Iris Feigenwinter

Last Name

Feigenwinter

First Name

Iris

ORCID

0000-0001-7493-6790

Organisational unit

03648 - Buchmann, Nina / Buchmann, Nina

Show all metadata

Search Results

Publications 1 - 10 of 24

Forest-floor greenhouse gas fluxes in a subalpine spruce forest: Continuous multi-year measurements, drivers, and budgets
Krebs, Luana; Burri, Susanne; Feigenwinter, Iris; et al. (2023)
EGUsphere
Forest ecosystems play an important role in the global carbon (C) budget by sequestering a large fraction of anthropogenic carbon dioxide (CO2) emissions and by acting as important methane (CH4) sinks. The forest-floor greenhouse gas (GHG; CO2, CH4 and nitrous oxide N2O) flux, i.e., from soil and understory vegetation, is one of the major components to consider when determining the C budget of forests. Although winter fluxes are essential to determine the annual C budget, only very few studies have examined long-term, year-round forest-floor GHG fluxes. Thus, we aimed to i) quantify the seasonal and annual variations of forest-floor GHG fluxes; ii) evaluate their drivers, including the effects of snow cover, timing, and amount of snow melt, and iii) calculate annual budgets of forest-floor GHG fluxes for a subalpine spruce forest in Switzerland. We measured GHG fluxes year-round during four years with four automatic large chambers at the ICOS Class 1 Ecosystem station Davos (CH-Dav). We applied random forest models to investigate environmental drivers and to gap-fill the flux time series. Annual and seasonal forest-floor CO2 emissions responded most strongly to soil temperature and snow depth (2.34±0.20 kg CO2 m-2 yr-1). No response of forest-floor CO2 emissions to leaf area index or photosynthetic photon flux density was observed, suggesting a strong direct control of environmental factors and a weak or even lacking indirect control of canopy biology. Furthermore, the forest-floor was a consistent CH4 sink (-19.1±1.8 g CO2-eq m-2 yr-1), with annual fluxes driven mainly by snow depth. Fluxes during winter were less important for the CO2 budget (6.0–7.3 %), while they contributed substantially to the annual CH4 budget (14.4–18.4 %). N2O fluxes were very low, negligible for the forest-floor GHG budget at our site. In 2022, the warmest year on record with also below-average precipitation at the Davos site, we observed a substantial increase in forest-floor CO2 emissions compared to other years. The mean forest-floor GHG budget indicated emissions of 2317±200 g CO2-eq m-2 yr-1 (mean±standard deviation over four years), with CO2 fluxes dominating and CH4 offsetting a small proportion (0.8 %) of the GHG budget. Due to the relevance of snow cover, we recommend year-round measurements of GHG fluxes with high temporal resolution. In a future with increasing temperatures and less snow cover due to climate change, we expect increased forest-floor CO2 emissions even at this subalpine site, with negative effects on its carbon sink behaviour.
Climate scenarios and agricultural indices: A case study for Switzerland
Tschurr, Flavian; Feigenwinter, Iris; Fischer, Andreas M.; et al. (2020)
Atmosphere
The CH2018 Climate Scenarios for Switzerland are evaluated with respect to the representation of 24 indices with agricultural relevance. Furthermore, future projections of the considered indices until the end of the 21st century are analyzed for two greenhouse gas scenarios (Representative Concentrations Pathways RCP2.6 and RCP8.5). The validation reveals good results for indices that are based on one or two climate variables only and on simple temporal aggregations. Indices that involve multiple climate variables, complex temporal statistics or extreme conditions are less well represented. The climate projection analysis indicates an intensification of temperature-related extreme events such as heat waves. In general, climate change signals in the indices considered are subject to three main patterns: a horizontal pattern across Switzerland, a vertical pattern depending on elevation and a temporal pattern with an intensification of change in the course of the 21st century. Changes are in most cases more pronounced for the high-emission RCP8.5 scenario compared to the mitigation scenario RCP2.6. Overall, the projections indicate a challenging 21st century climate for the agricultural sector. Our findings furthermore show the value and the necessity of a robust validation of climate scenario products to enable trustworthy and valuable impact analyses, especially for more complex indices and models.
Permanent grasslands in Europe: Land use change and intensification decrease their multifunctionality
Schils, Rene L.M.; Bufe, Conny; Rhymer, Caroline M.; et al. (2022)
Agriculture, Ecosystems & Environment
Permanent grasslands cover 34% of the European Union’s agricultural area and are vital for a wide variety of ecosystem services essential for our society. Over recent decades, the permanent grassland area has declined and land use change continues to threaten its extent. Simultaneously, the management intensity of permanent grasslands increased. We performed a systematic literature review on the multifunctionality of permanent grasslands in Europe, examining the effects of land use and management on 19 grassland ecosystem service indicators. Based on the evidence in 696 out of 70,456 screened papers, published since 1980, we found that both land use change and intensification of management decreased multifunctionality. In particular, preventing conversion of permanent grasslands to croplands secured the delivery of multiple ecosystem services. A lower management intensity was associated with benefits for biodiversity, climate regulation and water purification, but impacted the provision of high-quality animal feed. Increasing the number of species in the sward enhanced multifunctionality of permanent grassland without significant trade-offs such as losses in production. Our review covered many aspects of land use, management and ecosystem services, but we also identified areas with no or only few studies. The most prominent gaps were related to comparisons between permanent and temporary grasslands, and effects of management practices on the provision of cultural values, and on erosion and flood control. We suggest that, despite apparent changes in human dietary preferences, the protection of permanent grasslands in Europe must be prioritised. At the same time, considering the need to reduce ruminant livestock’s contribution to climate change, the time seems ripe to increase support for low-intensity grassland management to optimise the provision of essential ecosystem services from Europe’s permanent grasslands.
Ecosystem service research in grasslands at 31 experimental farms, networks and demonstration platforms across Europe
Klaus, Valentin; Newell Price, J. Paul; Bufe, Conny; et al. (2022)
Grassland Science in Europe ~ Grassland at the Heart of Circular and Sustainable Food Systems
Grassland research stations and experimental farms are essential for applied grassland science and related outreach activities. A large proportion of the experiments conducted at these stations aims to test methods to optimize the ecosystem services (ES) delivered by permanent grasslands. We used the framework of the multi-actor research project SUPER-G to assess a selection of experiments recently conducted, completed (since 2011), and planned at 31 European experimental research stations, farms, or networks. We further provide an overview of the ES measured at these experiments. Results show that on average two ES were assessed per experiment. The most frequent ES measured were production (87% of all experiments), followed by the supporting ES biodiversity (59%) and climate regulation (33%). Our overview on ES research at European research stations highlights that permanent grassland is a multifunctional ecosystem that provides many benefits to society. Yet, research considering more than two ES is still relatively rare and should thus be strengthened in the future.
Modeling carbon and water fluxes in agro-pastoral systems under contrasting climates and different management practices
Leolini, Luisa; Costafreda-Aumedes, Sergi; Brilli, Lorenzo; et al. (2025)
Agricultural and Forest Meteorology
Grasslands are worldwide spread ecosystems involved in the provision of multiple functional services, including biomass production and carbon storage. However, the increasingly adverse climate and non-optimised farm management are threatening these ecosystems. In this study, the original semi-mechanistic remotely sensed-driven VISTOCK model, which simulates grass growth as limited by thermal and water stress, was modified and integrated with the RothC model to simulate the ecosystem fluxes. The new model (GRASSVISTOCK) showed satisfactory performance in simulating above-ground biomass (AGB) in dry matter (d.m.) and fractional transpirable soil water (FTSW) along Alps (AGB, RMSE = 85.39 g d.m. m⁻²; FTSW, RMSE = 0.21) and Mediterranean (AGB, RMSE = 136.84 g d.m. m⁻²; FTSW, RMSE = 0.13) grasslands. Also, GRASSVISTOCK was able to simulate the net ecosystem exchange (NEE - RMSE = 0.03 Mg C ha⁻¹), the gross primary production (RMSE = 0.04 Mg C ha⁻¹), the ecosystem respiration (RMSE = 0.04 Mg C ha⁻¹) and the evapotranspiration (RMSE = 1.44 mm), where these observations were available (Alps). The model was applied under present and two climate datasets characterised by temperature increase and precipitation decrease (+2 °C temperature, -10 % precipitation) and reference or enriched CO₂ concentration (394 vs. 540.5 ppm) scenarios. The results showed that, while changes in temperature and precipitation alone had a negative impact by increasing NEE (+0.69 Mg C ha⁻¹) and decreasing total biomass (-0.20 Mg d.m. ha⁻¹) in the reference CO₂ scenario, the enriched atmospheric CO₂ concentration partially smoothed the NEE trend (+0.27 Mg C ha⁻¹) and increased total biomass (+0.60 Mg d.m. ha⁻¹) compared to the present period. It is concluded that the GRASSVISTOCK model represents a first step towards an integrated tool for estimating the performance of the agro-pastoral systems in terms of biomass production, water and carbon fluxes, in the face of ongoing climate change.
Eddy covariance flux measurements of gaseous elemental mercury over a grassland
Osterwalder, Stefan; Eugster, Werner; Feigenwinter, Iris; et al. (2020)
Atmospheric Measurement Techniques
Direct measurements of the net ecosystem exchange (NEE) of gaseous elemental mercury (Hg0) are important to improve our understanding of global Hg cycling and, ultimately, human and wildlife Hg exposure. The lack of long-term, ecosystem-scale measurements causes large uncertainties in Hg0 flux estimates. It currently remains unclear whether terrestrial ecosystems are net sinks or sources of atmospheric Hg0. Here, we show a detailed validation of direct Hg0 flux measurements based on the eddy covariance technique (Eddy Mercury) using a Lumex RA-915 AM mercury monitor. The flux detection limit derived from a zero-flux experiment in the laboratory was 0.22 ng m−2 h−1 (maximum) with a 50 % cutoff at 0.074 ng m−2 h−1. We present eddy covariance NEE measurements of Hg0 over a low-Hg soil (41–75 ng Hg g−1 in the topsoil, referring to a depth of 0–10 cm), conducted in summer 2018 at a managed grassland at the Swiss FluxNet site in Chamau, Switzerland (CH-Cha). The statistical estimate of the Hg0 flux detection limit under outdoor conditions at the site was 5.9 ng m−2 h−1 (50 % cutoff). We measured a net summertime emission over a period of 34 d with a median Hg0 flux of 2.5 ng m−2 h−1 (with a −0.6 to 7.4 ng m−2 h−1 range between the 25th and 75th percentiles). We observed a distinct diel cycle with higher median daytime fluxes (8.4 ng m−2 h−1) than nighttime fluxes (1.0 ng m−2 h−1). Drought stress during the measurement campaign in summer 2018 induced partial stomata closure of vegetation. Partial stomata closure led to a midday depression in CO2 uptake, which did not recover during the afternoon. The median CO2 flux was only 24 % of the median CO2 flux measured during the same period in the previous year (2017). We suggest that partial stomata closure also dampened Hg0 uptake by vegetation, resulting in a NEE of Hg0 that was dominated by soil emission. Finally, we provide suggestions to further improve the precision and handling of the “Eddy Mercury” system in order to assure its suitability for long-term NEE measurements of Hg0 over natural background surfaces with low soil Hg concentrations (< 100 ng g−1). With these improvements, Eddy Mercury has the potential to be integrated into global networks of micrometeorological tower sites (FluxNet) and to provide the long-term observations on terrestrial atmosphere Hg0 exchange necessary to validate regional and global mercury models.
X-BASE: the first terrestrial carbon and water flux products from an extended data-driven scaling framework, FLUXCOM-X
Nelson, Jacob A.; Walther, Sophia; Gans, Fabian; et al. (2024)
Biogeosciences
Mapping in situ eddy covariance measurements of terrestrial land–atmosphere fluxes to the globe is a key method for diagnosing the Earth system from a data-driven perspective. We describe the first global products (called X-BASE) from a newly implemented upscaling framework, FLUXCOM-X, representing an advancement from the previous generation of FLUXCOM products in terms of flexibility and technical capabilities. The X-BASE products are comprised of estimates of CO2 net ecosystem exchange (NEE), gross primary productivity (GPP), evapotranspiration (ET), and for the first time a novel, fully data-driven global transpiration product (ETT), at high spatial (0.05°) and temporal (hourly) resolution. X-BASE estimates the global NEE at −5.75 ± 0.33 Pg C yr−1 for the period 2001–2020, showing a much higher consistency with independent atmospheric carbon cycle constraints compared to the previous versions of FLUXCOM. The improvement of global NEE was likely only possible thanks to the international effort to increase the precision and consistency of eddy covariance collection and processing pipelines, as well as to the extension of the measurements to more site years resulting in a wider coverage of bioclimatic conditions. However, X-BASE global net ecosystem exchange shows a very low interannual variability, which is common to state-of-the-art data-driven flux products and remains a scientific challenge. With 125 ± 2.1 Pg C yr−1 for the same period, X-BASE GPP is slightly higher than previous FLUXCOM estimates, mostly in temperate and boreal areas. X-BASE evapotranspiration amounts to 74.7×103 ± 0.9×103 km3 globally for the years 2001–2020 but exceeds precipitation in many dry areas, likely indicating overestimation in these regions. On average 57 % of evapotranspiration is estimated to be transpiration, in good agreement with isotope-based approaches, but higher than estimates from many land surface models. Despite considerable improvements to the previous upscaling products, many further opportunities for development exist. Pathways of exploration include methodological choices in the selection and processing of eddy covariance and satellite observations, their ingestion into the framework, and the configuration of machine learning methods. For this, the new FLUXCOM-X framework was specifically designed to have the necessary flexibility to experiment, diagnose, and converge to more accurate global flux estimates.
Evaluation of the ECOSSE Model for Estimating Soil Respiration from Eight European Permanent Grassland Sites
Abdalla, Mohamed; Feigenwinter, Iris; Richards, Mark; et al. (2023)
Agronomy
This study used the ECOSSE model (v. 5.0.1) to simulate soil respiration (Rs) fluxes estimated from ecosystem respiration (Reco) for eight European permanent grassland (PG) sites with varying grass species, soils, and management. The main aim was to evaluate the strengths and weaknesses of the model in estimating Rs from grasslands, and to gain a better understanding of the terrestrial carbon cycle and how Rs is affected by natural and anthropogenic drivers. Results revealed that the current version of the ECOSSE model might not be reliable for estimating daily Rs fluxes, particularly in dry sites. The daily estimated and simulated Rs ranged from 0.95 to 3.1 g CO2-C m−2, and from 0.72 to 1.58 g CO2-C m−2, respectively. However, ECOSSE could still be a valuable tool for predicting cumulative Rs from PG. The overall annual relative deviation (RD) value between the cumulative estimated and simulated annual Rs was 11.9%. Additionally, the model demonstrated accurate simulation of Rs in response to grass cutting and slurry application practices. The sensitivity analyses and attribution tests revealed that increased soil organic carbon (SOC), soil pH, temperature, reduced precipitation, and lower water table (WT) depth could lead to increased Rs from soils. The variability of Rs fluxes across sites and years was attributed to climate, weather, soil properties, and management practices. The study suggests the need for additional development and application of the ECOSSE model, specifically in dry and low input sites, to evaluate the impacts of various land management interventions on carbon sequestration and emissions in PG.
Large inter-annual variation in carbon sink strength of a permanent grassland over 16 years: Impacts of management practices and climate
Feigenwinter, Iris; Hörtnagl, Lukas; Zeeman, Matthias J.; et al. (2023)
Agricultural and Forest Meteorology
Permanent grasslands cover one third of the European agricultural area and are known to store large amounts of carbon (C) in their soils. However, long-term assessments of their C sink strength are still scarce. Thus, we investigated the C budget of an intensively managed, permanent grassland in Switzerland over 16 years, compared the results to changes in soil C stocks, and determined the most important drivers of the net ecosystem CO2 exchange (NEE). Combining NEE fluxes with C imports and C exports, we quantified the grassland C budget, i.e., net biome production (NBP). We observed a large inter-annual variation in NBP, with 9 of the 16 years indicating a C sink, and 7 years indicating a C source. On average, the grassland was a small C sink to C neutral, with a NBP of -70±106 g C m−2 yr−1 (mean±95% confidence interval). Mean NEE fluxes were -284±115 g C m−2 yr−1, C exports via harvest 335±73 g C m−2 yr−1, and organic C imports via slurry -121±43 g C m−2 yr−1. Soil C stocks from 0 to 0.7 m did not change significantly (decrease of 27.5 g C m−2 yr−1 over 13 years). Inter-annual variation in NBP was affected by management practices and environmental conditions. In the last five years, NBP was positive (C source), most likely due to decreasing C imports in combination with extreme weather conditions. Our study demonstrated the importance of covering multiple years with different management events when assessing the C sink strength of a site. Maintaining even a small grassland C sink in the future will be challenging and will require continuous organic C imports.
GRASSVISTOCK: modeling water fluxes in agro-pastoral systems
Leolini, Luisa; Moriondo, Marco; Brilli, Lorenzo; et al. (2023)
2023 IEEE International Workshop on Metrology for Agriculture and Forestry (MetroAgriFor)
Climate change is currently threatening agro-pastoral systems around the world. Increased temperature and prolonged drought periods are reducing the capacity of these environments to provide several ecosystem services and their potential to mitigate climate change. In this context, grasslands and pastures monitoring gains a relevant importance for improving farm management and productivity, farmer incomes and to reduce input wastage and greenhouse gases emissions. In these perspectives, many crop models have been adopted with the purpose of allowing an accurate grassland monitoring, to promptly detect the impact of eventual abiotic stresses (e.g. thermal and water stresses) and to identify adequate adaptation strategies to cope with climate change. In this study, the grassland growth model GRASSVISTOCK was implemented for simulating the soil water dynamics and fluxes as well as their impacts on leaf area index (LAI) and above-ground biomass (AGB) in three Alpine (A, B and C) and three Mediterranean (D, E and F) grasslands. The results showed good model performances at simulating soil fractional transpirable soil water (FTSW) in the Alpine sites (site B: r = 0.81; RRMSE = 44.42%; site C: r = 0.78; RRMSE = 33.43%) while no comparisons between observed and simulated FTSW were performed for the other grasslands due to less data availability. The model also showed satisfactory performances at estimating LAI and AGB in both Alpine (LAI: r = 0.66; RRMSE = 33.03%; AGB: r = 0.60; RRMSE = 35.54%) and Mediterranean (LAI: r = 0.85; RRMSE = 43.58%; AGB: r = 0.77; RRMSE = 28.02%) sites. On these bases, this study proposes a prognostic tool for estimating water fluxes with the purpose of supporting agronomic decisions and to improve the sustainability of agro-pastoral systems.

Publications 1 - 10 of 24

Iris Feigenwinter

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results