Nina Buchmann

Last Name

Buchmann

First Name

Nina

ORCID

0000-0003-0826-2980

Organisational unit

03648 - Buchmann, Nina / Buchmann, Nina

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Publications 1 - 10 of 306

The effect of saline-alkaline and water stresses on water use efficiency and standing biomass of Phragmites australis and Bolboschoenus planiculmis
Liu, Ying; Ding, Zhi; Bachofen, Christoph; et al. (2018)
Science of The Total Environment
Relationship of leaf elongation rate of young wheat leaves, gross primary productivity and environmental variables in the field with hourly and daily temporal resolution
Merz, Quirina Noëmi; Walter, Achim; Maier, Regine; et al. (2022)
Agricultural and Forest Meteorology
Plant growth is controlled by an interplay of internal and external factors. The production of biomass via photosynthesis is dependent on the plant response to environmental variables such as temperature, vapour pressure deficit and light intensity. Short-term responses of plant growth to these variables at fine temporal scales of hours are not well investigated, especially under field conditions. The present study explores the relationship between leaf elongation rate (LER) of young wheat leaves in the field in very high temporal resolution (minutes). Turbulent fluxes of CO2 were measured with the eddy covariance technique and used to derive GPP, and environmental variables such as air and soil temperature, short wave radiation and vapour pressure deficit were simultaneously measured. The analysis revealed the importance of different variables on different temporal scales (hourly, daily). On an hourly scale, GPP and shortwave radiation explain most of the variance of LER, however on a daily scale, air temperature is the main driver. A cross-correlation analysis confirmed that the strongest immediate relationship can be found between LER and GPP and incoming shortwave radiation; variables that are determining photosynthesis. In principal, LER also shows the same diurnal patterns as air temperature and soil temperature, however air and soil temperature lag behind LER. Multivariate growth models show that combinations with GPP or incoming shortwave radiation and air temperature perform best. These results indicate that short term growth processes in young wheat leaves in the field are mainly controlled by incoming shortwave radiation, while the magnitude of growth is controlled by temperature.
Management matters: testing a mitigation strategy for nitrous oxide emissions using legumes on intensively managed grassland
Fuchs, Kathrin; Hörtnagl, Lukas; Buchmann, Nina; et al. (2018)
Biogeosciences
Replacing fertiliser nitrogen with biologically fixed nitrogen (BFN) through legumes has been suggested as a strategy for nitrous oxide (N2O) mitigation from intensively managed grasslands. While current literature provides evidence for an N2O emission reduction effect due to reduced fertiliser input, little is known about the effect of increased legume proportions potentially offsetting these reductions, i.e. by increased N2O emissions from plant residues and root exudates. In order to assess the overall effect of this mitigation strategy on permanent grassland, we performed an in situ experiment and quantified net N2O fluxes and biomass yields in two differently managed grass–clover mixtures. We measured N2O fluxes in an unfertilised parcel with high clover proportions vs. an organically fertilised control parcel with low clover proportions using the eddy covariance (EC) technique over 2 years. Furthermore, we related the measured N2O fluxes to management and environmental drivers. To assess the effect of the mitigation strategy, we measured biomass yields and quantified biologically fixed nitrogen using the 15N natural abundance method. The amount of BFN was similar in both parcels in 2015 (control: 55±5kgNha−1yr−1; clover parcel: 72±5kgNha−1yr−1) due to similar clover proportions (control: 15% and clover parcel: 21%), whereas in 2016 BFN was substantially higher in the clover parcel compared to the much lower control (control: 14±2kgNha−1yr−1 with 4% clover in DM; clover parcel: 130±8kgNha−1yr−1 and 44% clover). The mitigation management effectively reduced N2O emissions by 54% and 39% in 2015 and 2016, respectively, corresponding to 1.0 and 1.6tha−1yr−1CO2 equivalents. These reductions in N2O emissions can be attributed to the absence of fertilisation on the clover parcel. Differences in clover proportions during periods with no recent management showed no measurable effect on N2O emissions, indicating that the decomposition of plant residues and rhizodeposition did not compensate for the effect of fertiliser reduction on N2O emissions. Annual biomass yields were similar under mitigation management, resulting in a reduction of N2O emission intensities from 0.42gN2O-Nkg−1DM (control) to 0.28gN2O-Nkg−1DM (clover parcel) over the 2-year observation period. We conclude that N2O emissions from fertilised grasslands can be effectively reduced without losses in yield by increasing the clover proportion and reducing fertilisation.
Reply to: Plant traits alone are good predictors of ecosystem properties when used carefully
van der Plas, Fons; Schröder-Georgi, Thomas; Weigelt, Alexandra; et al. (2023)
Nature Ecology & Evolution
A guide to assess and value ecosystem services of grasslands
Richter, Franziska Julia; Jan, Pierrick; Benni, Nadja El; et al. (2021)
Ecosystem Services
Comprehensive mapping of Ecosystem Services (ES) is necessary to understand the impact of global change on crucial ES and to find strategies to sustain human wellbeing. Economic valuation of ES further translates their biophysical values into monetary values, which are then comparable across different ES and easily understandable to decision makers. However, a comprehensive synthesis of methods to measure ES indicators in grasslands, a central element of many landscapes around the globe, is still lacking, hampering the implementation of grassland ES-multifunctionality surveys. To identify suitable and recommendable methods, we reviewed the literature and evaluated labor intensiveness, equipment costs and predictive power of all methods. To facilitate the translation of biophysical ES into monetary terms, we further provide an overview of available methods for the economic valuation of ES. This review resulted in a toolbox comprising 85 plot-scale methods for assessing 29 different ES indicators for 21 provisioning, regulating, supporting or cultural ES. The available methods to measure ES indicators vary widely in labor intensiveness, costs, and predictive power. Based on this synthesis, we recommend 1) to choose direct over indirect methods and ES indicators, 2) to use the most accurate methods to estimate ES indicators, 3) to take into account that one ES indicator can have implications for more than one final ES, and 4) to utilize the wealth of available methods and indicators to assess as many ES for ES-multifunctionality studies as possible, especially including cultural ES. Moreover, the overview of approaches that can be used for the economic valuation of different grassland ES shall facilitate economic ES-multifunctionality assessments. Thus, this methodological guidance will considerably support researchers and stakeholders in setting up ES comprehensive assessments and monitoring schemes in grasslands and shall ultimately help overcome incomplete or superficial surveys based on single or few ES only.
Temperate grasslands under climate extremes: Effects of plant diversity on ecosystem services
Wang, Yi; Klaus, Valentin; Gilgen, Anna K.; et al. (2025)
Agriculture, Ecosystems & Environment
Temperate grasslands provide a broad set of ecosystem services (ES), which include both provisioning ES (e.g., yield production) and non-provisioning ES (e.g., soil carbon sequestration, weed suppression, aesthetics, recreation). Yet, ES can considerably decrease under climate extremes, potentially threatening grassland ES in the future. Meanwhile, some grassland ES were shown to increase with increasing plant diversity. However, whether plant diversity can mitigate the effects of extreme climate events on multiple ES is still unclear, as past studies frequently focused on a single ES, namely aboveground biomass production (AGB). Therefore, we conducted a systematic literature review to identify the potential mitigation effect of plant species richness against the impact of extreme drought and heat stress on multiple ES in temperate C3 grasslands, by synthesizing existing knowledge and identifying research gaps. Since the 1900s, the number of studies on plant diversity and grassland ES has increased. However, only few studies also addressed climatic extremes, despite a ten-fold increase of studies in the last two decades. Moreover, while all studies included in this review (n=31; 26 biodiversity experiments (sown and weeded), five on-farm studies) addressed provisioning ES (AGB), only 45 % of the studies investigated non-provisioning ES such as climate regulation or weed suppression. No study considered cultural ES. Overall, the positive effect of higher plant species richness on grassland provisioning ES persisted also under extreme conditions, despite reducing absolute magnitudes of ES. Since the number of studies per specific non-provisioning ES was small (n = 2 on average), the general effect of plant species richness acting as insurance against climate extremes for those ES remain largely unknown. In addition, we assessed four different indices commonly used to study biodiversity–ES relationships, but no best index for resistance, recovery, and resilience of ES against climate extremes was found. Overall, the existing evidence reviewed here suggests that maintaining or increasing plant diversity in temperate grasslands can indeed be considered as a natural insurance against current and future climate risks for AGB. However, for any non-provisioning ES, currently available research is too scarce to conclude such a mitigation effect. Closing this research gap, particularly for on-farm settings, could help advance policy and societal support for sustainable, climate change-adapted grassland management.
Functional groups differ in trait means, but not in trait plasticity to species richness in local grassland communities
Roscher, Christiane; Schumacher, Jens; Lipowsky, Annett; et al. (2018)
Ecology
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.
TreeNet–The Biological Drought and Growth Indicator Network
Zweifel, Roman; Etzold, Sophia; Basler, David; et al. (2021)
Frontiers in Forests and Global Change
The TreeNet research and monitoring network has been continuously collecting data from point dendrometers and air and soil microclimate using an automated system since 2011. The goal of TreeNet is to generate high temporal resolution datasets of tree growth and tree water dynamics for research and to provide near real-time indicators of forest growth performance and drought stress to a wide audience. This paper explains the key working steps from the installation of sensors in the field to data acquisition, data transmission, data processing, and online visualization. Moreover, we discuss the underlying premises to convert dynamic stem size changes into relevant biological information. Every 10 min, the stem radii of about 420 trees from 13 species at 61 sites in Switzerland are measured electronically with micrometer precision, in parallel with the environmental conditions above and below ground. The data are automatically transmitted, processed and stored on a central server. Automated data processing (R-based functions) includes screening of outliers, interpolation of data gaps, and extraction of radial stem growth and water deficit for each tree. These long-term data are used for scientific investigations as well as to calculate and display daily indicators of growth trends and drought levels in Switzerland based on historical and current data. The current collection of over 100 million data points forms the basis for identifying dynamics of tree-, site- and species-specific processes along environmental gradients. TreeNet is one of the few forest networks capable of tracking the diurnal and seasonal cycles of tree physiology in near real-time, covering a wide range of temperate forest species and their respective environmental conditions.
Global distribution and changes of leaf-level intrinsic water use efficiency and their responses to water stress
Wang, Xiang; Fu, Zheng; Ciais, Philippe; et al. (2026)
Nature Communications
Intrinsic water use efficiency (iWUE) at the leaf level measures water expenditures by terestrial plants during photosynthesis, yet its global spatiotemporal dynamics and responses to water stress remain poorly understood. Using machine-learning models and carbon isotope observations in C3 foliage, here we elucidate global patterns, trends, and water-stress responses of leaf iWUE. We find high iWUE in cold, arid regions and lower values in warm, humid areas. From 2001 to 2020, global iWUE increases at 0.2 ± 0.02 μmol mol-1 year-1, with strong biome specific differences. Grasslands exhibit the highest mean iWUE but the slowest increase, whereas evergreen broadleaf forests show the lowest iWUE yet the fastest increase. iWUE rises with increasing water stress, but the rate of growth diminishes as water stress intensifies. Vapor pressure deficit influence iWUE more broadly than soil moisture. The ecological optimality model reproduces the spatial patterns of leaf iWUE and identifies vapor pressure deficit as the dominant driver, but overestimates mean iWUE and its trend. Our findings suggest that increasing water stress may slow the rate of global iWUE increase as the climate continues to warm.

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