4Drylands (NL4DL; https://www.newlife4drylands.eu/), the LIFE Preparatory project, focuses on the use of remote sensing for the identification of a framework for the monitoring of land degradation and results of nature-based restoration interventions for achieving LDN. With this aim, Indicators and/or their proxies have been extracted from satellite data as essential variables for land degradation status assessment. Six Mediterranean Natura 2000 study sites located in Italy, Greece and Spain were considered as case studies and pressures and threats affecting each of them were analysed as land cover mappings, burn severity mappings, time series of climatic and phenology spectral indices, precipitation indices, soil organic carbon mappings.  Freely available satellite data from Landsat and Sentinel-2 programs were considered: in the case of sites less than 50 hectares in size, commercial satellite data at very high spatial resolution were used for evaluation. The indices analyzed will be integrated for the computation of SDG 15.3.1 indicator “proportion of land that is degraded over the total land area” according to the 2030 Agenda for Sustainable Development and UNCCD guidelines. SDG 15.3.1 standard formula considers sub-indicators to be integrated: trends in land cover, primary productivity and soil organic carbon. The novelty in the project outcomes is two-fold: 1) the estimation of drivers/disturbance (drought, fire, etc.) of LDN together with sub-indicators will allow to give practical indication to land manager; 2) sub-indicators have been computed at the local scale. For each study site, short-term and long-term analyses will be approached. Results will be part of a protocol for the assessment of land degradation and monitoring restoration interventions of degraded land.

How to cite: Tarantino, C., Vicario, S., Adamo, M., Labadessa, R., Assennato, F., Alessi, N., Riitano, N., Vitale, M., Perez, M., Domingo-Marimon, C., Montero, P., and Carabassa, V.: Land degradation estimation by SDG 15.3.1 computed at the local scale: the case of the six Mediterranean study sites of the NewLife4Drylands project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12400, https://doi.org/10.5194/egusphere-egu23-12400, 2023.

Shifting cultivation, also known as slash-and-burn agriculture, on steep terrain has been criticized for causing high rates of soil erosion thus promoting land degradation in South and Southeast Asia. Particularly, short fallow periods resulting from increasing land pressure are suspected of accelerating degradation processes. In addition, the rising frequency of high-intensity precipitation events associated with climate change can be expected to further increase the pressure on shifting cultivation. However, abandonment of shifting cultivation has turned out to be hardly feasible or desirable, particularly, where it provides food security and cultural identity to the tribal population, as is the case in Northeast India. This raises the question how increasing pressure from reduced fallow periods and climate change will affect future soil erosion of uphill shifting cultivation systems. As measured data on these interactions are not available, we applied a modeling approach to identify trends in soil erosion for different slope inclinations, fallow periods, and climate change scenarios. We used the Environmental Policy Integrated Climate (EPIC) Model to simulate daily soil loss for three different climate scenarios (SSP126, SSP370, SSP585) derived from five climate models for the near (2021-2050) and far (2071-2100) future. Simulations were carried out for six collected soil profiles, short, medium, and long fallow periods, and slope inclinations up to 70 %. Our results indicate a negative, non-linear relationship between the length of the fallow period and erosion, with soil loss being more than twice as high for systems with a 10-year compared to a one-year fallow regime. Further, our research demonstrates that long fallow periods can compensate, to a limited extent, for steep slopes. However, climate change, particularly under the medium-high (SSP370) and high-end (SSP585) emission scenarios, will lead to substantial increases in erosion by a factor of 2.2 and 3.1, respectively, towards the end of the century, thus reducing the possibility space for sustainable shifting cultivation.

How to cite: Schröder, L. S., Rasche, L., Jantke, K., Mishra, G., Lange, S., and Schneider, U. A.: Future soil erosion of shifting cultivation on hillslopes – modeling interactions between slope steepness, fallow periods, and climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13380, https://doi.org/10.5194/egusphere-egu23-13380, 2023.

Soil erosion represents a serious challenge for agricultural production and for the environment. Soil erosion impacts, such as reduction of fertile soil, alteration of the carbon cycle and pollution and eutrophication of water bodies, represent a significant management concern for the European Union. Modelling can help define efficient and targeted mitigation strategies by identifying the long-term controlling factors and the areas where, and periods during which, soil is at high risk of erosion. However, to define such strategies, there remains a lack of modelling approaches a) able to provide with longer term baseline information which to measure the success or otherwise of mitigation strategies at the catchment scale and b) accessible and robust enough to be used, understood and trusted by users with more or less expertise, including researchers, land managers and policy makers. In response, this project will improve the robustness and accessibility of quantitative methods for supporting agricultural land management. The objectives of this project are: (i) to develop an accessible soil erosion model, iMPACt-erosion, based on interactive Jupyter Notebooks, to support agricultural land management at the catchment scale, (ii) to apply a robust model evaluation based on the use of both long-term soil loss observations and global sensitivity analysis to achieve greater confidence in model predictions and (iii) to identify the soil erosion controlling processes and vulnerable areas and periods to define targeted and effective mitigation strategies until 2100. We present the model and the first model evaluation results, which show that simulations are consistent with observed soil loss rates (estimated from both fallout radionuclides and tree mound measurements) in the last 60 years in olive orchard catchments in South Spain.

How to cite: Peñuela, A. and Vanwalleghem, T.: iMPACt-erosion: A robust and accessible model for a long-term effective management of agricultural soil erosion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13611, https://doi.org/10.5194/egusphere-egu23-13611, 2023.

Worldwide, soil erosion is one of the main causes of soil degradation and the loss of important soil functions. Wind, water and tillage erosion and their environmental, economic and social impacts have been researched for decades. Soil erosion by root and tuber crop harvesting (SLCH), however, is rarely focused in research, although erosion rates can reach up to 22 Mg ha^-1 harvest^-1 (Parlak et al. 2016).
The aim of this study is to raise awareness of SLCH and to advance research on this topic. To achieve this aim, all available peer-reviewed studies on this topic are used to provide an overview of investigated soil erosion rates worldwide and to identify the environmental impact of SLCH. In addition, the differences between SLCH and other forms of erosion are highlighted. Furthermore, important future research aspects for an enhanced understanding of SLCH are identified.
Comparing soil loss due to crop harvesting with other forms of erosion, it can be stated that (i) erosion rates of SLCH are as high as for water erosion and wind erosion, (ii) SLCH always and only occurs during the harvest of tuber and root crops, which affected 8.4 % of the world’s arable land in 2019 (1.1 million km²), (iii) SLCH can occur at any relief position and any parent material, thus it can be the only erosion process of an affected field without the appearance of wind or water erosion and (iv) SLCH always affects entire fields that are harvested multiple times over several years, depending on the crop rotation.
Based on the reviewed studies, the following further research activities are necessary for a better understanding of the processes of SLCH: (i) global data collection of crops whose erosion rates have not been studied yet, (ii) conduct studies on continents such as North America, South America and Oceania, where data on SLCH erosion rates are currently missing, (iii) development of models to predict SLCH erosion rates and (iv) monitoring the distribution of the adhering soil to evaluate the environmental effects of SLCH.
This review shows that further studies on the topic of SLCH are necessary to quantify actual data on erosion rates for different crops in different regions and provide more awareness of this topic in erosion research.

How to cite: Busche, F., Kuhwald, M., Saggau, P., and Duttmann, R.: Soil loss due to crop harvesting – a spotlight on research gaps and the need of further research activities at the global scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13709, https://doi.org/10.5194/egusphere-egu23-13709, 2023.

In 1993, the Government of Navarre (northern Spain) began the installation and operation of a network of experimental watersheds in order to assess, among other aspects, soil erosion in representative agricultural areas of the territory. Initially, sediment sampling at the outlet of each of the five basins was performed on a daily basis, despite which it was possible to get a highly fruitful and novel knowledge on sediment export (Merchán et al., 2019). However, in the last 16 years, with the aim of studying sediment export in more detail, the sampling frequency was increased so that the behavior of the sedimentogram at the event level could be known. In these cases, when the amount of sediment was large enough, the sediment texture was also determined. In addition, from the beginning of the observations, a turbidimeter was used to record turbidity data every 10 minutes. The aim of this work is to deepen the knowledge of sediment export dynamics in representative agricultural watersheds of Navarre by analyzing the database described above and focusing in specific events. To do this, first, the entire database was represented in graphs that include variables such as sediment texture, samples taken per event, daily mean precipitation, turbidity, flow rate, etc. Next, events with a minimum of six samples were selected and the linear relationship between turbidity and sediment concentration was analyzed using simple linear regressions, as this is the method used in similar works. Subsequently, these same event data were added to set up monthly samples where again linear regressions were performed. Apart from the simple linear analysis, where the linear relationship with turbidity was analyzed as the only predictor variable, different artificial intelligence methods have been explored, such as the generalized linear model (GLM), support vector machine (SVM), multivariate adaptive regression splines (MARS) and random forest (RF), adding additional variables such as accumulated precipitation, and season or water level in the analysis. The results from all these statistical studies have been disappointing, since no pattern or generalization has been found to predict sediment concentration from the variables considered. These results suggest that the sediment export behavior of small agricultural watersheds is particularly complex and controlled by spatially and temporally varying variables. It is evident that at least some of these variables have not been taken into account in the study. The high variability found in sediment textures supports the hypothesis that the erosive behavior of watersheds is of great complexity. We believe that the consideration of variables such as vegetation on slopes and channels and its evolution can be helpful in the analysis.

Merchán, D., Luquin, E., Hernández-García, I., Campo-Bescós, M. A., Giménez, R., Casalí, J., & Del Valle de Lersundi, J. (2019). Dissolved solids and suspended sediment dynamics from five small agricultural watersheds in Navarre, Spain: A 10-year study. CATENA, 173, 114–130. https://doi.org/10.1016/J.CATENA.2018.10.013

How to cite: Barberena, I., Luquin, E., Campo-Bescós, M. Á., Eslava, J., Gimenez, R., and Casalí, J.: Challenges and progress in the detailed estimation of sediment export in agricultural watersheds in Navarra (Spain) after two decades of experience, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13925, https://doi.org/10.5194/egusphere-egu23-13925, 2023.

Freezing is an important factor in soil degradation. In order to predict soil erosion in mountainous areas, the freezing process and the frequency and extent of freezing must be understood. This study aims to identify a relationship between air temperature and a depth of freezing, taking into account soil water content. The soil is considered to be frozen when all the free water within the pores freezes which, according to our numerical model, mainly occurs at temperatures slightly below 0°C. On the other hand, the temperature is not homogeneous in the soil as it is driven by the process of heat diffusion from the soil-atmosphere interface to depth, controlled by soil thermal conductivity and heat capacity, which depend on ice and water contents. As a consequence, the relationship between air temperature and the thickness of the frozen layer is not direct, and the relevance of using air temperature as a measure of frozen depth is to be evaluated.

A small N-S-oriented claystone ridge in an Eastern Pyrenees badland is being monitored. A series of thermometers, water content sensors, and specific heat sensors are collecting data in 5-minute intervals on both sides of the ridge. The data show an attenuation of temperature oscillation with an increasing depth and a time delay of the surface temperature propagation. The differences in the soil temperatures on the north and south side are moreover showing the importance of solar radiation in the process. These observations are further integrated into a procedure allowing for the analysis of possible ad-hoc relationships between current and past air temperature and depth of the frozen layer.

How to cite: Bočková, K., Moya, J., Macías, A., and Vaunat, J.: Field monitoring of cyclic freezing process: effect of air temperature on frozen layer thickness, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14413, https://doi.org/10.5194/egusphere-egu23-14413, 2023.

Land degradation is a global topic in climate change debates resulted from different types of human activities as well as from physical processes. Resilient, healthy soils are important to help reduce the ecological and economic impact of environmental change and extreme conditions. The development of adequate and broadly applicable indicators and thresholds is challenged by the great diversity of European soils and climate, as well as different political, economic, and social conditions which lead to different priority settings for targets and indicators. This work built upon current environmental awareness (e.g CAP, SDGs, etc.) to design a methodological framework for environmental performance metrics related to land degradation. The framework was oriented towards a data-driven environmental metric approach leveraging Copernicus Sentinel-2, existing open-access databases such as LUCAS (Land Use/Cover Area frame statistical Survey) and GEOSS (e.g., Soil Grids) vast dataset archives to provide metrics for environmental actors. Based both on the international literature and European commission documentations this work is focused on the combination of vital importance indicators of soil degradation and soil health. A novel deep learning architecture was implemented to support the final knowledge extraction with a pixel-based spatial resolution of 10m for the determination of Soil Organic Carbon (SOC) and Clay content. The above indicators are used as enhanced geospatial inputs to a soil erosion modelling approach providing improved predictions. A proper approach was followed for the SOC:clay ratio generation and with the soil erosion product combination to provide an ambitious land degradation index. An agricultural area in Northern Greece was used as a demonstration test site area for the proposed methodology.

How to cite: Samarinas, N., Tziolas, N., and Zalidis, G.: Assess land degradation status based on Earth Observation driven proxy indicator, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14553, https://doi.org/10.5194/egusphere-egu23-14553, 2023.

Healthy soil can be defined as a dynamic ecosystem that performs a variety of essential functions such as controlling plant disease, nutrient cycling, improving soil function with positive effects for filtering and storing water, and nutrient capacity, and contributing to improving crop production. Healthy soil also contributes to mitigating climate change by maintaining or increasing its carbon content. Therefore, information on spatial variability of key soil properties is essential for prioritizing and tracking land management interventions, from the small-scale farm level to the global landscape level. In addition, healthy soil is critical for achieving several SDGs such as #2, 3, 6, 13, 15 and 17. However, the determination of soil properties through wet chemistry measurements is often expensive and time-consuming process, and consequently, soil analyses are restricted to a limited number of soil samples. A method that predicts the soil properties fast, inexpensively, and accurately is soil spectroscopy, which can provide immense opportunities for monitoring important soil health indexes. In this study, the evaluation of three algorithms for predicting three key soil properties, soil organic carbon (SOC), pH and Magnesium (Mg) using mid-infrared spectral data were studied using a dataset of more than 3400 samples. The soil samples were collected across Sub-Saharan Africa (SSA) region using the well-established Land Degradation Surveillance Framework (LDSF) method developed from World Agroforestry (ICRAF). The developed trained calibration models were based on the widely used in the soil spectroscopy research Partial Least Squares (PLS) and Random Forest (RF), and the not applied so far Bayesian Regularization for Feed-Forward Neural Networks (BRNN). The dataset was split into calibration (70%) and validation (30%) sets. Furthermore, the threshold of 5% was applied and thus, only the data with value that lie between 5% and 95% of each soil property were included. In this way, the extreme values that will bias the model and the predictions were excluded. Results has shown that the calibration model developed based on the BRNN algorithm yielded the more robust predictions among the three studied soil properties (R² of val 0.90, 0.92, 0.87 for pH, Mg, SOC, respectively). The predictions utilizing soil spectroscopy for determining soil properties in this study are showing its extremely potential to be beneficial in the support of soil health.

How to cite: Pittaki, Z., Vagen, T.-G., Karari, V., Weullow, E., Ateku, D. A., and Winowiecki, L. A.: Towards a more sustainable global soil health monitoring through soil spectroscopy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15335, https://doi.org/10.5194/egusphere-egu23-15335, 2023.

The present study performs a simulation of soil organic carbon (SOC) dynamics in Romania by coupling an evolution model of organic carbon with an erosional model. The simulation starts from the current SOC reserve, computed for the first 20 cm of soil, based on organic carbon content and bulk density, the latter being estimated through a pedotransfer function. The evolution model of SOC takes into account the annual accumulation of organic residues, the active and stable organic carbon contents, the humification and mineralization rates. The annual accumulation of organic residues is estimated from crop type for the arable land and from Corine Land Cover land use / cover types for the rest of the territory. The humification rate of organic residues is expressed through the izohumic coefficient, which depends on the land use/cover type. The mineralization rate of the active organic carbon content depends on climate factors (temperature) and granulometry (clay content). The application of the SOC evolution model produces an estimation of SOC accumulation under automorphic conditions. On the other hand, erosional processes determine soil loss and implicitly soil carbon loss. To account for this impact, we used an erosion model based on the universal soil loss equation, which was adapted and validated for the Romanian territory. Assuming the annual erosion rates are constant, our 50 years simulation show that important areas of the country, situated in the plateau and hilly regions, are experiencing a regressive dynamic of SOC. Under climate change scenarios, the temperature increase may enhance the mineralization of active SOC, leading to a more intense depletion of soil fertility.

How to cite: Patriche, C. V., Vasiliniuc, I., Roșca, B., and Pîrnău, R. G.: Simulation of spatial and temporal dynamics of soil organic carbon reserve in Romania, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16219, https://doi.org/10.5194/egusphere-egu23-16219, 2023.

Tunisia is an agriculture country. Such as many other Mediterranean countries precipitations  remains a decisive factor not only for the different agricultural uses of lands (rainfed or irrigated system) but also for the soils erosion. The latter  is accentuated by agricultural practices (tillage, pesticide inputs, low crop residue restitution…) which are often productive but do not protect natural resources. All these factors have led to the development of conservation agriculture based on no-tillage as a mean to combat soil erosion. In fact, in Tunisia, no-tillage areas increased from 52 ha in 1999 to 17000 ha in 2020. Based a set of 20 plots covering 6 soils types and located in the semi-arid area of the country, a periodic monotoing of a set of soil parameters were done during three years, which include soil sensitivity to erosion according Le Bissonnais method, soil organic matter content and soil microbial respiration. For each plot, a half  of the surface was no-tilled and the other half was conducted according the conventional method based on soil returning. The results show a rapid effect of no-tillage on soil erosion, since an improvement of 18%, 42% and 39% of soil resistance to erosion, respectively after the first, second and third year of switching to no-tillage system. The soil microbial activity response was also significative, whit a progressive increase of soil respiration in the no-tilled treatments compared to tilled treatments. The microbial respiration was higher in non-hydromorphic soils and particularity in the red Mediterranean soils, calcic-magnesic soils and isohumic soils were moisture conditions was the most favorable for a development of soil microorganisms. For soil organic matter content, the evolution trend was not detectable in relation to the slow evolution of this soil parameter. However, the evolution of particulate organic matter content (a part visible of soil organic matter, with a size larger than 2mm) shown an increase in no-tilled treatments comparative to the tilled treatments. The increase of the particulate organic matter content was more important in vertisols, podzol, calcic-magnesic soils and isohumic soils in relation with their higher wheat production compared to other studier soil types.

How to cite: Annabi, M., Bahri, H., Cheikh M'hamed, H., Barbouchi, M., and Toukebri, W.: Conservation Agriculture to Rebuilt Soil Fertility in Northern Tunisia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16736, https://doi.org/10.5194/egusphere-egu23-16736, 2023.

Gully is an issue of the climate crisis in most coastal areas of the world. More than 70% of the world's sandy coastlines would be eroded in recent decades. Anthropogenic climate change is one of key factors controlling soil erosion occurrence. Soil erosion control is extremely important for soil conservation work and territorial planning. The municipality of Nacala, province of Nampula, Mozambique, has gully susceptibility as a known problem. The Japan International Cooperation Agency (JICA), concerned about the intense urban erosion in the Nacala region, which causes problems not only for the population living in critical areas but also for the proper functioning of the Nacala Port, has been making efforts to identify the causes and mechanisms of the phenomenon and suggest corrective and preventive measures covering the area of the Mocone basin, Nacala. Thus, we obtained information on the causes and mechanisms of evolution of these phenomena to allow the joint search for the features that determine the natural susceptibility to erosion of the municipal territory. We also identified that the soil type in the Mocone basin is sandy-clayey, with an infiltration capacity of 50mm/hour, erodible, with a drainage network mainly characterized by rills and gullies, with periodic surface runoff, only during heavy rains. Our studies indicated a catchment with a significant area upstream of the erosion process (2.34 km²). The maximum project flows obtained in the our preliminary hydro-meteorological studies, considering intense rains with a return period of 100 years, and with duration equal to the time of concentration of the catchment basin (90 min), also proved to be quite significant, with values above of 25 m³/s. Accelerated erosion in this location seems to occur, preferentially, in sectors where those natural factors have been exacerbated by anthropic factors due to inadequate occupation of the physical environment. This urbanization resulted in waterproofing, an increase in surface runoff volumes and a reduction in the concentration time of this basin. In addition, the rainwater drainage of some streets was released directly into the natural terrain, without the proper hydraulic works to reduce energy. The rapid development of the erosion branch towards the Nacala Port proves this close relationship between inadequate urban drainage and the evolution of the analyzed erosion process. The results obtained also prove, once again, the importance of analysis and mitigation approaches for large scale erosion processes that contemplate the catchment basin in its entirety, where erosion control practices or changes in soil cover are necessary.

How to cite: Ferreira Lima, I., Kobayashi, C., da Silva, B., So, Y., and Hitomi, Y.: Influence of anthropogenic climate change on soil erosion occurrence: Gully Nacala, Mozambique, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16894, https://doi.org/10.5194/egusphere-egu23-16894, 2023.

Wildfires consist in an environmental problem with a global dimension, but also with future demands as fire prone regions will likely increase, driven by new climate constrains but also socioeconomic drivers. Similarly to other land degradation pressures, despite the large scale of its occurrence, wildfires impacts require assessment and mitigation actions at local scale. Therefore, there is an urgent need to identify local agent’s perspectives regarding wildfires impacts in the ecosystems, and incorporate their local knowledge into post-fire land management decision making. Can a local analysis contribute to political decision-making, streamlining and simplifying processes established at national level?

In an attempt to assess the local perception that technical forest managers have on soil erosion after wildfire, an investigation was conducted, having the central region of Portugal as case study. In this project, we assessed the relevance that technical forest managers give to post-fire soil erosion, by identifying the priority of their activities, established procedures, and their perception of present and future risk following wildfires. Thus, a survey was structured and provided to 108 entities (100 municipalities and 8 inter-municipal communities), being active for reply between 14 September and 14 October 2022. The survey was structured in three main sections: i) general characterization of the entity, ii) description of its global relationship with forest land management and actions after wildfire, and iii) identification of procedures and technical tools used for post-fire land management.

From the 108 requests, 78 answers were obtained, and 52 were considered valid for analysis. The results identified a general concern with soil erosion after wildfire. However, the focus of individual local concerns with wildfires impacts is mostly targeted to loss of biodiversity, the abandonment and degradation of affected areas, followed only then by the soil losses by erosion. Respondents also identified that they have implemented, or are aware of the implementation, of erosion mitigation measures in their actuation area, being these measures mainly represented by the construction of organic barriers and interventions in water bodies, for soil stabilization and overflow redirection. Technical tools are generally used for forest management planning, but not with the main intention to control soil erosion neither to promote its rehabilitation. Respondents also refer that an open source, and updated, technical tools on this scope would allow them to design an emergency strategy on time. This would also enable the support of the local decision-making process, and contribute to a standardized and streamlined response from diverse municipalities affected by the same wildfire.

According to the results obtained, two main strategies can be inferred in order to promote the local conservation of forest soils after an wildfire: i) local empowerment to act and contribute with technical support to private local forest owners and managers, and ii) the reinforce of the awareness-raising process, by adapting campaigns (information/language) to the different, affected and interested, stakeholders.

How to cite: R. Lopes, A., Valente, S., Keizer, J., and Vieira, D.: Local assessment of technical forestry awareness on soil erosion after wildfire – the case study of Central Portugal region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-277, https://doi.org/10.5194/egusphere-egu23-277, 2023.

Mediterranean mountains have been affected by an intense process of cropland abandonment since the middle of the last century, as a result of the rural exodus. This has led to the activation of natural revegetation processes in marginal areas that have not been managed. Literature has recorded different soil responses to secondary succession depending on factors such as climate, altitude, soil depth and type, but still very little is known about the influence of soil pH. Thus, the main objective of this work is to identify how soil quality and carbon sequestration are affected by secondary succession after abandonment for two types of soil lithologies (acidic and alkaline). For this purpose, the Leza Valley (La Rioja, Spain) was selected as the representative study area. Soil samples were collected for each lithology, at different depths (0-40 cm), for 5 stages of succession (cropland (CRL); shrubland (SH); bushland (BS); young forest (YF); and old forest (OF)), and their physicochemical properties were analysed in the laboratory. Data analysis was carried out and these are the most relevant results: i) there are significant differences between acidic and alkaline organic carbon stocks; ii) the alkaline soils increase their SOC stock with the advance of succession, and significant differences were observed between the first stages of abandonment and BS, YF and OF; iii) while in the acidic soils no significant differences were observed, and the highest values were recorded in YF; iv) these results may be the combination of interactions between pH, soil properties and plant and microbiological communities that establish in these areas. Our work has shown the relevance of considering the lithology of our soils in order to determine which post-abandonment management practices may be the most appropriate for our study area. Therefore, it is necessary that policies and management strategies include this type of analysis to achieve the best results of soil carbon sequestration.

Acknowledgement: This research project was supported by the MANMOUNT (PID2019-105983RB-100/AEI/ 10.13039/501100011033) project funded by the MICINN-FEDER. Melani Cortijos-López is working with an FPI contract (PRE2020-094509) from the Spanish Ministry of Economy and Competitiveness associated to the MANMOUNT project

Keywords: abandoned croplands, natural revegetation, carbon sequestration, soil pH, Iberian System (Spain)

How to cite: Cortijos-López, M., Sánchez-Navarrete, P., Lasanta, T., and Nadal-Romero, E.: How acidic or alkaline soils affect SOC stock in a post-abandonment secondary succession process: a case study in th Mediterranean mid-mountains., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1570, https://doi.org/10.5194/egusphere-egu23-1570, 2023.

Archaeological anthrosols constitute a heritage of long-term carbon storage and soil fertility. Their anthropogenic features are affected by the type and intensity of ancient human activities. Human activities can follow a gradation of disturbance intensity, with lower intensity related to a weak human pollution of natural soil, and stronger intensity related to anthropogenic materials inputs (e.g. refuse pits). Soil properties are indeed deeply modified by the addition of objects (e.g. bones, ceramic) and of organic matter with distinct chemical composition and biological stability (e.g. charcoal). The aim of the study was to establish a new analytical approach to distinguish intensities of human activities, based on organic matter characteristics. To this end, we studied intertropical soil profiles (0-120 cm) from Cameroon, Brazil and Bolivia, with spatial or temporal intensity variations of human activities. We used standard compositional parameters (hydrogen index, HI, and oxygen index, OI) and advanced thermal parameters (I-index and R-index) from Rock-Eval^® pyrolysis, as well as magnetic susceptibility, to characterize anthrosols.

Results demonstrated the potential of Rock-Eval^® pyrolysis parameters to identify human activities changes. First, the deviation of I-index (delta-I) between our samples and a reference value from natural sites informed about the intensity of human impacts, allowing for the distinction between artificial infilling of refuse pits and soil profiles with no or few human impacts. Second, positive HI:OI correlation established the importance of charcoal as main organic C source. The magnetic susceptibility informed about the presence of burnt soils in a Brazilian and one of the Bolivian sites. The combination of all these parameters, when represented with soil depth, allowed for the estimation of temporal changes in Brazilian and Bolivian sites. The topsoils were similar for all sites, relative to a low intensity of human activities or to the resumption of natural pedogenesis, thereby alleviating the effects of ancient human activities on organic matter characteristics. In contrast, the subsoils exhibited higher intensities of ancient human activities, with even higher values of intensities in Bolivian sites, thereby evidencing the long-term conservation of their effects on organic matter characteristics.

To conclude, anthropogenic activities may durably affect organic matter characteristics in tropical sites, even after several centuries. Beyond being of interest for archaeological research, this new approach raises questions about the long-term consequences of our current human activities.

How to cite: Aubertin, M.-L., Malou, O. P., Arroyo-Kalin, M., Lombardo, U., Chevallier, T., Oliva, P., Delarue, F., Thiesson, J., Quenea, K., Sebag, D., and de Saulieu, G.: New approach to evaluate the intensity of ancient human activities, based on organic matter characteristics using Rock-Eval® thermal analysis., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3504, https://doi.org/10.5194/egusphere-egu23-3504, 2023.

The sandy soils of Eastern Germany show a high gradient in soil organic carbon (SOC) between topsoil and subsoil. This is reflected in the low nutrient supply, water storage capacity and increased compaction susceptibility of the subsoil. In view of these productivity limitations, ameliorative fractional deep tillage (aFDT) was developed in the late 1950s.

The aim of this subsoil melioration measure is to create shafts enriched with organic-rich topsoil material in the subsoil to remediate root restricting layers and promote accessibility of subsoil resources. At the same time, organic C sequestration is induced by mixing of subsoil material low in organic matter into the topsoil. The 50 cm deep and 7-15 cm wide shafts are created at 35-80 cm intervals by a special plough or modified loosener. Thereby, solid zones remain between the shafts to ensure stability and reduce the risk of re-compaction of the strip wise deep tillage.

We studied three 37- to 43-year-old historical field trials representing a soil quality gradient near Müncheberg to investigate the long-term effects of aFDT on SOC accumulation as well as nutrient stocks in the subsoil and organic carbon sequestration in the topsoil. Besides the shaft, the topsoil, the area next to the shaft, the subsoil material below the shaft and reference topsoil without aFDT outside the trial plot were sampled. In total, 43 shafts were sampled.

We found that the 50-75% of the original SOC was still preserved in the shafts. The shafts had significantly higher SOC contents (+286%) and nutrient contents (P+75%, K +33%, Mg +50%) compared to surrounding subsoils (E/Bw horizons). These results indicate that aFDT is an effective melioration method to increase the SOC and nutrient stocks.

How to cite: Gerriets, M., Leue, M., Koszinski, S., and Sommer, M.: Sustainable increase of SOC stocks and nutrients in sandy subsoils by ameliorative fractional deep tillage (aFDT), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5949, https://doi.org/10.5194/egusphere-egu23-5949, 2023.

The development of the balance of carbon stocks is at the EU level as well as nationally a key issue related to climate change and the state of the environment, and nowadays it is also strongly linked to the economic perspective through common agreements related to taxonomy. This places the need to produce new researched information as a basis for decision-making.

In Finland, the lack of soil information is becoming a limitation of climate-resilient agriculture and forestry policy measures. Because of this, Geological Survey of Finland (GTK) and its partners have launched several projects to improve the situation. In the new projects, remote sensing methods, digital tools and the use of artificial intelligence have been developed in particular to expand the regional coverage of soil data and to enable the assessment of the national carbon stock. By developing the production of information and making the use of databases more efficient, land use measures can be directed and targeted in such a way that they maintain and strengthen carbon sinks and stores.

GTK's partners in the projects have been the Natural Resources Institute Finland, the Universities of Helsinki and Turku, the Finnish Food Authority, the National Land Survey of Finland and RADAI, and the work would not be possible without interdisciplinary cooperation.

How to cite: Pihlaja, J.: Development of soil research supporting climate resilience and decision-making in Finland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6129, https://doi.org/10.5194/egusphere-egu23-6129, 2023.

The European Mediterranean region is heralded globally for both its high vulnerability to soil degradation and realization of the climate crisis, with ambient temperatures increasing at rates 20% faster than the global average. Maize crops in this region experience moderate to severe water stress during late spring and summer, although such trends are being exacerbated by lack of agricultural irrigation, which has exhausted ~70% of freshwater reserves to date. Future water scarcity is expected to increase as evaporative demand ramps in line with global warming, with rainfall intensity and distribution becoming more variable, and with intensification of weather extremes including drought. Agricultural droughts occur when soil moisture for a prolonged period is below the wilting point threshold, leading not only to yield reduction or failure, but also impaired soil biogeochemical processes, enhanced losses of terrestrial carbon and soil biodiversity. Thus, agricultural water management is key not only in terms of global food security but also in terms of natural capital and environmental stewardship, namely planning for net-zero greenhouse gas emissions. Here, our aim was to identify adaptations for maize crops that improve water-use efficiency, resulting in greater production for lower water requirement. Using the Agricultural Production Systems sIMulator (APSIM) crop model, we simulated maize growth in 14 regions across the European Mediterranean region under historical (1984-2021) and future (2064-2100) climate horizons, assuming a 22% decrease in precipitation and a 5.6ºC increase in temperature following the Six Assessment Report of the IPCC (IPCC, 2022). Treatments included a range of irrigation quanta per season (0 mm, 200 mm, 400 mm, 560 mm, 920 mm, 1400 mm, 1600 mm and 2000 mm) and several representative irrigation infrastructures. Irrigated water was applied with furrow, sprinkler and drip-irrigation systems. Under future climates, we reveal that penalties in rainfed maize yields range from between 30% to complete catastrophic collapse. Increasing irrigation applied helped alleviate negative impacts of the climate emergency. However, even under optimal irrigation, maize yields decreased by 6-44% (except for modest increases in Villamanan [north Spain] and Montelier [south France]). For the same amount of water applied over the season, drip and sprinkler systems were conducive to greater yields than furrow irrigation (1-63% and 1-52%, respectively), with the rotating sprinkler (pivot) irrigation providing the highest average water use efficiency (10-17 kg grain/mm water). Drip irrigation – characterised by smaller amounts of water applied more frequently for a longer duration - was conducive to higher evaporation losses than pivot and furrow. Understanding the impacts of climate variability under future climates will be critically important for developing productive, profitable, efficient irrigation strategies that improve security of carbon, water and food.

Keywords: Climate change, irrigation management, crop yield, water use efficiency, Mediterranean region

How to cite: S.S. Ferreira, C., T. Harrison, M., F. Martin, N., S. Marcillo, G., Zhao, P., Tao, R., Hovakimyan, N., and Kalantari, Z.: Adapting irrigated maize cropping to a changing climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6290, https://doi.org/10.5194/egusphere-egu23-6290, 2023.

Soils are often underestimated and overlooked in reviewing national economic structures. Soils and groundwater are the essential basics for food production. Beyond securing nourishment, quantity and quality of soils are pivotal factors in farming, forestry and further land use. The potential of soils governs the availability and variety of its products for national food security and trading. In most industrial European countries, farming has only a share of about 1% of the national gross domestic product but secures vital needs. In the Sub-Saharan region, the same share varies between 16% and 20%, largely depending on regional weather, water availabilty and soil quality. The largest threats are climate change and depletion of soils. Whereas European countries aim for steadily increasing sustainability, countries in Southern Africa are often struggling between short term profits, preservation of soils and necessary climate adaptions. The study sheds some light on the different roles of soils in European and Southern African economies, their inter-dependencies, the necessity to map quantities and qualities of soils for managemant measures and growing needs with a still fastly rising population in Southern-Africa. 

How to cite: Meyer, U.: Soils and Economy - Snapshots on Europe and Southern Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6715, https://doi.org/10.5194/egusphere-egu23-6715, 2023.

A governance perspective of the European Union, that increasing efforts are dedicated towards reducing emissions of air pollutants, including ammonia. To reach this goal, Directive 2016/2284 (NEC) has been adopted, which sets a total annual emission limit value for all EU countries to be achieved by 2030. To contribute to the ambitions of sustainable agriculture, Hungary needs to reduce ammonia emissions by 32% compared to 2005 levels. Since 90% of ammonia emissions are related to agriculture, change in agrotechnical practices is needed to reach the target.

Our goal is to find optimal land use management practices in order to minimize ammonia emission, thus creating interactions between land degradation reduction and climate neutrality. A small-scale plot field trial was set up to demonstrate the possibilities of reducing ammonia emissions from urea fertilizer (46.6% active N ingredient), due to agrotechnical treatment combinations [split dose (60-40%) fertilizer application and incorporation] taking into account different test crops (wheat, triticale, grain sorghum, maize, sunflower), soil properties, climatic factors and vintage effect. In the experiment, urease inhibitor (Limus  Yellow) was tested, which was designed to inhibit the urease enzymes catalyzing the hydrolysis of urea, thus reducing and slowing the formation of ammonium, and reducing the loss of ammonia. Treatment combinations were set up in 4 replicates in a randomized design, with a total of 32 plots and 4 controls on four different soil types (Arenosol in Őrbottyán, Chernozem in Nagyhörcsök, Luvisol in Keszthely and Gleyic Chernozem in Karcag – according to WRB) with sand, loam, clayey loam and clayey loam texture, respectively. The volatilized ammonia was investigated using a passive  chamber method (phosphoric - acid  and glycerol mixture as trap to NH₃) for 6 weeks in the case of hoe culture and for 12 weeks in the case of cereals, during which the ammonia release was determined at 2-week intervals.

The inhibitor delayed the rate of ammonification in all soil types, thus reducing ammonia emissions in the weeks following application, but at a decreasing rate. The order of the soils from high to low ammonia reduction due to the inhibitor (2-year averages) was Arenosol (52%) > Chernozem (50%) > Luvisol (46%) > Gleyic Chernozem (20%), which shows a correlation with soil texture (from low to high clay content).

Split fertilizer application reduced ammonia emissions by 48% (3-year average) compared to treatments where 100% of the N dose was applied at the start (2020, 85%; 2021, 24%; 2022, 35%).

Incorporation has an ammonia emission reduction effect of 57% (3-year average) (2019, 53%; 2021, 70%; 2022, 49%). On Gleyic Chernozem, ammonia emission reduction was 68%, while on Luvisol it was 71% (2021) and 49% (2022) compared to leaving it on the surface.

Considering the test crops, incorporation was the most effective in reducing ammonia emissions in maize (62%), sunflower (67%) and grain sorghum (68%), against inhibitor effect (49, 54 and 3 %, respectively). In contrast, the inhibitor effect was the strongest in winter wheat (46 %) and triticale (52 %), against split dose application (28 and 31%, respectively).

How to cite: Balog, K., Koós, S., Pirkó, B., Szűcs-Vásárhelyi, N., Magyar, M., Mészáros, J., Árvai, M., Szabó, A., Kovács, Z. A., Takáts, T., and László, P.: Options for reducing agricultural ammonia emissions on different soil types, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7463, https://doi.org/10.5194/egusphere-egu23-7463, 2023.

Climate change and agricultural intensification are placing enormous pressure on soil to provide essential services, from water storage and nutrient provision to carbon sequestration. Indeed, storing carbon in agricultural systems is proposed as an effective climate mitigation approach. Yet, storing carbon comes often at a cost in terms of water consumed—water used either to increase productivity and carbon inputs to soil, or to create conditions in the soil that promote carbon storage. These linkages are perhaps most evident in rice paddy systems.

Rice – a staple food for 3 billion people – consumes more water than any other crop, leading to unsustainable water withdrawals. However, this large water consumption allows paddy soils to store more carbon than under other land uses, because flooding of the fields keeps soils saturated and inhibits organic matter decomposition. Therefore, changing water saving approaches such as alternate wetting and drying has the potential to reduce carbon storage and alter the provision of other ecosystem services. But how much can soil organic carbon change across land uses and when water management is altered?

In this contribution, we discuss the mechanisms of carbon storage in paddy fields, using data from a meta-analysis of soil carbon budgets in tropical rice paddies and from a detailed investigation of carbon storage along a gradient of a land use and soil age in a temperate rice system. The meta-analysis shows that, as expected, reducing the time of flooding decreases soil organic carbon, but also results in a net decrease of greenhouse gas emissions. The more detailed study shows that in temperate conditions with relative short flooding time, rice paddies can store as much organic carbon as forest sites, despite the higher carbon inputs of forests compared to rice systems. This higher carbon storage is achieved thanks to decreased soil respiration in anaerobic conditions and increased mineral associations of organic carbon. These results show that water management strongly affects soil carbon storage, and that trade-offs emerge between sustainable water use and long-term provision of soil-related ecosystem services.

How to cite: Schwarz, E., Johansson, A., Lerda, C., Livsey, J., Scaini, A., Said-Pullicino, D., and Manzoni, S.: Trading water for carbon in agricultural systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8708, https://doi.org/10.5194/egusphere-egu23-8708, 2023.

Soils constitute a carbon reservoir that can help to mitigate climate change, or conversely accelerate greenhouse gas emissions if not managed properly. Soils are heterogenous and dynamic systems, which physico-chemical properties impact their current soil organic carbon (SOC) stocks and their capacity to store more carbon. Land-use planning aiming to preserve and increase SOC stocks should therefore be aware of the spatial repartition of various soil types and of the SOC dynamics therein.

This project aims to map the effect of soil typology on the spatial and vertical repartition of soil carbon stocks, additional storage potential and storage dynamics at a regional scale to improve guidance of SOC storage strategies. The study site is a 320 km² temperate rural region in NE France. Eight dominant soil types are defined, notably Calcaric cambisols in the agricultural valleys, deep silty and acidic soils in the forested plateaus, shallow rocky calcaric soils on the hillslopes, and deep clay-rich hydromorphic soils in the alluvial valleys.  

Based on logarithmic fits of soil carbon data extracted from 197 full-depth soil profiles, mean soil organic carbon stocks are obtained as a function of depth for each represented soil type and land cover. The additional storage potential corresponds to the difference between the current stock and the maximum stock, as estimated by the fit of the upper 25% of the soil carbon content data.  Finally, a depth-dependent SOC dynamic model using multilayer soil modules is used to simulate SOC stock evolution. Results are mapped by combining the spatial information given by a pedological map and a map of land covers.

Median soil carbon stocks over the full soil profile range from 78 to 333 tC ha^-1, of which 59 to 148 tC ha^-1 are in the topsoil (0-30 cm). The lower stocks are found in the shallow, rocky cultivated soils, and the highest stocks in the gleysols under grasslands. The additional storage potential varies from 19 tC ha^-1 for shallow, rocky forest soils to 197 tC ha^-1 for cultivated gleysols. SOC build-up is heterogenous and depends on the mean residence time of carbon in the represented soil types.

Maps of carbon stocks show the areas to preserve to avoid C losses, and maps of additional storage capacity for different time horizons show areas in which to implement carbon storage practices. Going forward, the association of carbon stock mapping and modelling should allow us to estimate at which depths and over which timescales.

How to cite: Derrien, D., Chirol, C., Saint-André, L., and Séré, G.: Mapping spatial and vertical repartitions of soil carbon stocks, additional storage potential and storage dynamics at the regional scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11518, https://doi.org/10.5194/egusphere-egu23-11518, 2023.

Improved soil and cropland management changes the soil carbon stocks and thereby mitigate climate change. However, spatially explicit insights on management impacts as well as critical thresholds for optimum SOC levels are lacking, which is crucial for actionable changes in farming practices. In this study we unravelled the contribution of soil texture, geohydrology and soil quality to changes in SOC in the Netherlands using a data-driven approach (using XGBoost) using 21.123 soil analyses done by agricultural laboratories. The current C stock of the 0-30cm soil layer is 119 ton C ha-1 and could be increased by 21 to 59 ton C ha-1 depending on soil type, land use and the agronomic measures taken. The SOC saturation capacity, expressed as the ratio between the actual and potential SOC stock varied from 85 to 93% in grassland soils, from 55 to 83% in arable soils and from 69 to 91% in other land uses. On average, the actual C saturation degree was 75%. The key factors controlling the potential of soils to sequester additional carbon within environmental limits for N and P included the crop sequence in the last decade, soil texture (i.e. oxide extractable aluminium, iron and phosphorus), the acidity, and groundwater depth. The data driven approach shows that spatially explicit recommendations for carbon farming are possible up to the farm and field scale, facilitating the implementation of carbon farming and the mitigation of climate change. When all agricultural fields are saturated with C, an equivalent of 257 Mton of CO2 can be stored.  

How to cite: Fuijta, Y., Verweij, S., van der Voort, T., and Ros, G.: Quantifying the potential of agricultural soils to store carbon. A data-driven approach illustrated for the Netherlands. , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12830, https://doi.org/10.5194/egusphere-egu23-12830, 2023.

The main hurdle in instrumentalizing agricultural soils to sequester atmospheric carbon is a development of methods to measure soil carbon stocks on farm level which are robust, scalable and widely applicable. Specifically, it is necessary that socio-economic barriers related to cost, usability and accessibility are overcome. We present the Wageningen Soil Carbon Stock pRotocol (SoilCASTOR), a method for soil carbon stock assessment using satellite data, direct soil measurements via mobile soil sensors and machine learning which can help overcome these socio-economic hurdles. The method has a low cost per hectare and uses plug-and play tools (soil scanner), which lower the threshold users need to overcome. The method has been tested and applied for multiple farms in Europe and the United states on agricultural fields with variable crop rotations, soil types and management history. Results show that the estimates are precise, repeatable and that the approach is rapidly scalable. Carbon stocks in the top 30 cm range between 1.8-6.1 kg C/hectare and resolution is up to 10x 10 meters. The precision of farm C stocks is below 5% enabling detection of SOC changes desired for the 4 per 1000 initiative. The assessment can be done robustly with as few as 0.5 samples (or 2-3 minutes) per hectare over a range of scales, for farms varying from 20 to 200 hectares.These findings can enable the structural and widespread implementation of carbon farming. This approach has recently been awareded the Bayer Grants4Tech innovation prize.

How to cite: Verweij, S., van Doort, M., Fuijta, Y., van der Voort, T., and Ros, G.: Enabling carbon farming: a robust, affordable and scalable approach leveraging remote and proximal sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13552, https://doi.org/10.5194/egusphere-egu23-13552, 2023.

A szén-elnyelő erdők és talajok előtérbe kerülnek a szénsemlegesség mielőbbi elérése érdekében. A folyamatosan növekvő kibocsátás felborítja a légkör egyensúlyát, és a folyamatok eltolódásával klímaváltozásban vagy időjárási szélsőségekben nyilvánul meg. Kutatásunk célja az erdei ökoszisztémákban különböző éghajlati és erdészeti viszonyok között tárolt szerves széntartalom felmérése volt. A talajelemzésre helyeztük a hangsúlyt, mert a talaj szén mennyisége közel azonos a föld feletti biomasszában tárolt szén mennyiségével. Mintegy 40 kijelölt erdőállományból vettünk mintát, hogy meghatározzuk az egyes erdőállományok talajában tárolt szerves szén mennyiségét. A talajmintákat 40 cm mélységű fúrással gyűjtöttük. A talajmintavétellel egyidejűleg a mintavételi pont közelében lévő egyes állományok élőfaállományát is felmértük. A 40 kijelölt erdőállományban eddig végzett vizsgálatok alapján a területek Cambisols, Luvisols és Arenosols talajosztályokba sorolhatók (WRB 2020). A talajminták pH-értéke többnyire savas (átlag = 5,9), az állaga vályogként határozható meg. A 0-40 cm-es termőtalajok talaj szervesanyag-tartalma (SOM) 1,45%, ami ~14 t széntartalmat jelent hektáronként. A környéken még mindig van elegendő csapadék a növényzethez zavartalanul; így a szénmérleg a térségben jelenleg stabil annak ellenére, hogy az alommennyiség csökkenése miatt a készletek már most is csökkennek. 9) és a textúra vályogként határozható meg. A 0-40 cm-es termőtalajok talaj szervesanyag-tartalma (SOM) 1,45%, ami ~14 t széntartalmat jelent hektáronként. A környéken még mindig van elegendő csapadék a növényzethez zavartalanul; így a szénmérleg a térségben jelenleg stabil annak ellenére, hogy az alommennyiség csökkenése miatt a készletek már most is csökkennek. 9) és a textúra vályogként határozható meg. A 0-40 cm-es termőtalajok talaj szervesanyag-tartalma (SOM) 1,45%, ami ~14 t széntartalmat jelent hektáronként. A környéken még mindig van elegendő csapadék a növényzethez zavartalanul; így a szénmérleg a térségben jelenleg stabil annak ellenére, hogy az alommennyiség csökkenése miatt a készletek már most is csökkennek.

Ez a cikk a TKP2021-NKTA-43 projekt keretében készült, amely a Magyar Innovációs és Technológiai Minisztérium (jogutód: Kulturális és Innovációs Minisztérium) a Nemzeti Kutatási, Fejlesztési és Innovációs Minisztérium támogatásával valósult meg. Alap, a TKP2021-NKTA támogatási konstrukció keretében finanszírozott. A Kulturális és Innovációs Minisztérium ÚNKP-22-3-I-SOE-99 Új Nemzeti Kiválósági Programja pedig a Nemzeti Kutatási, Fejlesztési és Innovációs Alapból támogatott.

How to cite: Végh, P., Balázs, P., Bidló, A., and Horváth, A.: Investigation of soil carbon sequestration and storage in Hungarian forest sites under different climatic conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14111, https://doi.org/10.5194/egusphere-egu23-14111, 2023.

Since 1922, the territorial proportion of forests has increased from 12% to 22% due to large-scale afforestation in Hungary. These planted forests bind huge amounts of carbon dioxide from the atmosphere. The sequestered carbon is partly stored in the above-ground biomass of forests in the form of organic matter. At the same time, a similar amount of carbon can be found underground. The research aims to assess the effect of afforestation on the amount of organic carbon stored in the soil (SOC).

During our investigations, we collected samples from 3 study areas from the Hungarian Great Plain. We compared the soil of the poplar and acacia forests in the sample areas with the grassland soils located directly next to these plantations. By the natural conditions, the pH of forest (7.75 and 8.29 pH(H₂O)) and grassland (8.01 and 8.45 pH(H₂O)) samples was weakly alkaline/alkaline. We measured a lower pH value in case of forests, which clearly shows the leaching effect in the forest soils. The average humus content of the tested soil samples was 0.94%. The lowest measured value was 0.09%, while the highest was 4.21% which clearly showed that dry sandy soils have a low organic matter content.

The soil and the litter cover contain 7 to 37 tons SOC/ha. The differences between the studied areas were very large. The carbon stock of the soils was higher in forest stands in every case. This shows that in long term the afforestation increases the amount of carbon stored in soils compared to grasslands.

This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

How to cite: Bidló, A., Csorba, M., Balázs, P., Végh, P., and Horváth, A.: Effect of afforestation on the organic carbon stock of soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14616, https://doi.org/10.5194/egusphere-egu23-14616, 2023.

Cropland soils show large potential to sequester carbon to achieve climate neutrality. Changes in management can affect an increase of carbon sequestration or reducing carbon losses in form of emissions or leaching. However, the impact of management changes on the sequestration and other processes needs to be quantified to provide advice to farmers. Experiments to analyse impacts of management changes are costly and labour intensive. Additionally, these experiments take time and cover only a small range of environmental conditions. Therefore, modelling is widely used to over-come these limitations. Model results allow the estimation of all relevant fluxes for the overall greenhouse gas emission balance or, depending on the model, for some parts. This is a fast and efficient method to quantify soil organic carbon (SOC) changes due to modifications in agricultural management. Even though, models proved their quality of simulating SOC changes, there are some restrictions in the use of models for actual advice based on model results. In the here presented study, three key points will be analysed: First, the additional impacts beside the SOC changes. Carbon sequestration can be offset by emission of other greenhouse gases or management changes affect yield, which needs to be included in the analysis. While these two variables are well covered by usual model approaches, other aspects like food quality are more difficult to include. Second, how does the complexity of the model affect the result. The simple assumption that more complex models are potentially more accurate, but also require more input data is in most cases realistic (this is a generic assumption which is not always true). More input data and more complexity are also associated with potentially increased uncertainty. Third, who is running the model. While research-based advice using more complex models might be potentially more accurate, models used by farmers might be more specific and direct in providing key information. Additionally, the impact of the increased data demand and required data can affect an increased error. These points are analysed on examples and case studies. This includes an analysis beyond the carbon sequestration and how to include these aspects in the analysis. Further, results of a tool developed for stakeholders/farmers is compared with results of a biogeochemical model for selected sites. Finally, an analysis of the limitations of the models due to data demand and data availability. The analysis of wheat yields shows mainly positive impacts on the SOC change, but mainly reduced yield. The comparison of the two models indicates the impracticability of the more complex option, as the data demand is not orientated on the data availability. The decision based on model results requires a careful use of models and a good understanding of the results.

How to cite: Kuhnert, M.: Using modelling and tools for advice on improved agricultural management to achieve climate neutrality in croplands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14833, https://doi.org/10.5194/egusphere-egu23-14833, 2023.

With rising population growth, there is a need for increased food production. With rising temperatures and more frequent droughts due to climate change, it becomes more challenging to keep up with this increased demand for food. Therefore, a change in land use and management is needed in which enhanced silicate weathering (ESW) can play an important role. Weathering of silicate rocks has been regulating the atmospheric CO2 concentrations for over decades, but with the rise in atmospheric CO2, the natural weathering is too slow. Grinding the silicate rocks into a fine powder and spread it over for example agricultural fields will increase the reactive surface area and hence, the amount of CO2 that is stored in soils. The application of silicate minerals to soils can enhance plant growth by multiple processes, for example by counteracting soil acidification and by the release of plant nutrients. In this way, ESW can be used on agricultural fields without competing for land like other carbon capture techniques (e.g. Bio-Energy with carbon capture and storage). This study investigates the use of olivine (a fast-weathering Mg-rich silicate mineral) as a fertilizer in agriculture using a full-factorial mesocosm experiment. Barley and wheat were grown under two different rain regimes (daily rain vs weekly rain) and with application of two different grain sizes of olivine (p₈₀ = 1020 µm and p₈₀ = 43.5 µm). Our results showed increased plant growth and biomass with olivine addition, albeit only for fine olivine. However, this was not translated in an increase in yield of wheat and barley. Besides changes in biomass, we found significant differences in plant nutrient concentrations. As expected, Mg concentration increased significantly. However, BSi and Ca concentrations decreased with fine olivine application. Nitrogen in grains was also increased in the fine olivine treatment. In contrast to fine olivine, coarse olivine addition had almost no influence on nutrients. Ca, Mg and Si concentrations in plant samples followed the same trend as in the soil pore water, in contrast to metal concentrations. Olivine addition increased Ni and Cr availability in the soil pore water, but the concentrations of these elements in plant tissue did not increase and were even below detection limit for the majority of samples. While the influence of olivine on metal concentrations in plant samples was not affected by rain treatment, the influence of olivine on nutrients in the plants and plant growth was. Fine olivine addition enhanced the plants resistance to drought as it reduced the decrease in biomass with weekly rain treatment compared to daily rain treatment. This positive effect of olivine addition can be due to the increased weathering rate in combination with enhancement of soil properties like increased soil water retention. In this way, the use of olivine as a fertilizer on agricultural fields can mitigate climate change while it can also contribute to the solution for increased food demand.

How to cite: Rijnders, J., Vicca, S., Struyf, E., Amann, T., Hartmann, J., Meire, P., Janssens, I., and Schoelynck, J.: The effects of olivine fertilization on growth and elemental composition of barley and wheat differ with olivine grain size and rain regimes., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15333, https://doi.org/10.5194/egusphere-egu23-15333, 2023.

Understanding dynamics of soil organic carbon (SOC) stock in agroecosystems under climate change is imperative for maintaining soil productivity and offsetting greenhouse gas emissions. Simulations with the SPACSYS model were conducted to assess the effects of future climate scenarios (Representative Concentration Pathway (RCP) 2.6, 4.5 and 8.5) and fertilization practices on crop yield and SOC stock by 2100 for a continuous winter wheat cropping system in southeast England. Weather data between 1921 and 2000 was considered as a baseline. SPACSYS was first calibrated and validated with the data of the Broadbalk continuous winter wheat experiment for over a century. Six treatments were used: no fertiliser (control), a combination of chemical nitrogen, phosphorus and potassium with three N application rates (N1PK, N3PK and N5PK), manure only (FYM) and a combination of manure and chemical nitrogen application (FYMN). SPACSYS simulated grain yields and the dynamics of SOC and TN stocks well compared with the observations. Future climatescould significantly increase wheat yield by an average of 8.3% as compared to the baseline. FYMN was characterized by the highest grain yield. Moreover, when considering NPK practices, the relative increase in SOC stock under the RCP8.5 (+3.3%) was higher than those under the RCP4.5 (+1.4%), whereas the RCP2.6 indicated a negative effect (-0.6%) on SOC stocks. When considering manure amendments, the SOC stock decreased (-1.2%) under all RCP scenarios. However, continuous manure amendments can still be considered as a sustainable strategy for SOC sequestration with C stock increases between 34-106 kg C ha^-1 yr^-1. Future climates generally had positive effects on C sequestration in continuous wheat system with an annual C sink of 43-425 kg C ha^-1 yr^-1. Mineral fertiliser plus manure could be recommended as a good practice for simultaneously increasing crop productivity and having a rather high C sink under future climate change.

How to cite: Liang, S., Sun, N., Meersmans, J., Longdoz, B., Colinet, G., Xu, M., and Wu, L.: Climate change impacts on crop production and soil carbon stock in a continuous wheat cropping system in southeast England, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15465, https://doi.org/10.5194/egusphere-egu23-15465, 2023.

The Himalayan Mountain range is the most prominent and active intracontinental range in the world. The outer part of this range is marked by the Himalayan foreland basin (HFB) in south that resulted due to the thrust loading and subsidence with synorogenic sedimentation from the hinterland. The lowermost part of the HFB is marked by the molassic sediments of “Siwalik” which thins out to the south. The time frame between 11Ma to 6 Ma (mid to late Miocene) is critical to understand the changes related to monsoon and vegetation as there is no detailed record or systematic study of late Cenozoic weathering and paleopedogenesis in fluvial sediments of the HFB. In the present study, we present a high-resolution paleopedological record of the paleosols along a traverse of ~ 1.8 km in the Kotla-Brail section of the Kangra sub-basin of the HFB. In the field, the paleosols are characterized by 1-2 m thick Bw, Bt, Bk, Bss, Bk horizons, rhizocretions, pedogenic carbonates (PC), and Fe/Mn mottles and concretions. The paleosols in the Lower Siwaliks show a dominance of 2.5 Y and 5 YR hue, whereas in the Middle Siwaliks they are defined by 5 YR and 7.5 YR hue. Micromorphology of these paleosols confirmed varying degrees of weathering, and paleopedogenesis showing a blocky structure, clay coatings, biogenic activity, and diffused impure micritic nodules as PC in the Bw and Bt, Btk horizons. These pedofeatures are more strongly developed in paleosols of the Lower Siwaliks than in comparison to weakly-moderately paleosols of the Middle Siwaliks.

Clay mineralogy determined based on XRD study of the total (<2 µm) fine clay (<0.2 µm) fractions of these paleosols is characterized by the dominance of smectite, vermiculite, and mixed-layer minerals in paleosols of the Lower Siwalik. The clay mineral assemblage shows a  decrease in the abundance of smectite and increase of kaolinite towards the transitions to Middle Siwalik at ~10 Ma. This also shows transformation of the smectite and vermiculite to interstratified clays at about ~8 Ma. After ~8.5 – 8.0 Ma, the paleosols are again marked an increase of the amount of smectite, vermiculite, and mixed-layer minerals in paleosols of the Middle Siwalik towards their transitions to Upper Siwalik. The varying intensity of weathering, paleopedogenesis, and clay mineral assemblage of the paleosols in the Lower and Middle Siwalik suggest fluctuating climatic conditions that evolved from initial semi-arid to sub-humid at ~11 Ma that to higher precipitation at ~8.5 to 8 Ma then again to semi-arid to arid conditions at ~6.5 Ma.

Keywords: Himalayan Foreland Basin (HFB), Siwalik, Paleosols, Micromorphology, Clay Minerals

How to cite: Yadav, P., Hameed, A., Kumar, R., and Srivastava, P.: "Paleopedology of Siwalik Paleosols of Kangra Sub-Basin, NW Himalaya: Implication for Weathering and Climate change 11 Ma to 6 Ma", EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-828, https://doi.org/10.5194/egusphere-egu23-828, 2023.

In the present study we report paleopedology of the fluvial sequences of the Siwalik Group in the Himalayan Foreland Basin, NW Himalaya that formed during ~12 Ma -5.5 Ma. The paleosols formed during this time period are critical to understand weathering and paleopedogenic processes during the evolution of foreland basin over the entire Himalayan range. This work highlights field-characteristics, micromorphology, clay mineralogy, and geochemistry of the ~0.5 km thick Lower Siwalik and ~1.7 km thick Middle Siwalik successions along the Katilu Khad, Kangra sub-basin. In the field, the paleosols are characterized by 1-2 m thick Bw, Bt, Bk, Bss, and BC horizons, blocky and wedge-shaped pedogenic structures, root traces, color mottling, Fe-Mn oxide concretions, slickensides, pedogenic CaCO₃ (PC), and bioturbation features. 

Micromorphological observations show the dominance of moderate to well-developed paleopedofeatures in paleosols of the Lower Siwalik in contrast to the moderately to weakly-developed paleopedofeatures in paleosols of the Middle Siwalik. The comparative analysis of various pedogenic features i.e., PC, illuvial clay, mottles, Fe-Mn concretions, microstructures, and bioturbation features confirmed varying degree of the paleopedogenic maturity in the paleosols at different intervals of the Siwalik successions.

Clay mineralogy of the total clay (<2 μm) and fine clay fraction (< 0.2 μm) of the Lower and Middle Siwalik paleosols suggests varying chemical weathering of silicates and change of paleoclimatic conditions during paleopedogenic processes during this time period. The clay mineral assemblage of the total clay and fine clay fraction show the varying distribution of illite, chlorite, kaolinite, smectite, vermiculite and interstratified clay minerals in these paleosols. Large amounts of smectite together with pedogenic carbonates in part of the Lower Siwalik at 12.0 Ma, and at 10.9 Ma and in Middle Siwalik at 9.2 Ma, and at 5.5 Ma suggest arid to semiarid dry climatic conditions Whereas, dominance of kaolin, illuvial features, and dissolution of pedogenic carbonates suggests sub-humid to humid climatic condition at 11.6 Ma, 8.5 Ma, 7.1 Ma, and at 6.5 Ma.

The bulk geochemistry of the paleosols also confirmed varying degree of pedogenic weathering showing high CIA and CIA-K (CIW) values and ~ 800 mm to 1400 mm MAP for paleosols of the Lower and Middle Siwalik. The high MAP (~ 1200 mm to 1400 mm) at ~11.6 Ma, ~8.5 to 8.0 Ma, and 7.1 to 6.5 Ma in paleosols of the Lower Siwalik and Middle Siwalik correspond to increased chemical weathering and paleopedogenesis. While the intervening periods correspond to less MAP (~800 mm to 1100 mm) with large amount PC and less chemical weathering. Based on micromorphology, clay mineralogy, and geochemical characteristics of the paleosols it is interpreted that climate change during ~12 Ma to 5.5 Ma is characterized by humid (11.6 Ma) to semiarid (11.0 Ma to 8.5 Ma), and humid-subhumid (8.5 Ma to 6.5 Ma) in response to Himalayan orogeny and its linkage to regional and global atmospheric conditions.

Keywords: Himalayan Foreland Basin, Paleosols, Siwalik, Micromorphology, Clay mineralogy, Geochemistry

How to cite: Hameed, A., Yadav, P., Kumar, R., and Srivastava, P.: Paleopedological evolution of Siwalik succession from Kangra sub-Basin, NW Himalayan: Implications for climate change and weathering conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-838, https://doi.org/10.5194/egusphere-egu23-838, 2023.

Colluvisols, representing a significant part of the erosional catena in undulating landscapes, often changed by long-term agricultural management, undergo a complex development with alternating phases of material deposition and slope stability, with subsequent initiation of soil formation processes. The presented study focuses on the detailed description of the post-depositional evolution of four up to 4m-deep colluvial profiles, formed in different colluvial positions in two environmentally and historically distinct areas of Czechia, situated in the loess region of South Moravia and Central Bohemian Upland, built on plutonic rocks. A multi-proxy approach consisting of analyses of clay mineralogy, micromorphology, humic acids and geochemical parameters was applied to distinguish the inherited and in-situ developed pedogenetic features and link them with the sedimentary history of the studied soils, assessed using optically stimulated luminescence dating and 137Cs activity. Marked differences in the type and maturity of pedogenetic features were identified not only in individual plots but also in different colluvial positions within the same plot. While signs of bioturbation, mainly related to root activity and soil fauna, were observed even in recent colluvial layers after a short period of stabilization, more advanced processes of weathering, organic matter stabilisation and clay illuviation are typical only for early-sedimented layers with long post-depositional development. Redoximorphic features were more pronounced in the side valleys compared to the toe-slope colluvial positions; similarly marked differences between colluvial positions were observed for humus quality, with significantly more stable organic matter concentrated within side valleys. In both sites, distinct and largely contradictory trends in the transformation of clay minerals, reflected in the proportions of different phyllosilicate layers, were observed, corresponding to the specific conditions of soil development. 

Study was supported by grant nr. 21-11879S of the Czech Science Foundation.

How to cite: Zádorová, T., Penížek, V., Koubová, M., Lisá, L., Žížala, D., Pavlů, L., Tejnecký, V., and Drábek, O.: Post-sedimentary pedogenesis in colluvial soils in the context of the landscape sedimentary history (Czechia), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2241, https://doi.org/10.5194/egusphere-egu23-2241, 2023.

As one of the soil types, peat is an important soil carbon storage and archive of past environmental changes. Here we used multi-core and multi-proxy records from a peatland near Da’erbin Lake in the Arxan region of Northeast China to reconstruct peatland development and carbon accumulation history and to understand their responses to past climate changes during the last 2500 years. Our macrofossil results show that the peatland was characterized by a sedge-dominated fen from 490 BCE to 1450 CE, changed to a Sphagnum-dominated poor fen or bog with abundant shrubs (mostly Ericaceae) during the period of 1450–1960 CE, and finally became predominated by Sphagnum after 1960 CE. The time-weighted mean apparent carbon accumulation rate (aCAR) from three cores range from 19.5 to 53.0 g C m^-2 yr^-1 with a mean value of 32.4 g C m^-2 yr^-1, but increase rapidly to 139.2 g C m^-2 yr^-1 during last several decades. During the early stage of the past 2500 years, three coring sites that are only 50 m apart were all in the fen phase but they had highly variable peat properties. The fen-bog transition occurred at different times at these sites due to local influences of autogenic process, permafrost dynamics, or fire disturbance. These observations suggest that fens are highly heterogeneous, not only in peat properties but also in ecosystem dynamics. The dramatic increase in aCAR during the late stage of bog phase after 1960 CE cannot be explained entirely by limited decomposition of recently-accumulated peat. Instead, this was likely due to increasing Sphagnum dominance and resultant low decomposition of Sphagnum-derived organic matter, suggesting the important role of vegetation change in controlling carbon accumulation rates. Around the 1990s CE, an increase in allogenic CAR—after removing the age-related long-term autogenic effect—seems to correspond with a period of increase in regional summer precipitation, revealing a sensitive response of ombrotrophic bog ecosystem to climate change at decadal timescale.

How to cite: Xia, Y., Yang, Z., and Yu, Z.: Responses of peatland development and carbon accumulation to climate change over the past 2500 years in the Arxan region, Northeast China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2515, https://doi.org/10.5194/egusphere-egu23-2515, 2023.

Up to today, the reason for the genesis of chernic horizons in Germany is a matter of discussion. Recent literature is strongly suggesting a purposeful anthropogenic soil management from neolithic times as an origin of these soils. Here we provide another example of neolithic activities meliorating the soil from a calcic Luvisol to a Chernozem with a dimension of several hectares. This is striking, since it is the first finding of a chernic horizon of this extensiveness in Bavaria, Germany.

The Chernozem has been discovered close to the city of Straubing (48°53′N, 12°34′O, MAP 757 mm, MAT 8,6°C), which is situated in the highly arable Danubian Gäuboden and part of the so called Altsiedelland. It has been home to human settlers ever since the first settlers belonging to the Linearbandkeramik (LBK) culture immigrated, among other things like the optimal climatic conditions due to its very favorable soil characteristics (luvisols) developed on Loess. The neolithic Chernozem is located directly next to a graveyard with graves dating in early neolithic times and later as well as neolithic settlements 500 m away. Collected ¹⁴C and OSL-data strongly suggest that part of the Chernozem was covered by a roman colluvium probably eroded from the former graveyard hill by roman ploughing activities. Our obtained ¹⁴C data places the chernic horizon itself into the early LBK and onwards. Nowadays the chernic horizon is mostly overprinted by the ongoing soil genesis as an argic horizon. Small charcoal flakes (< 0.5 mm) make the chernic horizon appear greyish-black up to today, with carbon-contents of around 1%. The colour intensifies in the center of the Chernozem area closely by the settlements and graveyard and fades out to a distinct grey shadow in the argic horizon of the calcic luvisol above around 2 km away.

These findings leave no room for doubt: The Chernozem has an anthropogenic origin and was created by the neolithic settlers, following a purpose in managing and meliorating the soil.

How to cite: Völkel, Prof. Dr., J., Holmer, A. S., Bösze, I., and Moosbauer, Prof. Dr., G.: Neolithic Agronomists shaped Chernozem in South-Eastern Bavaria, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2822, https://doi.org/10.5194/egusphere-egu23-2822, 2023.

The Volyn’ Upland is a “loess island” in the middle of the European loess belt. In the previously studied sections of this region, the Pleistocene palaeosols are mainly polygenetic; therefore, the pedocomplexes comprise no more than two soils. The study of the sections located both on the slopes of the river valleys and in the buried gullies, contributed to detailed stratigraphy of the pedocomplexes.  

Three pedocomplexes have been distinguished in the sections, which, according to palaeopedological and palynological data, were tentatively correlated with MIS 5, 7 and 9, respectively. The lower pedocomplex (S3, MIS 9) comprises two soils. The lower soil (S3-II) is a Luvisol with multi-phased clay coatings in the Bt horizon. However, micromorphology detects a clear primary A horizon with abundant coprolites. The upper soil (S3-I) has a well-developed A horizon and Ag horizon in the depression. However, clay coatings in the Bt horizon testify to the clay translocation.

The middle pedocomplex (S2, MIS 7) comprises two welded soils separated by a thin loess bed. The lower soil (S2-II) is a Luvisol, in places marked by a pronounced A horizon, in which clay coatings occur, whereas in the E horizon secondary carbonate nodules appear.  In places, the upper soil (S2-I) turns into two separate soils: the lower Haplic Chernozem and the upper Cambisol, both densely dissected by soil veins. These soils are dark, leached of carbonates, with crumby and granular microstructure. Many krotovinas occur in the subsoil.

The upper pedocomplex (S1, MIS 5) is subdivided into three sub-pedocomplexes, interbedded with sandy facies in depressions and thin loess-like deposits at the topographically higher positions. The lower sub-pedocomplex (S1-III, MIS 5e) is represented, depending on the parent material, by Luvisol, Retisol or Podzol with abundant clay coatings in the Bt horizon. In places, the forest soil is overlain by Entic Podzol with a more pronounced A horizon and is underlain by a Gleysol in depression. The middle sub-pedocomplex (S1-II, MIS 5c) comprises three soils: the lower Entic or Albic Podzol, the middle Chernozem and the upper Cambisol. A distinguished feature of these soils is the rapid increase in sand content in almost all studied sections. The upper sub-pedocomplex (S1-I, MIS 5a) is interpreted as a Cambisol, in places with a well-developed A horizon. In the upper soils of S1, pale brown spots occur.

Three Gleysols have been distinguished in the upper thick loess unit (L1, MIS 2-4). The lower Gleysol (MIS 3) is better developed and mostly polygenetic; in places the soil turns into a pedocomplex consisting of two or three soils: the lower Gleysol, the middle Gleyic Cambisol and the upper Calcaric Cambisol. The middle Gleysol appears to be polygenetic, as evidenced by palynology and micromorphology. Large ice-wedge pseudomorphs are associated with the upper Gleysol, which makes it possible to interpret soil as tundra-gley.

The study was supported by the National Research Foundation of Ukraine, grant number 2020.02/0406.

How to cite: Bonchkovskyi, O.: A detailed palaeosol record of Middle and Upper Pleistocene from the central part of the Volyn’ Upland (the NW Ukraine), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3857, https://doi.org/10.5194/egusphere-egu23-3857, 2023.

Geophysical data with noise issues are quite common, resulting in low detection conditions. This prevents the ground content from being evaluated to determine the existence of structures buried in the ground in an archaeological site. Standard processing on ground-penetrating radar and magnetic data does not effectively eliminate or mitigate this effect. The use of advanced and customized data processing is a viable solution to the problem. This processing can be applied using mathematical transforms in conjunction with data decomposition techniques, allowing for easier and less computationally intensive data manipulation. The circular symmetry of the data is enabled by the 2D Fourier transform, making operations like filtering easier to implement. In the transformed domain, factoring techniques such as singular value decomposition can be used (SVD). After analyzing the decomposed signal, the components can be matched to the signal and noise. The 2D wavelet transform allows for data decomposition, with operations such as multiresolution SVD and multidirectional gradient calculation applied to each channel to select the most informative content from a dataset. The chain application of these operations allows for the improvement of geophysical data despite an apparent lack of information. Testing on field data obtained at Villa Romana de Pisões (Beja, Portugal) is an example of successful application. Advanced geophysical data processing operations can improve the data and should be used in conjunction with standard operations.

Acknowledgment: The work was supported by the Portuguese Foundation for Science and Technology (FCT) project UIDB/04683/2020 - ICT (Institute of Earth Sciences).

How to cite: Oliveira, R. J., Caldeira, B., Borges, J. F., and Bezzeghoud, M.: Using advanced geophysical data processing to improve low detection data in archaeological sites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5502, https://doi.org/10.5194/egusphere-egu23-5502, 2023.

As sea levels rose since the end of Last Glacial Maximum (LGM) ancient coastal communities were often forced to abandon their settlements and move inland. Today, many of these abandoned sites are covered by sand or lay in shallow water. Examining these can shed light on past coastal communities as well as settlement patterns in ancient times. Archaeological excavation along the coast is particularly tricky and often sporadic in nature. Thus, high‐resolution shallow geophysical methods, which have become a standard in archaeological studies since they provide a noninvasive way of imaging the subsurface before an excavation, would seem like a perfect solution. However, most methods are limited in their ability to work near the shoreline – the transitional zone between classical land-based methods and standard marine ones. Ground penetrating radar (GPR), for example, is greatly affected by moisture and salinity and is therefore limited in its ability to work in areas saturated with seawater. Seismic reflection is time consuming to overcome issues of poor vertical and spatial resolution and sensitive to urban noise, while magnetics would provide poor results for sand covered sandstone. Other techniques, such as electrical resistivity tomography (ERT) have been shown to work in coastal areas and in shallow water. However, this method can be slow, as it involves setting up complex arrays for each cross section measured. This study will present the frequency domain electromagnetic (FDEM) method, which has the potential to overcome these problems and can bridge the gap in knowledge by measuring in the nearshore environment. The ease of use and quick scanning capability means that large areas can be covered in a relatively short time. There are no electrodes or loops to set up. Since it measures swaths, results are obtained in map-view and not cross-section, with little interpolation. Different frequencies penetrate to different depths (lower frequencies corresponding to deeper penetration). Therefore, the result is a series of frequency maps corresponding to the integration of all subsurface data in a specific sampled volume (i.e. down to the frequency-related depths), providing important information on shallow subsurface properties. The use of multiple frequencies allows for the resolving of internal structures within the depth range. Overall, the FDEM method has proven to be a valuable tool for studying coastal archaeology, and it is likely to continue to play an important role in the field in the coming years. Its ability to detect buried objects and structures and to study the geomorphology of submerged landscapes makes it an essential tool for researchers working in this field.

How to cite: Lazar, M. and Basson, U.: Frequency domain electromagnetic methods for coastal archaeology – a new(ish) approach for the detection of ancient settlements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5919, https://doi.org/10.5194/egusphere-egu23-5919, 2023.

The characterization of the shallow subsoil at complex archaeological sites requires sufficient spatial coverage and resolution as to provide the necessary information. This is all but trivial, particularly where historical superposition of layers requires also sufficient depth investigation and resolution. The Scrovegni Chapel in Padua, with its Giotto's fourteen century frescoes, and recently added to the list of UNESCO World Heritage Sites, stands on the remains of the local Roman amphitheater. The hypogeum located under the chapel shares its western wall with a part of the wall of the amphitheater. To date, no information is available about the soil below the apse of the chapel. Over the past decade, several ERT and GPR measurements have been conducted outside the chapel, straddling the amphitheater structure for archaeological and geomorphological characterization of the area. In 2021, a first 3D active and passive seismic survey was conducted using about 1500 wireless sensors, aiming at using surface waves to provide a 3D image of the subsurface in terms of shear wave velocity. In 2022 three 20 m deep boreholes were drilled around the chapel and equipped with fiber optics, ground deformation sensors, and electrodes for cross-hole ERT, and about 200 1-C and 3-C wireless seismic sensors were placed around the drilling area. During the drilling, additional 3D seismic data were acquired from the surface, which completed the datasets acquired in 2021. The geophysical data thus acquired and the time-lapse monitoring that will be possible around the area of the Scrovegni Chapel in Padua will allow reconstructing the geomorphology of the subsurface on which the chapel rests, but also to better study and analyze the possible interactions between the structure of the chapel and the buried structure of the Roman amphitheater from the mechanical point of view as well as from the perspective of the seismic response of this specific site.

How to cite: Cassiani, G., Barone, I., Pavoni, M., Boaga, J., and Deiana, R.: Geophysical characterization of the shallow subsoil at a heavily urbanized archaeological site: the Roman Amphitheater and the Scrovegni Chapel in Padua., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8737, https://doi.org/10.5194/egusphere-egu23-8737, 2023.

Ancient anthropogenic long-term effects on soil chemical composition is a well-known phenomenon in large archaeological sites. In the current presentation, this effect will be shown in Khalat al-Saharij, a small site located in central Israel, in the footslope of the main highlands of the country. The site served as a farmhouse during the Neo Assyrian rule and was dated to the second half of the 8th century BCE.

Archaeological excavations of the site revealed a building that included two strips of rooms built around a square courtyard, a rock-hewn water reservoir, and agricultural facilities scattered in the area east and west of the building, including agricultural terraces.

The main aim of the current research was to find an anthropogenic signature in the sediments of the site, and in the sediments of the surrounding fields. 

POSL, PXRF and XRF methods were applied in order to achieve this aim.

The results showed that a significant anthropogenic signature was recorded on the sediments of the building and its square courtyard. This is reflected in the chemical composition that was enriched by phosphorus (P) and calcium (Ca), and by the mixed pOSL signal values. In the anthropogenic fields, the chemical signature is typical of natural soil with a high amount of Iron (Fe) and Manganese(Mn) which reflect high water availability.  

It is interesting that although the site is small in size and was inhabited for a short period of time, the human imprint has remained hundreds of years after its abandonment.

How to cite: Ackermann, O., Marcus, J., Fišer, J., Itach, G., Janovský, M., and Wieler, N.: Khalat al-Saharij - An Iron Age Small Site and Long Anthropogenic Effect on the Soil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9663, https://doi.org/10.5194/egusphere-egu23-9663, 2023.

Kurgans are funeral chambers, evidence of burial tradition dating back to the first thousand years BCE, of nomadic populations that covered a vast area in-between Europe and Asia. In Azerbaijan, past archaeological explorations revealed numerous large kurgans from the Early Bronze, which correspond to Kura-Arexed period (ca. 3500-3000 BCE), and relatively smaller burials of Late Bronze/Early Iron Ages. To improve the efficiency of the excavation process, geophysical methods have been widely and effectively applied for many years to provide clear and useful images of archeological targets hidden underground such as kurgans.

In this work, we introduce a multi-method archaeo-geophysical survey done in May 2022 to investigate Early Bronze Age kurgans located in Uzun Rama Steppe of Goranboy region in Azerbaijan. Applied method cover different depth of investigation and resolution to provide a wealth of information on the structure of three kurgans aligned in a North-South direction. It comprises coincidental DC-resistivity and seismic refraction tomographies of 70.5 m with a 1.5 m spacing going over all kurgans, a Ground Penetrating Radar (GPR) 40 m long profile using a 500 MHz antenna on the northern kurgans going from East to West and a magnetic map 24 x 25 m on the southern one.

The DC-resistivity profile shows two layers, a medium resistivity layer (500 to 600 W.m) from the surface to 6 m depth and a very conductive layer (> 10 W.m) under it. The first layer contains three areas of lower resistivity (~ 60 W.m) that are limited in thickness and length. As these three spots are marked by higher height on-site, we interpret them as the three kurgans. The coincidental seismic profile is a lot less detailed (due to physical properties and higher spacing between receiver) and define only three homogeneous layers, a first layer from the surface to 1 m depth with a P-wave velocity of 300 m/s, a second layer of higher velocity (1000 m/s) from 1 m depth to approximately 6 m depth and a final third layer of 2000 m/s velocity. Even though, the resolution is lower, we interpret the first layer as an attempt of the model to represent the kurgans. The GPR profile give a high attenuate image due to low resistive layer. However multiple diffractions can be seen in the first meter of the subsurface that can indicate the presence of ancient artefact related to the kurgans. Finally, the magnetic map defines the limit of the kurgan as a positive-negative anomaly probably due to the burning ritual that ended the implementation of a kurgan.

This geophysical campaign allowed us to accurately locate the kurgans as well as provide information on the environment. DC-resistivity and magnetic mapping seem to get the best results in our case. A future archaeological investigation will be put in place based on these results.

How to cite: Bayramov, K., Jodry, C., Alizada, G., Mammadov, S., Azimov, V., and Abdullayev, M.: Geophysical investigation of kurgans in Uzun Rama steppe, Goranboy region, Azerbaijan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10838, https://doi.org/10.5194/egusphere-egu23-10838, 2023.

Based on surveys and three excavation seasons, we report details on one of the first major utilizations of loose aeolian sand for construction and (hypothesized) vegetable agriculture at the Early Islamic Plot-and-Berm (P&B) agroecosystem south of Caesarea Maritima, along the Mediterranean coast of Israel. P&B agroecosystems are an innovative initiative to reconstruct sand bodies and dunefields into agricultural plots sunken between sand berms. These agroecosystems are sporadically found between Iran and Iberia and some are still in use. The plots, usually ~1 m above the groundwater table allowed easy access to the water via shallow wells for irrigation.

Research methods included pedological and sedimentological analyses, micromorphology and compositional analyses such as Fourier Transform Infrared Spectroscopy to detect heating of cultural additives (e.g., fired clays, pyrogenic lime); plant ashes (e.g., deliberate enrichment of fuel and/or recycling of former crop cycles as part of plot maintenance); and pollen and phytolith analysis to detect micro-botanical proxies of crops. Relative chronologies were obtained from portable luminescence profiling (pOSL). OSL ages along with artifacts analysis indicate that the agroecosystem was established during the late 9^th or 10^th century and functioning until the early decades of the 12^th.

Refuse, including ash, carbonate, trace elements and artifacts, extracted from the dumps of Caesarea was combined with local sand to stabilize the berm surface but also partly altered the physical and chemical properties of the sand and increased its fertility, mainly in the plots, to form grey sandy to sandy loam anthrosols. This refuse was combined in different mixtures along the ~5 m thick berm fill and upon its slope and crest surface to stabilize the earthwork and comprise an anti-erosive agent. Similar mixtures were used to support berms and foundations of structures that served for lime production, agroecosystem management and local farming utilities. A 5 m high mound constructed out of interchanging anthrosediments was also piled up within a plot to support a presumable guarding structure. 

Plot anthrosols appear to include a basal, dark grey 20-40 m thick unit, ~ 1 m above the groundwater table that was enrichened with carbonate overlaid by a ~1 m thick grey sand anthrosol. The lower unit probably served for preserving infiltrating irrigation water that was applied to the crops grown atop the light grey anthrosol.

The agroecosystem remained well-preserved and untouched until the mid-20th century. Its pristine preservation is evidence of the ingenious and widespread utilization of refuse for construction and agriculture in sand. The untouched shape of this agrotechnological earthwork in the last millennia is intriguing and may be due to either lack of knowledge, or resources per revenue for similar endeavors.

How to cite: Robins, L., Roskin, J., Grono, E., Bookman, R., and Taxel, I.: Construction and Agriculture in Sand at the Early Islamic Plot-and-Berm Groundwater Harvesting Agroecosystem South of Ancient Caesarea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10982, https://doi.org/10.5194/egusphere-egu23-10982, 2023.

Soil marks are detectable by airborne images due to the difference in soil colour between the archaeological feature and the surrounding background soil. Colour of the soil only represents the visible part of the soil spectrum which contains physical and chemical information of the soil. This study will present a spectral analysis method to prospect soil mark features and buried archaeological remains using airborne image data. This method statistically calculates the difference between the targeted spectrum and the background (non-archaeological) soil spectrum. The difference is quantified by an R-value. If the R value is larger than 1, then the spectral behaviour of the targeted spectrum is different from the spectrum of the background soil and, thus, likely to be an archaeological soil spectrum (soil mark). In this study, the spectral analysis method will be applied to APEX imaging spectroscopy data collected from an archaeological site in Sárvíz Valley, Hungary. Previously, the method was successfully applied to the same archaeological site using soil spectra gathered by a portable hand-held VIS-NIR spectrometer. Here, the results showed clear spectral difference between soil mark features and background soil. This study will 1) compare the results of the method from hyperspectral image and ground-based spectral data, and 2) investigate the most effective waveband for identifying archaeological spectral signatures to verify the effectiveness of the method.

How to cite: Choi, Y. J.: Detection of archaeological soil marks using airborne hyperspectral images, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11168, https://doi.org/10.5194/egusphere-egu23-11168, 2023.

Most of the Alpine range was influenced by glacier movement or by intense erosive processes during Pleistocene glacial periods, which erased previously existing soils and landforms. Thus, most of the soils in the Alps began developing since at least the end of the Last Glacial Maximum (LGM). However, some surfaces located above the trimline (the upper limit reached by valley and cirque glaciers) still retain “old” morphologies and can be considered paleosurfaces, often covered by fossil or active periglacial features.

After having found very well developed Umbrisols hidden inside blockfields at 3030 m a.s.l. on the Stolenberg Plateau, Monte Rosa Massif – NW Italian Alps (Pintaldi et al. 2021a, 2021b, 2022), we explored other relict cryogenic landforms located above the Pleistocene trimline, such as blockfields and blockstreams, observing the soils hidden below the surface stone layers.

In most cases, we found extremely well-developed soils, such as Podzols with extremely thick E horizons or Umbrisols with A-Bh horizons up to more than 1-m thick. One of the most important properties was the large organic carbon content, up to 10-13% in soils located inside barren blockstreams and blockfields presently devoid of vegetation, at elevations between 1000 and 2950 m a.s.l..

The age of this organic matter is likely very old. For instance, inside the blockfield on the Stolenberg Plateau (3030 m a.s.l.), the organic matter was up to 22 ka old, corresponding to the early retreat glacial phase after the LGM. The age and nature of the organic matter in the other soils is still being analyzed, and it will be able to give important information on past environmental condition in understudied high-elevation areas in the Alps.

References

Pintaldi E., D’Amico M.E., Colombo N., Colombero C., Sambuelli L., De Regibus C., Franco D., Perotti L., Paro L., Freppaz M. (2021a). Catena. https://doi.org/10.1016/j.catena.2020.105044

Pintaldi E., D’Amico M.E., Colombo N., Martinetto E., Said-Pullicino D., Giardino M., Freppaz M. (2021b). https://doi.org/10.1016/j.gloplacha.2021.103676

Pintaldi E., Santoro V., D’Amico M.E., Colombo N., Celi L., Freppaz M. (2022). European Journal of Soil Science. https://doi.org/10.1111/ejss.13328

How to cite: D'Amico, M., Pintaldi, E., Melacarne, D., Benech, A., Colombo, N., and Freppaz, M.: Intense pedogenic development and large carbon contents in soils above the Pleistocene trimline (NW Italian Alps), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12360, https://doi.org/10.5194/egusphere-egu23-12360, 2023.

Several types of secondary carbonate accumulations have been reported, but some of them are not completely well defined in the field due to unclear nomenclature. This is the case of the “queras”, reported in several Loess-palaeosol sequences of the Ebro Valley, which have often been described as pseudomycelia. Micromorphologically, they are complex pedofeatures (including calcified root cells, infillings and hypocoatings of carbonates and a decarbonated zone), resulting from calcification/decalcification processess at a microscale. They are composed of a central channel (1-2 mm wide and 2-3 cm long) filled with biosparite crystals (Herrero et al., 1992). The study of these secondary carbonate bioaccumulations are important archives for climatic reconstructions in terrestrial environments and can be used for paleoenvironmental reconstructions. The aims of this research are the characterization (morphological, optical and isotopically) of the biocalcifications present in Loess-palaeosols sequences, OSL-dated, to determine the main factors that originate them and their possible use as a palaeoenvironmental proxy. We collected soil samples from seven profile of Loess-palaeosols where the presence of these biocalcifications was recorded. We isolated and manually cleaned complete fragments of queras to describe them and to determine their isotopic composition. For that purpose, we used the queras fraction (sieved fraction of bulk soil between 100-250 µm) removing the residues of micrite with a buffer solution and manually separating the quera fragments with the help of a stereoscope. Thin sections were made to analyse the micromorphology in a petrographic microscope and cathodoluminescence techniques to determine the origin of the calcite. The micromorphology of these biocalcifications is similar in most cases: they present the same number of rows around the central channel (4 to 5), and a decarbonated hypocoating around it, supporting the hypothesis that their origin is derived from the calcification of cells of the root tips as a strategy to acidify the soil surrounding to absorb nutrients. Under cathodoluminescence biosparite has a different behaviour than non-biological calcite crystals. The age of the queras was similar in most horizons and their formation is independent of the age of the loess deposit. The isotopic composition of δ¹³C correspond mainly to CAM plants and the temperatures of precipitation calculated correspond to a Mediterranean template climate (Cerling and Quade, 1993), implying that the biocalcifications developed in warm environments. Finally, we hope to gain some more certainty of their origin and formation processes from the ongoing analyses of DNA sequencing and pollen recording.

How to cite: Alvarez, D., Torres-Guerrero, C. A., Poch, R. M., and Preusser, F.: Morphology, distribution and origin of soil biogenic carbonates “queras” presents in Loess-palaeosols of Ebro Valley, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14081, https://doi.org/10.5194/egusphere-egu23-14081, 2023.

A multi-element and multivariate geochemical analysis has been carried out at a medieval farm site and village settlement, which belonged to the Cistercian monastery of Plasy (in W Bohemia). The results of our geochemical survey have been evaluated in context of the LiDAR survey covering the same area and the available historic maps (Habsburg Military surveys), which helped to locate relict landscape features and land-use changes. Approximately 300 samples were taken in a grid point pattern within the courtyard of the farm, as well as randomly, in the surrounding areas, in order to identify geochemical signals related to the observable surface phenomena. We have applied different analytical techniques, including PCA, log-transformation and isometrical log-transformation, and through spatial interpolation (IDW) it was possible to link  signals of both anthropogenic and geogenic character to archaeological, cultural and land-use phenomena. The results illuminated more intensive anthropogenic impact in connection to the courtyard area, and the intravillain area of the village, and additionally helped to locate different land-use activities in the  surrounding area (agricultural and possibly industrial). In that regard, this methodology was successfully applied to trace anthropogenic impact beyond narrowly defined archaeological sites. This abstract has been reformulated on the basis of our recently published paper (Horák et al 2023).

Horák, J., Janovský, M.P., Klír, T., Malina, O., Ferenczi, L., 2023. Multivariate analysis reveals spatial variability of soil geochemical signals in the area of a medieval manorial farm. Catena 220. https://doi.org/10.1016/j.catena.2022.106726

This abstract is part of the research project: “Monastic manors and the landscape impact of Cistercian estate management: A landscape archaeological and historical ecological study on Plasy Abbey“ financed by the GAČR - Czech Science Foundation, grant No. 21-25061S.

How to cite: Janovský, M., Horák, J., Klír, T., and Ferenczi, L.: Geochemical analysis in the area of a medieval Cistercian manorial farm, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14576, https://doi.org/10.5194/egusphere-egu23-14576, 2023.

Silver content and isotopic composition were studied in 3 selected 210Pb-dated profiles of ombrotrophic peat bogs in the Jizera Mountains, Ore Mountains and Sumava. The individual peat bogs differ in the rate of peat accumulation and intensity of immission load.

All peat bogs show a peak in the 1970s, which is related to the peak of industrial production in Europe and the associated coal burning. This peak is found at a depth of 7-12 cm in the peatlands studied.

In peat bogs in the Jizera and Ore Mountains, a smaller peak at a depth of 22-25 cm is followed by a peak in Pb concentration, probably related to Ag metallurgy in the 17th century.  This peak is not evident in the Šumava profile, where it is suppressed by elevated Ag concentrations in the underlying rocks.

The individual sources of silver are documented by isotopic composition that appears in the studied geochemical archives.

How to cite: Mihaljevič, M., Vaněk, A., Vaňková, M., and Ettler, V.: Elemental and isotopic composition of silver in selected peat profiles of the Czech Republic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15478, https://doi.org/10.5194/egusphere-egu23-15478, 2023.

Paleosol horizons preserved in loess-palaeosol sections (LPS) provide valuable archives of Quaternary palaeoenvironmental changes over time and spatial palaeoenvironmental gradients during the same period. Here, we present the characteristics of paleosol horizons in two LPS near the western edge of the Rhône Rift Valley in southeastern France: (1) the LPS “Baix” (total thickness: 14 m), located about 17 km north of Montélimar (44°42’36”N, 4°43’21”E), thus, in the transition zone between the presently temperate and the Mediterranean region of Europe; (2) the LPS “Collias” (total thickness: 9 m), located in the Uzès Basin, about 15 km northeast of Nîmes (43°57’11.94”N, 4°27’56.71”E), thus, in presently fully Mediterranean climate. Investigation of the paleosol horizons in the main profile at Collias was complemented by those of three smaller nearby LPS, “Collias-North_D112” (43°57’12.55”N, 4°27’55.83”E), “Collias-South_D112” (43°57’12.44”N, 4°27’53.36”E), and “Collias-North” (43°57’21.67”N, 4°28’6.99”E), in order to capture the spatial variability of the characteristics of some key horizons.

To our knowledge, no LPS have been analysed yet in such a transitional position between the presently temperate and Mediterranean climate. Primarily the LPS Baix may provide a crucial link between the rigorously analysed LPS in the presently temperate regions further north (e.g., in northern France, the Alsace region and Germany) and the LPS in the Mediterranean region (e.g., in southern France, Catalonia, Italy and Croatia), including the LPS Collias. Therefore, we aimed to decipher the paleoenvironmental record of the LPS Baix and Collias, and to identify similarities and differences between them. Optically stimulated luminescence (OSL) dating provided a chronological frame for both LPS.

The basal part of the LPS Baix starts with reddish Bt(g) horizons of a Stagnic Luvisol, representing the remains of an Eemian to Early Würmian (MIS 5) pedocomplex formed under warm and - at least temporarily - relatively moist conditions. The corresponding pedocomplex in the profile Collias-North_D112 displays an intensive red (chromic) Bt horizon overlain by several Bw horizons formed in reworked soil sediment and underlain by a massive calcrete. In the main profile at Collias, this red horizon has been entirely reworked by slope processes and has regained an angular blocky structure afterwards. Thus, it appears as a dark orange-red Bw horizon. Both, the LPS Baix and Collias include a prominent brown Bw horizon of a truncated Cambisol that developed in middle Pleniglacial (MIS 3) deposits. It is associated with large, elongated, vertically oriented calcium carbonate nodules, indicating that considerable amounts of calcium carbonate must have been leached from the former middle Pleniglacial Cambisol and accumulated in the underlying loess unit. No distinct palaeosols were observed in the Late-Pleniglacial deposits of the LPS Baix and Collias; a slightly brownish colour indicates very weak weathering (several BCk horizons) in the Late-Pleniglacial sediments of both LPS.

How to cite: Sauer, D., Pfaffner, N., Kadereit, A., Kreutzer, S., Karius, V., Kolb, T., Bertran, P., and Bosq, M.: Palaeosols in the loess section of Baix (Rhône Rift Valley, SE-France), compared to those of Collias: a unique Late-Pleistocene record of the transition zone between the presently temperate and the Mediterranean region of Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15899, https://doi.org/10.5194/egusphere-egu23-15899, 2023.

Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous membrane-spanning lipids with a wide environmental distribution. In soils, branched GDGTs are produced by a possibly large diversity of bacteria. The relative abundance of methyl groups attached to the central alkyl chains is at the basis of the paleotemperature proxy MBT’_5ME. However, MBT’_5ME values in soils can also be directly influenced by pH (De Jonge et al., 2021). A second group of compounds, the isoprenoid GDGTs, are produced by archaea. They have been used only sparsely as environmental proxies in soils, although they are at the base of the marine paleotemperature proxy TEX₈₆. In soils, a recent compilation by Yang et al. (2016) illustrates that the temperature dependency of TEX₈₆ is sometimes present, but potentially influenced by other soil (chemistry) parameters.

In addition to temperature, other soil parameters are expected to vary with time, even on a Holocene timescale. For instance, soil mineral fertility (specifically, the concentration of exchangeable cations) will vary following climate or land use changes. As soil mineral fertility will impact the soil nutrient status for vegetation, and impact the soil capacity to store organic carbon (von Fromm et al., 2021), it is a relevant parameter to reconstruct over time. However, as soil fertility of surface soils will decrease during eroision or burial, this parameter can currently not be reconstructed quantitatively.

To investigate the potential of GDGTs as soil fertility proxies, branched and isoprenoid GDGTs were measured in soils from 5 elevation transects (Austria, Bolivia, China, Indonesia and Tanzania, n=74) that cover a large gradient in mean annual temperature (0-28 ℃), seasonality, and soil chemical parameters. Supplemented with climate (temperature and precipitation) data, we evaluate both changes in absolute concentration and relative distribution of the GDGTs. Of the chemical parameters, exchangeable calcium and exchangeable iron are shown to correlate with the absolute abundance of several branched (6 methyl brGDGTs) and isoprenoid (crenarchaeol isomer) GDGT compounds. Based on these relations we have developed ratios to quantify calcium (and summed bases) and iron (and summed metals) [r2=0.61-0.68, p<0.001] using GDGTs in soils. As GDGTs are stable on geological timescales, their presence in paleosoil sequences will thus allow us to reconstruct changes in surface soil fertility (specifically, calcium and iron) through time, even after the mineralogy of the original topsoil has changed.

Based our promising preliminary data we propose that GDGT ratios to reconstruct soil mineral fertility should be developed further using well-characterized modern soils. In addition, we look forward to testing our proxies on paleosoils by starting new collaborations.

De Jonge, C. et al. The influence of soil chemistry on branched tetraether lipids in mid- and high latitude soils: implications for brGDGT- based paleothermometry. Geochimica et Cosmochimica Acta (2021).

von Fromm, S.F., et al. Continental-scale controls on soil organic carbon across sub-Saharan Africa. SOIL 7, 305–332 (2021).

Yang, H., et al. The Response of Archaeal Tetraether Membrane Lipids in Surface Soils to Temperature: A Potential Paleothermometer in Paleosols. Geomicrobiology Journal 33, 98–109 (2016).

How to cite: De Jonge, C., Guo, J., Hallberg, P., Griepentrog, M., Smittenberg, R., Peterse, F., Boeckx, P., and Dercon, G.: Using biomarker lipids to reconstruct soil fertility through time, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16684, https://doi.org/10.5194/egusphere-egu23-16684, 2023.

The Roman villa of Pisões (Beja, Portugal), was part of the Lusitanian colony of Pax Iulia. This place stands out for the predominance of the water element in several structures of the villa, highlighting the balneum and the large natatio, one of the largest known in Roman Hispania. The records of the initial excavations that took place since 1967 do not allow the establishment of clear functionalities of the villa. The University of Évora, owner of the site, conceived an action plan for the requalification and enhancement of the archaeological site. One of the tasks aims to investigate using Applied Geophysics. This work analyses the landscape directly related to the villa, given that it is in the flooded area of a river, with a Roman containment dam. It is uncertain whether the water supply comes from this structure or other nearby springs. The use of ground-penetrating radar, combined with unnamed aerial vehicles, all integrated in a geographic information system, allows us to know the location of underground water connections and create a topographic model with high resolution. Considering all the information, we propose a model for the water transport inside the villa and estimate the location of the water supply.

Acknowledgment: The work was supported by the Portuguese Foundation for Science and Technology (FCT) project UIDB/04683/2020 - ICT (Institute of Earth Sciences).

How to cite: Trapero, P., Oliveira, R., Caldeira, B., Borges, J. F., and Carneiro, A.: Studying the water supply system of the Roman villa of Pisões (Beja, Portugal) using ground-penetrating radar and geospatial methods, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17056, https://doi.org/10.5194/egusphere-egu23-17056, 2023.

The study of some classic cases in archeology could provide key information to track where geoarchaeology came from. Joseph Anderson made great contributions to Chinese archaeology and geoarchaeology from the 1920s to 1940s. Previous academic historical studies reflected particularly on pure archaeological methodology; however, in rare cases there has been a focus on the decisive transition from geology to archaeology. Anderson was one of the pioneers who used his knowledge from field work in Europe and America to inform his geoarchaeological work in China. His earliest geoarchaeological study addressed earlier human-environmental interactions by deploying basic concepts and tools. Anderson combined methods from geology with archaeology in three case studies from the 1920s to the 1940s. He came across three dilemmas: i) Analogy dilemma: homological fossils or multiregional origin of artifacts; ii) Principle dilemma: cross-cutting relationships in stratigraphy or archaeology; iii) Time dilemma: synchronic or diachronic systems. At the time, his conclusions drew massive criticism from some archaeologists, especially because of confusion in terminology or principles arising from immature archaeological methodology and neglect of premises in different disciplines. After the development of stratigraphy in the work of classical archaeology before the 1900s and studies on Quaternary human-environmental interactions during the 1900s to 1920s, Anderson found a means to approach the Anthropocene. In summary, here we review the initial geoarchaeological exploration of China during the 1920s to1940s, which is crucial to better understand archaeological academic history and the early history of the Anthropocene as an independent stratigraphic geological unit.

How to cite: Zhao, Y., Zhu, Z., Benton, M. J., and Lu, H.: The infancy of Chinese geoarchaeology: dilemmas from the Quaternary to the Anthropocene, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-171, https://doi.org/10.5194/egusphere-egu23-171, 2023.

The settlement of Chimtou located in the Medjerda valley is known for its marble quarry, where yellow marble was mined for the entire roman empire. During the Roman period Chimtou has been a major roman city but little is known about the changes during the transition to the Arab period. The interdisciplinary project ISLAMAFR aims to understand the cultural, economic and landscape transformations of the western Medjerda Valley from late antiquity to the early medieval period (600 to 1000 AD).

Earlier studies in the region by Christoph Zielhofer and Dominik Faust have shown that the landscape evolution of the Medjerda Valley derived from alluvial records indicates short-term changes in fluvial dynamics in the Holocene. During the upheaval from Roman to Arab period they reconstructed great flooding events for the Western Medjerda Valley with a brief slow-down in fluvial activity during the Arab conquest. On the basis of their work we will densify the landscape history using two fluvial and alluvial archives from the hinterland of Chimtou for the period from 600 to 1000 AD. We analyzed sediment cores in the laboratory from an infilled oxbow lake of the Oued Medjerda and a flood channel, which regularly overflows. The successive phases of channel infill of the archives allow us to reconstruct the fluvial activity and landscape changes in their surroundings. A multi-proxy approach was applied, integrating the analysis of the dated high-resolution sediment records with geomorphological mapping, archaeological records, and geological and topographical data. Coupling the long-term landscape changes with high resolved short-term landscape changes identifies the human-environmental interactions in the hinterland of Chimtou from late antiquity to early medieval period.  

How to cite: Pagels, J., von Rummel, P., Chaouali, M., and Bebermeier, W.: Meso-scale landscape changes reconstructed from fluvial and alluvial sedimentological archives around the roman town Chimtou (Medjerda Valley), North Tunisia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-809, https://doi.org/10.5194/egusphere-egu23-809, 2023.

Long-term human-environmental interactions in naturally fragile drylands are an actual topic of geomorphological and geoarchaeological research. Furthermore, many prehistoric societies in drylands were also affected by seismic activity. The semi-arid Shiraki Plain in the tectonically active southeastern Caucasus is currently covered by steppes and largely devoid of settlements. However, numerous Late Bronze to Early Iron Age city-type fortified settlements suggest early state formation between ca. 3.2 – 2.5 ka that abruptly ended after that time. A paleolake was suggested for the lowest plain, and nearby pollen records suggest forest clearcutting of the upper altitudes under a more humid climate during the Late Bronze/Early Iron Ages. Furthermore, also an impact of earthquakes on regional Early Iron Age settlements was suggested. However, regional paleoenvironmental changes and paleoseismicity were not systematically studied so far. We combined geomorphological, sedimentological, chronological, paleoecological and hydrological modelling data to reconstruct regional Holocene paleoenvironmental changes in the Shiraki Plain, and identify possible natural and anthropogenic causes as well as possible seismic events during the Late Bronze/Early Iron Ages. Our results show a balanced to negative Early to Mid-Holocene water balance probably caused by forested upper slopes. Hence, no lake but an incipient Chernozem developed in the lowest plain. Following, Late Bronze/Early Iron Age forest clear-cutting obviously caused lake formation and the deposition of lacustrine sediments derived from intensive soil erosion. Subsequently, regional aridification obviously caused slow lake desiccation. Remains of freshwater fishes indicate that the lake potentially offered valuable ecosystem services for regional prehistoric societies even during the desiccation period. Finally, colluvial coverage of the lake sediments during the last centuries could have been linked with hydrological extremes during the Little Ice Age. Our study demonstrates that the Holocene hydrological balance of the Shiraki Plain was and is situated near a major hydrological threshold, making the landscape very sensitive to also small-scale human or natural influences with serious consequences for local societies. Furthermore, seismites in the studied sediments do not indicate an influence of earthquakes on the main and late phases of Late Bronze/Early Iron Age settlement. Altogether, our study underlines the high value of multi-disciplinary approaches to investigate long-term human-environmental interactions and paleoseismicity in drylands on millennial to centennial time scales.

How to cite: von Suchodoletz, H., Kirkitadze, G., Koff, T., Fischer, M. L., Poch, R. M., Khosravichenar, A., Schneider, B., Glaser, B., Lindauer, S., Hoth, S., Skokan, A., Navrozashvili, L., Lobjanidze, M., Akhalaia, M., Losaberidze, L., and Elashvili, M.: Holocene human-environmental interactions and seismic activity in a Late Bronze to Early Iron Age settlement center in the southeastern Caucasus, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1479, https://doi.org/10.5194/egusphere-egu23-1479, 2023.

When looking into land use and human agency in the modification of the landscape, the concepts of socio-economic opportunities vs. natural constraints is one of the key issues. In comparison with the modern world, past human communities relied much more upon local resources and a tight societal structure to better adapt to the conditions and changes in the surrounding environment. Therefore, in the study of prehistorical cultures land use is both a strong source of information about sustenance strategies and community behaviours and a subject potentially easier to model within a set of natural and social parameters. To this purpose, we investigated the settlement distribution patterns of Bronze Age structures of the Nuragic culture on the island of Sardinia (Italy) using spatial point pattern analysis. We investigated different covariates divided into natural (topography, water and geological resources) and cultural (type of structure, settlement hierarchy), alone and in combination, and looked at how each could explain the distribution of Nuragic sites.

Several covariates from both natural and cultural groups show significant values, with the best representing models of pattern distribution coming from the combination of covariates from both groups. Aside from topographic parameters, distance from known ore deposits seems to have an impact on structure density. Among cultural covariates, there is a clear association between simple and complex megalithic structures (nuraghes). This pattern suggests the collation of smaller structures around larger settlements, either by the former emerging from the presence of the latter or vice versa. These findings offer new insight on the development and ways of life of the Nuragic society in their geographical context, and highlight how the relationship between the physical and the social aspects of human-landscape interactions is fundamentally interdependent. This approach could also represent a potential tool to compare to other Bronze Age and prehistorical communities.

How to cite: Mariani, G. S., Brandolini, F., and Melis, R.: Natural and social patterns in the distribution of Bronze Age Nuragic sites (Sardinia, Italy): using the Widom-Rowlinson penetrable sphere model to understand past human occupation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5051, https://doi.org/10.5194/egusphere-egu23-5051, 2023.

The transition from roaming/mobile hunters-gatherers to sedentary settlements in the southern Levant during the Late Epipaleolithic (Natufian) is considered a decisive point of no return in the history of mankind. While the first sedentary settlements are known predominantly from the Mediterranean area of the Levant, the reasons for this fundamental change in subsistence are deeply rooted in socio-economic adaptations of the last mobile hunters-gatherers in the region at large, and in particular, the Sinai-Negev desert. Here diverse nomadic Epipaleolithic groups left behind numerous small open-air sites along the fringe of the northwestern Negev desert dunefield (Israel). Geoarchaeological and palaeoenvironmental analysis of newly discovered Epipaleolithic sites allow better understandings of the unique socio-economic adaptations of these humans.    

The studied middle Epipaleolithic (Ramonian) open-air Ashalim-west site is situated in a unique geomorphic setting atop a slightly deflated surface upon a 3-5 m thick falling dune at the southeastern edge of the Negev dunefield. The dune is comprised of very fine sand that differs from the common vegetated linear dunes (VLD) of the Negev dunefield, dominated by fine sand. The falling dune mantles a 2^nd-order wadi slope of a ~40 m high plateau of Eocene chalk, interbedded with chert beds that probably served for lithic production. The small wadi drains into the Besor basin, the largest ephemeral stream in the northwestern Negev, and the only one that currently transverses the dunefield. Therefore, opposed to smaller basins, it was prone to damming by a wide band of encroaching dunes that may have led to extensive water bodies upstream dune dams and possibly beyond drainage divides.

Four OSL ages in the range of 16.5±0.8 – 15.5±0.8 ka from the upper ~2 m of two sections at the Ashalim-west site correlate with raw portable OSL signals, and reflect rapid aeolian deposition. This deposition, synchronous with the main sand incursion episode into the Negev dunefield during the Heinrich 1 cold event (Roskin et al., 2011), closely fits the age associated with the Ramonian character of the overlaying lithics.

The Heinrich 1 massive aeolian episode may have led to major damming of the Besor basin and widespread expansion of dune-dammed water-bodies upon the Besor floodplains. 1.5 km northeast to Ashalim-west site, remains of slightly later Middle Epipaleolithic (Geometric Kebaran) and Late Epipaleolithic (Natufian and Harifian) are sited on top of fossilized aeolian sand between synchronous seasonal dune-dammed water bodies (Goring-Morris, 1997; Vardi et al., 2018). Here OSL ages of aeolian and fluvial sand beneath the sites also date to the Heinrich 1 period. Later and less intense episodes of dune-damming in these parts of the Besor basin may have allowed for short-term camping upon dune crests and flanks adjacent to water bodies. The perched setting of Ashalim-west, overlooking the largest Besor basin, along with two other Middle Epipaleolithic (Ramonian and Mushabian) sites (Rosen, 1990; Rosen and Kolska-Horwitz, 2005) therefor differs from the abundant Epipalaeolithic open-air sites along the dunefield fringe and may indicate a local choice of high grounds during times of intense dune-damming and water body expansion.

How to cite: Roskin, J., Robins, L., Greenbaum, N., Porat, N., and Yaroshevich, A.: Reconstructing palaeoenvironments of the last mobile hunters-gatherers in the southern Levant during the middle Epipaleolithic period, northwestern Negev dunefield, Israel, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9267, https://doi.org/10.5194/egusphere-egu23-9267, 2023.

Archaeological sequences and landscapes preserve evidence of the complex relationship between human communities and climatic/environmental changes occurred in the Quaternary. In this perspective, archaeological sediments and landscapes are proxy data for past ecosystems evolution, as much as for changes in land use, exploitation of natural resources, and human behavior. Most of the latter can be detected and explored with a geoarchaeological approach, using the tools and methods offered by Earth Sciences. For that reason, accurate sampling during the excavation of archaeological sites allows to increase the number and quality information useful to reconstruct the formation of an archaeological sequence, its preservation, and human activities. What can we do when archaeological excavations were carried out before the application of methods from the Earth Sciences? How can we gather information from residual strips or archaeological sediments? The SPHeritage Project (MUR grant: FIRS2019_00040, P.I.: M. Pappalardo) is coping with this challenging task reinvestigating the Balzi Rossi archaeological area (Western Liguria, Northern Italy). This area represents a key site for the reconstruction of how human populations have responded to Pleistocene environmental changes and sea-level variations since the Middle Pleistocene. Local anthropogenic cave sequences have been excavated since the half of the XIX century; unfortunately, the geological processes in charge of the formation of such deposits have been only occasionally considered. As most of the local archaeological sequences were removed, we are combining the analyses of the remnants of strips of anthropogenic sediments still preserved inside local rock shelters as much as sediment samples preserved in museums. Moreover, our geomorphological survey identified new sedimentary sequences preserving information on relative sea level changes, better constraining the time and steps of climate change, sea-level oscillations, and human settlements. Our results confirm that this approach is an effective tool to reconstruct the formative processes of anthropogenic sequences excavated in the past, thus expanding our possibility of understanding the climate-environment-human nexus.

How to cite: Zerboni, A., Perego, A., Ryan, D., Starnini, E., and Pappalardo, M.: Documenting the diversity of human responses to Quaternary environmental changes when the stratigraphic record is gone. The experience of the SPHeritage Project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11087, https://doi.org/10.5194/egusphere-egu23-11087, 2023.

Human impact on the environment as derived from colluvial deposits – example from the La Tène Period until the Middle Ages in the Siegerland (Germany)

Reetz, K¹., J. Kirch¹, J.J. Birk^1,2, A. Stobbe³ and S. Fiedler¹

¹ Johannes Gutenberg-University Mainz

² recent adress Georg - August - University Göttingen

³ Goethe - University Frankfurt am Main

The Siegerland is one of the most cohesive mining regions in the Iron Age in Central Europe. While the number of settlement and smelting sites has been increasingly better researched over the last few years, it was basically unknown which impacts by the La Tène iron production on the primary forests have to be considered, and how are such correlated with other activities and soil erosion. Below a smelting site in the southwestern part of the Siegerland, we made a rare find of colluvial deposits in the valley of the Obersdorfbach. It tells about the human impact between the Earlier Iron Age and the heyday of iron production during the La Tène period and the Middle Ages. In addition to pollen and NPP analysis, we used element contents, and molecular markers (n-alkanes, steroids).

The small stream has cut in sections in meanders up to 180 cm deep into the relatively narrow floodplain. There, they lie on a gravel bed with embedded peat (Obersd 1, 170 – 153 cm, calibrated age 700/500 – 350 BC). In the uppermost 10 cm of the fen peat, the proportion of mineral components increases and pebbles are intercalated (Obersd 2, 153 – 145 cm, 350 – 200 BC).  On top are multi-textured sandy-clayey colluvial/floodplain loams with charcoal bands (Obersd 3, 145 – 125 cm, 200 BC – unknown). It is followed by a sandy colluvium from the Middle Ages (Obersd 4, 125 – 110 cm).

In the 7th to the middle of the 4th century BC the forests near Obersdorf consisted mainly of beech and linden trees. Nevertheless, non-arboreal pollen provides evidence of anthropogenic impact (Obersd 1). According to the mountain-archaeological picture, at first iron was produced only on a small scale and the interventions in the vegetation were still small. Although the area should have been sparsely populated at the time, fecal markers suggesting human presence can be found. However, human influence on the landscape increased significantly from about 350 cal. BC (zone Obersd 2). Pollen and n-alkanes show a distinct impact into the vegetation. Forest clearing led to erosion and the accumulation of thick colluvial deposits. Pollen from ruderal places increase significantly, cereals and coprophilous spores occur. The strong anthropogenic influence in zone Obersd. 2 can be correlated with the archaeologically known smelting site. In addition to wood for firing the furnaces, large quantities of clay were needed for their construction. During the transformation of the landscape, erosion increasingly occurred on the slopes. The result is clayey silt sediments with intercalated charcoal bands (Obersd 3). The following sandy colluvium (Obersd 4) from the early Middle Ages shows a dominance of beech, hornbeam, and rye. Steroids show the presence of humans and livestock here.

How to cite: Reetz, K., Kirch, J., Birk, J. J., Stobbe, A., and Fiedler, S.: Human impact on the environment as derived from colluvial deposits – example from the La Tène Period until the Middle Ages in the Siegerland (Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12609, https://doi.org/10.5194/egusphere-egu23-12609, 2023.

The project »From Romans to the Anthropocene, from Carnuntum to Vienna: An Urban Anthropocene Field Lab« (WWTF ESR20-027) focuses on the urban transformation from the Roman legionary camps of Carnuntum and Vindobona to Vienna's periurban areas. Combining historical and geoarchaeological methods, we investigate the diverging development of the two sites and their manifold relations over time.

The Danube river crosses the mountain ranges of the Wienerwald and Malé Karpaty, forming the eastern and western limits of the central Vienna Basin. For many centuries, the river was both a barrier and a transportation route. The floodplains and river terraces along the Danube served as concentration areas and battlegrounds during countless conflicts between central Europe and its enemies.

The legionary camps of Carnuntum and Vindobona were built during the first century AD at the rim of glacial river terraces, next to the shortest passages across the Danube. During late antiquity, the former provincial capital Carnuntum lost importance. However, Vindobona became first a local center and later the capital of the Austrian rulers. After a sudden Turkish siege in 1529, the fortifications of Vienna were strengthened and maintained until the middle of the 19^th century.

Urban development of the region over the centuries was limited not only by permanent military threats. North of the Danube, agriculture was always restricted climatically by aridity and sand drift. Most settlements on the riverbanks of the Danube and its tributaries were affected frequently by floods and erosion. Many villages vanished completely as a consequence of such natural hazards. Since some decades, natural river dynamics have been restricted technically, and many areas under cultivation are now irrigated artificially. The analysis of the sedimentary record downstream of Vienna clearly shows the anthropogenic impact on sedimentation processes.

Contrary to Carnuntum, Vienna could evolve from a legionary camp step by step into a capital and a strong fortress. The demolition of the city walls after the middle of the 19^th century, the following long period of peace, and, in particular, the consequent river engineering, were preconditions for the development into a modern metropolis.

How to cite: Weissl, M., Hatzenbühler, D., Baumgartner, C., and Wagreich, M.: From Romans to the Anthropocene: Geoarchaeological Investigations in the Central Vienna Basin (Austria), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12871, https://doi.org/10.5194/egusphere-egu23-12871, 2023.

The catchment basin of the Sarandopotamos on Evia Island (Greece) has been an environment of habitation and worship since the early Neolithic. Many settlements from different periods have been found in this area. It is also in this catchment, close to the Sarandopotamos delta, that the Swiss School of Archaeology in Greece discovered in 2007, the sanctuary of Artemis Amarysia after centuries of investigation. This discovery aside, we still do not understand if, and the extent to which, the human history of occupation and abandonment in this region is related to its environmental history. Thus, the aim of this research is to use a suite of paleoenvironmental reconstruction methods to recreate ancient landscapes, their environments and their evolution to understand the society-environment relation. The sanctuary and its eventual abandonment could potentially be impacted by synergistic reactions between changes in sediment supply, changes in basin hydrology and sea-level all of which may have impacted both the magnitude and frequency of local flooding via changes in river bed level, lateral shifting of the river and water table rises and falls. Thus, the aim of this project is to undertake an integrated, multi-method reconstruction of the local water-sediment environment and to relate this to the history of the sanctuary and wider human settlement. This will then test whether an environmental influence needs to be retained as a hypothesis for wider societal changes in this area. In order to do this, a model of the sedimentary dynamics of the catchment is being carried out using LAPSUS software, and sedimentary cores are being obtained in order to understand the relationship between environmental and human-driven (e.g. land use) change in the catchment, the geomorphic response of the delta and the history of human occupation. The relationship between the delta and eustatic and isostatic history also has to be understood. A single beam eco sounder survey is been conducted in order to investigate the different delta created by the shift in the Sarandopotamos bed. Moreover, in order to better understand the local context and the landscapes observed today, this project is also interested in the geomorphological history of periods prior to human occupation. These different aspects emphasize the complexity of the project but through developing a multi-disciplinary and multi-scale appraisal of environmental history and how it links to human history we may get a better understanding of the extent to which the two are connected. This poster will present preliminary modelling results that demonstrate the sensitivity of the land-ocean interaction to sea-level rise and delta dynamics from the late Pleistocene through the Holocene to the present.

How to cite: Talas, T.: Society-environment links in the area of the sanctuary of Artemis Amarysia (Evia Island, Greece) based upon paleoenvironmental reconstruction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13095, https://doi.org/10.5194/egusphere-egu23-13095, 2023.

Twelve potsherds from the 3rd millennium BCE pottery in southeastern Lithuania were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to obtain the bulk geochemical and mineralogical characteristics of the ceramic paste. Microstructures and geochemical variability of the clay matrix and temper were studied by Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). The purpose of this study was to characterize the pottery attributed to the foreign Corded Ware Culture and local Hunter-Gatherers, to imply possible sources of raw material and to evaluate technology choices.

The main clusters of major and trace elements in the bulk compositions (XRF; Šatavičė et al., 2022) reflect the five technological styles identified by the manipulation, shaping, and firing conditions of the ceramic raw material. The XRD and FTIR analysis (Šatavičė et al., 2022) indicated a predominance of iron-rich illite clay, quartz, and alkali feldspar minerals. The early coarse pottery was fired at low to medium temperatures, accompanied by a decrease in the firing temperature of both the cord-decorated and hunter-gatherer pottery. The FTIR and XRD results are not indicative of firing in a reducing atmosphere.

The SEM-EDS with SE and BSE imaging and point analysis allowed to determine the detail mineral chemical composition of the ceramic pastes and tempers. The SEM SE and BSE images showed textural differences in the clay matrix, some of which may be explained by intentionally mixing the clay or a specific pottery surface treatment. The other may be attributed to internal differences in glacial till formation. No grog temper characteristic for the classic Corded Ware was detected, only clay pellets, ferruginous nodules and weathered minerals, which may look like grog to the naked eye. The SEM-EDS point analysis allowed us to investigate the gradual changes in the chemical composition of the clay matrix and to evaluate weathering process. To sum up, both the Corded Ware and the local Hunter-Gatherer pottery were made from the same hydro-micaceous variegated clay from the local Quaternary glacial sediments, which contain weathered granitoid fragments, but display different technological choices for the clay paste preparation, surface treatment, and firing strategies.

The study provided a lot of hitherto unknown information on glacial till, glacial lacustrine and post-glacial lacustrine sediments in SE Lithuania. Their composition, textural properties, susceptibility to weathering were evaluated for the first time in this region.

Šatavičė, E. et al., 2022. Minerals 12, 1006. https://doi.org/10.3390/min12081006.

How to cite: Skridlaite, G., Šatavičė, E., Zaludiene, G., and Selskiene, A.: Linking geology and archeology: investigations of Corded Ware and contemporary Hunter-Gatherer pottery from SE Lithuania by micro-invasive spectroscopic methods, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14840, https://doi.org/10.5194/egusphere-egu23-14840, 2023.

In order to investigate the interaction between different human societies and their effect on the natural environment, we focus on three main questions. 1: Where were historical settlements located? 2: Where have the routes connected these settlements passed? 3: How have both these settlements and routes interacted with local pedological and geomorphological processes? The northern Ethiopian Highlands (Tigray) have a documented settlement history spanning at least the last three millennia. Some sites have a centuries- or even millennia-long settlement continuity and the reconstruction of their entanglement can help to learn about the interaction between past societies. Pathways, be it over long- or short distances, provide the potential to investigate past and present decision-making processes in route planning. Furthermore, pathways are an impressive example of human-environment interactions. These pedogeomorphological expressions of human trampling on the same piece of land over a certain period of time have different soil characteristics (soil compaction, pedogenic iron contents) than adjacent land areas and can influence the surface hydrology. Under certain conditions in hilly terrain, pathways can either stabilize or destabilize the landscape, depending on their orientation with regard to the local hydrological network, and their degree of incision into the surface (holloways). As such, we analyzed geomorphic and pedogenic properties of pathways as well as feedback mechanisms between pathways and gully erosion, and how these may influence route planning. The reconstruction of historical routes in northern Ethiopia using a combined approach of geolocating historical travel reports and historical maps dating back to the 15^th century as input data for least-cost-path analyses, have the potential to reveal points of interest for further archaeological research.

How to cite: Busch, R., Hardt, J., Nir, N., and Pfeiffer, K.: Routes of Interaction – Research on pre-modern route-setting, pedogenic and geomorphic effects of trampling, and feedback mechanisms between pathways and gully erosion in the Northern Ethiopian Highlands (Tigray), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14877, https://doi.org/10.5194/egusphere-egu23-14877, 2023.

Technical improvements at the end of the Bronze Age led to the rise of a 1rst generation of major sea powers around the Mediterranean Sea, such as Etruria in modern Italy. The Etruscan coast was the fringed by a series of large lagoons. Only one survives today: the lagoon of Orbetello. The lagoon is preserved by two subparallel sand spits that connect former Argentario island to mainland Italy, as situation that today protects it from rapid infilling. A third sand spit, in the middle of the lagoon, hosts the Etruscan city of Orbetello. Today, three canals connect the lagoon to the sea. A massive phase of eutrophication driven by the ingress of fertilizers has plagued the lagoon in late 20th Century. Eutrophication at times has spurred fish and bird kills, and the release of mercury in the water column. Major contingency plans have been implemented to fight off eutrophication, with various success. 

              However little is known of the lagoon management and the evolution of Orbetello before the 17th century CE. Nonetheless, the wealth of the city and the health of its lagoon have been tightly related during the past three millennia. To track this coevolution, a large team of researcher has been assembled to conduct an analysis of the lagoon sediments using XRF scanning of cored sediments, SMIR, Rock Eval, hyperspectral imaging of chromatic pigments, analysis of mercury and phosphorus content, ostracods and pollen assemblages, to document the links between sediment facies, eutrophication and salinity crises, as a result of successive phases of rise and demise of lagoon management over the past three millennia. Here, we focus on the sub-bottom imaging conducted in the very shallow (< 1.5m) waters of this extensive (30 km2) lagoon. The Exail Echoes 10 000 sub-bottom profiler reveals individual layers that can be traced across the lagoon, allowing stratigraphic correlations between cores, and highlighting the environmental significance of the sedimentary facies. Acoustic imaging using a 3.5 kHz Chirp systems from Exail (Haliotis R/V) was conducted offshore to document the architecture of the sand spits protecting the lagoon. The architecture of the deposits, 14C, OSL, and U-Th dating reveal that the lagoon results from the drowning of strandplains that started forming on both side of the older, central sand spit, at the end of the postglacial transgression. Drowning accompanied the final rise in sea level over the past 6.5 ka, forming two lagoons on both sides of the central spit. These initial lagoons eventually coalesced after drowning the central sand spit. Continuation of the lagoon level rise since Antiquity led to the flooding of Bronze Age, Etruscan and Roman settlements. Sub-bottom imaging in the lagoon reveals buried structures possibly used for navigation and salinity control. Sedimentation is marked by an alternation of black, shelly organic silty clays and decimeter-thick layers of broken shells. Radiocarbon dating indicates that the cores capture up to five millennia of sedimentation, with a sharp decrease in sedimentation rates four millennia ago.

How to cite: Vittori, C., Jouve, G., Brocard, G., Goiran, J.-P., Vitale, Q., Darras, L., Mattio, L., Conforti, A., Oberlin, C., Preusser, F., Sabatier, P., Pons-Branchu, E., Gonçalves, C., Bomou, B., Develle, A.-L., Goyon, A., Chapkanski, S., Jacq, K., and Debret, M.: O’Estrucan Ports, Where Are Thou ? Multiproxy sedimentological investigation of the Orbetello Lagoon, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16741, https://doi.org/10.5194/egusphere-egu23-16741, 2023.

Agricultural activities affect soil fauna and may thus impede biological soil functions. In the field of soil biology, uncertainty remains about which specific activity adversely affects biological soil functions.  This study aimed: (i) to quantify the effect of ploughing activity on earthworm abundance in an experimental farm of the University of Göttingen, Reinshof, and (ii) to compare the earthworm abundance between an ecologically managed field vs. a conventionally managed field. Earthworm sampling, using the mustard method, was done between the 22^nd of April and 3^rd of May 2021. Three differently managed fields were sampled: ecologically managed with ploughing, conventionally managed with ploughing and conventionally managed without ploughing. Earthworms were collected in 30 locations per field. Soil organic matter contents, penetrometer resistance, and soil moisture were also measured. The conventionally managed ploughed field exhibited a mean earthworm abundance of 98.9 individual per square metre, which was more earthworms than the ecologically managed field that showed a mean earthworm abundance of only 7.86 individuals per square metre. The highest mean earthworm abundance of 160.8 individual per square metre was observed in the conventionally managed non-ploughed field. Species richness of earthworms was also higher in the conventionally managed fields compared to the ecologically managed field. The conventionally managed non-ploughed field had the highest soil organic matter content, moisture status, nitrogen content, and penetrometer resistance, in contrast to the ecological ploughed field, which showed the lowest values for all these parameters. The findings of this study are consistent with previous studies that the non-ploughed fields provide a suitable environment for earthworm communities, as perturbation of earthworms is avoided and soil organic matter levels are maintained, which is a key requirement for earthworms’ survival, therefore increasing their abundance. The very low earthworm abundance of the ecologically managed field was unexpected, but might be explained by the frequent ploughing, used for weed control instead of herbicides. We concluded that ploughing is an important activity that impacts the abundance of earthworms.

Keywords: soil, earthworms, conventional farming, ecological farming, ploughing

How to cite: Bhattarai, S., Asabere, S., Sauer, D., and Friedel, J.: Higher earthworm abundance in conventionally managed agricultural fields than ecologically managed fields, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-148, https://doi.org/10.5194/egusphere-egu23-148, 2023.

Crop diversification has gained importance in Brazilian soybean (Glycine max L.) cropping systems, usually cultivated in soybean/2^nd season maize (Zea mays L.) successions. Brachiaria grass (Urochloa spp.), a forage highly grown in Brazilian livestock systems, can be a suitable option for the soybean systems diversification. Brachiarias are well adapted to tropical conditions, produce high amounts of above and belowground biomass, have high nutrient cycling capacity, and release exudates known as biological nitrification inhibitors (BNI). All these traits might increase soybean yield and nutrient use efficiency in the agroecosystem.

Brazilian cropping systems rely on plant growth-promoting bacteria (PGPB), like seed inoculation of soybean with the nitrogen-fixing bacteria Bradyrhizobium, alone or in combination with Azospirillum, to replace mineral N fertilizers.

In this study, we aimed to investigate the soil bacterial community (activity and diversity) response to the diversification of soybean/maize cropping systems with Urochloa ruziziensis and inoculation with different combinations of PGPB. We hypothesize that inoculation with PGPB and diversification of the system with maize intercropped with Brachiaria will enhance microbial community activity and diversity.

A 5-year experiment has been conducted in Londrina (Paraná State, Southern Brazil) in a randomized complete block design with a split-plot arrangement and six replicates. Main plots consisted of soybean during the cash crop season (S: soybean without inoculation; Si: soybean inoculated with Bradyrhizobium; Sc: soybean co-inoculated with Bradyrhizobium + Azospirillum). Sub-plots consisted of different diversification systems after the cash crop season (M: succession with maize; M+U: maize intercropped with U. ruziziensis; Mi+Ui: maize intercropped with U. ruziziensis, both inoculated with Azospirillum). After the soybean harvest in the 2021/2022 cropping season, soil samples were taken at the 0-10 cm soil layer. We analyzed soil enzymes (arylsulfatase, β-glucosidase, and acid phosphatase), environmental factors (soil pH and nutrients), and the 16S gene sequence.

Preliminary results suggest an increase in the relative abundance of some bacterial phyla with Brachiaria. The phylum Proteobacteria, which harbors numerous PGPB, showed higher relative abundance in the cropping systems with Brachiaria, independently of the inoculation strategy in the summer soybeans. On the other hand, for the Nitrospirota phylum, which contains nitrite-oxidizing bacteria, higher relative abundance was observed in S/MiBi and Si/MiBi, compared with Sc/MiBi. Additional results on bacterial community diversity and composition and their relationship with microbial activity and environmental indicators will be discussed.

This study provides novel insights into how crop diversification combined with PGPB affects the soil microbial community and nitrogen dynamics, supporting agricultural and soil management practices to achieve more sustainable production systems.

How to cite: Rewa Charnobay, A. C., Lalonde-Haman, C., Ferraz Helene, L. C., Gumiere, T., Hungria, M., and Nogueira, M. A.: Crop diversification and seed inoculation strategies effects on soil microbial community in soybean cropping systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-524, https://doi.org/10.5194/egusphere-egu23-524, 2023.

When soils dry, water flow and nutrient diffusion cease as the liquid phase vital for soil life becomes fragmented. To delay soil drying locally and related adverse effects, bacteria and plants modify their surroundings by releasing extracellular polymeric substances (EPS). As a result, the physical properties of hotspots like biological soil crusts or the rhizosphere differ from those of the surrounding bulk soil. Specifically, EPS-induced modifications delay evaporative soil drying. Despite the evidence of reduced evaporation from EPS-amended soils, the mechanisms controlling soil water content dynamics remain elusive. Thus, our study aimed to elucidate the potential of bacteria to modify their environment when exposed to oscillations in soil water content. We incubated sand microcosms with two contrasting strains of Bacillus subtilis for one week in a flow cabinet. At the end of the incubation period, local water loss was quantified and spatially resolved using time-series neutron radiography. Strain NCIB 3610, a complex biofilm producer steadily modified soil evaporation dynamics during the incubation period resulting in substantially delayed soil drying due to hydraulic decoupling of the evaporation front from the soil surface. Evaporation dynamics remained largely unaltered in the microcosms inoculated with the domesticated EPS-deficient strain 168 trp⁺ compared to the control treatment. The mechanism of hydraulic decoupling induced by NCIB 3610 was verified by estimates of diffusive fluxes and the position of the evaporation plane in the microcosm. Additionally, the role of polymeric substances in hydraulic decoupling was confirmed by an evaporation experiment using xanthan as an EPS analogue.

How to cite: Benard, P., Bickel, S., Kaestner, A., Lehmann, P., and Carminati, A.: Extracellular polymeric substances from soil-grown bacteria delay evaporative drying, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1050, https://doi.org/10.5194/egusphere-egu23-1050, 2023.

Soil drying and rewetting (DRW) events are perceived differently by the soil microbes depending on their adaptation to the previous soil moisture history. Microbes adapted to intense cycles of DRW can experience an experimental DRW event as less harsh than microbes adapted to stable and moist conditions. The perceived harshness in turn can affect the carbon balance after DRW because it can determine the responses of microbial growth (eventually leading to SOC gains) and respiration (SOC loss) after rewetting. These responses have been categorized as “type 1” with immediate fast recovery, or “type 2” with a time lag before fast recovery, due to low and high levels of perceived harshness, respectively. However, we lack a quantitative definition of perceived harshness and how it varies depending on pedoclimatic conditions. Moreover, microbial response types could vary continuously along a continuum from prototypical type 1 to type 2. Therefore, if the shapes of the response curves could be synthesized by using a single function, then the fitted parameters could be used to reflect the harshness levels perceived by the microbes. In turn, these parameters might be combined into an index of harshness with biological interpretation. Relating this index to climatic and edaphic factors would then help to understand the drivers of harshness and microbial recovery after rewetting. To these aims, we described microbial growth with a single logistic function G(t)=G_max/(1+e^b(t-τ)) and respiration with a rescaled gamma distribution R(t)=Ckⁿt^n-1e^-kt/Γ[n] using data from 15 papers (in total 97 datasets). These functions described well the rates of fungal and bacterial growth, and whole community respiration after rewetting, resulting in a range of shapes consistent with the idea that soil microbial responses form a continuum between types 1 and 2. The product of growth parameters τ (delay time) and b (growth rate at time τ) allowed separating type 1 and 2 responses better than τ or b alone or than any other parameter describing the growth or respiration response. Thus, the product τ×b could be regarded as an effective index to quantify harshness. This index varied depending on soil and experimental conditions: τ×b increased with rewetting intensity (the difference in soil moisture between dry and wet conditions) and declined with higher pH; moreover, bacteria in carbon-rich soils had lower τ×b and thus perceived lower harshness. These results suggest that both fungi and bacteria facing the challenges of acidic soils are also worse adapted to respond to DRW compared to microbes from near-neutral soils. Carbon-rich soils might instead promote bacterial resilience thanks to the more available resources compared to carbon-poor soils. In conclusion, this study places soil microbial responses to DRW along a continuous gradient from fast to slow recovery as quantified by perceived harshness (which in turn is quantifiable by fitting growth and respiration curves to data). Our results help to predict the microbial carbon allocation to growth and respiration at rewetting across ecosystems and environmental conditions.

Keywords: soil drying and rewetting, microbial resilience, microbial resistance, growth, respiration

How to cite: Li, X., Leizeaga, A., Rousk, J., Hugelius, G., and Manzoni, S.: Soil microbial responses to rewetting depend on rewetting intensity and soil properties, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2907, https://doi.org/10.5194/egusphere-egu23-2907, 2023.

Microbial respiration is the main process contributing to soil carbon (C) loss and is simultaneously regulated by changes in mean temperature and temperature fluctuation. The magnitude of the feedback between soil microbial respiration and increased mean temperature may decrease (i.e., thermal adaptation) or increase over time, and accurately representing this feedback within models improves predictions of soil C loss rates. However, climate change entails changes not only in mean thermal conditions but also in the patterns of temperature fluctuation, and whether temperature fluctuation could also cause thermal adaptation has never been addressed. Here, we collected soil samples from 6 sites along a 2,000-km-long west-east transect extending across subtropical forests in China and used them in an incubation experiment involving various temperature regimes to explore how temperature fluctuation influences the thermal response of soil microbial respiration and the underlying mechanisms of this process. We revealed that soil biomass-specific microbial respiration (R_mass) was significantly lower with increasing temperature fluctuation during incubation regardless of the assay temperature, while a positive relationship between R_mass and temperature was observed under increased constant incubation temperature. Structural equation modelling further indicated that increased bacterial species turnover and reduced substrate affinity (K_m) promoted the decrease in R_mass associated with greater temperature variation. Our results demonstrate that if such an adaptive response of soil microbial respiration occurs under greater temperature variation, the stimulatory effect of climate warming may be less than that predicted and thus may not increase atmospheric CO₂ concentrations as much as anticipated.

How to cite: Zhang, Y. and Nie, M.: Temperature fluctuation promotes the thermal adaptation of soil microbial respiration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3959, https://doi.org/10.5194/egusphere-egu23-3959, 2023.

Thermal adaptation of soil microbial respiration has the potential to greatly alter carbon cycle-climate feedbacks through acceleration or reduction of soil microbial respiration as the climate warms. However despite its importance, the relationship between warming and soil microbial activity remains poorly constrained. Part of this uncertainty stems from persistent methodological issues and difficulties isolating the interacting effects of changes in microbial community responses from changes in soil carbon availability. To address these challenges, we sampled nearly 50 soils from around New Zealand, including from a long-term geothermal gradient, with mean annual temperatures ranging from 11-35°C. For each of these soils we constructed temperature response curves of microbial respiration given unlimited substrate and estimated a temperature optima (T_opt) and inflection point (T_inf). We found that thermal adaptation of microbial respiration occurred at a rate of 0.29°C ± 0.04 1SE for T_opt and 0.27°C ± 0.05 1SE for T_inf per degree of warming, demonstrating that thermal adaptation is considerably offset from warming. These relatively small changes occurred despite large structural shifts in microbial community composition and diversity. We also quantitatively assessed how thermal adaptation may alter potential respiration rates under future warming scenarios by consolidating all of the temperature response curves. Depending on the specific mean and instantaneous soil temperatures, we found that thermal adaptation of microbial respiration could both limit and accelerate soil carbon losses. This work highlights the importance of considering the entire temperature response curve when making predictions about how thermal adaptation of soil microbial respiration will influence soil carbon losses.

How to cite: Alster, C., van de Laar, A., Goodrich, J., Arcus, V., Deslippe, J., Marshall, A., and Schipper, L.: Quantifying soil microbial thermal adaptation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4609, https://doi.org/10.5194/egusphere-egu23-4609, 2023.

Increasing forest disturbance is among the most profound impacts of climate change on terrestrial ecosystems. Insect outbreaks, storms, or wildfires can destroy the whole tree layer, with serious consequences for biogeochemical cycles until succession returns the ecosystem back to a forested state. However, tree regeneration is often inhibited by ungulate herbivory and herbaceous competition, and disturbed ecosystems remain in non-forested states for decades. The impact of such vegetation changes on soil carbon (C) and nitrogen (N) cycles is highly unknown, because a multitude of plant-soil feedbacks are involved, and underlying processes have hardly been investigated. Here, we studied soil microbial community structure, gene abundance of bacteria, fungi, and N cycling microorganisms, soil enzymes, and C-N dynamics across a disturbed forest landscape in Central Europe, covering a range of successional stages after storm damage and bark-beetle attacks. We used a chronosequence-approach including disturbed sites regrown with Picea abies stands, and disturbed sites dominated by herbaceous pioneer plants, particularly Calamagrostis grasses. Soil C and N stocks increased under a prolonged herbaceous cover. Three decades after disturbance the stocks were ca. 45% higher than those of regrown forest stands. Beside C inputs from herbaceous fine roots, we link this increase to changes in the structure and functioning of the microbial community, which reduces the decomposition of organic matter. With a prolonged herbaceous cover, decreasing fungal abundances coincided with declining activities of phenol oxidase and of hydrolytic enzymes used to acquire nutrients. Since ectomycorrhizal fungi were almost absent compared to regrowing forest stands, this may be linked to reduced ectomycorrhizal mining for organic N. Moreover, ammonia-oxidising (amoA) gene abundances increased along with ammonium and nitrate concentrations, pointing towards an accelerated inorganic N cycle under a prolonged herbaceous cover. A surplus of inorganic N and grass-rhizodeposits renders it also likely that saprotrophs are less dependent on organic matter-bound C and N. Taken together, we found strong evidence for a linkage between above- and belowground communities following forest disturbance. We suggest a prolonged cover of herbaceous pioneer plants opens the nitrogen cycle through microbial communities which reduces mining for organic N and thus, increases soil C storage.

How to cite: Mayer, M., Hechenblaikner, F., Rosinger, C., Stierli, B., Frey, B., and Hagedorn, F.: Vegetation changes following forest disturbance affect soil carbon and nitrogen cycles through microbial communities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8185, https://doi.org/10.5194/egusphere-egu23-8185, 2023.

Tropical forest soils represent some of Earth's largest stores of soil carbon. Humid and warm conditions promote high primary productivity offsetting high ecosystem respiration rates, and this balance has resulted in significant carbon accumulation in plant biomass and soils. These vast carbon stocks can be destabilized under a changing climate, and model projections predict tropical and subtropical regions will experience disturbance to the hydrological cycle, with an increased likelihood of more frequent and prolonged droughts interspersed with periods of intense precipitation. Herein, we examine the functional response of belowground communities to a reduction in throughfall across a 1 m precipitation gradient (2350 to 3400 mm) spanning three sites from the Caribbean coast to the interior of Panama. At each site, 4 throughfall exclusion plots (10 x 10 m) were established to reduce precipitation, and exacerbate the natural variability in seasonal hydrological cycles. In January 2020, approximately 18 months since the inception of throughfall exclusion, each plot was sampled at six locations and two depths (0-10 and 10-20 cm). To identify the traits and mechanisms involved in responding to drought perturbation, we sequenced the microbiomes of the soil samples from the throughfall exclusion and corresponding controls at each site, and measured metabolite accumulation within the soils. Here we report on the accumulation of distinct metabolites along the precipitation gradient and under throughfall exclusion. We note that constitutive production of compatible solutes increases from the wettest to the driest site, indicative of trait selection due to climate history. However, under throughfall exclusion the gradient end members show a more muted metabolic response than the intermediate site. We discuss these responses with respect specific pathways invoked under drying stress, and soil carbon dynamics.  

How to cite: Chacon, S. S., Karaoz, U., Louie, K., Bowen, B., Northen, T., Dietterich, L. H., Cusack, D. F., and Bouskill, N.: Microbial metabolic response to throughfall exclusion and feedback on soil carbon dynamics along a tropical forest precipitation gradient, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9543, https://doi.org/10.5194/egusphere-egu23-9543, 2023.

Coffea arabica (coffee) is cultivated on ~28-million acres and is essential to local economies in the tropics. Coffee cultivation, however, is threatened by ongoing climate change as its optimal growth occurs in narrow temperature and precipitation ranges. Areas currently growing coffee might become unsuitable leading to increased deforestation and negative effects on coffee quality. These impacts may be especially strong in coffee cultivated in sun-grown monocultures (~75% of all production) versus shade-grown agroforestry systems given relatively higher temperatures in deforested landscapes. As such, shade-grown coffee systems might be one management strategy used to buffer from future climatic shifts. While shade-grown systems provide many ecosystem benefits, the impact of the cultivation system on soil microbiomes is poorly understood. Soil microorganisms perform vital ecosystem functions including aiding plants in nutrient acquisition, buffering against stress, as well as improving nutrient cycling. This is particularly true in shade-grown coffee systems where soil carbon could be increased through increased microbial biomass and soil nitrogen could be increased through increased plant-association with N-fixing bacteria. Therefore, further understanding of the effects of coffee cultivation methods on soil microbial communities may be key to future coffee productivity and local soil biogeochemical function. To explore these themes, we sampled the soil microbial communities at 30 coffee farms in Colombia, Peru, and El Salvador. These farms varied in cultivation system (sun vs. shade) and flavor profiles that separate specialty grade from conventional quality. Our aim was to explore if soil microbiome diversity and composition differ among the three countries, cultivation systems, and coffee quality. We sequenced the DNA of bacterial (16S) and fungal (ITS) communities in coffee soil on an Illumina MiSeq with analysis completed in QIIME2 to identify microbial taxa and composition. Coffee soil microbiomes had similar relative abundance of phyla and similar number of bacterial and fungal taxa, regardless of country of origin or cultivation system. However, coffee soil microbiomes showed pronounced differences in the microbial community composition among the different countries and cultivation systems. We show that biogeography is an important determinant of coffee soil microbiomes and location-specific impacts need to be considered in future coffee management. Further, our data suggests that sun-grown systems can alter microbial community composition compared to more-sustainable shade-grown systems potentially changing soil functionality. As an example, there were increases in taxa punitively classified as mycorrhizal fungi and N-fixing bacteria in shade-grown coffee systems. Our next steps are to link this microbial data to coffee quality and soil characteristics to uncover potential factors influencing the community structure as well as nutrient cycling rates.

How to cite: Kutos, S., Bennett, R., and Muletz Wolz, C.: What’s brewing? Impacts of cultivation management on the Coffea arabica soil microbiome, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10184, https://doi.org/10.5194/egusphere-egu23-10184, 2023.

Land use intensification, particularly a shift from extensively to intensively managed agroecosystems is often seen as one of the main drivers of global biodiversity decline and is considered the main factor applying pressure on soil biodiversity. When confronted with future land use change, understanding the responses of soil biodiversity to different land use regimes is decisive for adequate land management. However, there is still substantial uncertainty about how consistently different taxonomic groups respond to land use intensification. Oftentimes, different taxa show divergent responses to more intense land use regimes, and the community composition is rarely correlated with land use intensity, which may suggest that the drivers of community composition may not be the same as drivers of diversity. The mechanisms that determine the response of different taxa to land use intensification may be regulated by changes in the plant community and abiotic environmental drivers. We systematically assessed and quantified through meta-analysis the effects of land use intensification on soil organisms in global agroecosystems and analyzed the dependence of these effects on abiotic factors such as soil properties (organic matter, pH, nutrient and water availability, texture) and climatic zone.

How to cite: Betancur-Corredor, B. and Russell, D.: Response of soil fauna to land use intensification in a global meta-analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10271, https://doi.org/10.5194/egusphere-egu23-10271, 2023.

Microorganisms are known to form a matrix of extracellular polymeric substances (EPS) on several solid surfaces such as soils. The formation of this matrix provides various benefits not only to the microbial community, but also to the surface it is attached. In soils, for instance, it promotes protection and adherence of microorganisms to soil aggregates and benefits the soil increasing aggregate stability. Even in spite of this knowledge, the contribution of EPS to soil organic matter (SOM) and to SOM turnover is yet unclear, mainly due to methodological limitations. Furthermore, it has also not been determined how the EPS composition affects soil structure, fertility and organic matter dynamics. It is therefore of uttermost importance to study the composition of the EPS matrix and how different microbial functional groups produce EPS in face of varying environmental conditions. To this end, 10 bacterial and 10 fungal species commonly found in soils were grown under different treatments in order to stimulate EPS production. Microorganisms were grown in either glycerol or starch medium with or without the presence of sterile quartz. EPS was extracted using a cation-exchange resin (CER) and its composition was subsequently determined with the quantification of proteins, carbohydrates, amino sugars and DNA. We hypothesized firstly, that EPS production would be higher in cultures with quartz. Secondly, we also expected bacterial EPS production to be higher in cultures with glycerol whereas fungal cultures would produce more EPS in starch medium, reflecting contrasting substrate effects on bacterial and fungal EPS formation. Lastly, we hypothesized that considerable amounts of galactosamine would be found in all extracted EPS, similarly to mucins excreted in the intestines of vertebrates, protecting enzymes. Mucins are a family of proteins with high GalN contents, consequently, GalN might be an indicator to EPS production in soils.

How to cite: Leme Oliva, R., Bahadur Khadka, U., Dyckmans, J., Redmile-Gordon, M., and Georg Jörgensen, R.: Composition of extracellular polymeric substances (EPS) produced by a range of soil bacteria and fungi, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11850, https://doi.org/10.5194/egusphere-egu23-11850, 2023.

Almost half of Earth’s terrestrial surface is covered by drylands, where limitation of water restricts vascular plant growth. In these ecosystems, a substantial part of primary production instead takes place directly at the soil surface, within complex microbial communities forming biological soil crusts (biocrusts) that include intricately bound soil particles. These communities, composed mainly of cyanobacteria, algae, fungi, and bryophytes, are fundamental actors for dryland biogeochemical cycles, as they fix atmospheric CO₂ and N₂ and constitute one of the primary, if not the only, sources of soil C and N. Due to the vast spatial extent of biocrusts, accounting for up to 70% of the living land cover in drylands, their importance for C and N cycling extend to the global scale, i.e. accounting for 7% of global net primary production of total terrestrial vegetation. However, warming temperatures and increasing soil dryness following climate change are estimated to have critical implications on these systems; recent studies show i.e. warming-induced reduction of biocrust cover and, thus, reduced CO₂ uptake.

Our aim is to contribute to this relatively new research field by providing insights into biocrust-soil-microorganism interactions under elevated temperatures and drought at the process-scale. This was realized in a phytotron incubation experiment of soil-biocrust mesocosms with experimental warming and drought, during which CO₂ uptake and heterotrophic respiration was monitored. Dual labelling pulses (¹³CO₂ and ¹⁵N₂) were applied to follow the fate of recently fixed ¹³C and ¹⁵N into both particulate and mineral-associated SOM pools via physical fractionation and into microbial biomass via PLFA. Further, hyperspectral VIS-NIR images of the surface were recorded to quantify and determine crust cover and composition.

The results revealed clear drought effects—not only in a distinct reduction in CO₂ fixation by the biocrusts, but also in the elemental distribution of soil C underneath; the effect extended down into underlying soil layers, where biocrust-derived C contents were reduced by half due to drought. The change in the translocation of biocrust-derived C into the underlying soil was reflected in the ¹³C-PLFA profiles, showing how mainly fungi transform recently fixed C from the biocrust into their biomass in the biocrust layer, extending down into the underlying soil via fungal hyphae expansion. While drought clearly restricted the microbial abundance, warming further induced a microbial community shift, where a greater relative fungal dominance was determined under experimental warming—a shift, however, that was not reflected under dry conditions. A further combined effect was determined in N fixation, where we confirm a decrease in biocrust-derived N under drought under warming.

Our results showcase the implications of elevated temperature and drought on C and N fixation and cycling—the two most fundamental ecosystem functions in biocrust-soil systems. The results support the growing body of evidence of major implications for biogeochemical cycles in drylands in a warming world.

How to cite: Witzgall, K., Hesse, B. D., Grams, T. E. E., Pietrasiak, N., Seguel, O., Oses, R., Jansa, J., Guigue, J., Rojas, C., Rousk, K., and Mueller, C. W.: Soil carbon and nitrogen cycling at the atmosphere-soil interface: quantifying the response of biocrust-soil interactions to climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12299, https://doi.org/10.5194/egusphere-egu23-12299, 2023.

High-latitude soils are particularly vulnerable to temperature-driven C losses and may contribute substantially to the increasing atmospheric CO₂ concentrations. The magnitude of their contribution is, however, uncertain, and largely dependent on the interactions between C and nitrogen (N) biogeochemical cycles, soil microbial activities and the feedbacks between plants and soil microbes. Warming may cause a particularly pronounced acceleration of soil N transformation in N-poor cold regions. The consequent alleviation of plant N limitations in cold ecosystems may increase plant productivity and C inputs to the soil, compensating the expected soil C loss, at least partially. Alternatively, warming may desynchronize or unbalance the intimate coupling between microbial N mineralization and vegetation N uptake, leading to potential soil N loss, but also higher soil C losses. We aimed to elucidate potential mechanisms of ecosystem N losses in subarctic grasslands by determining the effects of soil warming on the seasonal patterns of plant N acquisition and microbial net N immobilization. For this, we performed a seasonal isotope tracing experiment using a mix of ¹⁵N-labelled amino-acids along soil temperature gradients in geothermal systems in Iceland.

Soil microbial biomass acted as a temporal reservoir of N by increasing N immobilization particularly during unfavorable winter periods for vegetation, likely due to the alleviated microbial C limitation. However, soil warming exacerbated microbial C limitation and decreased the N storage capacity of soil microbes during snowmelt periods. As a result, a higher proportion of N remained in the extractable soil fraction susceptible to leaching losses.  , however, this increased plant N uptake did not compensate for the lower microbial biomass N storage, leading to ecosystem N losses. Our results highlight the relevant role of soil microbes to safely store and immobilize N when plants do not need it and to release N when plants require it. Warming can weaken this particularly important soil microbial function in cold regions, leading to substantial ecosystem N and fertility losses, which may also promote irreversible soil C losses in these ecosystems.

How to cite: Marañón Jiménez, S., Luo, X., Richter, A., Gündler, P., Fuchslueger, L., Sigurdsson, B. D., Janssens, I., and Peñuelas, J.: Warming may cause substantial nitrogen losses from subarctic grasslands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12303, https://doi.org/10.5194/egusphere-egu23-12303, 2023.

Soil bacterial communities play an important role in soil health, carbon (C), and nutrient cycling, as well as in soil-plant relationships in agroecosystems. However, our understanding of the drivers and distribution of soil bacterial communities across landscapes is limited. For example, it is not clear how changes in soil management practices (i.e. Till vs No-till vs cover crop), soil diagnostic units, and their associated physical-chemical properties interact to influence the composition and abundance of soil bacterial communities at a larger scale. Here, using samples collected in a countrywide soil survey in Hungary, we combined soil metagenomic sequencing, soil management practices, and soil geochemical data to develop a mechanistic understanding of the drivers of bacterial communities in contrasting agroecosystems. We found that bacterial community composition and distribution significantly differed between soil management practices. Furthermore, we found that soil geochemical properties influenced soil bacterial composition and abundance under similar soil diagnostic units, suggesting that the effects of soil management practices on bacterial communities outweighed the ones of pedogenic processes. Together, these results suggest that soil management practices influence soil geochemical properties that drive the composition and spatial distribution of soil bacterial communities. Consequently, effects and types of soil management should be taken into account when developing soil health indicators for agroecosystems.

How to cite: Bukombe, B., Csenki, S., Szlatenyi, D., Czako, I., and Láng, V.: Distribution and drivers of soil bacterial communities across different soil management practices and soil diagnostic units in agricultural ecosystems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13475, https://doi.org/10.5194/egusphere-egu23-13475, 2023.

Forest soils store large amounts of organic matter from aboveground litter. Consequently, practices that affect plant development and soil properties may have crucial impacts on forest ecosystem functions and C feedbacks. In Europe, thinning of forests is a commonly used management practice to promote natural trees regeneration through increasing the temperatures, microbial activity, nutrient availability and irradiance of soil. Forest management influences the occurrence of tree species, the maximum stand density, the organic matter input to the soil decomposer system and hence the availability and quality of microbial resources. Thus, forest management can alter soil microbial community and key ecosystem functions they perform affecting the related ecosystem services, although the functional redundancy of soil microbial communities may minimize these impacts.
Due to the importance of forest soils as both sink and potential source of carbon and their predicted sensitivity to climate change, they became in the last years, one of the key targets of microbial ecologists.
In the present study, we assess the effects of forest management (coppice and high forest) on soil properties and microbial community functions in two Italian forests (turkey oak and beech), in two different seasons, summer and autumn. We investigated functional diversity of microbial communities based on the carbon consumption patterns (by community-level physiological profile, CLPP, and derived average well color development AWCD) and several enzyme activities linked to biogeochemical cycles of C, N and P.
The soil microbial community showed higher metabolic activity in both beech and turkey oak under coppice management (1.32 and 1.54 AWCD, respectively) respect to high forest regime (1.09 and 1.32 AWCD, respectively), only in summer. Significant differences in AWCD values between seasons were found only in forests under high forest management.
Among the investigated soil enzyme activities, only hydrolase showed in summer higher value in beech under coppice respect to high forest management (0.41 vs 0.25 mg FDA g^-1soil d.w. h^-1). This enzyme activity, however, showed higher values in summer than autumn in both forest soils, regardless the management. Hydrolase activity measures the total microbial activity in soil and is a good general index of organic matter turnover in natural ecosystems.
The results will provide useful data for: improving the sustainability of ecosystems in a scenario of climate change; identifying new biological indicators of soil health and fertility to predict the effects of forest practices.

How to cite: Picariello, E. and De Nicola, F.: The impact of forest management on soil microbial community functions in two forests of South Apennines (Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13840, https://doi.org/10.5194/egusphere-egu23-13840, 2023.

The last decades were characterized by rising temperatures, enhanced atmospheric CO₂ concentrations, and by an increasing frequency of extreme events such as drought. Soil microorganisms are major drivers of biogeochemical processes, yet the effects of climate change in shaping microbial communities remain poorly understood.

To address this knowledge gap, we examined how future climate conditions (combined +300 ppm CO₂ and +3 °C warming, relative to ambient) and drought, alone and in combination, affect microbial community composition throughout the vegetation period in a sub-montane managed grassland (‘ClimGrass’ experiment; Styria, Austria). We combined amplicon sequencing of bacteria, archaea, and fungi with droplet digital PCR to perform quantitative microbiome profiling of seasonal and drought-legacy effects on soil microbial communities.

Drought strongly shaped the bacterial/archaeal and the fungal community structure during peak drought conditions, and this effect could still be detected two and fourteen months after ending drought by rewetting and removing rain-out shelters. In comparison, future climate conditions were observed to exert less pressure on the structure of bacterial/archaeal and fungal communities. Interestingly, abundances of members of Actinobacteria and Bacteroidota for bacteria, as well as Cladosporiaceae and Phaeosphaeriacea for fungi (amongst others) significantly increased during peak drought. Our findings suggest that drought can have immediate and lasting effects on the soil microbial community structure by contributing to the establishment of drought-tolerant microbial communities.

How to cite: Schmidt, H., Séneca, J., Canarini, A., Simon, E., Dietrich, M., Prommer, J., Bogdanovic, I., Martin, V., Mohrlok, M., Hausmann, B., Pötsch, E., Schaumberger, A., Wanek, W., Bahn, M., and Richter, A.: Drought legacy effects on microbial community structure in a managed grassland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14006, https://doi.org/10.5194/egusphere-egu23-14006, 2023.

Soil particle wettability controls the water dynamics of dry and unsaturated soil and has an impact on many processes where water is involved. Pure soil minerals are usually wettable, but under environmental conditions they are easily covered by organic compounds, changing their surface properties and potentially making them water repellent. Besides organic compounds such as alkanes, fatty acids, free lipids and waxes, research also indicates a direct influence of bacterial cells on the development of soil water repellency. In a series of stress experiments with different Gram-negative and Gram-positive strains of bacteria we could show that cell surface wettability measured in terms of contact angle is affected by cell stress response caused by hypertonic or drought environmental conditions. The changes in wettability were found to be accompanied by changes in physicochemical surface properties and surface elemental composition of the cells, as indicated by X-ray photoelectron spectroscopy. Furthermore, coverage of minerals by cells caused significant changes in particle wettability, rendering originally wettable minerals water repellent, with the effect being more pronounced for cell-mineral associations (CMA) formed with stressed cells. To investigate the physical stability of these CMA, we conducted an incubation experiment with CMA formed by quartz particles and Bacillus subtilis cells either grown under physiological or hypertonic conditions. The CMA were incubated at different water potentials (pF 2.5 and 4.2) and part of them subjected to wetting-drying cycles. The results showed that the quartz–B. subtilis CMA formed with stressed cells remained significantly more water repellent than those formed with unstressed cells during the whole incubation time of 80 days and independent of the incubation conditions. Furthermore, we observed a slight tendency of increasing contact angle with increasing incubation time. Besides the generally lower wettability of the stressed cells, the lower wettability of the CMA formed with stressed cells can be related to a higher degree of microbial coverage, as indicated by higher surface C content and lower surface O/C and Si/C ratios compared to the CMA formed with unstressed cells. The higher microbial coverage can probably be explained by attachment conditions being more favorable in case of the stressed cells, as suggested by interaction free energies calculated using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. In summary, the results indicate that the hydrophobizing effect of hypertonic stress on B. subtilis was stable over time and support the assumption that stress-related changes in cell surface properties remained also in necromass and their effect on surface properties of CMA can persist.

How to cite: Goebel, M.-O., Karagulyan, M., Miltner, A., Abu Quba, A. A., Diehl, D., Schaumann, G. E., Kästner, M., and Bachmann, J.: Bacterial cell-mineral associations and their stability under varying moisture conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15148, https://doi.org/10.5194/egusphere-egu23-15148, 2023.

Ecosystem restoration is known to enhance the functioning and stability of plant communities in the face of climate extremes. However, the effects of ecosystem restoration on soil microbial communities and their functional stability remain poorly understood. Here, we used a long-term (33 years) multiple factorial grassland restoration experiment to assess how different restoration approaches, including farmyard manure (FYM) addition, low amounts of inorganic fertiliser, mixed seed addition, and promotion of red clover, affect multiple dimensions of soil microbial functional stability in response to drought. We found that specific restoration approaches (e.g., FYM addition) not only increased the stability of plant biomass production, but also enhanced drought resistance of soil microbial multifunctionality. Moreover, we identified key factors that drive the multi-dimensional stability of plant and soil microbial communities, which provide mechanistic insights into how grassland restoration impacts above- and below-ground stability in the face of drought.

How to cite: Liu, S., Bilton, A., and Bardgett, R.: Restoration of soil microbial functional stability in the face of climate extremes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15955, https://doi.org/10.5194/egusphere-egu23-15955, 2023.

Arctic ecosystems are experiencing a strong and fast warming in the realms of climate change, and understanding the involved processes are important to predict impacts and feedbacks on their C cycling. Winter warming leads to frequent and reoccurring snow melts and as a consequence exposed bare ground. This leads to accelerated freeze-thaw cycles, since the snow cover that was insulating the soil below to temperature variations around a few degrees minus now can be exposed to much harsher freezes. We experimentally exposed soil crusts from Greenland to freezing-thawing cycles of different intensities and frequencies and measured the abundance of the three soil microbial groups bacteria, fungi and protists with help of microfluidic soil chips. The soil chips are brought into tight contact with the soil sample, and the microbial community colonizes their transparent pore spaces which enable us to image-based analysis of microbial abundance and interactions. We found that increased freezing frequency (daily versus bi-weekly) strikingly reduced bacterial populations, stronger than increased freezing intensity (-5°C vs -18°C). We also exposed the soil chips to live-freezing under the microscope to analyze direct effects of the approaching ice front on the microbial community. At intermediate freezing temperatures, dead-end pockets in the pore space remained liquid-filled and could act as refugia for the organisms. Fast approaching ice fronts caught fleeing organisms and in some cases led to detrimental outcomes, especially for protists. Disturbances in the trophic network differently affecting predators and pray may thus also contribute to changes in the bacterial carbon cycling.

How to cite: Hammer, E., Duljas, J., Klingenhammer, F., Zou, H., Elberling, B., and Andresen, L. C.: Effects of intensified freezing-thawing cycles on arctic soil microbiota investigated via soil chips, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16057, https://doi.org/10.5194/egusphere-egu23-16057, 2023.

The Catalonia Plot System for Terrestrial Biodiversity Monitoring (SISEBIO) is a long-term project aiming to monitor above- and below-ground biodiversity changes due to global change in permanent experimental sites. The project aims: a) to catalogue the existing biodiversity using metabarcoding, b) to describe the environmental drivers explaining such, and c) to identify habitats acting as biodiversity hotspots.

For this purpose, 109 permanent plots were set up in natural areas to covering all the main habitats and climates of Catalonia (NE Spain). Plant, microbial (bacteria and fungi), protists, and microarthropods richness and diversity were assessed between 2018-2021, together with a variety of environmental drivers (soil physicochemical properties, habitat structure, climate, and topography). While plant diversity was assessed through traditional morphological identification, that of soil organisms was assessed by metabarcoding and using operational taxonomic units (OTUs) for this purpose.

Concerning soil biodiversity, 42077 unique OTUs were identified, with around 40% of them only found in once. The highest biodiversity values corresponded to sites located in the Pyrenees, and the environmental factors driving biodiversity were clearly different depending on the taxa studied. However, we failed to find habitat-specific hotspots except for microarthropods, with higher richness values in conifer forests when compared to deciduous forests, shrublands and grasslands.

The existence of biological interactions and historical factors may hinder the emergence of strong environmental trends to describe soil biodiversity patterns. Our results might may guide stakeholders with the implementation of management policies in the most vulnerable habitats to protect their biodiversity, but are also of interest for modelling the impact of global change on soil biodiversity and their ecosystem services.

How to cite: Domene, X., Olmo-Gilabert, R., Fernández-Martínez, M., and Comas, L.: Soil properties, habitat structure, climate, and topography as drivers of soil biodiversity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16820, https://doi.org/10.5194/egusphere-egu23-16820, 2023.

Self-succession of winter wheat (WW) in crop rotations results in substantial yield decline. This decline has been mostly attributed to the soil-borne fungus Gaeumannomyces graminis var. tritici (Ggt; take-all) causing earlier root senescence. A broad shift in the soil microbial community has also recently been proposed to confound this effect even in years without significant Ggt infestation in the field. We aimed to establish a mechanistic basis for the relationship between rotational position of WW and yield decline at an early wheat growth stage. To this end, an outdoor experiment with 1 m deep rhizotrons was set up using a sandy loam soil. WW was grown in soil after oilseed rape (KW1), soil after one season of WW (KW2) and soil after three successive seasons of WW (KW4). The plants were grown until the beginning of stem elongation (BBCH 30). At harvest, both shoot and root dry weight were markedly affected by the preceding crop, with a pronounced reduction of plant biomass of KW2 (-43%) and KW4 (-45%) compared to KW1. At BBCH 30, KW1 soil had much lower mineral N compared to KW2 (-49%) and KW4 (-39%). Non-purgeable organic C, a readily available energy source for soil microorganisms, was further reduced in successive WW rotations compared to KW1. Increased NH₄⁺ and NPOC concentrations were found in root-affected soil compared to root-free bulk soil, indicating a strong hotspot for organic N mineralization in the rhizosphere. At the same time, the markedly higher shoot N concentration led to a lower C:N ratio of 31 for KW1 compared to KW2 and KW4, which had a C:N ratio of 46 and 44, respectively, suggesting a better exploitation of soil mineral N sources by KW1. In contrast, microbial biomass C and N were higher in KW2 and KW4 compared to KW1, pointing to enhanced microbial N immobilization in KW2 and KW4. The higher C:N ratio of WW straw compared to oilseed rape residues that are returned to the soil following harvest, obviously stimulated immobilization of soil N in microbial biomass, thereby limiting the availability of N for WW growth in KW2 and KW4. Root growth traits exhibited a strong response to WW rotational position, with higher root tissue density, root mean diameter and lower specific root length for KW1 compared to KW2 and KW4. Root length density (RLD) was overall higher in KW1 compared to KW2 (-29%) and KW4 (-31%), especially at 0-30 cm soil depth. Interestingly, higher RLD values for KW1 were also observed at the lowest depth of 60-100 cm compared to KW4, suggesting a strong effect of rotational position on nutrient accessibility in the subsoil. Successive WW invested more in acquisitive root traits that did not compensate for the reduction of biomass production. Our results highlight the effect of rotational position of WW on soil and plant properties and provide guidance for management-based adaptations at field level to improve WW productivity.

How to cite: Kaloterakis, N., Rashtbari, M., S. Razavi, B., Braun-Kiewnick, A., Giongo, A., Babin, D., Smalla, K., Kummer, C., Kummer, S., and Brüggemann, N.: Preceding crop history modulates the early growth of winter wheat by influencing root growth dynamics and rhizosphere processes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-73, https://doi.org/10.5194/egusphere-egu23-73, 2023.

Thermodynamic characterization of soils is a developing field that involves the calculation of the enthalpies, Gibbs energy, and entropy of the soil organic matter, SOM. Its achievement would contribute to the development of the bioenergetics of soil systems beyond the existing theoretical models.

This work shows different experimental procedures and theoretical models for the complete thermodynamic characterization of SOM. It was applied to a total of 31 samples representing different soil horizons from different locations.

Thermodynamic characterization of SOM was achieved through the calculation of empirical formulae for SOM from the SOM elemental composition, application of Patel-Erickson, Sandler-Orbey, and Battley methods, as well as direct measurements of the energy content by simultaneous TG-DSC.

The used computational methods belong to a group of approaches modeling thermodynamic properties of SOM as a sum of contributions from its constituent elements. The first computational approaches were those from the Patel-Erickson and Battley equations. Patel-Erickson equation was used to find the standard enthalpy of combustion, Δ_CH⁰_PE, of SOM based on its elemental composition:

Δ_CH⁰_PE(SOM) = –111.14 kJ/mol ∙ (4n_C + n_H – 2n_O – 0n_N + 5n_P + 6n_S)

where n_J is the number of atoms of element J in the empirical formula of SOM. The Battley equation gives the standard molar entropy, S⁰_m, of SOM:

S⁰_m(SOM) = 0.187 ∑_J [ S⁰_m(J) / a_J ] n_J

where S⁰_m(J) and a_J are standard molar entropy and the number of atoms of element J in its standard state elemental form. The enthalpy from the Patel-Erickson equation is combined with entropy from the Battley equation, to find the Gibbs energy of SOM.

The second computational approach handled equations proposed by Sandler and Orbey that allow finding standard enthalpy of combustion Δ_CH⁰_SO and standard Gibbs energy of combustion, Δ_CG⁰, of SOM:

Δ_CH⁰_SO(SOM) = –109.04 kJ/C-mol ∙ (4n_C + n_H – 2n_O – 0n_N + 5n_P + 6n_S)

Δ_CG⁰(SOM) = –110.23 kJ/C-mol ∙ (4n_C + n_H – 2n_O – 0n_N + 5n_P + 6n_S)

The enthalpy and Gibbs energy obtained using the Sandler-Orbey method were combined to find entropy.  

Results obtained by the application of Patel-Erickson and Sandler-Orbey methods to calculate the enthalpy of SOM combustion did not significantly differ when comparing data given by the TG-DSC with those obtained from the SOM empirical formulation. The same results were obtained when comparing the Gibbs energy. These results enabled the calculation of the entropy of SOM and the comparison of those values among different soil layers and sampling sites.

How to cite: Barros, N., Popovic, M., and Pérez-Cruzado, C.: Complete thermodynamic characterization of the soil organic matter from forest ecosystems., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1389, https://doi.org/10.5194/egusphere-egu23-1389, 2023.

Soils represent the largest terrestrial carbon (C) sink and understanding its dynamics is crucial. The metabolic degradation and stabilization of soil organic matter (SOM) follow the rules of thermodynamics. In the catabolic reaction, SOM is oxidized to CO₂ and the part of the energy delivered by this reaction is used in anabolism, during which biomass formation and, thereby, energy and C conservation take place. C and energy fluxes are thus linked and contribute to the C transformation and stabilization in natural soil systems. These processes are among others largely influenced by environmental conditions (e.g. temperature, soil moisture, C/N ratio).

Due to the complexity and heterogeneity of soil, thermodynamic models and experimental approaches to study the linkage of C and energy fluxes in soil systems are rare and still in their infancy. To establish it, we use calorimetric and carbon mass balancing methods to study both C and energy fluxes in artificial soil systems in incubation experiments over 64 days with cellulose and over 16 days with glucose as substrates. This simplified system allows reliable measurement and interpretation of energy input, accumulation and output and their interaction with SOM turnover processes. Carbon and Energy Use Efficiency (CUE and EUE) are studied under varying environmental conditions. The heat production rate and the reaction enthalpy of metabolism in artificial soil systems are monitored with isothermal microcalorimeters. C mass balances consist of mineralization (measured using gas chromatography coupled with thermal conductivity detector), changes in total carbon (quantified by elemental analysis - isotope ratio mass spectrometry), and carbohydrates (recorded via a phenol sulphuric acid assay). In addition, biomass and necromass contents are quantified by phospholipid fatty acid and amino sugar analysis.

EUE will be calculated from calorimetric data and further we will build an energy balance model. Furthermore, evolution of carbon input and output measurements will be further utilized for carbon balance model. Calorimetric and respirometric data provide the calorespirometric (CR) ratio of the soil system, which is closely related CUE (Chakrawal et al., 2020; Hansen et al., 2004). Experimentally determined CUE will be compared to that derived theoretically from CR ratio through calorimetric data and biomass yield modelling (Brock et al., 2017). Preliminary results on the linkage between carbon and energy balance in soil systems will be presented.

Brock, A. L., Kästner, M., & Trapp, S. (2017). Microbial growth yield estimates from thermodynamics and its importance for degradation of pesticides and formation of biogenic non-extractable residues. SAR and QSAR in Environmental Research, 28 (8), 629–650. https://doi.org/10.1080/1062936X.2017.1365762

Chakrawal, A., Herrmann, A. M., Šantrůčková, H., & Manzoni, S. (2020). Quantifying microbial metabolism in soils using calorespirometry — A bioenergetics perspective. Soil Biology and Biochemistry, 148 (May), 107945. https://doi.org/10.1016/j.soilbio.2020.107945

Hansen, L. D., MacFarlane, C., McKinnon, N., Smith, B. N., & Criddle, R. S. (2004). Use of calorespirometric ratios, heat per CO₂ and heat per O_2, to quantify metabolic paths and energetics of growing cells. Thermochimica Acta, 422 (1–2), 55–61. https://doi.org/10.1016/J.TCA.2004.05.033

How to cite: Yang, S., Rupp, A., Kästner, M., Miltner, A., and Maskow, T.: Linking mass balances and thermodynamic energy balances in simplified model systems with artificial soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1397, https://doi.org/10.5194/egusphere-egu23-1397, 2023.

As N limitation strongly influences ecosystem functioning, numerous studies explored the transformation process of mineral nitrogen. In contrast, the importance of organic nitrogen, which can short-circuit the mineralization step, for plant nutrition in different ecosystems often overlooked. A spatial link between the sources of organic N and N-acquiring enzymatic activity in soil is still missing due to the lack of suitable techniques. Here we developed a novel approach: in situ amino-mapping and coupled it with time-lapse zymography to quantify distribution of organic nitrogen in the rhizosphere of Zea mays L and tested spatial association of enzymatic activity with organic nitrogen abundance at the root-soil interface. Coupling the two approaches enabled identification the hotspots of amino-N, and revealed their co-occurrence with N-related enzymatic activity in seminal roots and root tips: intensive enzymatic activity was accompanied by large amino-N content, especially in the rhizosphere of seminal root tips. This work was conducted within the framework of the Priority program 2089 “Rhizosphere spatiotemporal organization – a key to rhizosphere functions”, funded by German Research Foundation (DFG – Project number: 403664478). Seeds of the maize were provided by Caroline Marcon and Frank Hochholdinger (University of Bonn).

How to cite: Shen, G., Guber, A., Khosrozadeh, S., Ghaderi, N., and Blagodatskaya, E.: Combining the time-lapse amino-mapping and zymography to co-localize spatial distribution of organic N with enzymatic activity in the rhizosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2713, https://doi.org/10.5194/egusphere-egu23-2713, 2023.

Soil organic matter plays important roles in soil reactivity and fertility as well as soil physics. Nevertheless, we know relatively little about the individual molecules that make up soil organic matter but ultimately determine its properties. Ultrahigh-resolution mass spectrometry like FT-ICR-MS has revealed an enormous molecular diversity yet it often remains limited to the water-soluble fractions (i.e., dissolved organic matter) analyzed with electrospray ionization (ESI) that represent only a small fraction of the total organic matter contained in soils. To extend the analytical window and leverage the value of non-targeted mass spectrometry, parallel analyses of soluble (via ESI) and particle-associated organic matter (PAOM) via laser-desorption ionization (LDI) and FT-ICR-MS detection is a promising approach, that has yet to prove its full potential. Here, we studied the sensitivity and robustness of the LDI technique based on a combination of dried arable soils, their aqueous DOM extracts, reference DOM samples (Suwannee River Fulvic Acid, SRFA), model compounds (syringic acid, sinapic acid, syringaldehyde, vanillic acid and tannic acid) and model mineral phases (goethite, illite). DOM samples were used to study the effects of a mineral matrix and dilution, while model compounds and SRFA were used to test the effects of laser strength and presence of an organic matrix on intact ionization of analytes. Lastly, non-extracted and extracted soil samples were used to assess if DOM composition trends observed in solution are reproduced in PAOM composition. In general, ESI ionized a very different fraction of the DOM mixture, being more polar and more saturated, while LDI ionized rather small, low-to-mid polar, and less saturated ions. Besides clear differences in PAOM and DOM analytical windows, molecular trends such as aromaticity or nominal oxidation state were well-aligned. Although most insight was gained by combining both types of analyses, our results therefore suggest that direct analysis of soil particles is a fast, reproducible, sensitive and less invasive alternative to routine protocols employing FT-ICR-MS detection, and avoids additional extraction or purification steps.

How to cite: Simon, C., Pietsch, P., Stumpf, K., Kaiser, K., and Lechtenfeld, O.: Development of ultrahigh resolution mass spectrometry techniques to extend the molecular view of soil organic matter in solution and on mineral particles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3113, https://doi.org/10.5194/egusphere-egu23-3113, 2023.

Vegetation patchiness is hypothesized to affect the spatial heterogeneity of resources and soil nutrient distribution in drylands. Nutrient accumulation under perennial vegetative patches leads to faster nitrogen (N) cycling in times of water availability. Compared to perennials, annual plant patches have a shorter life cycle, and labile nutrient buildup can occur more quickly in these patches due to faster nutrient turnover rates of litterfall and root death. The buildup of these labile nutrient pools, in surface soils under annual plant patches over time, may indirectly facilitate succession by other plants, thus aiding in the establishment of fertility islands. To understand how the establishment of annual plant patches affects soil nutrient dynamics, we planted replicated patches of a widespread local summer annual plant, saltwort (Salsola inermis Forssk.), and assessed how these patches influence the soil N cycle and soil N oxides (N₂O and NO) emissions. We also assessed rates of surface litter decomposition of the saltwort plant. We found that rates of soil N transformations and soil N oxides emissions were highest under the plant patch, while they decreased across the patch-to-bare-soil gradient. Water extractable organic carbon (WEOC) accumulation increased in the surface soil beneath the plants and was associated with a large burst in soil N oxides emissions within the patch, following dry soil wetting by the first winter rains. Soil N₂O emission pulse increased by 5.2 folds, whiles NO increased by 95.8 folds. Each N-oxide gas, however, had a different post-wetting pattern, with N₂O peaking a few hours after wetting and NO after one day. We measured a second pulse in soil N oxide emissions after the third rain event. This pulse occurred only with the plant patch and not outside the patch and was reduced by 54% and 31% for N₂O and NO respectively. However, the temporal (peaking) pattern of the second N-oxides pulse was similar to that of the first pulse. Suggesting a reduction in substrate availability as a cause of the reduced pulse. We also found 43% mass loss from the plant litter after 12 months of decomposition. Together, these results suggest that the establishment of saltwort plants affects soil nutrient dynamics and accumulation, thus creating nutrient-rich microsites for potential succession by other annuals and perennials, leading to fertility island establishment in the Negev Desert ecosystem.

How to cite: Yagle, I., Segoli, M., and Gelfand, I.: Patch establishment of the summer annual saltwort plant (Salsola inermis Forssk.) increases N cycling rates and soil N-oxide emissions in Israel’s Negev Desert, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3645, https://doi.org/10.5194/egusphere-egu23-3645, 2023.

The role of biochar-microbe interaction in plant rhizosphere mediating soil-borne disease suppression has been poorly understood for plant health in field conditions. Chinese ginseng (Panax ginseng C. A. Meyer) is widely cultivated in Alfisols across Northeast China, being often stressed severely by pathogenic diseases. In this study, topsoil of a continuously cropped ginseng farm was amended at 20 t ha^-1 respectively with manure biochar (PB), wood biochar (WB) and maize residue biochar (MB) in comparison to conventional manure compost (MC). Post-amendment changes in edaphic properties of bulk topsoil and the rhizosphere, in root growth and quality and in disease incidence were examined with field observations and physicochemical, molecular and biochemical assays. Three years following amendment, increases over MC in root biomass was parallel to the overall fertility improvement, being greater with MB and WB than with PB. Differently, survival rate of ginseng plants increased insignificantly with PB but significantly with WB (14%) and MB (21%) while ginseng root quality unchanged with WB but improved with PB (32%) and MB (56%). For the rhizosphere at harvest following three years growing, total content of phenolic acids from root exudate decreased by 56%, 35% and 45% with PB, WB and MB respectively over MC. For rhizosphere microbiome, total fungal and bacterial abundance was both unchanged under WB but significantly increased under MB (by 200% and 38%), respectively over MC. At phyla level, abundances of arbuscular mycorrhizal and Bryobacter as potentially beneficial microbes was elevated while those of Fusarium and Ilyonectria as potentially pathogenic microbes reduced, with WB and MB over MC. Moreover, rhizosphere fungal network complexity was enhanced insignificantly under PB but significantly under WB moderately and MB greatly, over MC. Overall, maize biochar exerted great impact rather on rhizosphere microbial community composition and networking of functional groups, particularly of fungi, and thus plant defense than on soil fertility and root growth.

How to cite: Liu, C. and Pan, G.: More microbial manipulation and plant defense than soil fertility for biochar in food production: A field experiment of replanted ginseng with different biochars, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4105, https://doi.org/10.5194/egusphere-egu23-4105, 2023.

Agricultural soils are increasingly polluted by antibiotics, and this makes them a source of antimicrobial resistance (AMR). However, antibiotics may also change microbial communities in soils, and so alter microbiological processes. Given the knowledge gap on how antibiotics affect soil functioning, in particular soil organic carbon (C) cycling, we conducted an experiment to investigate how different concentrations of the model antibiotic sulfamethoxazole (SMX) alter soil heterotrophic respiration (C mineralization) and priming of soil C.

  We collected Austrian soils rich and poor in soil organic C from Seibersdorf and Grabenegg, respectively. After the samples were sieved at 2 mm, we incubated 80 g of soil in 100 mL jars at room temperature for 30 days. SMX was added at day 1, at six rates (0; 0.01; 0.1; 1; 10 and 100 mg.kg^-1) in water solution. Soil moisture was kept constant at 45% of the soil water-filled pore space throughout the incubation experiment. The flux of CO₂ and isotopic composition of C in respired CO₂ were determined with a Picarro 2201-i laser isotope analyzer using Keeling plots.

In general, SMX negatively affected the CO₂ production rate. The negative effect was larger with a higher SMX concentration. The inhibitory effect of SMX followed a logarithmic function, after excluding outliers. The fitted equations may be used to predict how much the microbial activity is inhibited if the concentration of SMX in soil is known. However, it was also observed in our study that when the antibiotic concentration increases, the marginal toxic effect declines at some specific concentrations, and even a stimulation of CO₂ production could be found. This observed increase can be related to the following processes: it may be concentration-dependent AMR, or SMX may act as a C source, but the most likely explanation is that bacterial growth is inhibited. This last suggested process may then reduce competition, so that other microbial groups may proliferate and actively decompose soil organic matter.    

The estimated priming of soil C was positively related to SMX concentration. When readily available C source (glucose) was added, mineralization of soil C increased and this effect was accelerated with an increase in SMX concentration. Overall, the incubation experiment with different concentrations of SMX provided important insights on the toxicological effects of SMX on soil microbial life and the soil C cycle in agricultural soils. The SMX was shown to inhibit soil heterotrophic activity, but would increase losses of soil C in the presence of readily available C.

How to cite: Menyailo, O., Deroo, H., Eichinger, C., and Dercon, G.: Biogeochemical consequences of agricultural soil contamination with Sulfamethoxazole (SMX), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4926, https://doi.org/10.5194/egusphere-egu23-4926, 2023.

Soil carbon dynamics is strongly controlled by depth globally, with increasingly slow dynamics found at depth. The mechanistic basis remains however controversial, limiting our ability to predict carbon cycle-climate feedbacks. Combining radiocarbon and thermal analyses with long-term incubations in absence/presence of continuously ¹³C/¹⁴C-labelled plants, we show here that bioenergetic constraints of decomposers consistently drive the depth-dependency of soil carbon dynamics over a range of mineral reactivity contexts. The slow dynamics of subsoil carbon was tightly related to both its low energy density and high activation energy of decomposition, leading to an unfavorable ‘return-on-energy-investment’ for decomposers. We also observed strong acceleration of millennia-old subsoil carbon decomposition induced by roots (‘rhizosphere priming’), showing that sufficient supply of energy by roots is able to alleviate the strong energy limitation of decomposition. These findings demonstrate that subsoil carbon persistence results from its poor energy quality together with the lack of energy supply by roots due to their low density at depth. These findings provide insights into the bioenergetic control of SOC persistence and indicate that an increase in plant rooting depth induced by global change could threaten the storage of millennia-old SOC in deep layers.

How to cite: Henneron, L., Balesdent, J., Alvarez, G., Barré, P., Baudin, F., Basile-Doelsch, I., Cécillon, L., Fernandez-Martinez, A., Hatté, C., and Fontaine, S.: Bioenergetic control of soil carbon dynamics across depth, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5193, https://doi.org/10.5194/egusphere-egu23-5193, 2023.

Microbial composition and functions in the rhizosphere – an important microbial hotspot – are among the most fascinating yet elusive topics in microbial ecology. Based on the similarity of rhizosphere properties with respect to carbon availability and nutrient depletion, we hypothesized that (i) rhizobacterial populations are recruited from the bulk soil, but are preselected by excess released root carbon, so that bacterial diversity is lower in the rhizosphere and bacterial networks are less stable, (ii) the rhizosphere is home to more abundant copiotrophic bacteria than the bulk soil, and iii) the functional capacity involved in the carbon and nitrogen transformation would be greater in the rhizosphere.

We used 557 pairs of published 16S rDNA amplicon sequences from the bulk soils and rhizosphere in natural and agricultural ecosystems (forests, grasslands, croplands) around the world to generalize bacterial characteristics with respect to community diversity, composition, and functions.

The rhizosphere selects microorganisms from bulk soil to function as a seed bank, reducing microbial diversity. The rhizosphere is enriched in Bacteroidetes, Proteobacteria, and other copiotrophs. Highly modular but unstable bacterial networks in the rhizosphere (common for r-strategists) reflect the interactions and adaptations of microorganisms to dynamic conditions. Dormancy strategies in the rhizosphere are dominated by toxin–antitoxin systems, while sporulation is common in bulk soils. Functional predictions showed that genes involved in organic compound conversion, nitrogen fixation, and denitrification were strongly enriched in the rhizosphere (11–182%), while genes involved in nitrification were strongly depleted. Thus, rhizosphere is the most powerful factor shaping the composition, structure and functions of the soil microbiome and of biogenic element’s cycling.

Reference

Ling N, Wang T, Kuzyakov Y 2022. Rhizosphere bacteriome structure and functions. Nature Communications 13, 836. https://doi.org/10.1038/s41467-022-28448-9

How to cite: Kuzyakov, Y., Ling, N., and Wang, T.: Microbiome of rhizosphere: from structure and functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6404, https://doi.org/10.5194/egusphere-egu23-6404, 2023.

Soil organic matter (SOM) represents a continuum of progressively decomposing organic compounds mainly provided by primary producers and predominantly metabolized by adapted dynamic microbial communities. The carbon (C) in SOM flows through the microbial biomass, which needs – beside C and nutrients – Gibbs energy for growth and maintenance. The microbial metabolism and thus the degradation and stabilization of SOM follow thermodynamic laws. The thermodynamic perspective on soil systems is increasingly becoming the focus of research and has the potential to take us a substantial step towards a mechanistic understanding of SOM turnover and stabilization. An integral part of new bioenergetic concepts and models is the energy content of SOM, but the number of empirical studies dealing with soil C cycling or storage in relation to energy contents and flux is small.

In this study, topsoil profiles (comprising organic forest floor horizons OL, OF, OH and the mineral soil layer 0-5 cm) at an afforested post-mining site were investigated to evaluate the influence of (i) soil depth – representing different stages of organic matter (OM) turnover – and (ii) litter quantity and quality (litterfall and fine root tissues) provided by different tree species (Douglas fir – Pseudotsuga menziesii, black pine – Pinus nigra, European beech – Fagus sylvatica, red oak – Quercus rubra) on the energy contents of SOM. The total energy content stored in soils and plant litter was determined using two calorimetric approaches: bomb calorimetry and differential scanning calorimetry combined with thermogravimetry (DSC-TG).

The results of the litter inputs obtained with both methods showed the same trends: the C cycle in the soil was fueled by aboveground and belowground litter inputs, with energy-richer litterfall tissues (needles > leaves) compared to fine root tissues. However, with bomb calorimetry higher energy contents were generally observed in plant litter but also in the upper two forest floor horizons (OL, OF) of the soil profiles. The energy content per unit C (calorific value) changed with increasing depth due to the progressive turnover and stabilization of organic compounds but surprisingly, we identified opposite depth trends with both methods: bomb calorimetry revealed decreasing calorific values, while with DSC-TG increasing calorific values were determined. The few existing studies reported either the one trend or the other with ongoing decomposition, leading to different interpretations of the energetic driven microbial modulated formation and turnover of SOM.

It is mandatory to overcome this fundamental challenge to achieve a reliable integration of the promising bioenergetic approaches into conceptual and modelling frameworks to assess SOC turnover and persistence based on robust empirical data.

How to cite: Lorenz, M., Diehl, D., Maskow, T., and Thiele-Bruhn, S.: Energy content of soil organic matter in soil profiles investigated by bomb calorimetry and DSC-TG, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6542, https://doi.org/10.5194/egusphere-egu23-6542, 2023.

Hydroxyapatite nanoparticles (nHAs) deriving from by-products have gained increasing interest as novel phosphorus (P)-based fertilisers, since they can provide a slow P release, minimising P losses and adverse environmental side-effects, and reducing the dependency of agriculture on mineral fertiliser inputs. Phosphate solubilising bacteria (PSB) have proven to release P available for crop uptake from different inorganic sources (e.g. tricalcium phosphate, TCP, hydroxyapatite, HA). In the present study, nHAs were prepared from salmon (S-nHAs) and tuna (T-nHAs) bones by a calcination process, followed by a high energy ball milling. The obtained fine powders were characterised by scanning electron microscopy (SEM) for size and shape and by X-ray diffraction (XRD) for crystal phase composition. The phosphate solubilisation activity of seven selected PSB strains belonging to Pseudomonas and Paraburkholderia genera was in vitro investigated under acidic (pH = 5.5) and alkaline (pH = 7.5) conditions by a quantitative assessment of the solubilised PO₄^3- from TCP, S-nHAs and T-nHAs over time. Moreover, time trend of pH and organic acids in the liquid media were investigated. Characterization of S-nHAs by XRD and SEM revealed a biphasic composition of the material consisting of TCP and HA – about 50 wt% of each phase - and a heterogeneous rounded-shape (Ø < 50 nm) material. By contrast, XRD pattern of T-nHAs showed a single-phase composition mainly made of pure HA (> 95 wt%) and SEM micrographs exhibiting an elongated shape uniform in size (200 x 30 nm). At day seven, Pseudomonas graminis PG0319 solubilised the highest proportion of the total PO₄^3- in the TCP substrate under acidic pH (83%), followed by Pseudomonas rhodesiae PR0393 and P. graminis PG1211 (79% and 72%, respectively). In S-nHAs under alkaline pH, Paraburkholderia terricola PT0405, PR0393, PG0319 and PG1211 solubilised from 53% to 57% of the total PO₄^3-, whereas in T-nHAs under acidic pH the maximum solubilisation efficiency was 27% by PT0405 at day seven. The difference in the solubilisation of S-nHAs and T-nHAs is due to the lower solubility of HA in comparison with TCP. Values of pH in in the liquid media decreased over the time along with an increasing PO₄^3- solubilisation activity, suggesting an extracellular secretion of organic acids by PSB. Accordingly, differential patterns of organic acids were detected among strains with TCP as well as S-nHAs and T-nHAs. Notably, gluconic, propionic, fumaric and acetic acids played key roles during P solubilisation with all the tested strains, substrates, and pH conditions. Our results indicate that the use of microbial inocula together with P-based nanofertilisers is a promising option for a sustainable agricultural transition.

How to cite: Quattrocelli, P., Pellegrino, E., Piccirillo, C., Pullar, R. C., and Ercoli, L.: Designing of novel hydroxyapatite nanoparticles from fish by-products to be coupled with highly efficient phosphate solubilising bacteria, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7293, https://doi.org/10.5194/egusphere-egu23-7293, 2023.

Soil structure is a key feature in controlling microbial access to organic matter in soils. The spatial arrangement of solids and pores in agricultural soils is shaped by the used tillage and crop system. However, spatial heterogeneities make it difficult to determine relationships between soil biology and soil structure, and often homogenized, sieved soils are used to evaluate organic matter turnover in soils. In this study, we used heat dissipation as an indicator for biological activity in soils taken from two different tillage systems (conventional vs. reduced tillage) and two different cropping systems (crop rotations with either maize or winter wheat as main crop) running for 12 years. In order to evaluate the impact of soil structure, we investigated the response of both repacked and undisturbed soil cores (3 cm in height, 2.7 cm in diameter) to water and glucose addition. Pore structure indicators and particulate organic matter content were quantified by X-ray computer tomography at a resolution of 15 µm.

We will show that calorimetry is a suitable tool to monitor the biodegradation of C sources in undisturbed soil cores and that both tillage system and crop rotation effect biological activity in soil. In summary, soil under maize cultivation dissipated more heat compared to the wheat crop rotation. In both, repacked and undisturbed samples, conventional tillage promoted heat dissipation in response to water addition, likely due to the annual incorporation of labile organic matter. However, structural and organic matter indicators could only explain the variance in heat dissipation to some extent. Thus, the usage of undisturbed soil cores provides new challenges to evaluate the link between soil structure and microbial activity due to increased variability.

How to cite: Leuther, F., Fischer, D., Nunan, N., and Herrmann, A.: Evaluating soil structure and biological activity in soil cores under different management systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8157, https://doi.org/10.5194/egusphere-egu23-8157, 2023.

The spatial arrangement of the soil surrounding the root can improve plant resource acquisition under drought and is closely related to the fate of soil organic carbon (SOC). Thus, the formation of soil structure and the establishment of a stable rhizosheath can potentially improve plant drought resistance and contribute to maintained crop yields during drought events. Yet, soil structure formation is a complex process determined by the interaction between various functional plant and soil properties, such as the soil (micro)biome, root exudation, or root morphological characteristics. To date, it is not understood how water scarcity affects soil aggregation in the vicinity of roots, by which functional traits these drought effects can be modified, and how this feedbacks on the cycling of SOC. 

Thus, we investigated drought effects on rhizosheath properties and their link with functional plant traits. We conducted a greenhouse experiment with 38 maize varieties where half of the plants were grown under optimum moisture, while the second half of replicates were subjected to drought stress after an initial establishment phase. For each plant, the rhizosheath soil was sampled and its aggregate size distribution, carbon (C) and nitrogen (N) content, and the proportion of newly maize-derived C were analysed via natural abundance ¹³C. In addition, we recorded functional plant and rhizosphere traits, such as morphological and chemical root properties, microbial enzyme activities, and plant biomass.

Drought-stressed plants formed lower amounts of rhizosheath, with a decreased physical aggregate stability and increased concentrations of SOC, N, and newly maize-derived C. Furthermore, under drought larger proportions of the elements were allocated into the microaggregate fractions. In particular, maize-derived C, along with N, accumulated under drought stress in the smaller aggregate size classes of the rhizosheath. Maize varieties forming larger amounts of roots under drought stress tended to maintain higher macroaggregate stability in the rhizosheath. In contrast, cultivars that invested little in root growth but promoted higher microbial enzyme activities in the rhizosheath and maintained root N contents under drought were associated with a strong accumulation of maize-C and N in the smaller aggregate size classes. 

Trait-based experimental approaches, such as the one presented here, are deepening our mechanistic understanding of drought effects in the crop rhizosheath and can thus help to guide future crop selection for improved drought resistance.

How to cite: Steiner, F., Wild, A. J., Tyborski, N., Tung, S.-Y., Köhler, T., Buegger, F., Carminati, A., Eder, B., Groth, J., Hesse, B. D., Pausch, J., Lüders, T., Vahl, W., Wolfrum, S., Mueller, C. W., and Vidal, A.: Functional traits of Zea mays L. varieties determine drought effects on soil structure and carbon allocation in the rhizosheath, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8238, https://doi.org/10.5194/egusphere-egu23-8238, 2023.

Root elongation is affected by biological, physical, and chemical soil properties. Key soil physical properties determining soil strength are water content and bulk density. Highly compacted soils provide strong resistance to root growth. Therefore, it is vital to understand the effects of water content and density on the ability of roots to penetrate soil. Plant roots release a polymeric gel consisting of polysaccharides and lipids called mucilage. Mucilage also affects the physical, chemical, and biological properties of the soil, and thus is expected to have a significant effect on the penetration forces associated with root growth. In this study, penetration resistance is investigated for two soil types (sand and loam) treated with two types of mucilage obtained from flax and chia seeds. To determine penetration forces, a rheometer (MCR 102e, Anton Paar, Germany) equipped with a stainless steel needle with a shaft diameter 1 mm and an apex angle of 60° was used to mimic a root. In all measurements, the needle penetrated the soil with a velocity of 40 µm/s. Soil samples were prepared with various water content (6%, 9%, 12%, and 15%) while keeping the dry density of the soil constant following standard procedures of a mini-compaction test.  To investigate the effect of mucilage concentration, penetration tests were carried out for different concentrations (control, 0.1%, and 0.5%). Results suggest that an increase in water content significantly reduced the penetration forces. A clear effect of the type and the concentration of root exudate on the penetration resistance was also observed. It is concluded that root penetration forces are significantly affected by soil type, water content, and the type and concentration of mucilage in the rhizosphere. 

How to cite: Mysore Janakiram, R. K., Vanderborght, J., and Huisman, J. A.: How do soil mechanical properties and mucilage affect the root penetration resistance to root growth?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8627, https://doi.org/10.5194/egusphere-egu23-8627, 2023.

Flavonoids are known to perform complex physiological functions in the plant organism. The synthesis of flavonoids, their quantitative and qualitative composition depends on the genotype, age and habitat of the plant. Flavonoids are predominantly synthesized in assimilating organs and then distributed throughout the plant organism. Part of the flavonoids is released through the roots into the rhizosphere. Depending on the chemical structure, flavonoids in the soil can be ionized, oxidized or form covalent adducts with thiol compounds, complexes with metals or ammonium forms of nitrogen.

Rutin (quercetin-3-O-rutinoside), when excreted by plant roots in a slightly alkaline environment, like most flavonols, is partially ionized, acquiring greater mobility in soil solutions. In combination with ammonium nitrogen, rutin actively spreads in the rhizosphere and is recognized by rhizospheric bacteria. Thus, PGPR (plant growth-promoting rhizobacteria) isolated from the seed coat of soybean (Glycine max (L.) Merr.) reveal high sensitivity to rutin-ammonium complexes. Pseudomonas putida strain PPEP2-SEGM-0220 (GenBank: MW255059.1) stimulated the growth of main and lateral roots in soybean seedlings. The sensitivity of this strain to the rutin-ammonium complex on nutrient medium (King's B) was found at a solution concentration of 5 µg/ml. This indicates that the ionized form of rutin is biologically active and performs the function of a selective attractant for symbiotic microorganisms in the rhizosphere. Obviously, isolated PGPRs have molecular mechanisms for recognition of the rutin-ammonium complex. The presence of positive chemotaxis increases the probability of colonization of the plant with the PGPR strains it needs. Thus, the processes of transformation of quercetin-3-O-rutinoside in the soil are extremely important in the formation of plant-microbial systems.

How to cite: Likhanov, A.: Positive chemotaxis of plant growth-promoting rhizobacteria to the ionized form of rutin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8644, https://doi.org/10.5194/egusphere-egu23-8644, 2023.

Isothermal microcalorespirometry is a non-destructive technique widely used to study terrestrial activity in ecosystems by measuring the heat and the carbon dioxide (CO₂) released by metabolic reactions of soil organisms. Therefore, microbial communities naturally present in the soil play a key role in the C and N cycle thereby releasing heat and CO₂ which are quantitatively related to the matter fluxes via the law of Hess. In order to measure both quantities simultaneously, current methods follow mainly a purely calorimetric approach (absorbent method or GC analysis) ^[1]. In the absorbent method, CO₂ is measured indirectly via the heat released during the absorption reaction in a NaOH-solution (CO₂-trap), which is placed in the sample vessel together with the soil sample. This approach presents a few disadvantages, e.g. indirect CO₂ measurement, small sample size, low sample throughput, low CO₂ partial pressure and oxygen limitation. 

To overcome the drawbacks of the current calorespirometric approach, a newly designed isothermal macrocalorespirometer (IMCR) was developed by combining a classic respirometer and the proven concept of isothermal microcalorimetry. The IMCR is composed of 10 mobile channels placed in a thermally isolated box, water-thermostated at 20°C. Each channel is composed of a heat sink and a heat sensor directly in contact with the sample vessel (calorimetric unit), plus a vessel with a KOH-solution (CO₂-trap) in which a pair of electrodes is immersed (respirometric unit) connected to the channel’s lid. The spatial separation between the two units, the use of electrodes and the size of the channel, make it possible to overcome the disadvantages of the absorbent method (NaOH-solution) mentioned above. The new approach has been successfully tested with glucose-induced microbial metabolic activity in soil samples, allowing the quantification of the calorespirometric ratio . Additionally, TGA-DSC-MS and GC-MS analysis will be performed, necessary to close balances of mass and energy fluxes.

This newly designed IMCR will be applied in the wider frame of calorimetric environmental soil studies, aiming at understanding the carbon dynamics in soil, the latter being known as the biggest carbon pool among the natural matrix. New knowledge in this area support potential solutions for climate change, intimately connected to the global carbon fluxes.

^[1] Wadsö L., A method for time-resolved calorespirometry of terrestrial samples, Methods 76 (2015) 20–26

How to cite: Di Lodovico, E., Meyer, M., Maskow, T., Schaumann, G., and Fricke, C.: Isothermal Macrocalorespirometry – Novel Instrument Design to Analysis Microbial Metabolism in Soil Systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9096, https://doi.org/10.5194/egusphere-egu23-9096, 2023.

Background. High plant diversity is known to increase carbon inputs to soils, impact soil microbial community composition and promote soil microbial activity. Large pores are likely to hold more roots residues, provide more efficient oxygen supply, and have more dissolved nutrients and carbon carried by water fluxes. Soil pore structure also impacts the activities of soil microbial communities. The aim of this study was to investigate the effects of 1) plant systems, representing a 9-year gradient of plant diversity (no plants, monoculture switchgrass (Panicum virgatum L.), and high diversity prairie), 2) soil pore size (small (4-10 µm Ø) and large (30-150 µm Ø)), and 3) incubation time (24 hr (short-term) and 30 days (long-term)) on the microbial communities involved in the utilization of a newly added carbon (glucose). This is the first work to explore the influence of soil micro-habitat, as presented by pores of different sizes ranges, on the microbial communities’ responses to new carbon inputs.

Methods. The intact soil cores (5 cm Ø) from the three systems were supplied with either 50 μM C g^-1 soil of ¹³C labeled glucose, unlabeled glucose, or no glucose. Glucose was added to small or large pores based on matrix potential approach. After 24 hr or 30 day incubations stable isotope probing (SIP) was used to identify the phylotypes actively responsible for glucose assimilation in the small and large pore micro-habitats. Both extracted DNA and the fractions separated by SIP were subject to 16S rRNA gene sequencing. PICRUST2 was used to predict the microbial functions of the sequencing data from KEGG orthologs.

Results. The overall microbial communities were affected by multiple years of contrasting vegetation, but not by pore sizes or incubation times. Pseudomonas (Proteobacteria) played an important role in carbon uptake from glucose in all short-term incubations and in the long-term incubations within large pores. In the long-term incubations of both switchgrass and prairie systems’ soils, the community compositions of carbon consumers acting within the small and large pore micro-habitats differed and could be linked to disparate carbon assimilation strategies (r- vs. K-strategists) and to disparate carbon acquisition ecological strategies (plant polymer decomposers, microbial necromass decomposers, predators, and passive consumers). The predicted enriched functional genes indicated the dominance of glucokinase in the soil of the prairie, but not switchgrass system, suggesting a competitive advantage for consuming glucose.

How to cite: Li, Z., Cupples, A., Guber, A., and Kravchenko, A.: Soil Microorganisms Involved in Glucose Assimilation in Small and Large Pore Micro-habitats of Different Plant Systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9613, https://doi.org/10.5194/egusphere-egu23-9613, 2023.

The presence of oxygen in soil controls the occurrence and rates of biogeochemical processes underlying soil nutrient transformations and greenhouse gas dynamics.  Oxygen (O₂) levels within the rhizosphere are heavily modulated by both root and microbial respiration.  Thus, a microscopic environment near the root may be a microbial hotspot and not well represented by broader, non-rhizosphere soil.  Here we examine the millimeter-scale oxygen consumption or loss processes in the rhizosphere of sorghum, how they are influenced by irrigation practices, and the relationship between oxygen dynamics and nitrification in the rhizosphere.

In a field study at a research farm at the University of Illinois Urbana-Champaign, sorghum was grown under a rainout shelter with plants undergoing one of 2 irrigation treatments.  Soil O₂ concentration and isotopic ratios, nitrous oxide (N₂O), and carbon dioxide (CO₂) were measured in the rhizosphere of the sorghum via an array of novel microvolume probes coupled to an Aerodyne TILDAS (Tunable Infrared Laser Direct Absorption Spectrometer).  Probes were placed within the rhizosphere or outside the root zone with the aid of root windows installed at the site.

We collected continuous, real-time, in situ measurements of O₂, O₂ isotopes, CO₂ and N₂O over the 2022 sorghum growing season.  The high spatial and temporal resolution of the measurements allowed us to observe spatiotemporal heterogeneity of biogeochemical activity in the rhizosphere as a function of agricultural activity.  

We will also report on controlled laboratory incubations to quantify the impact of soil microbial oxygen consumption on ¹⁸O enrichment as compared to water displacement in the soil; and controlled greenhouse experiments to measure fine scale gradients of oxygen concentrations and isotopic composition near roots.

The novel microvolume sampling system coupled with the O₂ detection method can provide insights into fine scale gradients driven by higher microbial activity in microbial hotspots within the rhizosphere.  Measurements on this mm-scale have further applications for monitoring other trace soil gases and their spatial and temporal heterogeneity in soil systems. 

How to cite: Shorter, J., Roscioli, J. R., Lunny, E., Eddy, W., and Yang, W.: Exploring Real-time Oxygen Dynamics in the Rhizosphere of Sorghum with High Spatial and Temporal Resolution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9746, https://doi.org/10.5194/egusphere-egu23-9746, 2023.

The growth-stimulating bacteria (PGPB-group) in the increasing of the plant-microbial interaction potential in the winter wheat agrocenosis

Boroday V.V.^{1, 2},

Doctor of Agriculture Science,

Yakovenko D.O.¹,

¹ Institute of Agroecology and Environmental Management, Metrologichna str., 12, Kyiv, 03143, Ukraine

²National University of Life and Environmental Sciences of Ukraine, Heroiv

Oborony str.15, building 3, of. 207, Kyiv, 03041, Ukraine

The use of microorganisms of the PGPB group will contribute to the activation of nitrogen fixation and phosphate mobilization in the soil, and increase the potential of plant-microbial interaction. The purpose of our research was to find out the effect of biological preparations Groundfix® and Azotofit-r® (“BTU-Center”) on the main physiological groups of soil microorganisms during the cultivation of wheat plants of the Bohdana variety in the conditions of the Western Forest-Steppe of Ukraine. The biological preparation Groundfix® includes Bacillus subtilis, B. megaterium var. phosphaticum, Azotobacter chroococcum, Enterobacter spp., Paenibacillus polymyxa. Azotofit-r® contains nitrogen-fixing bacteria A. chroococcum and its biologically active products.

It is established that in the agrocenosis of winter wheat, biological preparations Groundfix® and Azotofit-r® affect the ratio of ecological and trophic groups of microorganisms, in particular nitrogen-fixing, oligotrophic and microorganisms involved in the mineralization of humic substances, and the direction of mobilization processes in the soil. The complex application of biological preparations in different phases of plant development contributed to the slowing down of mineralization processes, the preservation of soil nitrogen in a more accessible form to plants during the period of active growth.

The coefficient of oligotrophicity for the soil with the use of biological preparations in the spring weeding phase was low (<1). This indicates a high supply of soil microbiota with easily digestible organic substances and the formation of optimal conditions for the functioning of the soil microbial complex.

The use of Azotofit and Groundfix (3 l/ha) for pre-sowing cultivation contributed to the abundance of saprotrophic species in these variants within 88.9-90.0% of the total abundance of micromycetes.

Thus, the use of biological preparations Azotofit and Groundfix contributed to reducing the infectious potential of the soil and  increasing its microbiological activity in the agrocenosis of winter wheat.

How to cite: Boroday, V. and Yakovenko, D.: The growth-stimulating bacteria (PGPB-group) in the increasing of the plant-microbial interaction potential in the winter wheat agrocenosis , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10067, https://doi.org/10.5194/egusphere-egu23-10067, 2023.

Microorganisms possess the ability to adapt to different environmental conditions through the use of various strategies. This diversity in strategies allows us to categorize them based on their functions in the ecosystem. Copiotrophs have a fast growth rate but a low carbon use efficiency (CUE), while oligotrophs have a slow growth rate but a high CUE. In the rhizosphere, the effect of root exudation on different functional microbial groups is not well understood. Process-based modeling is a useful tool to analyze the complex feedback between roots and soil in the rhizosphere. Here, we present a rhizosphere model that explicitly considers two different microbial groups (oligotrophs and copiotrophs) classified based on their microbial traits that correlates each other due to physiological trade-offs and organic carbon accessibility (dissolved organic carbon, mucilage and sorbed carbon). The model is one-dimensional axisymmetric, simulating a soil cylinder around individual root segments. The model was conditioned using a novel constraint-based Markov chain Monte Carlo parameter sampling method. Applying this approach enabled the identification of parameter sets that led to plausible model results in agreement with experimental findings from a comprehensive literature review. The conditioned model predicts organic matter concentration curves from the root surface into the soil driven by root exudation. Our simulations show a decreasing pattern of dissolved organic carbon, which is utilized by oligotrophs and copiotrophs, away from the root surface. Furthermore, we observe a slightly higher proportion of copiotrophs than oligotrophs near the root surface and dominance of copiotrophic biomass at very high nutrient availability conditions as expected from ecological theory and experimental evidence. However, the model predictions are still highly uncertain. Thus, further experimental data and observations are required for model conditioning.

How to cite: Sırcan, A., Streck, T., Schnepf, A., and Pagel, H.: Traitbased modeling of microbial distribution and carbon turnover in the rhizosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12829, https://doi.org/10.5194/egusphere-egu23-12829, 2023.

Climate change scenarios forecast increasing droughts in large areas globally with significant effects on food production. Nutrient availability is an imperative factor for plant growth and it is greatly modulated by water availability. Nitrogen (N) availability extensively constrains plant growth in most terrestrial ecosystems especially in sub-Saharan Africa, where soils are unfertile and often degraded. How rhizosphere traits at the plant soil-interface affect N uptake in response to drought in N poor tropical soils remains elusive. We used ¹⁵N, and ¹³C pulse labelling to trace and quantify N transport from a root-restricted compartment by AMF across an air gap to the host plants coupled with quantifying the allocation of carbon to below-ground pools. Three sorghum genotypes were grown under optimal and water deficit conditions. By tracer analysis in the plant tissues, we assessed that drought enlarged uptake and delivery ¹⁵N by arbuscular mycorrhizal fungi (AMF) from the root restricted compartment across the air gap to the host plant. In addition, drought induced enhanced below-ground incorporation of recently assimilated carbon (C) into the microbial biomass pool both in rhizo-hyphosphere and hyphosphere. Enzyme assays revealed that whereas potential enzymatic reaction (Vmax) of chitinase was reduced under drought, that of leucine amino peptidase (LAP) was upregulated by water scarcity suggesting that N input from protein mineralization was relatively enhanced to that of chitin following moisture limitation. Michaelis-Menten constant (Km) of LAP strongly increased by drought compared to that of chitinase which displayed genotype-specific shifts in rhizosphere enzyme systems. We conclude that in addition to AMF symbiosis, enzyme regulation and enhanced belowground C allocation are key strategies to enhance nitrogen uptake under adverse conditions of resource limitations.

How to cite: Munene, R., Mustafa, O., Loftus, S., Ahmed, M., and Dippold, M.: Drought increases the relative contribution of mycorrhiza-mediated mineral N uptake of Sorghum bicolor, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14382, https://doi.org/10.5194/egusphere-egu23-14382, 2023.

The rhizosphere is a highly dynamic biological interface where most decomposition processes of soil organics are performed by actively growing microorganisms producing extracellular enzymes. As the rate of enzymatic reactions and affinity of enzymes to the substrate are influenced by plant genotype and water content in soil, we hypothesized to boost genotype effect of wild and root hair deficient maize plants after a short-term drought due to resources limitation. We further hypothesized that (1) maximum enzymatic rates (V_max) for ß-glucosidase, leucine-aminopeptidase, acid phosphatase, and N-acetylglucosaminidase will decrease due to low accessibility to substrates; and (2) microbial growth will be retarded due to limited nutrients availability. We tested these hypotheses on the Zea mays L. (WT) and a root hair deficient mutant (rth3) grown in soil columns. Drought effect was compared between the brushed soil from roots called root-affected soil, and the rhizosphere soil obtained after the subsequent washing of roots. Microbial growth induced by glucose and nutrients application was determined by microcalorimetry.

Only two of four enzymes tested were sensitive to drought: ß-glucosidase and phosphatase. Maximum enzymatic rates of ß-glucosidase and phosphatase in the rhizosphere were, respectively, 73 and 47 % slower under drought treatment, compared to the well-watered plants. In the rhizosphere of rth3, only ß-glucosidase activity was reduced by 32 % under drought treatment compared to well-watered plants In root-affected soil, drought decreased ß-glucosidase activity by 72 and 57% for WT and rth3 plants, respectively. In the rhizosphere of WT plants, higher affinity for substrates was revealed for ß-glucosidase and phosphatase, respectively, as 31 and 42% lower Michaelis-Menten affinity constant (K_m) under drought versus optimal watering. In the root-affected soil of rth3 mutant, only ß-glucosidase showed a 39 % lower K_m under drought compared to well-watered plants. Higher enzymatic affinity under drought versus optimal moisture indicated a different set of enzymes either of microbial or plant origin. On the other hand, plant genotype effect was visible under drought for ß-glucosidase activity in rhizosphere soil, when maximum rate was 54 % lower for WT plants compared to rth3, suggesting that ß-glucosidase activity hotspots were not associated to root-hairs.

Glucose-induced microbial growth was retarded for 12 to 14 hours under drought compared to well-watered treatment. A prolonged lag phase could be due to the smaller fraction of active microorganisms, which is driven by a non-optimal moisture of the soil. Moisture appeared to be a more determinant factor for microbial growth and enzymatic activity compared to plant genotype, whose effect was reinforced under drought.

How to cite: Martín Roldán, M., Hartwig, R., Wimmer, M., and Blagodatskaya, E.: Short-term drought effect on biochemical processes and microbial growth in the rhizosphere of two maize genotypes., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15250, https://doi.org/10.5194/egusphere-egu23-15250, 2023.

Plants' roots promote changes in soil structure, forming a strongly-bound soil layer in the surroundings of the root, which is named as rhizosheath. Rhizosheath formation is attributed mainly to the root hairs' presence, that favors the enmeshment of the soil particles around the roots, and the release of mucilage and exudates, which acts as gluing agents of those soil particles. In the present work, we studied the rhizosheath aggregate formation of two Zea mays L. genotypes with contrasting root hair development: a mutant with root hair defective elongation (rth3) and a corresponding wild type (WT). We also tracked the fate of recently-deposited C in the rhizosheath aggregates using two ¹³CO₂ pulse labeling approaches (single vs. multiple pulse labeling). The sampled rhizosheath aggregates were further separated using dry-sieving fractionation into three aggregate size classes: primary small particles and smaller microaggregates (<53 µm), larger microaggregates (53-250 µm) and macroaggregates (>250 µm). We observed that the aggregate size distribution followed the same pattern in both genotypes. This result reinforces the assumption that other soil properties are more important for rhizosheath aggregation than root hair elongation. We observed that the higher potion of the recently-deposited root-derived C (57%) was accumulated in the macroaggregates. Moreover, the multiple pulse labeling approach proportioned a higher ¹³C enrichment of the rhizosheath aggregates fractions than applying a single pulse. Despite both single and multiple labeling approaches have resulted in a similar distribution of ¹³C in the rhizosheath aggregates, multiple pulse labeling provided a higher enrichment in the rhizosheath aggregates, which allowed a better separation of significant differences between the genotypes.

How to cite: de C. Teixeira, P. P., Trautmann, S., Buegger, F., J.M.N.L. Felde, V., Pausch, J., W. Müller, C., and Kögel-Knabner, I.: Role of root hairs in rhizosheath aggregation and in the carbon flow into the soil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15947, https://doi.org/10.5194/egusphere-egu23-15947, 2023.

Predicting soil organic carbon (SOC) mineralization under changing climatic conditions is complicated by the diversity of SOC composition. We combined incubation experiments with continuous respiration measurements and thermal analysis to investigate the informativeness of SOC thermal stability. Thermogravimetry is used in studies to determine soil properties such as total organic C, nitrogen, and clay content and to investigate the relationships between thermally labile and stable SOC and biodegradability. Soil respiration (SR) was measured in forest soils with added organic materials (wood, litter, and weeds with C contents of 49, 10, and 35%, respectively, and N contents of 0.1, 0.6, and 3%, respectively) at 20°C and 10°C and different soil moisture contents (5, 10, 20, 40, and 75% of field capacity). Wood amendments were further subdivided into pine (Pinus sylvestris) and beech (Fagus sylvatica) with three different particle sizes. We used topsoil samples from a pine forest, a beech forest, and a long-term agricultural experiment with different properties (C in %: 1.5, 2, and 4; clay in %: 5, 9, and 25, respectively). Basal respiration increased with soil C content, while Q10 levels decreased with field capacity 10 > 40 > 75% in forest and agricultural soils. This order changed depending on the sampling location when organic material was added. Decreasing wood particle size significantly increased SR. Weed additions caused the highest increase in soil respiration. After 10 weeks of incubation at different moisture and temperature conditions, organic amendments were mineralized faster in beech forest soils than in soils under pine forests. A multifactorial analysis of variance showed a significant influence (p < 0.01) of the interactions between temperature, moisture, site, and wood particle size on SR. Preliminary results from analysis of changes in thermal mass loss (TML) between 200 and 550 °C (reflecting SOC thermal stability) due to added organic material and incubation will be presented. Approaches to determine relationships between TML and carbon mineralization will be discussed.

How to cite: Krahl, I., Kalbitz, K., and Siewert, C.: Influence of organic amendments, moisture content and temperature on carbon mineralization of forest soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16129, https://doi.org/10.5194/egusphere-egu23-16129, 2023.

Phosphorus (P) availability to rice plants is influenced by its strong interaction with iron (Fe). In the rhizosphere microenvironment, the soil-plant interactions cause the formation of Fe-plaques that can retain porewater components, such as P. The Fe-P processes have been extensively described in paddy soils managed under continuous flooding, although, due to the increasing water scarcity, new water-saving techniques have been adopted. However, their effects on P retention/release mechanisms are largely unknown.  

In order to assess the impacts of water-saving techniques on the rhizosphere Fe-P dynamics and P availability to rice, a macrocosm experiment was conducted to compare the effects of three different water management practices: continuous water flooding (WFL), alternated wet and dry (AWD), and delayed flooding (DFL). Three P fertilization levels were tested for each water management strategy. The concentrations of Fe and P in porewater were monitored until rice harvesting. The plant tissues were analyzed for P concentration, and the content of amorphous and crystalline Fe (hydr)oxides in root plaque was estimated via oxalate and dithionite extractions at mid-tillering, stem elongation, heading and harvesting.

The molar P/Fe ratio in porewater and the formation of Fe plaques differed as a result of the combined effect of water management and P fertilization.  The WFL and DFL treatments led to a higher Fe plaque formation with respect to AWD, while in all water management treatments, Fe plaque formation was higher without P fertilization. The early rice development stages were characterized by a greater amount of amorphous Fe (hydr)oxides in root plaques. The proportion of crystalline Fe (hydr)oxides increased with plant development, despite the lower amount of total Fe plaques, suggesting a reduction of the poorly ordered fraction, especially when no P was supplied. Rice plants could be supposed to respond to P-limited conditions, exuding protons and/or organic acid anions that increase P availability through Fe plaque dissolution. This was confirmed by the negative correlation between porewater P concentration and the content of crystalline Fe in the plaques. These results indicate the complex spatio-temporal interconnection between P and Fe cycling at the root-soil interface. The amount of Fe plaques formed on the root surface and their crystallinity degree can explain the mechanisms that regulate their potential in P retention/release and the consequent effects on plant uptake.

This study was funded by the PSR Lombardia 2014-2020 (“P-rice Fosforo in risaia: equilibrio tra produttività e ambiente nell'ottica delle nuove pratiche agronomiche”)

How to cite: Celi, L., Martinengo, S., Schiavon, M., Romani, M., Said-Pullicino, D., Seyfferth, A., and Martin, M.: The role of water management technologies in regulating iron-phosphorus interaction in rice rhizosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16135, https://doi.org/10.5194/egusphere-egu23-16135, 2023.

Large fluxes of solar energy conserved in organic matter pass through soil as conduit from primary production to mineralisation. Soil organisms are channelling the flux, are fuelled by the energy, and contribute by their bio- and necromass. Previous research targeted either biogeochemical turnover processes or the microbiome but rarely linked both. Microbial biomass and its necromass were identified as major constituents of soil organic matter (SOM) and highly counterintuitive results were found on the relation of the microbiome to the systems boundary conditions provided by water, oxygen, nutrients, and minerals etc. A major deficit is that soils are currently not considered as energy driven open systems. Energy is the `fuel´ of all animate systems including soils in which microbial biomass consume the organic matter and energy input. With the necromass plus other SOM it constitutes carbon and energy containing intermediates.

The general aim of SoilSystems is to link energy and matter turnover and fluxes in soils to functional and structural biodiversity. SoilSystems proposes a systems ecology concept for linking balances of changes of Gibbs energy and heat production to organic matter turnover and the microbiome. This concept will be applied in model experiments with various bulk soils and isotope labelled substrates with defined energy supply and molecular structures in order to evaluate losses, efficiencies, and the modes of energy and matter retention.

This presentation gives an overview on the recently started research priority program SoilSystems, funded by the German Research Foundation. The planned research will be outlined that is aimed to elucidate microbial processes driving organic matter along energy use channels, thereby converting easily degradable detritus molecules to microbial biomass and finally long-term stabilised necromass. Thermodynamic principles are generally valid for the Earth system and thus also for soils; however, only few studies exist regarding energy use and maintenance (energy budgets) of microbiomes related to carbon use and ecosystems in soil.

SoilSystems aims to answer the key-question: What drives the interrelated energy and matter fluxes in soil systems exemplified by carbon turnover and storage? The microbiome, energy input, mineral and boundary conditions, and how do they interact?

How to cite: Thiele-Bruhn, S., Kästner, M., Miltner, A., Maskow, T., and Lorenz, M.: SoilSystems, a research program on systems ecology of soils – energy discharge modulated by microbiome and boundary conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16304, https://doi.org/10.5194/egusphere-egu23-16304, 2023.

Biochemical processes in the rhizosphere are distributed heterogeneously and depend on biotic and abiotic factors such as root morphology and physiology which affect the allocation of substrates, nutrients and water availability. In the frame of Priority Program ‘Rhizosphere Spatiotemporal Organisation – a Key to Rhizosphere Functions ’ we aim to visualize and quantify enzymatic activity related to C, N and P turnover in order to link them with microbial functional traits in space and time. To do that, we apply a time-lapse zymography of hydrolytic and oxidative enzymes coupled to micro-sampling of rhizosphere hotspots for enzymatic kinetics determination at the early vegetation stage of maize. Kinetic parameters of microbial growth will be estimated by micro-calorimetry. Traditional approaches of rhizosphere sampling will be compared with novel methodology at the level of individual soil aggregates. Specific strategies of two plant genotypes (wild type and root hair deficient mutant) in response to limiting conditions of water and nutrients content will be tested on two soil substrates of contrasting texture (loam and sand). Field experiments in a long-term maize monoculture will help disclose the interactions between rhizosphere and detritusphere from decaying roots of previous years.

How to cite: Blagodatskaya, E., Martin Roldan, M., and Shen, G.: Enzymatic kinetics and microbial growth in the rhizosphere of maize: visualization and quantification of the functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16674, https://doi.org/10.5194/egusphere-egu23-16674, 2023.

Soil saprophagous fauna strongly impacts litter decomposition through its modification of microbial communities and activity. However, soil fauna is very diverse, with different feeding strategies. For example, arthropods such as woodlice and millipedes and epigeic earthworms (litter-feeders) are known to feed on the litter layer, while endogeic earthworms feed on organic particles mixed with the soil mineral layer. Distinct fauna may have a very different impact on the final forms of the soil organic matter. They could act synergistically as endogeic earthworms may require the fragmentation and incorporation of litter into the soil by litter-feeders to access their food. We performed a three-months microcosm experiment in which we tested the effect of litter fragmentation and presence of litter-feeders (isopods or epigeic earthworms of Dendrodrilus rubidus species) on the survival and change in biomass of endogeic earthworms (of Aporrectodea caliginosa species). We also tested whether different combinations of fauna and litter fragmentation affect microbial biomass and respiration, and the forms of the soil organic matter. We used a recent post mining soil, to create a stressful environment with poor food resources for the endogeic species. The hypotheses were that endogeic earthworms would be positively affected by the fragmentation and mixing of litter with the soil, whether it would be done manually or by epigeic earthworms or isopods, and that this would impact soil properties. First results showed no decrease in the biomass of A. caliginosa in any of the treatments. A. caliginosa was able to consume the alder litter added at the soil surface at a similar rate than the epigeic D. rubidus, even without previous fragmentation and in the absence of litter-feeders. A loss of carbon through respiration and an increase of dissolved organic carbon content in the soil were associated with the presence of epigeic earthworms, while an increase in soil microbial biomass carbon was induced only by endogeic earthworms when litter was added at the soil surface. Nitrates content was increased when both types of earthworms were present. Interestingly, endogeic earthworms had an opposite impact on microbial biomass and dissolved organic carbon content when litter was mixed in small pieces with the soil or added at the soil surface. First conclusions are that though the endogeic earthworm A. caliginosa do not seem to require a first fragmentation of the litter to access it, the final effect on decomposition differ according to the other fauna present and to the fragmentation of the litter. Analyses of the forms of the organic matter in the different treatments will allow to determine how this impacted the incorporation of organic matter into the soil.

How to cite: D'Hervilly, C. and Frouz, J.: Do interactions between litter-feeders and endogeic earthworms impact soil organic matter content and its forms? Results of a microcosm experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-837, https://doi.org/10.5194/egusphere-egu23-837, 2023.

Globally soil fauna can consume about half of litter fall. Important question is how this activity affect mineralization and stabilization of soil organic matter. Here we explore how much fauna effect litter decomposition and organic matter stabilization in soils of various ages supplied by litter of various quality.   Laboratory mesocosm consist from litter and mineral layer mineral soil originated either from spruce and alder stand which were growing either on post mining soils (young soil) or from soil in close vicinity of post mining sites (mature soil), mineral soils were supplied by matching litter, mesocosms were either without fauna or supplied by two individuals of earthworm Aporectodea rosea. Results show significant effect of tree, soil age and earthworm; alder respire more than spruce, young soil respire more than old soil, and mesocosms with earthworms respire more than without earthworms.  Earthworm effect show statistically significant interaction with tree and soil age, earthworms always increase respiration in alder soil, but in spruce only in mature soil while opposite was true for young soil.  In general earthworms promote removal of litter from soil surface and its accumulation in mineral soil. Earthworms promote C storage in MAOM  namely in young spruce soil. Results indicate that in young soils which are far from saturation (spruce on post mining soil) earthworm activity promote soil C storage most likely by promoting C storage in MAOM, in the contrary in mature,  C saturated soils, earthworms rather promote soil respiration.

How to cite: Frouz, J. and Irshad, S.: How the effect of earthworms on soil organic matter mineralization and stabilization is affected, by litter quality and stage of soil development., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1118, https://doi.org/10.5194/egusphere-egu23-1118, 2023.

The impact of climate change on soil processes depends on how abiotic stressors (drought, flood, heatwave…) affect soil species physiology directly, but also indirectly through their interactions. A number of different theoretical frameworks have been designed to conceptualize the latter. The most widely used is the stress gradient hypothesis, which states that facilitation should be more common in stressful environments. However, these interactions are notoriously difficult to investigate in soils, because of the difficulty to isolate low competitor species and of the sheer number of species in soil, and therefore of interactions to test experimentally. Consequently, this topic has been traditionally approached through network analyses, that are based on frequency of co-occurrences, but has its own flaws.

In this paper, we used a combination of isolation methods to recover the widest possible range of soil fungi with randomized co-cultivation tests to cover as many interactions as possible. This way, we investigated how multiple pairwise competitive interactions were affected by abiotic stress (high temperature, low water availability).

In absence of abiotic stress, the presence of another species mostly affected growth positively, demonstrating facilitation among soil fungal species under benign conditions. In presence of temperature stress, either alone or combined with water stress, these positive effects became negative, contradicting the stress gradient hypothesis. We did not find the interaction outcomes to be predictable by some of the trait data we investigated, such as abiotic stress tolerance or intrinsic growth rate.

Overall, our results demonstrate that in a very simplified but controlled system, climate change shifts the interaction types from mostly facilitative to mostly negative. We discuss further potential implications in the presentation.

How to cite: Rineau, F., Reyns, W., Carpentier, C., Van Der Plas, F., Bardgett, R., Beenaerts, N., and De Laender, F.: Fungal pairwise interactions shift from positive to negative under warming stress, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1282, https://doi.org/10.5194/egusphere-egu23-1282, 2023.

Among the high diversity of urban soils, of particular interest are soil constructures (Technosols) created by man to solve certain problems: landscaping and recultivation. Microorganisms quickly respond to external influences and are indicators of changes occurring in ecosystems. Microfungi determine the soil health, and the activity of saprotrophic microscopic fungi can lead to improved soil properties associated with soil fertility.

The aim of the study was to evaluate the quantitative indicators of soil fungal communities of 2-years-old Technosols, created on the basis of peat, sand and loam, in different climatic zones in comparison with background soils.

The studies were carried out in cities located in different climatic zones: subarctic (Apatity), temperate continental with a humid climate (Moscow), and temperate continental with a dry climate (Rostov-on-Don). Soil sampling was carried out at stations with soil constructures of a composition universal for all regions: peat/sand/loam in the ratio 1/1/1.

Quantitative assessment of the content of ribosomal genes of fungi was performed by real-time polymerase chain reaction (PCR). The fungal biomass was determined by luminescence microscopy method.

The predominance of fungal biomass over that of prokaryotes was revealed in all climatic zones, both in background soils and in Technosols. The fungal biomass in Technosols of different climatic zones varied from 0.073 to 0.790 mg/g of soil. In Apatity and Moscow, its values 2 years after the creation of Technosols were lower than in the background soil; in Rostov, the values were close. In the Technosols of Apatity and Moscow, microfungi were mainly in the form of mycelium, while in Rostov-on-Don, spores prevailed over mycelium. However, small spores prevailed in all zones, both in background soils and in Technosols. Over the 2-years period of Technosols development in the subarctic and the temperate zone, similar trends in the state of the fungal community were noted, while in the area with a warmer climate, other patterns were revealed.

The number of the fungal ITS rRNA ribosomal genes copies in the soils varied from 5.95×10⁸ in the Technosols of Apatity to 3.39×10⁹ gene copies/g soil in the background soil of the Moscow region. According to the quantitative content of fungal genes copies over a two-year period, the Technosols of Rostov-on-Don correspond to the background soils and slightly exceed the values of the latter. In the subarctic, the values of this indicator are also comparable for Technosols and background soils, while in Moscow, the number of copies of Technosols genes is 2.5 times less.

Thus, the change in the quantitative indicators of soil fungal communities over time makes it possible to judge the dynamics of the development of Technosols in different climatic zones. However, for such a short period (2 years), the state of fungal communities does not reach the state of the background ecosystems in any of the regions. We can only talk about trends in the parameters of the fungal community in the direction of background ecosystems.

How to cite: Korneykova, M., Nikitin, D., Vasilieva, M., and Vasenev, V.: Microscopis fungi of Technosols in cities of different climatic zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2092, https://doi.org/10.5194/egusphere-egu23-2092, 2023.

Enhanced Silicate Weathering (ESW) has emerged as a promising Carbon Dioxide Removal (CDR) technology. However, it is still not clear which factors could maximize ESW rates. Previous studies have shown the potential of soil biota to amplify mineral weathering rates. Among the relevant soil biota are earthworms, which have been found to enhance nutrient release from soil minerals. This is indicative of their ability to increase weathering rates and further inorganic carbon (C) sequestration. Here we aim to accelerate ESW rates in a bio-reactor through earthworm activity. First, we identified the optimal conditions for earthworm survival and activity in an environment exclusively composed of ground silicate rocks and organic substrate. Second, we determined to what extent earthworms can enhance inorganic C sequestration in such a system. We carried out 5 rounds of 2-month experiments in a climate chamber at 25°C. The set-up of the experiments consisted of 200 columns, each topped by a sprinkler connected to an irrigation system, which allowed for different water irrigation rates and watering frequencies. The leachate of each column was collected in a jerrycan kept at 4˚C. Within this set-up, we used two endogeic earthworm species (Aporrectodea Caliginosa and Allobophora Chlorotica) at different densities (10, 20, and 30 earthworms kg^-1 soil), three types of rock flours (Basalt, Lava and Dunite) of two grain sizes (0.063 and 1.5 mm), one organic source (straw) and two water irrigation rates (125 and 250 ml day^-1 kg^-1 soil) at three watering frequencies (1, 2 and 5 times/day). Rock flours were used not only as single type or single size, but also as mixtures of types and/or sizes. At the end of each experiment, we measured earthworm survival and activity, and inorganic C sequestration rates by summing cumulative dissolved inorganic C in the leachate and the newly formed solid inorganic C content. We found no differences in survival and activity between the two earthworm species, but we did find an optimum for both parameters at a density of 10 earthworms kg^-1 soil. Earthworms showed a clear preference for a mixture of grain sizes compared to single size, and for single mineral type compared to a mixture of mineral types. The response of earthworm survival and activity to the two water irrigation rates was similar, but at a water irrigation rate of 250 ml day^-1 kg^-1 soil a frequency of 5 times/day resulted in higher activity. Preliminary results indicate that earthworms increase mineral weathering rates and thereby sequester inorganic C. We demonstrate that earthworms can thrive in a fully artificial environment designed to ESW rates, removing one hurdle for designing a bio-reactor aimed at optimizing carbon sequestration.

How to cite: Calogiuri, T., Hagens, M., van Groenigen, J. W., and Vidal, A.: Can earthworms increase inorganic carbon sequestration in an artificial environment?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3352, https://doi.org/10.5194/egusphere-egu23-3352, 2023.