Orals: Tue, 5 May, 08:30–10:15 | Room 2.44
Semi-arid ecosystems dominate the interannual variability and trend of the terrestrial carbon sink. They are sensitive to anthropogenic environmental changes, including shifts in the nitrogen (N) to phosphorus (P) ratio driven by increasing N deposition.
In 2015, a large-scale fertilization experiment was established at Majadas de Tiétar, a tree-grass ecosystem in western Spain. Three eddy covariance towers operate simultaneously at the site: one serves as unfertilized control plot, one measures an area fertilized with N, and the third samples an area with N and P addition. This setup provides an exceptional opportunity to study the long-term influence of altered N:P ratios on ecosystem functioning. Flux measurements are complemented by a variety of other instruments, such as lysimeters, mini-rhizotrons, soil chambers, soil sensors, phenocams and proximal sensing instruments. The comprehensive measurement setup at Majadas de Tiétar therefore enables a deeper understanding of the trends and interactions among climate change, nutrient availability and the biogeochemical cycles of carbon, N, and P in semi-arid ecosystems.
We found that both fertilization schemes increased carbon uptake, and that N+P addition enhanced the water use efficiency more than N-only addition. Fertilization also increased the inter-annual variability of net ecosystem exchange (NEE) and altered the sensitivity of seasonal NEE to its drivers. However, water limitation in summer and energy limitation in winter overweighed fertilization effects at the seasonal scale.
How to cite: Nadolski, L., Paulus, S., Hanggara, B., Nair, R., El Madany, T., Carrara, A., Migliavacca, M., Reichstein, M., and Lee, S.-C.: Lessons learned from a long-term manipulation experiment in a semi-arid savanna ecosystem, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12631, https://doi.org/10.5194/egusphere-egu26-12631, 2026.
Coastal marshes are critical carbon sinks in the global carbon system, yet rising temperatures may alter microbial processes that regulate carbon and nutrient cycling. In a recent ex-situ warming experiment conducted in the Climate Change Marsh Mesocosm Facility (CCMMF) at the University of Hamburg, Germany, we could show that warming can alter soil microbial communities, and that responses vary with environmental context, such as plant community diversity and ecosystem age. We also found that warming favored microbial taxa with traits supporting plant growth and nutrient cycling. Here, we expanded our analysis and included microbial 16S rRNA gene sequencing data sets from two in-situ coastal marsh warming experiments: MERIT (“Marsh Ecosystem Response to Increased Temperatures”) in northern Germany and SMARTX (“Salt Marsh Accretion Response to Temperature eXperiment”) in a brackish marsh on Chesapeake Bay, USA. By this, we combined three genetic microbial data sets of coastal marshes characterized by different soil type, ecosystem age, vegetation type, tidal regime, and soil carbon and nitrogen stocks.
We will show how warming-induced shifts in microbial community relate to ecological parameters across sites building on the hypothesis that microbial responses to warming vary strongly with vegetation composition and ecosystem age. With this meta study, we will be able to identify key factors controlling microbial responses to experimentally increased temperatures to better understand how climate change reshapes microbial composition and thereby carbon dynamics in coastal wetlands.
How to cite: Schwarzer, J., Liebner, S., Bartholomäus, A., Logemann, E. L., Mittman- Goetsch, J., Jensen, K., Thomsen, S., Megonigal, J. P., Rich, R., Noyce, G., and Mueller, P.: Integrating microbiome responses across warming experiments in coastal marshes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7113, https://doi.org/10.5194/egusphere-egu26-7113, 2026.
This presentation will articulate a metaphor about painting. If it is successful, you should be convinced that there are things out there that, if we made better use of them, would significantly enhance our understanding of the critical zone. Before working on the actual painting, most artists apply one or more coats of primer. In most finished paintings, you don’t see the primer, but without it, the painting would likely not be as good. Just because we don’t usually think about the primer doesn’t mean it isn’t there.
One can make the same argument for monitoring and research infrastructures; hopefully you can be convinced that infrastructures could provide the primer behind the critical zone painting. Infrastructures such as the International Cooperative Programme on Integrated Monitoring of Air Pollution Effects (ICP-IM) collect, curate and report monitoring data to assess compliance with European legislation. In some ways, the data they collect are a by-product or intermediary step in regulatory assessments. However, these long-term, standardized, well curated and increasingly open access data series can be a resource in and of themselves as well as providing vital context for new data collection.
Some infrastructures, e.g., the Swedish Infrastructure for Ecosystem Science (SITES) and the Integrated European Long-Term Ecosystem, critical zone and socio-ecological system Research Infrastructure (eLTER) not only collect and curate environmental data, they function as a platform to support field sampling and experiments across multiple ecosystems and spatial scales. The background monitoring data collected by the infrastructure enhances the scientific value of these experiments. Platforms can also help to grow networks by providing the opportunity for people to work together on new questions, such as in the global Aquatic Mesocosm network (AQUACOSM).
Often, the role of these networks, platforms and infrastructures is mentioned in the acknowledgements, if at all. Even if they are not visible, they are vital. The future of infrastructures and platforms is not guaranteed. If we as a community make more use and highlight what they have to offer, it helps them to secure their future and to give us a primer for our scientific canvas.
How to cite: Futter, M., Grandin, U., Kothawala, D., Villwock, H., Wallin, M., Weldon, J., and Denfield, B.: Infrastructures – a primer for the Critical Zone, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12381, https://doi.org/10.5194/egusphere-egu26-12381, 2026.
Although scientific disciplines are becoming increasingly specialised and expert, they nevertheless isolate themselves from one another. This is particularly evident in the study of the Earth's surface. Over time, the geosciences have diverged from ecology, despite the fact that the historical concept of ecosystem (Tansley, 1935) included both biotic and abiotic components. With time and investment from also compartmented institutions, this has led to independent communities developing parallel research and equipping themselves with field laboratories (long-term observatories): geosciences focusing on the biophysical components of water, relief, and soils, and ecology focusing on biodiversity. Even within geosciences, disciplines are isolated and have developed their own “dialects”.
The Critical Zone Initiative, which originated in the US in 2003, was an attempt to encourage these different Earth science communities to collaborate at the level of instrumented scales (Critical Zone Observatories). This initiative has expanded further in Europe, particularly through the SoilTrec FP7 programme (2009–2014), the CRITEX program in France (2022-2021) or the OZCAR and TERENO research networks in France and Germany respectively. Today, these divisions are no longer tenable. The deterioration of the planet's habitability means that we need to return to a much more systemic approach to habitats that support life, particularly humans and their societies. While disciplinary expertise, particularly in experimental developments and numerical modelling, is necessary, it is far from sufficient to understand how changes in biodiversity will affect biogeochemical cycles, water and food resources.
The eLTER (Long-Term Ecosystem, critical zone, and socio-ecological) Research Infrastructure represents a unique and even historic achievement to (re)connect scientific communities working in the field of environmental and sustainability sciences on continental surfaces. At a backbone of permanently operated sites, eLTER promotes a holistic approach from the local/regional to the continental and global scales. In this contribution, we will present eLTER and show how the list of eLTER Standard Observations selected, distributed across different layers or “spheres,” and the categorization of sites (with a focus on the geosphere and hydrosphere) make it possible to capitalize on the previous works of the critical zone community and enrich it with ecological measurements or socio-ecological practices (Zaccharias et al., 2025). The services offered by eLTER RI also exploit recent advances in critical zone modeling. They provide access to a network of sites spanning large environmental conditions open to transnational access and an open data base and hence a unique opportunity for the moving forward critical zone science, at the local to global scales.
eLTER is the European future of critical zone science.
Tansley, A. G. (1935). The use and abuse of vegetational concepts and terms. Ecology,16, 284–307.
Zacharias, S., Lumpi, T., Weldon, J., Dirnboeck, T., Gaillardet, J., Haase, P., ... & Mirtl, M. (2025). Achieving harmonized and integrated long-term environmental observation of essential ecosystem variables-eLTER's Framework of Standard Observations. Authorea Preprints.
How to cite: Gaillardet, J. and Mirtl, M.: The future of critical zone research in Europe imbedded in eLTER research infrastructure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16343, https://doi.org/10.5194/egusphere-egu26-16343, 2026.
Since its first definition by the National Research Council in 2001, the concept of Critical Zone has known undeniable success over the last quarter of a century. A success that is often reflected by the evolution and diversification of its meanings. Recently, Lee et al. (2023) proposed a review that literally focuses on “the meanings of the Critical Zone”. Through an extensive review of the literature across the disciplines and journals, they have identified three loosely overlapping meanings. An ontological meaning, where the Critical Zone is mostly seen as the Earth’s spatial interface where geochemical and biological activity sustains life. An epistemic meaning, where the Critical Zone is considered a product of collaborative efforts between scientific communities to build a whole-system knowledge data-base and library. And finally, an anthropocenic meaning, where the Critical Zone is the vulnerable home of the human species. In this contribution, we aim at revisiting these three meanings through the creation and development of the French network OZCAR (Critical Zone Observatories: Research and Application).
Created in 2015 to enhance the collaborations between Critical Zone observatories (Gaillardet et al., 2018), OZCAR is a French Research Infrastructure that gathers 23 national observation services and +120 study sites in metropolitan France and on 5 continents. If most observation services existed prior to the creation of OZCAR, we have seen major evolutions over the last decade as the OZCAR community developed and bloomed. Originally conceived as a spatial definition (ontological meaning), the “Critical Zone” words in OZCAR became a vast collaborative effort to develop the whole system approach and data base (epistemic meaning). It is now also fostering transformative research aimed at preserving our planet’s habitability, i.e., the giant spaceship in which we all live together (anthropocenic meaning).
References:
- Lee, R. M., Shoshitaishvili, B., Wood, R. L., Bekker, J., & Abbott, B. W. (2023). The meanings of the Critical Zone. Anthropocene, 42, 100377.,doi:10.1016/j.ancene.2023.100377.
- Gaillardet, J., Braud, I., Hankard, F., Anquetin, S., Bour, O., Dorfliger, N., et al. (2018). OZCAR: The French network of critical zone observatories. Vadose Zone Journal, 17(1), 1-24, doi:10.2136/vzj2018.04.0067.
How to cite: Jougnot, D., Braud, I., Tournebize, J., Boudevillain, B., Rivière, A., Marcais, J., Chatton, E., Pasquet, S., Bouchez, J., Bénard, H., and Gaillardet, J.: Revisiting the meanings of the Critical Zone through the OZCAR research infrastructure example, definitions and evolutions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16646, https://doi.org/10.5194/egusphere-egu26-16646, 2026.
A critical zone-based environmentalism understands that local habitability arises primarily in Earth’s material exchanges across bedrock, aquifers, soils, plants, and the lower atmosphere. With support from the Science For Africa Foundation, the Critical Zones Africa (CZA) consortium is working in specific locales of five African countries to understand how societal and policy processes are affecting circulations of water, soil nutrients and contaminants. This paper presents a first comparative assessment of these relations, and explores their implications for landscape governance, social sciences, and landscape repair.
Beginning with forensic accounts of flows and movements of water, soil nutrients and contaminants in landscapes, ie both horizontal and vertical relations, CZA team studies have explored where, how and why harms to habitability have arisen. If environmental governance sciences are to shift from their current basis in finance, property and objects, to molecular and energy flows and the processes between them, the comparative aspect of the CZA project asks with what concepts and analytics might damaged relations be described, understood, and remediated?
A first step to building a politics capable of habitability repair, is to recognise how specific patterns of social relations and concepts affect landscape flows, movements, interactions and transformations of matter and materials.
Reflecting comparatively on the research findings emerging from the CZA studies, this paper sets out a critical zone-based social science for local governance.
How to cite: Green, L.: Critical Zone Science, Social Sciences and Local Governance: An overview of the Critical Zones Africa Research Programme, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23229, https://doi.org/10.5194/egusphere-egu26-23229, 2026.
Cape Town, the legislative capital of South Africa, is renowned for is natural beauty and is ranked as one of the best developed and well governed cities in Africa. However, for whom is the city aesthetically pleasing, developed and well-governed for? When the language of development, growth and progress permeates all spheres of contemporary Cape Town city planning, what does this obscure? What are the lived experiences on the ground? The project takes the Cape Flats, an expansive low-lying area situated to the south-east of Cape Town’s central business district, as a critical zone, where urban metabolic flows shape policy and habitability. The Cape Flats, characterized by a geography defined by a unique combination of maritime geology, endangered biodiversity, wetlands, lakes and rivers, agricultural and mining land, formal and informal residential areas, industrial areas, a waste dump and several wastewater treatment works (WWTW), is marked by “slow violence”, where apartheid spatial planning and environmental degradation and contamination meet contemporary urban precarity. Described as “apartheid’s dumping ground”, the Cape Flats was where people of colour were forcibly relocated under the Group Areas Act of 1950, as well as a site where a significant portion of Cape Town’s waste is disposed of. In thinking about the critical zone, it is then important to think about how biologies, ecologies, society, geologies are shaped by this inheritance of colonial and apartheid city planning. The central question for Cape Flats’ Critical Zones project is therefore: How do Cape Town's modes of development address realities in inherited zones of abandonment and contamination in the Cape Flats critical zone? The project explores how changes in the landscape, under the guise of “development” through the different historical periods under the colonial, apartheid and contemporary neoliberal forms of governance, have shaped the poly-crises evident in the area today. Considering the Cape Flats’ critical zone from aquifer to cloud, the project explores how material flows and urban metabolic processes shape habitability, policy and politics in the area. By paying attention to how disrupted urban metabolic processes impact biodiversity, water and contamination, soil, waste cycles, infrastructure, health and governance, the project proposes an amendment to the approaches in environmental governance from one that seeks to command, predict and control, to one that sees urban ecology as urban metabolisms of flows and relations.
How to cite: Solomon, N.: Urban Metabolisms: What makes for Habitability in the Cape Flats Critical Zone, in Cape Town, South Africa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23148, https://doi.org/10.5194/egusphere-egu26-23148, 2026.
The Lilongwe River Upper Catchment Area (LRUC) exemplifies the urgent need for Critical Zone Science (CZS) in Africa, where biophysical degradation and socio-political inequities converge. This study applies a CZ lens to investigate how soil health deterioration, land commodification, governance fragmentation, and gendered struggles intersect to undermine ecological livability and community resilience. Preliminary findings reveal alarming soil erosion rates exceeding global tolerable limits, rapid land-use transformations driven by urbanization and infrastructure expansion, and persistent exclusion of women from land and resource governance.
By integrating soil health assessments, geospatial analysis, ethnographic inquiry, and participatory community engagement, the Malawi CZA team identifies critical micro-watersheds where ecological degradation and human vulnerability overlap. Modeling of Nature-Based Solutions (NbS), including reforestation, contour farming, and integrated agroecological practices, demonstrates pathways to restore soil function, regulate hydrology, and enhance resilience under future climate scenarios. Importantly, the research situates soil health as both an ecological indicator and a sociopolitical marker, revealing how commodification and complex tenure systems exacerbate inequities.
This work contributes to global CZ science by foregrounding African environmentalism and community-driven approaches, while linking directly to Sustainable Development Goals (SDGs) 1 (poverty reduction), 2 (food security), 5 (gender equality), and 15 (life on land). By framing LRUC as a social-ecological system shaped by material flows and governance structures, the Malawi CZA initiative demonstrates how CZ methodologies can inform inclusive policies, strengthen grassroots participation, and advance equitable sustainability in rapidly transforming landscapes.
How to cite: Kampanje Phiri, J.: “Our Soils are Sick”: Addressing Soil Health, Energy, Land, Governance and Gender Complexities through Critical Zone Approaches in Lilongwe River Upper Catchment Area of Malawi, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23138, https://doi.org/10.5194/egusphere-egu26-23138, 2026.
Urban watersheds in sub-Saharan Africa face unprecedented environmental degradation due to rapid urbanization, inadequate infrastructure, and governance failures. Lake Chivero, a shallow hypereutrophic reservoir constructed in 1952 on Zimbabwe's Manyame River, exemplifies this crisis. Serving as the primary water source for Harare and its dormitory towns of Chitungwiza and Ruwa a combined population exceeding 2.4 million. The lake has experienced catastrophic deterioration over seven decades. This study presents an innovative multidisciplinary framework combining Critical Zone Sciences with participatory diagnosis and community engagement to address complex socio-environmental challenges threatening water security in rapidly urbanizing African contexts. This framework offers scalable insights for addressing watershed degradation across African urban centers where rapid demographic transitions outpace infrastructure development and governance capacity, demonstrating how transdisciplinary approaches can bridge science-policy-community divides to achieve sustainable water resource management.
Lake Chivero's degradation manifests across multiple dimensions. Sedimentation has consumed 18% of the reservoir's storage capacity (49,126,170.34 m³), with annual capacity losses averaging 792,357 m³ year⁻¹ since 1953. Current sedimentation rates of 352.31 m³ year⁻¹ km⁻² project a remaining useful life of merely 106.63 years, pointing to a "2050 Doomsday Scenario." Sediment composition analysis reveals concerning proportions of mud (54%), sand (24%), and silt (22%). Nutrient pollution has escalated dramatically, with combined nitrogen and phosphorus loads surging from 3,524 tons in 2000 to 38,940 tons in 2012, an increase primarily attributable to untreated and partially treated sewage effluent. This pollution has triggered extensive water hyacinth (Pontederia crassipes) proliferation, linked to sewage effluent and abattoir waste discharge. Public health consequences include cholera outbreaks, waterborne diseases, and elevated cancer incidence rates, while ecological and economic impacts manifest in green-colored water and ecosystem collapse, as well as ballooned water treatment and public costs.
The research identifies governance fragmentation and knowledge silos as critical barriers to effective watershed management. Population growth from 200,000 during the colonial era to over 2.4 million by 2022, compounded by civil conflict in the 1970s, rural-urban migration, economic structural adjustment programs (ESAP), and informal settlement expansion, has overwhelmed water and sanitation infrastructure. Policy dissonance, corruption, informal waste management through opaque private contracts, chemically intensive agriculture, and politically connected land speculation further exacerbate environmental stress.
Our methodological innovation addresses these challenges through deliberate transdisciplinary integration. The research team comprises experts in social sciences, governance, environmental science, GIS, soil science, hydrology, waste management, and renewable energy. We hypothesize that fragmented relationships among stakeholder’s stem fundamentally from asymmetric data access and exclusion of local communities from knowledge production and decision-making processes. Our approach systematically reviews published literature while collecting primary field data, then transforms scientific findings into accessible formats for policymakers, government officials, planners, and local communities.
Participatory diagnosis employs ethnographic methods including "photovoice" to capture thick descriptions of lived experiences, validating local knowledge systems alongside scientific data. GIS-based time series analysis integrates scientific measurements with ethno-environmental perspectives, creating space for authentic dialogue. This methodology enables collaborative problem identification and solution co-creation grounded in shared visions and mutual trust. Thematic analysis using NVivo software ensures rigorous qualitative data interpretation.
How to cite: Mukamuri, B.: Experimenting with Multidisciplinary, Participatory Diagnosis and Community Engagement to Rehabilitate Endangered Watersheds in African Urban Settings: The Case of Lake Chivero in Zimbabwe, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23141, https://doi.org/10.5194/egusphere-egu26-23141, 2026.
The multiple roles of Kilombero Valley-Rufiji Delta as a watershed, national hub for food production and a critical landscape for biodiversity protection makes it a highly significant national and international site of interraction between different actors who represent international conservation and development partnerships, private and civil society interests, small-holder farmers and agri-business deallers. Over the years, the role of these actors in translating ecologies into financial values has transformed the social biogeophysical relations of the landscape in ways that raise concerns about the future habitability. The Critical Zone project addresses this concern by focusing on how financialization models leave issues of soil health and water quality unaddressed hence compromising the sustainability of their development interventions. Precisely, the crops are managed solely with an eye on commercial values, which miss the care for soil with agrochemicals and fertilizers increasing productivity in the short term but causing long term damage to soils and water bodies. This has downstream impacts to both biodiversity and agricultural floodplains in the Rufiji Delta. Our key question, then, is: How useful is the Critical Zone approach for improving land-use decisions for Kilombero-Rufiji landscape, in the context of Tanzania’s Green Revolution? We combine spatial and temporal biophysical analysis with bottom-up approaches that draw from people science and policy actor engagements to reflect on the future habitability of the landscape.
How to cite: Pallangyo, C.: The Changing Social and Biophysical Relations in Tanzania’s Kilombero– Rufiji Landscape, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23144, https://doi.org/10.5194/egusphere-egu26-23144, 2026.
Rising sea levels and intensifying storms are driving increased flooding and salinization of coastal forests, yet the mechanistic pathways linking belowground disturbances to forest mortality remain poorly constrained. We designed an ecosystem-scale flood manipulation experiment in a coastal forest to disentangle the roles of inundation and salinity in initiating the hypothesized “tree mortality spiral”. Our experimental plots are outfitted with an extensive array of sensors to complement high resolution sampling campaigns, allowing us to observe immediate and lagged responses to flooding. Experimental flooding drove rapid, consistent shifts in soil biogeochemistry indicative of oxygen stress and altered carbon cycling, followed by a lagged response in aboveground vegetation. The temporal disconnect between belowground process thresholds and observable forest impacts demonstrates how manipulative experiments can benchmark the early stages of transitions in the coastal Critical Zone.
Building on our field-based findings and substantial AI-ready datasets produced over multiple years of flooding experiments, we are developing a coupled modeling framework that leverages both AI-based and process-based models to predict forest responses under future flooding regimes. Through this integrated approach, we aim to understand how disturbance intensity, duration, and legacy effects propagate across time and space to control coastal forest resilience. The combination of controlled large-scale ecosystem manipulation and data-driven predictive modeling provides a framework for bridging disciplines and scales—linking soil biogeochemistry, ecohydrology, and vegetation dynamics—to improve projections of coastal forest mortality and its consequences for coastal Critical Zone carbon cycling.
How to cite: Regier, P., Bond-Lamberty, B., Megonigal, P., Sulman, B., Ward, N., and Bailey, V.: Manipulation to prediction: integrating flood experiments and AI to understand coastal forest mortality, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15714, https://doi.org/10.5194/egusphere-egu26-15714, 2026.
Understanding how small-scale processes interact to shape ecosystem development at landscape scales remains a major challenge in environmental science, particularly in post-mining environments where belowground processes are difficult to measure and manipulate. To address this, we established FALCON (2019), an array of four hydrologically isolated artificial catchments (0.25 ha each) in a post-coal mining area in Czechia, enabling controlled, landscape-scale experimentation. Two catchments were reclaimed by leveling and planting alder, while two were left to spontaneous succession on wave-like microtopography. Each catchment is fully instrumented to monitor water, nutrient, gas, and energy fluxes, and includes lysimeters to link small-scale processes to catchment-scale responses. Early studies demonstrate that erosion and deposition strongly control microhabitat formation, with wave-like topography generating pronounced heterogeneity in soil texture, hydrology, and water retention while homogenization prevail in flat catchments. These processes support surface run off in reclaimed and subsurface run off in unreclaimed catchments. Carbon flux measurements show rapid ecosystem recovery at both reclaimed and unreclaimed sites, with all catchments transitioning from CO₂ sources to sinks within four years; differences between treatments shifted from being driven by soil physical properties to vegetation productivity as alder established. Lysimeter-based assessments indicate that surface water fluxes and evapotranspiration can be reasonably upscaled, particularly in unreclaimed sites, but subsurface flow and solute transport remain poorly represented. Overall, FALCON provides a unique platform to experimentally link erosion, hydrology, biogeochemistry, and carbon exchange across scales
How to cite: Bartuška, M. and Frouz, J.: Large experimental fully hydrologically isolated catchment as a tool to study hydrological and ecological processes on multiple scales , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6970, https://doi.org/10.5194/egusphere-egu26-6970, 2026.
Peatlands are increasingly recognized as key components of the Critical Zone (CZ) - the thin layer at the surface of the Earth where major biogeochemical reactions occur - , because they tightly integrate, within a single ecosystem, hydrological, biological, and carbon cycle processes that all impact each other. Although they cover only about 3% of the global continental surface, they store over 30% of global soil organic carbon, highlighting their long-term role as carbon sinks, largely due to permanent water saturation and specific vegetation. However, climate change is increasingly disrupting the hydroecological balance of peatlands, potentially converting them from carbon sinks into sources of greenhouse gases (GHGs) and dissolved organic carbon (DOC).
In this study, we adopted an approach using innovative techniques developed within the TERRA FORMA initiative of the French OZCAR CNRS research infrastructure. Our work was focused on a temperate 7-hectare peatland (Frasne, French Jura Mountains) hosting a long-term Critical Zone observatory (SNO Tourbières) to unravel the mechanisms underlying the continuum of DOC production, mineralization and export to the atmosphere as GHGs (CO₂ and CH₄). Spatial variability in DOC quality - including aromaticity, molecular weight, and microbial origin - was compared to hydrological gradients, vegetation types and atmospheric GHG concentrations, the latter measured by drone surveys and ground-based accumulation chambers.
The results indicate a preferential production of recalcitrant DOC in the upstream part of the peatland, where conifers dominate the vegetation. In contrast, biochemical markers reveal intense microbial decomposition of organic carbon in the more frequently flooded downstream zones, producing DOC that is lower in concentration, less aromatic, and more labile. This area coincides with higher GHG concentrations in the overlying atmosphere, suggesting that the labile DOC is readily transformed into GHGs. This pattern is hypothesized to result from the presence of less aromatic molecules originating from vascular plants and Sphagnum moss exudates formed under anaerobic conditions, in areas where the water table is close to the surface. With declining Water Table Depth (WTD), this more labile carbon becomes exposed to aerobic conditions, enhancing microbial respiration and promoting GHG emissions.
Lateral DOC export at the outlet of the peatland is strongly controlled at seasonal scale: export increases in spring and autumn during WTD transitions, with generally higher fluxes in winter when the water table is near the surface. In the context of climate change, with progressively wetter winters and drier summers, this pattern suggests a potential intensification of winter DOC export and higher atmospheric GHG emissions during summer, thus leading both to increased annual organic carbon exports. However, the model still needs to account for changes in vegetation type and productivity to fully capture future dynamics.
Overall, this study emphasizes that understanding such a complex environment requires strong integration across scientific disciplines. The integrative framework enabled by the OZCAR research infrastructure provides a robust foundation for a better understanding of peatland carbon dynamics at different spatial scales.
How to cite: Poteaux, N., Lhosmot, A., Steinmann, M., Calisti, R., Jacotot, A., Coffinet, S., Binet, P., Boetsch, A., Toussaint, M.-L., Joly, L., Dumelie, N., Bonne, J.-L., Longueverne, L., Pons, M.-N., Loup, C., and Bertrand, G.: Hydro-ecological controls of dissolved organic carbon dynamics and greenhouse gas emissions in a temperate peatland: A multi-disciplinary collaboration in the Frasne peatland observatory (Jura Mountains, France), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12900, https://doi.org/10.5194/egusphere-egu26-12900, 2026.
Snowmelt-driven watersheds provide water for billions of people, yet warming temperatures threaten to reduce streamflow across these regions. One pathway for greater water loss is through increased evapotranspiration (ET), particularly during the warm summer growing months. However, the magnitude of summer transpiration and the water sources accessed by vegetation remain poorly understood. While snowmelt is the primary driver for peak runoff and supplies soil moisture for early summer transpiration, vegetation water use and its influence on summer baseflow are less well understood.
To study this pathway, we instrumented an 81 ha headwaters micro-catchment in the Upper Colorado River Basin (UCRB), where ET represents the largest annual water flux. This site includes eddy-flux towers, stream gages, shallow groundwater wells, sap-flux sensors, and a dense soil-moisture network. High-resolution eddy-flux observations show how ET is sustained even during extended summer droughts. Over three growing seasons, daily fluctuations in soil moisture, groundwater, and streamflow indicate roots intercept shallow groundwater to support the continued transpiration during these dry periods.
We extended this analysis basin wide across 18 headwaters catchments and observed that summer growing season conditions independently regulate streamflow, with effects rivaling those of snowpack. Warm summers suppress streamflow, causing high-snowpack years to be near-average, while cool summers elevate flow.
Together these results demonstrate upland vegetation suppresses summer streamflow in mountain headwaters by sustaining transpiration through shallow groundwater access during hot, dry periods. As warming continues, this vegetation-groundwater pathway will intensify summer streamflow declines across mountain regions, with significant implications for future water availability and management.
How to cite: Stone, H. and Maxwell, R.: Not Just Snowpack: Vegetation-Groundwater Controls on Summertime Streamflow in Colorado River Headwaters, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14762, https://doi.org/10.5194/egusphere-egu26-14762, 2026.
Coastal ecosystems along the Great Lakes play an important role in critical element cycling between land and lake ecosystems. Because lake water levels are highly dynamic, the dominant ecosystems (marsh, swamp, upland forest) constantly respond to the varying water line. Flood pulses are important controls on plant community zonation, as well as their respective biogeochemical functions, setting the boundary between herbaceous wetlands, forested wetlands, and/or upland forest based on the respective flooding tolerance. Because lake levels are predicted to increase in future decades (e.g. 2040-2049 vs. 2010-2019), shifts in ecosystem boundaries are expected but the change in ecosystem function is currently unknown.
To understand the impact these flood pulses have on soil biogeochemistry and plant function, we are implementing an ecosystem-scale manipulative experiment to create increasingly intense flood pulses by pumping water across an elevation gradient from forested wetland to upland (DELUGE - Disturbance and Ecohydrological Legacies in Upland Great-lakes Ecosystems). We follow a before-after-control-impact design using two diked parcels in the Ottawa National Wildlife Refuge at the coast of Lake Erie, one of which will be untreated and serve as a reference. The main objective is to gain a mechanistic understanding of how the effects of freshwater flooding and subsequent drainage propagate through water, soils, microbes, and plants to cause ecosystem state changes such as tree mortality and changes in biogeochemical cycling. Here we present the experimental design, site characterization, and results from sensor-based baseline measurements which started in June, 2025. Results from DELUGE will be incorporated into multi-scale process and Earth system models, with the overarching goal of an improved predictive understanding of coastal ecosystems.
How to cite: Forbrich, I., Doro, K., Malhotra, A., Fluet-Chouinard, E., Atiti, P., Foster, A., Grammenidis, E., Peixoto, R., Machado-Silva, F., Rich, R., Brewer, S., Howard, C., Rod, K., Ward, N., Weintraub, M., Megonigal, P., and Bailey, V.: DELUGE - Disturbance and Ecohydrological Legacies in Upland Great-lakes Ecosystems: An Ecosystem Scale experiment to study coastal critical zone, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22054, https://doi.org/10.5194/egusphere-egu26-22054, 2026.
The Critical Zone (CZ) in the Midwestern United States has transformed from predominantly prairie landscapes to highly productive row-crop agriculture that requires intensive management such as tillage, tile drains and fertilizer inputs. The Critical Interfaces CZ Network (CINet) project focused on three critical interfaces that are important regulators of material storage, transport and transformation in the CZ: the near-land surface, the active root zone and the river corridor. To investigate the root zone critical interface, we established instrument clusters called MIRZ (Management Induced Reactive Zone) in Illinois and Nebraska on both agriculture and restored prairie land management. The study sites differ in climate and geology: Illinois has wetter conditions (100 cm MAP) with loess over glacial till and extensive tile drainage, while Nebraska is drier (78 cm MAP), formed in loess, and lacks artificial drainage. At each site, precipitation, soil porewater (sampled at 20, 60, 110, and 180 cm depths), surface waters, tile drains, groundwater and soil gases were collected biweekly. In addition, co-located sensors were installed to monitor soil moisture, temperature, electrical conductivity, oxygen, carbon dioxide, and meteorological conditions at hourly intervals. Bulk soil measurements included geochemistry, carbon/nitrogen concentrations, mineralogy, density and particle size. Key findings from the MIRZ root zone measurements suggest that land use strongly controls how quickly water moves through soils and how much geochemical alteration occurs before water reaches streams. Longer water residence times and greater water–mineral interaction occur in agricultural soils, whereas stronger soil structure and deeper root systems in restored prairies promote rapid infiltration and more limited geochemical alteration. The geochemical similarity between agricultural porewaters and stream or tile-drain waters highlights strong hydrologic connectivity and implies that agricultural land use fundamentally alters root-zone structure, water flow paths, and ultimately stream geochemistry at the watershed scale. The diverse and deeply rooted prairie vegetation also influences soil gases, with higher carbon dioxide production rates and enhanced seasonal variability in prairie soils compared to agricultural soils. The widespread conversion of Midwestern USA prairies to intensive agriculture has therefore altered solute, carbon, and gas fluxes throughout the root zone critical interface, including the depth and intensity of the reactive zone where weathering, nutrient cycling, and carbon storage occur.
How to cite: Dere, A., Saccardi, B., Wang, J., Druhan, J., Blair, N., Welp, L., Filley, T., Jimenez-Castaneda, M., Schaeffer, S., Stumpf, A., Bauer, E., Haken, J., Noel, I., Deuerling, K., Anders, A., Goodwell, A., and Kumar, P.: Investigating the Root Zone Critical Interface in Intensively Managed Critical Zones, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15787, https://doi.org/10.5194/egusphere-egu26-15787, 2026.
The climate-related risks in South Africa’s Raymond Mhlaba Municipality and similar rural regions include erratic rainfall, recurring droughts, heatwaves, and shifting seasons. These directly threaten agricultural productivity, leading to frequent crop losses and food insecurity. Vulnerability is heightened by reliance on rain-fed small-scale farming, minimal irrigation infrastructure to buffer against climatic shocks, and the use of old farming methods.
The government uses radio, television, newspapers, and flyers to communicate climate change, and universities are trying to produce more extension officers to assist farmers, but the challenge remains unaddressed. The root causes of this vulnerability are multi-layered: weak data dissemination systems, socio-economic marginalization, land tenure insecurity, infrastructure deficits, and regulatory and governance gaps. Consequently, farmers make key agricultural decisions such as when and what to plant without critical zone science knowledge, leading to frequent crop losses, wasted inputs, and heightened poverty.
As such, having a Climate-Adapt-Farm-Wise-AI (CAFW-AI) which can inform the farmer about the climate change and provide customised suggestions to a farmer to a) use conservation agriculture, drought-tolerant crop varieties, and precision irrigation to enhance productivity and climate resilience b) integrate adaptation and mitigation strategies across the entire food value chain to ensure sustainable food production and reduce greenhouse gas emissions c) employ Sustainable Agricultural Practices (SAPs) such as agroforestry and millet resilience to improve soil health and enhance food security in climate-vulnerable regions, based on their geographical area.
These techniques are crucial for fostering innovation and resilience in agricultural economies, especially in the face of climate change. By integrating these innovations, farmers can enhance productivity, reduce environmental impact, and ensure food security.
The proposed solution to the problem
The initiative introduces an AI-enabled, open-source mobile platform that delivers localized, real-time agricultural advisories to rural small-scale farmers in climate-vulnerable regions such as the Eastern Cape. Its strategies are threefold:
- Localized Climate-Smart Decision Support:
By integrating real-time weather data from IoT sensors (local weather stations), information, and Indigenous Knowledge Systems (IKS), the AI model generates tailored recommendations on crop selection, planting times, and resource use. This ensures that decisions are data-driven, context-specific, and actionable for farmers with limited resources.
- Accessible Communication Channels: The platform disseminates advisories via SMS/USSD in local languages (e.g., isiXhosa), bridging the digital divide for communities with limited or no smartphone access.
- Feedback-Driven Learning: Farmers contribute local observations (e.g., rainfall, soil moisture, pest outbreaks) into the system. AI processes these inputs alongside satellite and meteorological data, enabling continuous model refinement and ensuring the system evolves with changing conditions.
What sets this initiative apart is the role of real-time weather data from IoT sensors (local weather stations), AI in combining heterogeneous data sources (real-time weather, soil characteristics, and farmer inputs) to generate hyper-local insights that would not be possible through traditional extension methods. Previously, climate advisories were generalized, delayed, and fragmented; now, AI enables predictive analytics and personalized recommendations at scale, even in remote areas.
How to cite: Vambe, W. T.: Climate-Adapt-Farm-Wise-AI (CAFW-AI): Utilizing IoT, AI, and Machine Learning to Enhance Decision-Making and Protect Crops More Effectively Against Climate Change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23177, https://doi.org/10.5194/egusphere-egu26-23177, 2026.
Australian catchments exhibit diverse hydrological responses across climates, ranging from humid tropical and temperate systems to arid regions with intermittent rivers. Accurately representing this diversity requires river routing models that resolve drainage connectivity, floodplain storage and travel times at high spatial resolution. In this study, we present a novel approach using an Australia wide CaMa-Flood configuration at ~1.5 km (1 arc-minute) resolution, using MERIT-Hydro and Australian Geofabric DEMs to parameterize drainage networks and river geometry
The routing system is driven by projected runoff from the Bureau of Meteorology's operational Australian Water Resources Assessment (AWRA) model, enabling multi-decadal simulations of river discharge and floodplain dynamics across contrasting hydro-climatic regimes. To allow investigating effects of hydrography-driven differences in discharge, water level and inundation, we perform paired CaMa-Flood simulations using identical AWRA runoff. We compare (i) a river network derived from the MERIT digital elevation model and (ii) the Australian Geofabric river network and attributes.
We investigate a range of river systems including low-gradient floodplains, endorheic basins and ephemeral river systems, where flow intermittency and channel–floodplain interactions strongly control downstream hydrological behaviour. Modelled discharge and water levels are evaluated against in situ streamflow and stage gauge observations, while simulated flood extents are compared with satellite-based inundation maps derived from ICEYE synthetic aperture radar imagery. Model behaviour is analysed across representative catchments spanning tropical monsoonal, temperate, semi-arid and arid climates to identify scale-dependent controls on hydrological response. We further assess numerical stability and computational performance to quantify the feasibility of kilometre-scale routing for large-domain and ensemble applications.
Our results demonstrate that high-resolution routing substantially improves representation of river connectivity and flood dynamics, particularly in dryland environments, providing a robust framework for catchment-scale hydrological analysis and climate-impact studies including future flood-risk assessment and across diverse Australian environments. Future developments will extend this framework through coupling with ocean circulation models to assess the combined influence of tides and storm surge on coastal flood hazard, enabling the evaluation of compound river-coastal flooding processes.
How to cite: Nelli, F., Pickett-Heaps, C., Woldemeskel, F., Brakhasi, F., Bahramian, K., Hou, J., Bende-Michl, U., and Sharples, W.: Influence of river network representation on discharge and flooding in kilometre-scale CaMa-Flood simulations across Australia , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4553, https://doi.org/10.5194/egusphere-egu26-4553, 2026.
The European Long-Term Ecosystem, Critical Zone, and Socio-Ecological Research Infrastructure (eLTER RI) aims to provide a continental-scale, site-based network for observing, understanding, and addressing major ecological, geochemical, and socio-ecological challenges. A core element of eLTER RI is the implementation of the eLTER Standard Observations (SOs), which establish a harmonised framework for the systematic collection and analysis of long-term environmental data across a diverse range of ecosystems. Ensuring methodological consistency and interoperability by the SOs is imperative in order to create a shared observational basis. Such a basis is essential for large-scale synthesis and international collaboration, particularly within the context of Critical Zone Science.
The eLTER Standard Observations adopt a multidisciplinary perspective, integrating biological, hydrological, geochemical, climatic, soil-related, and socio-economic variables. Core thematic domains include biodiversity, primary production, water quality, nutrient and carbon cycling, soil processes, and climate dynamics. This integrated design explicitly supports Critical Zone Science by enabling the coupled analysis of processes spanning the Earth’s surface, from the vegetation canopy through soils and groundwater to the underlying geology, while simultaneously accounting for human influences. Standardisation across sites and regions ensures data comparability over space and time, facilitating cross-site analyses, model development, and the identification of patterns and drivers of change.
The SOs are closely aligned with the concept of Essential Variables (EVs) and cover key elements of Essential Climate Variables (ECVs), Essential Biodiversity Variables (EBVs), and Essential Socio-Economic Variables (ESVs). Through this coverage, the SOs provide a comprehensive observational foundation to assess ecosystem status, track long-term trends, and analyse human–nature interactions. By harmonising observations and explicitly linking Critical Zone processes to existing EV frameworks, eLTER strengthens connections between national and international research initiatives and enhances the contribution of European long-term ecosystem research to global observation systems.
This presentation will outline the scope, methodology, and scientific relevance of the eLTER Standard Observations, with a particular emphasis on their role in fostering international collaboration in Critical Zone Science. It will demonstrate how the SOs support integrative ecosystem research and contribute to addressing global challenges such as climate change, biodiversity loss, and sustainable resource management through coordinated, long-term, and comparable observations.
How to cite: Zacharias, S., Bäck, J., Gaillardet, J., and Mirtl, M.: Connecting Ecosystems Across Scales: eLTER Standard Observations and Critical Zone Science, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18719, https://doi.org/10.5194/egusphere-egu26-18719, 2026.
Weighing monolith lysimeters enable precise measurement of water balance parameters, including infiltration, evapotranspiration, and deep percolation as well as studies of solute fluxes within the complex soil–plant–atmosphere continuum. At the experimental field of the Biotechnical Faculty, University of Ljubljana, two monolith lysimeters were installed to study solute transport and to measure evapotranspiration. In addition to the installed lysimeters, an advanced meteorological station is located at the same site, enabling measurement of other meteorological variables required for calculating evapotranspiration. To expand and establish a critical zone research site, the lysimeter station was equipped with two cosmic ray neutron sensors for proximity moisture sensing, as well as sampling points for drainage water and groundwater quality. The research center serves as a focal point for soil water balance studies in the peri-urban area of a pre-Alpine climate in central Slovenia, and is a part of SI-COSMOS network that spreads across the Continental, Alpine, Karst, Mediterranean, and Pannonian regions. Biotechnical faculty critical zone research field enables quantification of hydrological processes that control the upper critical zone water balance and contaminant transport under changing climate conditions. Evaluation after the first decade of operation shows that advances in weighing technology, lower boundary condition control, and data processing have made high-precision lysimeters very useful tools; however, they require intensive, regular maintenance to ensure data quality. Drainage water monitoring indicates favorable water quality conditions for developing circular water and nature based solutions in per-urban agricultural landscape.
Acknowledgements: This research was partially supported by ARIS research programme P4-0085, IC RRG-AG (IO-0022-0481-001), Interreg Alpine Space program, project Alpine Space Drought Prediction (A-DROP) (grant number 101147797), European Union – LIFE Programme (LIFE23-IPC-SI-LIFE4ADAPT), OPTAIN Horizon 2020 (grant number 862756), and the Slovenian CAP Strategic Plan 2023–2027 (grant number 33126-3/2025/23).
How to cite: Zupanc, V., Noč, M., Pečan, U., Golob, N., Glavan, M., Kuk, R., Pintar, M., Pogačar, T., Železnikar, Š., Žitko, V., Žnidaršič, Z., Žvokelj, L., and Cvejić, R.: Critical zone studies in pre-alpine climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7089, https://doi.org/10.5194/egusphere-egu26-7089, 2026.
In semi-arid southern Kenya, the Chyulu Hills consist of an alignment of Quaternary scoria cones and basaltic lava flows. This ~80-km-long, NW–SE volcanic fissure vent hosts underground water resources of importance to the local rural population and the savanna ecosystems. The subvolcanic topography allows groundwater to flow south and east, resulting in a line of springs along the base of the hills. Several springs are partially tapped to supply water for drinking water and farming activities. Mzima spring, in the south, yields 70% of the total outflow of the Chyulu Hills watershed, and 10% of Mzima water is diverted from its local use to supply the city of Mombasa, 200 km to the southeast. This generates conflict between local residents and regional water resource authorities. It is therefore crucial to quantify the water resources of the Chyulu Hills and establish to what extent these are suitable for sustainably supplying the local and wider regional population in the future, in a context of global change. The WATCH and Time2WATCH projects (2024–2026), funded by the Centre National de la Recherche Scientifique (France), aim to assess and monitor Chyulu-wide water budgets by setting up a multidisciplinary observatory combining meteorological, geophysical, geological, hydrogeological, and land use/land cover evaluations. This observatory was elaborated in close collaboration between Kenya (University of Nairobi, Technical University of Kenya, Regional Centre on Groundwater Resources Education, Training & Research) and France (Université Lumière Lyon 2, Université Claude Bernard Lyon 1, Université Marie and Louis Pasteur, Université de Montpellier, Sorbonne Université). The present contribution mainly focuses on preliminary hydrochemistry results. Their integration across the entire observatory provides the first functional insights into the Chyulu Hills groundwater system.
How to cite: Celle, H., Albaric, J., Barre-Rolland, Y., Gautier, S., Gunnell, Y., Ianigro, J.-C., Kaniu, I., Marteau, J., Mbugua, A., Mialhe, F., Murunga, P., Navratil, O., Nevers, P., Nyaga, E., Olaka, L., Roos, L., Tiberi, C., Tramontini, M., and Waga, D.: WATCH / Time2WATCH projects towards the implementation of a permanent observatory of groundwater in Kenya – A first hydrogeological model of the Chyulu Hills, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9220, https://doi.org/10.5194/egusphere-egu26-9220, 2026.
The soil security situation in Africa continues to worsen endangering both food production, population health and Sustainable Development Goal (SDG) achievement. While soil degradation and contamination happen in local areas, policies remain largely at national levels or beyond. This situation exists because of an organizational dependence on low-resolution top-down geospatial information which fails to detect the micro-scale mechanisms operating within African critical zones.
The study combines data from the Critical Zones Africa (CZA) project which studied five African countries including Ethiopia, Tanzania, Malawi, Zimbabwe and South Africa to understand the reasons behind different soil policies that do not match smallholder farming practices. The study evaluates the advantages and weaknesses of multiple geospatial tools through a systematic literature review framework to analyze land-use and land-cover mapping and vegetation indices and erosion models and hydrological simulations.
The study results demonstrate that geospatial methods successfully detect large-scale patterns of land deterioration and soil erosion vulnerability, but they do not solve essential soil management problems which need higher resolution at both farm and community levels. The main blind spots exist in Ethiopia where geochemical contamination occurs, and Tanzania faces groundwater contamination because of agricultural land growth and Malawi experiences soil degradation because of deforestation and Zimbabwe and South Africa struggle with water system nutrient waste. The evaluation process for all cases shows that soil investment choices and governance decisions face limitations because the available data does not match what happens in the field.
The achievement of soil security in African critical zones needs policymakers to adopt evidence-based integrated systems which operate at suitable scales. We recommend three essential measures which include: (i) providing all of Africa with access to detailed geospatial information (ii) African soil science education needs to be revitalized while laboratory facilities must be restored (iii) All fields must undergo ground-truthing assessments while local communities need to participate in the process. The study also recommends that proposed work program for AMCEN during 2026-2028 should enable UNEP to provide high-resolution data access which will help develop soil policies that fit the specific conditions of African territories.
How to cite: Chari, M. and Green, L.: Linking geospatial science with local knowledge systems to support soil security in African critical zones, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22760, https://doi.org/10.5194/egusphere-egu26-22760, 2026.
This study examines the hydrological, pedological, ecological, and socioanthropological evidence to unpack the drivers of land transformation in the Central Rift Valley (CRV) of Ethiopia. It identifies a nexus of unsustainable land use, over-extraction of water (leading to dramatic lake-level decline), industrial pollution, soil degradation, and biodiversity loss. These interlinked pressures manifest as acute resource scarcity, compromised water and food safety, heightened socio-economic insecurity, and organized violence as a desperate means to reclaim lost rights, a cascading crisis that is further aggravated by climate change.
A critical driver is state policy that prioritizes export-oriented agribusiness, such as floriculture. These policies grant flower farms preferential access to land and water, leading to the over-extraction and chemical pollution that degrade lakes and soils. While the flower farm investment aims to create jobs and boost the national revenue, it often affects the community through pollution, resource competition and dispossession. Toxification of water from industry activities, water overextraction by both commercial farms and industry, clearing of woodlands not only disrupts ecosystems but also dismantles the material basis of indigenous cultural orders, such as the Oromo moral-ecological code Safuu, which once regulated resource use and conflict resolution.
While trends of environmental change in the CRV are well-documented, the usual analytical and governance frameworks remain inadequate. Conventional approaches often treat soil, water, and biodiversity as isolated commodities, overlooking the fundamental biophysical and social processes that sustain these systems. Moreover, these frameworks lack meaningful community engagement. This underscores the necessity for transdisciplinary co-design processes that involve local farmers and indigenous communities to identify the problems and search for suitable repair mechanisms. This study applies a Critical Zone Science (CZS) framework to demonstrate how discrete forms of degradation are causally linked. For instance, soil degradation drives sedimentation and nutrient loading into lakes, exacerbating the shrinkage of lakes and aquatic biodiversity loss. Contaminants from floriculture cause widespread toxification and a human health crisis. Deforestation disrupts microclimates and hydrological cycles, while the erosion of cultural governance creates a vacuum in which resource scarcity fuels protracted violence.
Viable solutions, therefore, depend on integrating local knowledge with scientific. This study advocates for a paradigm shift to process-based, Critical Zone-centered governance, an approach that prioritize community-driven resource management, locally adapted climate responses, and the restoration of both ecological functionality and culturally legitimate conflict-resolution mechanisms to secure a sustainable future for the CRV.
How to cite: Degefa, S.: Navigating the Polycrisis: Flower farms in the Web of Unsustainable Practices Transforming Ethiopia’s Central Rift Valley, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23182, https://doi.org/10.5194/egusphere-egu26-23182, 2026.
The HSRC’s policy study component of the CZA project is anchored on the wide acknowledgement of the importance of building habitable futures by including bio-geophysical aspects of place in local governance. CZ thinking-informed policy practices are particularly relevant in African contexts, where livelihoods are closely tied to the geophysical ecosystem and climate variability. In these contexts, CZ approaches provide a powerful approach to informing policy innovations that are knowledge-plural and contextualized within lived realities.
To date, this in-progress study of policy in specific places provides evidence that policy development and implementation activities continue to ignore the complex interaction of societal practices, institutional arrangements, and biophysical processes. Drawing on foundational CZ literature and an analysis of selected site policies and data from science-policy-societal engagements conducted in Ethiopia and Zimbabwe, the study demonstrates how environmental policy practices continue to be narrowly shaped by fragmented, sector-based governance frameworks and profit-oriented thinking, in which financialised relations, historical legacies, and knowledge hierarchies shape whose voices are included in policy processes. This narrow framing leads to policy interventions that compromise the biogeophysical ecosystems resulting in problems such as material flows that lead to contamination and loss of wetlands and hydrological cycles (Tanzania’s Rufiji Delta, Zimbabwe’s Lake Chivero and the Cape Flats in South Africa); as well as soil quality degradation and loss (Ethiopia’s Central Rift Valley and Malingunde in Malawi). Over time, these non-inclusive policies create a feedback loop in which degraded ecosystems have limited adaptive capacity and future livelihoods and habilitability are compromised. What this study shows is that land use land cover change is not simply due to ‘humans’, as so much of the LULC literature suggests, but that specific macroeconomic policies and approaches to local governance, which pay little attention to biogeophysical relations with society, have a significant responsibility – and therefore also the potential to make a difference.
The presentation argues for policy process innovations that transcend discipline boundaries between society, economy and biogepphysical relations, integrating different knowledge systems and adopt adaptive approaches capable of responding to uncertainty and long-term change. Where co-creative and collaborative policy development and implementation practices bring together scientists, policymakers, and communities as co-producers of knowledge, there is potential for improved governance that builds habitable futures. By foregrounding knowledge plurality in policy as a tool, this presentation contributes to the session’s focus on international innovation and collaboration, and demonstrates how critical zone science can meaningfully inform local governance and policy across varied regional contexts.
How to cite: Sobane, K.: Innovating Environmental Governance through Critical Zone Thinking: Lessons from the Global South, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23241, https://doi.org/10.5194/egusphere-egu26-23241, 2026.
Posters virtual: Wed, 6 May, 14:00–18:00 | vPoster spot A
EGU26-7262 | ECS | Posters virtual | VPS9
CO2 Dynamics and Carbon Sources in the Critical Zone: An Isotopic Study in Aquifers of Southeastern SpainWed, 06 May, 14:09–14:12 (CEST) vPoster spot A
The Critical Zone, extending from the land surface through the vadose zone to groundwater, can store and transfer substantial carbon as CO2 and dissolved inorganic carbon (DIC). Yet CO2 behavior below the first meters of soil remains poorly constrained, particularly where water-table fluctuations, gas-water exchange, and water-rock reactions interact. In these settings, deep vadose CO2 may exhibit atmospheric and soil-respiration signatures with contributions linked to groundwater degassing and carbonate-system reactions, potentially creating transient subsurface CO2 reservoirs that couple the aquifer and the atmosphere.
We present a repeated sampling design to characterize carbon cycling across the Critical Zone in semi-arid southeastern Spain. We sampled the air columns of 11 boreholes belonging to six groundwater bodies during four campaigns (spring 2022, autumn-winter 2022, spring-summer 2024, and spring-summer 2025). In borehole air, we measured CO2, H2O vapor, and its carbon isotopes composition (δ¹³C-CO2); air was stored in gas-tight bags and analyzed by cavity ring-down spectroscopy (Picarro G2508 and G2201-i). In parallel, groundwater was sampled at each site. In situ, we measured pH, temperature, oxidation–reduction potential (ORP), HCO3-, and electrical conductivity. In the laboratory we analyzed pH, alkalinity, major ions, total organic carbon and total nitrogen, carbon isotopes of dissolved inorganic carbon (δ¹³C-DIC), and water isotopes (δ²H, δ¹⁸O). Water-table position at the time of sampling was used to interpret gas-water contact.
Critical Zone CO2 concentrations in borehole air ranged from 614 to 128700 ppm (pCO2=0.000587-0.102287 atm). Groundwater CO2 was estimated with the PHREEQC software, yielding values between 2240 and 9550 ppm (pCO2=0.002240-0.009550 atm), allowing comparison between the air column and the saturated zone, and evaluation of disequilibrium and exchange potential as the water-table varies. Carbon isotopes signatures constrain sources and transformations: δ¹³C-CO2 ranged from -11.14 to -23.62‰, δ¹³C-DIC from -6.27 to -20.11‰, and host-rock δ¹³C from 2.37 to -7.12‰. All values (δ¹³C‰) are reported relative to VPDB (Vienna Pee Dee Belemnite). Joint interpretation across gas, DIC, and rock enabled discrimination among biogenic CO2 production, atmospheric mixing, carbonate dissolution/precipitation (based on the saturation indices of the main carbonate mineral phases), and CO2 transfer from the aquifer to the deep vadose zone. The multi-campaign design provided a basis for quantifying seasonal and interannual shifts in these boreholes and for identifying hydrogeochemical conditions (e.g., pH-alkalinity evolution and redox state) that promote storage/mineralization versus release of CO2.
Our experimental design characterizes subsurface CO2 storage and transport at the Critical Zone scale. It identifies when the deep vadose environments act as reservoirs, conduits, or sources linking groundwater and the atmosphere. This information is rarely available but critical for improving carbon budgets and models for the Critical Zone.
This work was supported by the Spanish Ministry of Science and Innovation (projects PID2024-158786NB-C21 and PID2024-158786NB-C22, NATURAL), the University of Granada (project PPJIB2024-53), and the Regional Ministry of University, Research and Innovation, the Spanish Government and the and European Union – NextGenerationEU (projects BIOD22_001 and PCBIO).
How to cite: Echeverría-Martín, E., Fernández-Cortés, Á., Sánchez-Cañete, E. P., Serrano-Ortiz, P., Oyonarte, C., Riba Palou, A., Kowalski, A. S., and Domingo, F.: CO2 Dynamics and Carbon Sources in the Critical Zone: An Isotopic Study in Aquifers of Southeastern Spain, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7262, https://doi.org/10.5194/egusphere-egu26-7262, 2026.
