HS1.2.5 | Ecosystem research with lysimeters and ecotrons at the macrocosm scale - State of the art and future perspectives
Ecosystem research with lysimeters and ecotrons at the macrocosm scale - State of the art and future perspectives
Co-organized by BG2
Convener: Jannis GrohECSECS | Co-conveners: Francois Rineau, Reinhard Nolz, Thomas Puetz, Alexandru Milcu
| Mon, 15 Apr, 16:15–18:00 (CEST)
Room 2.17
Posters on site
| Attendance Mon, 15 Apr, 10:45–12:30 (CEST) | Display Mon, 15 Apr, 08:30–12:30
Hall A
Orals |
Mon, 16:15
Mon, 10:45
Understanding the complex interactions between soil-plant-atmosphere compartments and human activities is critical for ensuring the sustainable management and preservation of ecosystem functions and services. Global climate change and human activities threaten the functions and services of our terrestrial ecosystems. The complexity and holistic nature of the consequences have been difficult to assess so far, as simplified experimental approaches and long-term observations have methodological constraints and often focus on a very limited set of response variables.
Larger and more realistic experimental systems such as in situ lysimeters or ecotrons can supply a wide range of high quality continuous and high-resolution data sets on ecosystem services and functions in the Earths critical zone. Individual facilities and larger networks such as TERENO-SOILCan (lysimeter) or ANAEE’s ecotron experimental infrastructures provide a unique platform for a variety of interdisciplinary research to better understand the dynamic of ecosystems.
The session will focus on ecosystem research based on lysimeters and ecotron experiments, including model application. Additionally, we want to address upscaling approaches from lysimeter to landscape scale or between several types of ecosystem experimental infrastructures (e.g., lab, field, or control environments), uncertainty assessments, representativeness of lysimeter-scale observations, and comparability of water, and greenhouse gases flux to in situ measurements. We welcome contributions that (1) assess and compare terrestrial ecosystems functioning and services, (2) focus on water and solute transport processes, as well as greenhouse gases within the soil-plant-atmosphere continuum, including processes such as non-rainfall water inputs (i.e., dew, fog, soil water vapor adsorption), (4) develop new techniques for analyzing lysimeter and ecotron observations, (5) including ecosystem or hydrological modelling approaches that use in-situ observations from lysimeters or ecotrons.

Orals: Mon, 15 Apr | Room 2.17

Chairpersons: Jannis Groh, Alexandru Milcu, Reinhard Nolz
On-site presentation
Ralf Kiese, Marcus Schlingmann, Katrin Schneider, Sophie Reinermann, Anne Schucknecht, Jincheng Han, Thomas Koellner, Carolin Boos, and Michael Dannenmann

Pre-alpine grasslands provide important economic value through forage for milk and meat production. Grassland soils also support ecosystem services such as carbon and nitrogen storage, water retention, erosion control and biodiversity. These functions are currently threatened by climate change, which is likely to accelerate in the coming decades. In addition to climate change, management decisions such as mowing and fertilisation frequency have a major impact on grassland yields, biodiversity and soil C and N dynamics. In this presentation we will summarise results from long-term monitoring of control and translocated grassland soil monoliths (1m2; 1.4m height) as operated in TERENO and studied in detail in the SUSALPS project.

From 2012, moderate climate change (plus 2°C) has increased grassland productivity, unless water stress has reversed the temperature stimulating effect. However, this increase in plant growth is only possible because increased N mineralisation rates under climate change allow increased N demand to be met. As plant N uptake is already in the range of total N fertilisation rates under current climate conditions, N losses to the environment, such as microbial N2O emissions and nitrate leaching from montane grassland soils, are comparatively low. If other ecosystem N losses such as NH3 and N2 emissions are considered, it becomes clear that even under the present climatic conditions substantial N has to be provided by mineralisation of soil organic N, indicating soil N (and C) mining. As the latter is associated with negative effects on soil fertility/productivity, C sequestration and GHG exchange, as well as filtering functions to protect water bodies, this trend poses risks to key soil functions in the long term. The detailed investigations from long-term monitoring sites were essential for testing a process-based model (LandscapeDNDC), which was used together with remote sensing information for spatial and temporal upscaling of the results.

How to cite: Kiese, R., Schlingmann, M., Schneider, K., Reinermann, S., Schucknecht, A., Han, J., Koellner, T., Boos, C., and Dannenmann, M.: Influence of climate and land management on water, carbon and nitrogen cycling in grasslands of the pre-alpine region of southern Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11233, https://doi.org/10.5194/egusphere-egu24-11233, 2024.

On-site presentation
Georg Leitinger, Elena Tello-García, Lucía Laorden-Camacho, Lisa Ambrosi, Karl Grigulis, Bello Mouhamadou, Christiane Gallet, Ursula Peintner, Ulrike Tappeiner, and Sandra Lavorel

Throughout European mountains, changes in livestock production systems since the 1950s have resulted in the gradual segregation between more accessible, flatter, and productive grasslands with intensified fodder production, and more remote, steeper, and less productive meadows used for extensive grazing, and some abandoned. After cessation of grazing in subalpine grasslands, secondary succession promotes the gradual colonization of species and functionally diverse herbaceous communities by shrubs. Although shrub encroachment is considered a ‘Plant Functional Type transformation’, our knowledge about the impact of climate change on shrub encroached ecosystems is still limited. Mechanistic analyses of alpine grassland responses to drought have focused on carbon fluxes, and a few studies have targeted components of the ecosystem water budget or nutrient cycling. However, these studies are focused on herbaceous functional groups, and shrubs are usually neglected. Moreover, despite the prevalence of this original climate change driver in mountains, snow manipulations are still rare.

To improve understanding of nitrogen and water cycling processes of shrubs with expected increased drought and advanced snowmelt, small high-precision lysimeters (SFL®, Meter Group AG, Munich, Germany) were used to analyze the effects and mechanisms of climate change on shrub species. In a garden experiment in the LTSER-site Stubai Valley (970 m a.s.l.), Tyrol Austria, two congeneric shrubs contrasting a deciduous (Vaccinium myrtillus) and evergreen (Vaccinium vitis-idaea) were planted into 16 lysimeters. In a split-plot design of 3.5m x 3.5m each, two plots were subject to either (1) control, (2) earlier snowmelt, or (3) summer drought treatments.

The manipulative experiments indicate that a shortening of the period with snow cover at the end of winter affects soil freezing and hence, soil nitrogen (N) and carbon (C) availability. Results further highlight the interacting effects of climate manipulations on key plant traits, and their consequences for N- and water availability. Furthermore, summer drought seems to additionally affect biogeochemical cycling and evapotranspiration for both investigated shrub types. This study's results reveal the importance of addressing the impact of shrub encroachment not only from a land management perspective but also to increasingly raise awareness about climate change effects on shrubs. Moreover, it provides valuable insights into challenges and chances of growing shrubs in lysimeters, being a promising approach for future climate impact studies. The study was conducted as part of the LUCSES project, ANR-FWF (ANR-20-CE91-0009 and FWF-I 4969-B).

How to cite: Leitinger, G., Tello-García, E., Laorden-Camacho, L., Ambrosi, L., Grigulis, K., Mouhamadou, B., Gallet, C., Peintner, U., Tappeiner, U., and Lavorel, S.: Enhanced understanding of water cycling processes of dwarf shrubs using high-precision lysimeters and climate manipulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12759, https://doi.org/10.5194/egusphere-egu24-12759, 2024.

On-site presentation
Annelie Ehrhardt, Jannis Groh, and Horst H. Gerke

The soil water storage (SWS) defines crop productivity of a soil and varies under differing climatic conditions. Pattern identification and quantification of these variations remains difficult due to the non-linear behaviour of SWS changes over time.

We hypothesize that these patterns can be revealed by applying wavelet analysis to an eight-year time series of SWS, precipitation (P) and actual evapotranspiration (ETa) in similar soils of lysimeters in a colder and drier location and a warmer and wetter location within Germany. Correlations between SWS, P and ETa at these sites might reveal the influence of altered climatic conditions but also from subsequent wet and dry years on SWS changes.

We found that wet and dry years exerted influence on SWS changes by leading to faster or slower response times of SWS changes to precipitation in respect to normal years. This might be explained by a higher soil water content and the related higher soil hydraulic conductivity. Time shifts in correlations between ETa and SWS became smaller at the wetter and warmer site over time in comparison to the cooler and drier site where they stayed constant. This could be attributed to an earlier onset of the vegetation period over the years and thus to an earlier ETa peak every year and reflects the direct impact of changing climate on soil water budget parameters. 

How to cite: Ehrhardt, A., Groh, J., and Gerke, H. H.: Effects of changes in climatic conditions on soil water storage patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3404, https://doi.org/10.5194/egusphere-egu24-3404, 2024.

On-site presentation
Marcel Gaj, Stephan Costabel, Michèle Erlach, Julia Frank, Viktoriya Tarasyuk, Stephan Peth, and Vera Schimetzek

The research facility St. Arnold presented here consists of three individual lysimeters with an area of 400m² and 3.5m depth each. They are similar in soil types but differ in vegetation cover. This unique setup allows the direct comparison of the water balance of grassland, oak/beech forest and pine forest under the same climatic and topographic boundary conditions. The later site were cut after a significant storm occurred in 2007. Since a pioneer forest developed. 

The data collection of precipitation, groundwater recharge, temperature, humidity and sunshine duration started in 1964. In addition, stem diameter at certain trees has been determined once a year.  All data until 1997 were collected manually. After that automated collection of hydro climatic data were established and transmitted directly into the database of LANUV. From the data, evaporation rates were calculated with Penman-Montheith. More recently in October 2023 undisturbed soil cores where collected and analyses for their saturated and unsaturated hydraulic conductivity. In addition, the investigation of the water balance has been done with HYDRUS 3D.

The data shows significant trends. Further, it can be observed how storm damage and/ or clear-cut of forested areas impact the soil water balance.  The long-term average of the period 1965 to 2007 showed, the grassland basin turns more than half of its annual incoming precipitation into leachate and only 36% into evaporation while the deciduous forest exhibits a ratio of 36% leachate and 56% for evapotranspiration. The evergreen coniferous forest shows the highest evaporation rate 65% and the lowest leachate rate with 26%. (Harsch et al., 2009)

An upgrade of the entire facility with state of the art measurements devices is in progress. This will initiated with a geophysical survey in the beginning of 2024 along with the installation of soil moisture and tensiometer sensors. Depending on funding permanent and long term geophysical measurements and stable isotope analysis will be conducted all data will be available open source. We welcome collaborators for joint research at the facility.

 Harsch, N., Brandenburg, M., & Klemm, O. (2009). Large-scale lysimeter site St. Arnold, Germany: analysis of 40 years of precipitation, leachate and evapotranspiration. Hydrology and earth system sciences13(3), 305-317.

How to cite: Gaj, M., Costabel, S., Erlach, M., Frank, J., Tarasyuk, V., Peth, S., and Schimetzek, V.: Determining the soil water balance at a large-scale lysimetric facility with 60 years of uninterrupted data comprising a grassland basin, oak/beech and a pine basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20967, https://doi.org/10.5194/egusphere-egu24-20967, 2024.

On-site presentation
Annelie Holzkämper

Nitrate pollution of groundwater is still an issue of concern at many drinking water wells located in the Swiss lowlands, where agricultural areas are the main pollution source. Extensification measures (e.g. conversion of arable land to extensive grassland, reduction of vegetable/potato areas in favor of cereals) are generally considered to be effective to reduce nitrate leaching to groundwater. However, these measures are also associated with large losses in agricultural productivity and can thus only be implemented on small focused areas within contribution zones of drinking water wells. It is hypothesized here that the trade-offs between agricultural production and groundwater protection can better be managed if more nuanced mitigation strategies are implemented at a broader scale. Such strategies would target at an improved synchrony between plant nitrogen demands and soil nutrient availabilities (e.g. by inclusion of cover crops and optimizing crop rotations, through reduced soil management and demand-driven fertilization practices). Since evaluating the effects of such strategies is anything but trivial given the high complexity of the process interactions and the strong influence of climatic variability, it is the aim of this work to train a mechanistic field scale model that simulates soil water and nutrient dynamics at a field scale in response to soil, climate and management drivers (DAISY model). The calibration builds on an extensive dataset from the lysimeter station Zurich Reckenholz including detailed data since 2009 on nitrate leaching, seepage water generation, soil moisture, water tension, soil temperature, and crop yields for a series of different experiments including non-inversion tillage, cover cropping as well as different fertilization types and amounts. The calibration strategy and selected calibration/validation results will be presented and discussed in context with implications for model applications.

How to cite: Holzkämper, A.: Managing the trade-off between agricultural productivity and groundwater protection in Switzerland – a model-approach based on long-term lysimeter data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2703, https://doi.org/10.5194/egusphere-egu24-2703, 2024.

On-site presentation
Sascha Reth

The ongoing global concern regarding climate change necessitates innovative approaches to understand its complex dynamics. This presentation outlines the evolution of lysimeters and ecotrons, culminating in the development of a cutting-edge platform designed for comprehensive research on climate change parameters in both laboratory and field environments.

Lysimeters, traditionally employed to measure water movement and nutrient transport in soil, have undergone significant advancements. Enhanced instrumentation and sensor integration now allow for precise monitoring of multiple environmental factors, including soil moisture, temperature, and gas exchange. These improvements enable researchers to simulate and analyze various climate change scenarios in a controlled laboratory setting.

Simultaneously, ecotrons, specialized chambers designed to replicate natural ecosystems, have evolved to provide a more realistic representation of climate interactions. By incorporating advanced technologies such as remote sensing, automated data acquisition, and controlled environmental conditions, ecotrons now offer a holistic approach to studying the impact of climate change on ecosystems.

The integration of lysimeters under natural conditions and ecotrons into a unified platform represents a paradigm shift in climate change research. This new platform facilitates a seamless transition between controlled laboratory experiments and real-world field studies, allowing for a more comprehensive understanding of the intricate relationships between climate change parameters.

Researchers can now explore the effects of elevated temperatures, altered precipitation patterns, and increased greenhouse gas concentrations on soil health, plant growth, and ecosystem dynamics with unprecedented precision. The platform's adaptability and versatility make it a valuable tool for addressing urgent questions related to climate change impact mitigation and adaptation strategies.

In conclusion, the fusion of outdoor lysimeters and indoor ecotrons into a unified platform signifies a milestone in climate change research. This innovative approach provides researchers with a powerful tool to investigate and address the complex challenges posed by climate change, fostering a more sustainable and resilient future.

How to cite: Reth, S.: Advancements in Lysimeters and Ecotrons: A Novel Platform for Investigating Climate Change Parameters in Laboratory and Field Settings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9489, https://doi.org/10.5194/egusphere-egu24-9489, 2024.

On-site presentation
Joana Sauze, Oswaldo Forey, Clément Piel, Emmanuel S. Gritti, Sébastien Devidal, Abdelaziz Faez, Olivier Ravel, Yvan Capowiez, Damien Landais, Jacques Roy, and Alexandru Milcu

Recent studies have highlighted the potential role of earthworms in modulating soil greenhouse gas (GHG) emissions, yet the complexity of natural ecosystems and the lack of high-resolution temporal data have limited our understanding. To bridge this gap, a two-year experiment was undertaken in a controlled ecotron setting, utilizing large-scale lysimeters (5 square meters in area and 1.5 meters in soil depth) in the Macrocosms experimental platform of the Montpellier European Ecotron (CNRS). This study aimed to provide an understanding of the impact of earthworms (specifically endogeic and anecic ecotypes) on water and greenhouse gas emissions in a realistically simulated agricultural ecosystem undergoing a three-crop rotation.

We employed continuous, high-frequency monitoring to measure ecosystem-level exchanges of CO2, N2O, and H2O. While temporary increases in CO2 fluxes were noted in earthworm-inhabited replicates, the cumulative data over the entire study period did not demonstrate a significant increase in CO2 emissions. Interestingly, the presence of endogeic earthworms was correlated with a notable reduction in N2O emissions during wheat cultivation (by 44.6%), although this effect did not persist throughout the entire experimental timeline. Additionally, while earthworms had an impact on water infiltration along the soil profile, no consistent patterns were observed in terms of ecosystem evapotranspiration or water use efficiency (WUE) changes attributable to earthworm activity.

Our findings provide critical insights into the role of earthworms in terrestrial GHG dynamics, particularly in agricultural settings. Contrary to prevailing assumptions, this study suggests that earthworm activity does not lead to a significant increase in greenhouse gas emissions over a period of two years under conditions that closely emulate agricultural environments. These results underscore the importance of conducting long-term, high-resolution studies in realistically simulated ecosystems to better comprehend the intricate relationships between soil biota and greenhouse gas emissions.

How to cite: Sauze, J., Forey, O., Piel, C., Gritti, E. S., Devidal, S., Faez, A., Ravel, O., Capowiez, Y., Landais, D., Roy, J., and Milcu, A.: The need for realistic experimental setups in controlled environments: insights from a two-year ecotron experiment on earthworms’ impact on ecosystem H2O, CO2 and N2O dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9685, https://doi.org/10.5194/egusphere-egu24-9685, 2024.

On-site presentation
Gernot Klammler, Janja Vrzel, and Hans Kupfersberger

Soil temperature plays a central role in the complex processes in the vadose zone, particularly in connection with water and solute transport. As a major thermal factor, soil temperature influences not only the physical properties of the soil, but also the biochemical reactions responsible for the transport of water and solutes. The variation of soil temperature can have significant effects on the mobility of nutrients and pollutants and thus plays a key role in understanding and controlling important soil processes.

Ecotrons in combination with weighable lysimeters are generally able to investigate complex ecological processes (e.g. evapotranspiration, nutrient dynamics) under controlled conditions. However, the requirement for this is that the temperature control of the soil column can be simulated with sufficient accuracy over the entire height and cross-section. Furthermore, it must also be ensured that the required rates of temperature change in the soil column, which can vary depending on the scientific question, can be simulated.

In the course of the abstract submitted here, we would like to present the results of 3D heat transport model simulation for selected examples, which contribute to the optimization of the technical design of Lysimeter/Ecotron systems (e.g. with regard to insulation thickness, heat exchanger area, required inlet temperature in the heat exchanger, etc.).

How to cite: Klammler, G., Vrzel, J., and Kupfersberger, H.: Heat transport model simulations of Lysimeter/Ecotron systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21932, https://doi.org/10.5194/egusphere-egu24-21932, 2024.

On-site presentation
Zachary Kayler, Michael Strickland, David Williams, Rodrigo Vargas, Zeli Tan, Caley Gasch, Susan Crow, and Noah Fierer

The Deep Soil Ecotron will give researchers the unparalleled ability to investigate and experiment with deep soils while complementing established ecotrons across the globe. This facility, composed of twenty-four, highly instrumented ecounits, will allow for soil profiles up to three meters in depth to be repeatedly sampled and continuously monitored. This facility will be the first modern ecotron facility in the United States and as such will provide research infrastructure that this country currently lacks. The Deep Soil Ecotron will enable researchers to address the following four broad research needs using approaches and instrumentation that have been unattainable under more common field and laboratory experiments. First, the Deep Soil Ecotron will reveal how deep soil communities and processes affect and interact with surface soils to influence whole ecosystems. Second, the Deep Soil Ecotron will allow researchers to determine how deep soils and associated vegetation respond to global and land-use change, such as increasing soil temperature and agricultural management practices. Third, information gained from the Deep Soil Ecotron will be integrated into earth system models to improve model representation of soil carbon cycling. Fourth, the Deep Soil Ecotron will provide a testbed for the development of sensors for the in-situ monitoring of deep soils. This presentation will provide an overview of the Deep Soil Ecotron's design, capacity, and preliminary research agenda.

How to cite: Kayler, Z., Strickland, M., Williams, D., Vargas, R., Tan, Z., Gasch, C., Crow, S., and Fierer, N.: The Deep Soil Ecotron – A Facility to Explore, Model, and Sense Deep Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11711, https://doi.org/10.5194/egusphere-egu24-11711, 2024.


Posters on site: Mon, 15 Apr, 10:45–12:30 | Hall A

Display time: Mon, 15 Apr 08:30–Mon, 15 Apr 12:30
Chairpersons: Francois Rineau, Thomas Puetz, Jannis Groh
Thomas Puetz, Horst H. Gerke, Nicolas Brueggemann, Harry Vereecken, and Jannis Groh

For many studies in the fields of soil, hydrology, agriculture, ecology, meteorology, and environmental sciences and across disciplines, conventional field experiments are inadequate because the variables cannot be measured properly or controlled experimentally. In the soil-plant-atmosphere continuum, lysimeters can be used as an integrative experimental approach that enables precise measurements of water and matter fluxes in combination with field crops. The term lysimeter basically refers to two different types of experimental equipment. Porous suction cups, as well as containers/vessels filled with soil substrates or other materials, are termed lysimeters. Lysimeters are vessels of various sizes filled with ecosystem compartments, taking a holistic approach as each compartment interacts dynamically within the biosphere.

Lysimeter experiments are carried out in a wide variety of designs. To optimize the scientific exploitation of lysimeter data, various prerequisites should be met. The complexity of lysimeter experiments will be explained in more detail, the advantages of lysimeters, but also the restrictions and limitations will be examined in more detail. We would like to suggest some hints, norms, and rules for conducting lysimeter experiments that can optimize and increase the benefit and profit of lysimeter experiments. Special attention is paid to the important technical details that can significantly influence the quality of lysimeter measurements. The latest technical developments are also briefly presented.

How to cite: Puetz, T., Gerke, H. H., Brueggemann, N., Vereecken, H., and Groh, J.: What you do not know, and what you should know about lysimeter experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15370, https://doi.org/10.5194/egusphere-egu24-15370, 2024.

Towards a French lysimetric network: ONE WATER project
(withdrawn after no-show)
Antoine Sobaga, Florence Habets, Samuel Abiven, and Pierre Faure-Catteloin
Harald Crepaz, Johannes Klotz, Marco Cavalli, Ulrike Tappeiner, and Georg Niedrist

Climate change is advancing at an unprecedented pace, impacting terrestrial ecosystems, particularly those in alpine regions. Consequently, there is a growing need to comprehend the associated impacts, underlying mechanisms, and implications. Long-term monitoring may face challenges in capturing the effects of accelerated climate change, and in-situ experiments in remote alpine areas often grapple with logistical constraints. Furthermore, attributing vegetative responses to specific manipulated variables proves challenging, especially under extreme alpine conditions such as low atmospheric pressure, low temperatures, or high radiation levels.

Using a specially designed ecotron called 'TerraXcube' (Bozen, Italy), we investigated the feasibility of realistically reproducing harsh alpine conditions and explored the interactions among various parameters. For our measurements, we equipped the chamber with temperature and relative humidity probes, a spectrometer, barometer, and anemometer positioned at different heights within the chamber. We tested the spatial and temporal homogeneity of the variables— atmospheric pressure, temperature, relative humidity (RH), and radiation—independently, as well as their interactions over time and in space, by simulating various realistic alpine climatic scenarios.

The measurements, conducted between -20°C and +25°C with relative humidity ranging from 10% to 95%, yielded satisfactory results. Over several hours, the largest difference at a specific position was 0.6°C and 4.3% RH, while the maximum difference between two sensors simultaneously was 1°C and 7% RH. At a height of 170 cm, the LED system emitted radiation at an intensity of 1,002 W/m² within the wavelength range of 280 to 900 nm; however, with a sharp decrease in intensity from the light source. The photosynthetically active radiation (PAR) at the chamber's center reached 1,883 μmol·m−2·s−1, achieving 77% of the potential annual maximum measured at 2,400 m a.s.l. This enables us to replicate the PAR level for 97% of the days throughout the year. Despite the high light intensity, the heating effect of the LED system was limited to a maximum of 2°C in the upper 40cm of the chamber. Pressure manipulation, with the highest technical demand, nonetheless resulted in high temporal homogeneity up to 4,000m a.s.l., corresponding to 618.9 mbar.

In conclusion, the results emphasize the potential and utility of ecotrons in simulating a suitable climate for alpine ecological experiments. However, as in many ecotrons, it is crucial to acknowledge that minor island effects and irregularities are inevitable. Even more sophisticated parameters such as wind effects or pollinator function are currently not sufficiently addressed. A combined in- and outdoor usage of mobile field lysimeters might be a further step to bridge this gap between experimental results obtained in ecotrons and in the field.

How to cite: Crepaz, H., Klotz, J., Cavalli, M., Tappeiner, U., and Niedrist, G.: Can we bring alpine climate into ecotrons?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14816, https://doi.org/10.5194/egusphere-egu24-14816, 2024.

Francois Rineau and Nadejda Soudzilovskaia and the Ecotron consortium team

Ecotrons represent enclosed systems in which macrocosms are subjected to controlled environmental conditions, and their responses are closely monitored at a high frequency. This makes them particularly well-suited for investigating the impact of climate change on ecosystem functioning. In this presentation, we demonstrate the utilization of the UHasselt ecotron to examine the effects of climate change on two distinct ecosystems: a natural heathland and an agricultural pear orchard.

We delve into the results obtained thus far, covering aspects such as carbon balance, water balance, greenhouse gas emissions, soil water nutrients, plant biomass, phenology, soil microbial communities, and soil fauna. Additionally, we explore the strengths and limitations associated with ecotron-based approaches. The presentation concludes by identifying future challenges in this field.

How to cite: Rineau, F. and Soudzilovskaia, N. and the Ecotron consortium team: Effect of climate change on functioning of natural and agricultural ecosystems: an ecotron study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20671, https://doi.org/10.5194/egusphere-egu24-20671, 2024.

René Shaeffer, Francois Rineau, and Nadia Soudzilovskaia

Conversion of natural and semi-natural systems to agricultural use is one of the largest conservation
challenges of our time. As the world’s population continue to grow at unprecedented rates,
multinational organizations like the United Nations and its subsidiary the Food and Agriculture
Organization call for higher crop production and the expansion of existing agriculture to ensure future
food security, especially in the face of changing climate. However, these efforts will most likely endanger
numerous landscapes of historical and cultural value, including those found in northwest Europe. How
these possible changes in land use may alter the functions of these ecosystems and the associated
services they provide are questions that need to be answered before any policy decisions can be made.

Using a state-of-the-art ecotron facility, we compared soil moisture profiles between an intact dry
heathland system and heathland soils that had been cleared for cereal agriculture, both of which were
subjected to climate conditions projected for the year 2070, in line with the IPCC RCP8.5. After
continuously monitoring moisture changes in the top 1.5 meters of soil for three years, we found that
there are significant differences between the two modes of land use. Soils used for cereal crops were
significantly drier (up to >60%) in the upper 10-20cm than intact heathland soils, and significantly wetter
(up to >500%) at the lowest soil levels (140cm). This redistribution of moisture within the soil column
under different land use schemes can have serious implications for overall ecosystem functioning,
particularly with regard to potentially mitigating heathland soils’ ability to store and capture carbon and
exacerbating detrimental soil-climate feedbacks under agricultural use.

How to cite: Shaeffer, R., Rineau, F., and Soudzilovskaia, N.: Effects of land use change on dry heathland soil moisture in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15212, https://doi.org/10.5194/egusphere-egu24-15212, 2024.

Xiao Lu, Jannis Groh, Thomas Pütz, Alexander Graf, Mathieu Javaux, Harry Vereecken, and Harrie-Jan Hendricks Franssen

Evapotranspiration (ET) is a crucial terrestrial ecosystem process that links water, energy, and carbon cycles. ET can be limited by either energy or water availability. The transition between water- and energy-limited regimes is associated with the soil moisture content, and can be postulated as the soil moisture content reaching a threshold, denoted as critical soil moisture (θcrit). Knowledge of θcrit is important for improving land surface, hydrological and crop models and predicting hydroclimate extremes such as droughts and heatwaves. However, the quantification of θcrit and the factors that impact θcrit are still not well understood. Here we used precise lysimeter observations to quantify θcrit by analyzing the relationship between soil moisture content and evaporative fraction (EF), as well as the relationship between soil moisture content and the actual ET/ potential ET ratio during drydowns. We estimated θcrit not only at the surface layer using in situ soil moisture measurements at 10 cm depth, but also for the root zone using vertically integrated in situ soil moisture (0–50 cm) observations. We estimated θcrit across various soil textures (e.g., sandy loam, silty loam, clay loam), vegetation types (grass, crop), as well as weather conditions from western and eastern Germany (spatial distances: 10 ~ 600 km). Especially, with some lysimeters that were taken from their original environment and translocated to other regions, we can identify the shift of θcrit with the same soil and vegetation but under different weather conditions, which can provide implication on changes of θcrit under global warming. We would expect a dependence of θcrit on soil texture and weather condition. We found for example that at the same site with the same crop rotation on the lysimeters but different soils, the sandy loamy soil experienced a lower θcrit (approximate 0.15 m3/m3) than the silty loamy soil (approximate 0.17 m3/m3), indicating that the higher content of sand would lead to the lower θcrit. In addition, an increase in θcrit was observed when the lysimeter was translocated from a site with a lower potential ET to a site with a higher potential ET.

How to cite: Lu, X., Groh, J., Pütz, T., Graf, A., Javaux, M., Vereecken, H., and Hendricks Franssen, H.-J.: Critical Soil Moisture Content Estimated from Lysimeter Time Series for Different Soil, Vegetation and Weather conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2783, https://doi.org/10.5194/egusphere-egu24-2783, 2024.

Arno Rein, Anne Imig, Lea Augustin, Jannis Groh, Thomas Pütz, Martin Elsner, and Florian Einsiedl

The application of pesticides can induce severe impacts to the vadose zone, groundwater, and their ecosystems. A study was carried out on two lysimeters located in Wielenbach, Germany. Different soil textures were considered within the soil cores, consisting of sandy gravel and clayey sandy silt. The lysimeters were vegetated with maize, and four different herbicides were applied according to common agricultural practice. Over a period of 4.5 years, concentrations of the herbicides and selected metabolites were monitored in the lysimeter drainage. In addition, stable carbon isotopes (δ13C) were analyzed for investigating biodegradation influences of two of the applied herbicides.

In a first step, we characterized unsaturated flow in the lysimeters based on stable water isotope measurements (δ2H and δ18O) combined with modeling. Different setups within the numerical model HYDRUS-1D were compared, including single and dual porosity approaches. Then, the unsaturated flow models were extended for describing reactive transport of the herbicides, and simulations were interpreted in combination with measured δ13C values. 

At the end of the observations, 0.9 to 15.9% of the applied herbicides (up to 20.9% for herbicides plus metabolites) were recovered in lysimeter drainage. Some metabolites were observed to accumulate in drainage, and biodegradation was indicated by small isotopic shifts in δ13C to less negative values in the leached herbicides. In the later sampling campaign (7.5 months after herbicide application), a higher increase in δ13C (less negative values) compared to earlier sampling (19 days after application) points towards stronger biodegradation. This can be explained by a higher biodegradation potential when the infiltrated water and the herbicides were affected by longer mean transit times in the unsaturated zone.

Observations were reproduced by modeling, where the overall dynamics of herbicide concentration in the lysimeter drainage could be covered well by the model setups. The concentration peaks were partly associated with heavy precipitation, which in turn indicates that the transport was influenced by preferential flow. Limitations were found for describing preferential flow events by using single and dual porosity models, as some concentration peaks were over- or underestimated. The use of δ13C for compound-specific isotope analysis allowed obtaining some evidence on biodegradation of the two herbicides in the unsaturated zone, which was also validated with the model results. 

How to cite: Rein, A., Imig, A., Augustin, L., Groh, J., Pütz, T., Elsner, M., and Einsiedl, F.: Investigating herbicide transport and fate in vegetated lysimeters with numerical modeling and stable carbon isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9112, https://doi.org/10.5194/egusphere-egu24-9112, 2024.

Roukaya Eid, Katharina Lehmann, Karin Eusterhues, and Kai Totsche

Climate and land use change affect weathering and pedogenesis with potential consequences for the fate of Al-bearing minerals and the potential export of Aluminum to groundwater resources. These changes might result in strong acidification, originally known for “acid rain” affecting these areas until the second but last decade of the past century. To explore the fate of Al in areas now affected by climate and land use change, we investigated two sites of different geology in North-Bavaria. Site 1 is located on granitic rocks under a reforested 6-year-old Norway spruce forest. Site 2 is a hilltop site located on metamorphic rocks under a 60-80-year-old spruce forest. Soil samples (< 2mm) and clay fractions were analyzed by hydrochemical and spectroscopic techniques. Zero tension controlled lysimeter and automated tension controlled lysimeters were installed for monitoring the soil solution volume and composition at the topsoil-subsoil and the subsoil-regolith boundary. Monitoring started in June 2018. Since then, 85 sampling campaigns have been completed that amounted to 1500 individual lysimeter samples. Analysis comprised among others EC, pH, elemental composition major anions and cations, and carbon sum parameters (DOC, TOC, DIC, TIC).

Recent climate at the sites differs markedly from the 1961-1990 period, indicating a transient climate at the sites. Mean soil pH ranged from 3.2 to 4.7 at both sites and was comparable to values published in 1995 by Franken et al. (3.4 to 4.2). Thus, recent soil pH is as low as used to be under the conditions of strong acid precipitation of the last century. Soils developed from magmatic rock showed higher contents of variable Al phases than those developed from metamorphic rocks.

At both sites pyrophosphate extractable Al is the dominant Al pool accounting 19.4% of total Al in site 1(14.1 g/kg in Bs horizon), and 6.9% of total Al in site 2 (4.9 g/kg in Bs horizon).

Noteworthy, hydrological summer was more important for seepage generation than the hydrologic winter: Roughly 68% of the total annual seepage volume was found in the hydrological summer. As a result, the TOC flux from the subsoil in summer is 35.66 ± 20 mg/year, and only 13.88 ± 13.8 mg/year in winter. Similarly, the Al flux in summer is 1.02 ± 0.7 mg/year and only 0.43 ± 0.4 mg/year in winter.

Variation partitioning analysis showed that the seasonal variation and the difference between topsoil and subsoil combined explained less than 5 % of the particle-related soil solution properties ((pH, ∑LMWO, TOC, Al and Si(mg/L)) and less than 1% of the hydrochemical properties (TIC, Cl, SO42−, Ca, Mg, Na (mg/L)). Difference between the two sites explained 13.84% and 6.48% of the two sets, respectively and the sampling year explained 4.52% and 4.74%. We conclude that the Al system at our sites is controlled by climatic conditions and site properties (lithology, slope, vegetation..). There are no indications that the released Al is immobilized in any secondary immobile Al-phase in the subsoil or downstream, pointing to the potential transport of Al and other unwanted substances to the aquifers.

How to cite: Eid, R., Lehmann, K., Eusterhues, K., and Totsche, K.: Aluminum fate in forest soils developed from magmatic and metamorphic rock of mid-mountain areas in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16315, https://doi.org/10.5194/egusphere-egu24-16315, 2024.

Pablo Rosso, Kurt-Christian Kersebaum, Janis Groh, Horst Gerke, Kurt Heil, and Robin Gebbers

The dynamics of water availability for plant growth is particularly important for crop productivity simulation. Critical for the prediction of crop growth and development is the accurate simulation of soil moisture variation time. Soil capacity-based models assume that the vertical movement of water in the soil is mostly controlled by the intrinsic soil water retention capacities (WRCs), mainly field capacity (FC) and wilting point (WP). However, FC and WP are difficult to measure directly. Pedotransfer functions (PTFs) have been developed to determine these parameters from basic, more readily available soil attributes such as texture and soil organic carbon content. Functional evaluation, a procedure to assess the appropriateness of a PTF, entails testing the sensitivity of the different PTFs to model’s target simulation outcomes. This study constitutes an attempt to quantify and understand the impact of different PTFs on crop yield in a soil capacity-based model.

Six PTFs were used in the crop model HERMES to test their ability to simulate soil water dynamics and to determine their effect on yield simulation. This study, carried out in Germany, included three sandy soil sites in Brandenburg and a silty soil site in Bavaria. Five lysimeters at a site in Brandenburg provided a complete record for assessing the performance of PTFs. Measured soil texture and organic carbon were used as inputs in HERMES, which by applying the PTFs under study, produced the corresponding estimates of WRPs used for soil water dynamic simulations and yield predictions. Soil water records were statistically compared with model outputs to assess the accuracy of each PTF-based simulation. Differences in yield predictions were measured to estimate the sensitivity of the crop model to the PTFs tested.

Not a single PTF performed best in all sites. PTFs by Batjes and Rosetta were the best performers at the three Brandenburg sites. At Duernast, Bavaria, all PTFs resulted in higher errors than at the other sites. At this site, the measured soil water content maxima during the rainy months appeared very variable from year to year, which was unexpected if assumed that the maxima should stay around FC and be fairly constant. In general, HERMES simulations followed the trends in measured soil water dynamics regardless of the PTF applied, whereas differences between PTFs appear on the magnitude of the water maxima during the winter months. This shows that the accuracy of PTFs largely depended on their ability to correctly estimate FC. The highest variability in yield prediction for the different PTFs was observed in the three Brandenburg sites, which also corresponded with higher differences in FC estimation. A closer look at the sandy sites, and simulations with a synthetic soil database showed that differences in yield simulation between PTFs increased proportionally with soil sand percent. This points out at the empirical nature of PTFs and the care that needs to be taken when applied in new situations.

How to cite: Rosso, P., Kersebaum, K.-C., Groh, J., Gerke, H., Heil, K., and Gebbers, R.: Pedotransfer functions and their impact on water dynamics simulation and yield prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2305, https://doi.org/10.5194/egusphere-egu24-2305, 2024.

Gunther Liebhard, Peter Strauss, Peter Cepuder, and Reinhard Nolz

An accurate and reliable measurement system is essential for analysing transport processes within the soil-plant-atmosphere continuum and for calibrating and validating ecosystem or hydrological models. Weighing lysimeters are very suitable tools for these purposes, as they are the most direct tools to reliably and precisely measure water mass balance components such as rainfall and non-rainfall water inputs, evapotranspiration, and percolation at the system boundaries. Investigating the ecosystem by use of lysimeters is more or less limited to point measurements, though. Approaches are therefore required to link lysimeter mesurements to the landscape scale. We present our experimental approach to link point and large-scale parameter assessment at an experimental station in Groß-Enzersdorf, Austria. In particular, we use soil water content data across the soil profiles from capacitance sensors and t-test statistics to check the representativeness of the conditions in the lysimeter body with the surrounding field and to assess soil hydraulic properties for numerical modeling of water fluxes. Based on this, we transfer measurement data with high measurement accuracy and temporal resolution from the lysimeter scale to the large-scale measurement systems such as eddy covariance, scintillometry, or isotope hydrology. On the other hand, we are able to incorporate parameters from areal measurements and from measurements using disturbed and undisturbed soil samples into the lysimeter measurement system.

How to cite: Liebhard, G., Strauss, P., Cepuder, P., and Nolz, R.: A practical approach to link lysimeter and large-scale measurement systems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15321, https://doi.org/10.5194/egusphere-egu24-15321, 2024.