Plant Ecophysiology Lab Projects Publications Team Impressions Activities
A fundamental understanding of plant ecophysiology is necessary to address climate change impacts. Forests critically influence the Earth's climate and cycle large quantities of carbon and water, yet trees are increasingly at risk through an amplification of extreme climate events.

Pine and Mount Zugspitze

We address tree and forest resilience to climate change and extreme climate events. Our research provides process knowledge to predict and guide the potential of forests in mitigating climate change. We combine controlled experiments, observational studies and ecosystem modelling. We teach undergraduate and graduate students in process-based ecological research, as well as provide knowledge transfer into schools and society.

Research projects

The main focus of the DFG-funded Emmy Noether research group is to provide a detailed process understanding of carbon and water cycling in trees and forests exposed to varying stress scenarios, intensities and timing of stress. The main study object, Scots pine, one of the most widespread trees within Europe, has already shown significant decline in response to extreme drought events. We are particular interested in the underlying physiological responses including tree hydraulics, gas exchange, carbon allocation and growth during heat and drought stress and the ability to recover from stress. Based on experimental results and ecosystem observations we will improve a model framework (LandscapeDNDC) to assess pine forest responses to future climate extremes.

Tree recovery following stress release depends on critical stress impacts Ruehr et al (2019) Tree Physiology

As a consequence of climate change, the frequency of summer drought events is increasing worldwide. The combination of drought stress and high temperatures can cause lethal damage to trees. The dry summers in 2018 and 2019 have severely affected forests in large parts of Central Europe, and many million trees died, causing large financial losses to forest owners. To better understand the impacts of these extreme events on forests in Germany and Central Europe, we want to combine hyper-spectral satellite information with high-resolution imagery and forest monitoring data. This combined dataset will then be used to further investigate the environmental drivers that affect the spatial pattern of stress-induced forest damage. A refined spatial understanding of damage occurrence in relation to environmental factors is a prerequisite for model development and predictive analysis of forest health. This project is funded by the KIT Center for Disaster Management and Risk Reduction Technology . Birds-view of forest with dead trees identified using a deep-learning approach.

The International Tree Mortality Network aims to bring together a multidisciplinary team of experts to quantify trends and causes of tree mortality globally with the aim to provide crucial information for forest managers and policymaking.

Biogenic volatile organic compounds (BVOCs) are emitted from plants and can be highly reactive altering atmospheric chemistry and air quality. In this Georg-Forster fellowship from the Humboldt Foundation to Dr. Elizabeth Gaona, emissions of volatile organic compounds from trees under heat and drought stress are investigated. In addition, the atmospheric oxidation of stress-related BVOC emissions is quantified in a cooperation with colleagues from the Forschungszentrum Juelich using the Saphir-PLUS chamber. The overarching aim is to provide an integrated understanding of stress-induced BVOC emissions from trees in combination the atmospheric degradation of BVOCs.

In this joined DFG-funded project (2015 to 2019) with colleagues from the Weizmann Institute, we quantified responses of Aleppo pine trees to future, increasingly extreme conditions as predicted for the Negev region, where the Yatir forest, a large Aleppo pine plantation is growing. We focused on how the trees cope with heat waves and drought today and in the future under increased atmospheric carbon dioxide concentrations. We measured whole-tree gas exchange, emissions of volatile organic compounds and metabolites under controlled conditions. We found that heat and drought combined can kill seedlings due to overheating (Birami et al. 2018) and that dying seedlings could be identified at their unique VOC fingerprint (Birami et al. submitted). Further, we found no clear indications that elevated CO2 would mitigate hot drought stress responses in Aleppo pine seedlings (Birami et al 2020; Gattmann et al. accepted).

Oak leaves

Team

Publications Nadine Ruehr - Group head
Nadine has studied Environmental Science and received a PhD from ETH Zurich with a focus on soil-plant-atmosphere interactions. She strives to understand mechanisms of tree and forest responses to climate change aiming to contribute towards increasing forest resilience to extreme events. In her research she integrates physiological, biogeochemical and ecological methods and modelling approaches.
Publications Rüdiger Grote - Senior Scientist
Rüdiger holds a PhD in Forestry from Göttingen University and received his habilitation on ‘Ecosystem Modelling’ from TU Munich. He has developed several ecosystem models that describe forest development based on plant-atmosphere exchanges and is an internationally known expert in simulating the emission of biogenic volatile organic compounds. His particular interest is in describing tree physiological responses to drought and their impacts on resource uptake, allocation, and senescence.
Publications Daniel Nadal Sala - Postdoctoral researcher
Daniel studied Biology and received a PhD in Ecology from the University of Barcelona. His research interest is on plant responses to abiotic stress including drought and heatwaves at different temporal and spatial scales. He focuses on training simulation models with data and improving model descriptions of tree responses to drought and mechanistical descriptions of tree mortality.
Selina Schwarz - PhD student
Selina has studied Geoecology at the Karlsruhe Institute of Technology. Her research addresses environmental challenges through the application of remote sensing techniques. In her PhD she studies the impacts of recent summer droughts on European forests. She applies remote sensing and machine learning approaches to detect the environmental drivers of diffuse tree mortality.
Timo Knüver - PhD student
Timo has studied Geoecology at the University of Tübingen and is a PhD student at the University of Innsbruck. His research addresses the drought recovery potential of Norway spruce and European beech trees. To infer responses of tree carbon and water relations, he studies mature trees and joins us to pursue drought experiments on seedlings.
Andreas Gast - Engineer
Andreas has studied Environmental Engineering in Augsburg. He is responsible for all technical issues around the high-tech greenhouse facility including measurement automation. He has strong expertise in designing and building environmentally controlled plant chambers for automatic gas exchange measurements.
Anna Sontheim - Technician
Anna has studied Chemistry at the University of Heidelberg. She is responsible for the laboratory and has profound expertise in chemical analytics. She further supports experimental work on regeneration capacities of tree seedlings following forest fires.
Marie Roggenhofer - Intern
Marie studies Environmental Sciences at the University of Freiburg. She supports our ongoing experiments in the greenhouse, lab work and data analyses.

Dr. Ines Bamberger Postdoc – now at BayCEER
Dr. Elizabeth Gaona Postdoc – now at Forschungszentrum Jülich
Benjamin Birami PhD Student – now at University of Bayreuth
Marielle Gattmann PhD Student – now Climate Change Manager
Romy Rehschuh PhD Student
Andrea Jakab Lab technician – now in Switzerland
Dr. Andre Duarte MSc Student – now at U of Guelph, Canada
Mohitul Hossain MSc Student
Benedict Spaan MSc Student
Angelika Pointner MSc Student – now at DB Netz AG
Johanna Schnurr BSc Student
Tamara Wittmann BSc Student

Publications

Rehschuh R, Rehschuh S, Gast A, Jakab A-L, Lehmann MM, Saurer M, Gessler A, Ruehr NK (accepted) Tree allocation dynamics beyond heat and hot drought stress reveal changes in carbon storage, belowground translocation and growth. New Phytologist

Nadal-Sala D, Grote R, Birami B, Knüver T, Rehschuh R, Schwarz S, Ruehr NK (2021) Leaf shedding and non-stomatal limitations of photosynthesis mitigate loss of hydraulic conductance in of Scots pine saplings during severe drought stress. Frontiers in Plant Science

Nadal-Sala D, Grote R, Birami B, Lintunen A, Mammarella I, Preisler Y, Rotenberg E, Salmon Y, Tatrinov F, Yakir D, Ruehr NK (2021) Assessing model performance via the most limiting environmental driver (MLED) in two differently stressed pine stands. Ecological Applications

Birami B, Bamberger I, Ghirardo A, Grote R, Arneth A, Gaona-Colman E, Nadal-Sala D, Ruehr NK (2021) Heatwave frequency and tree death alter stress-specific emissions of volatile organic compounds in Aleppo pine. Oecologia

Nadal-Sala D, Medlyn BE, Ruehr NK, Ellsworth D, Barton C, Gracia C, Tissue D, Tjoelker MG, Sabaté S (2021) Increasing aridity will not offset CO2 fertilization in fast-growing eucalypts with access to deep soil water. Global Change Biology

Gattmann M, Birami B, Nadal-Sala D, Ruehr NK (2020) Dying by drying: timing of physiological stress thresholds related to tree death is not significantly altered by highly elevated CO2 in Aleppo pine. Plant, Cell and Environment

Bond-Lamberty et al. (2020) COSORE: A community database for continuous soil respiration and other soil-atmosphere greenhouse gas flux data. Global Change Biology 26 : 7268-7283

Joseph J, Decai G, Backes B, Bloch C, Brunner I, Gleixner G, Haeni M, Hartmann H, Hoch Gn, Hug C, Kahmen A, Lehmann MM, Li M, Luster Jr, Peter M, Poll C, Rigling A, Rissanen KA, Ruehr NK, Saurer M, Schaub M, Schönbeck L, Stern B, Thomas FM, Werner RA, Werner W, Wohlgemuth T, Hagedorn F, Gessler A (2020) Rhizosphere activity in an old-growth forest reacts rapidly to changes in soil moisture and shapes whole-tree carbon allocation. Proceedings of the National Academy of Sciences 117 (40) 24885-24892

Rehschuh R, Cecilia A, Zuber M, Farago T, Baumbach T, Hartmann H, Jansen S, Mayr S, Ruehr NK (2020) Drought-induced xylem embolism limits the recovery of leaf gas exchange in Scots pine Plant Physiology

Birami B, Naegel T, Gattmann M, Preisler Y, Arneth A, Ruehr NK (2020). Hot drought reduces the effects of elevated CO2 on tree water-use-efficiency and carbon metabolism New Phytologist

Toechterle P, Yang F, Rehschuh S, Rehschuh R, Ruehr NK, Rennenberg H, Dannenmann M (2020). Hydraulic redistribution of water by silver fir occurs under severe soil drought Forests 11(2):162

Schuldt B, Buras A, Arend M, Vitasse Y, Beierkuhnlein C, Damm A, Gharun M, Grams TEE, Hauck M, Hajek P, Hartmann H, Hilbrunner E, Hoch G, Holloway-Phillips M, Koerner C, Larysch E, Luebbe T, Nelson DB, Rammig A, Rigling A, Rose L, Ruehr NK, Schumann K, Weiser F, Werner C, Wohlgemuth T, Zang CS, Kahmen A (2020). A first assessment of the impact of the extreme 2018 summer drought on Central European forests Basic and Applied Ecology

Pascual-Benito M, Nadal-Sala D, Tobella M, Balleste E, Garcia-Aljaro C, Sabate S, Sabater F, Marti E, Gracia CA, Blanch A, Lucena F. (2020) Modelling the seasonal impacts of a wastewater treatment plant on water quality in a Mediterranean stream using microbial indicators Journal of Environmental Management, 261

Sperlich D, Nadal-Sala D, Gracia C, Kreuzwieser J, Hanewinkel M, Yousefpour R (2020) Gains or loss in forest productivity under climate change? The uncertainty of CO2-fertilization and climate effects Climate, 8(12), 141

Trugman AT, Anderegg LDL, Wolfe BT, Birami B, Ruehr NK, Detto M, Bartlett MK, Anderegg WRL (2019). Climate and plant trait strategies determine tree carbon allocation to leaves and mediate future forest productivity. Global Change Biology 25(10): 3395-3405

Ruehr NK, Grote R, Mayr S, Arneth A (2019). Beyond the extreme: Recovery of carbon and water relations in woody plants following heat and drought stress. Tree Physiology 39(8): 1285-1299

Etzold S, Zieminska K, Rohner B, Bottero A, Bose AK, Ruehr NK, Zingg A, Rigling A (2019). One century of forest monitoring data in Switzerland reveals species- and site-specific trends of climate-induced tree mortality. Frontiers in Plant Science 10(307)

Zeeman M, Shupe H, Baessler C, Ruehr NK (2019). Productivity and vegetation structure of three differently managed temperate grasslands. Agriculture, Ecosystems and Environment 270:129-148

Birami B, Gattmann M, Heyer AG, Grote R, Arneth A, Ruehr NK (2018). Heat waves alter carbon allocation and increase mortality of Aleppo pine under dry conditions. Frontiers in Forests and Global Change doi.org/10.3389/ffgc.2018.00008

Klein T, Zeppel MJB, Anderegg WRL, Bloemen J, De Kauwe MG, Hudson P, Ruehr NK, Powell TL, von Arx G, Nardini A (2018). Xylem embolism refilling and resilience against drought-induced mortality in woody plants: processes and trade-offs. Ecological Research. 33:839-855. doi.org/10.1007/s11284-018-1588-y

Brauner K, Birami B, Brauner HA, Heyer AG (2018). Diurnal periodicity of assimilate transport shapes resource allocation and whole-plant carbon balance. The Plant Journal.doi:10.1111/tpj.13898

Hartmann H*, Moura CF*, Anderegg WRL*, Ruehr NK*, Salmon Y*, Allen CD, Arndt SK, Breshears DD, Davi H, Galbraith D, Ruthrof KX, Wunder J, Adams HD, Bloemen J, Cailleret M, Cobb R, Gessler A, Grams TEE, Jansen S, Kautz M, Lloret F, and O'Brien M (2018). Research frontiers for improving our understanding of drought-induced tree and forest mortality. New Phytologist, 218(1):15-28. doi:10.1111/nph.15048
*Contributed as first authors in equal parts to the manuscript.

Hartmann H, Schuldt B, Sanders TGM, Macinnis-Ng C, Boehmer HJ, Allen CD, Bolte A, Crowther TW, Hansen MC, Medlyn BE, Ruehr NK, and Anderegg WRL (2018). Monitoring global tree mortality patterns and trends. Report from the VW symposium - Crossing scales and disciplines to identify global trends of tree mortality as indicators of forest health. New Phytologist 217(3):984-987. doi:10.1111/nph.14988

Bamberger I, Ruehr NK, Schmitt M, Gast A, Wohlfahrt G, and Arneth A (2017). Isoprene emission and photosynthesis during heat waves and drought in black locust. Biogeosciences 14 (15):3649-3667 doi:10.5194/bg-14-3649-2017

Rehschuh R, Mette T, Menzel A, and Buras A (2017). Soil properties affect the drought susceptibility of Norway spruce. Dendrochronologia, 45:81-89. doi:10.1016/j.dendro.2017.07.003

Duarte AG, Katata G, Hoshika Y, Hossain M, Kreuzwieser J, Arneth A, Ruehr NK (2016). Immediate and potential long-term effects of consecutive heat waves on the photosynthetic performance and water balance in Douglas-fir. Journal of Plant Physiology, 205:57-66 doi:10.1016/j.jplph.2016.08.012

Ruehr NK, Gast A, Weber C, Daub B, Arneth A (2016). Water availability as dominant control of heat stress responses in two contrasting tree species. Tree Physiology, 36(2):164-178 doi:10.1093/treephys/tpv102

Spring

Impressions

Plant research facility at KIT-Campus Alpin in Garmisch-Partenkirchen, Germany.
Control unit and scientific equipment.
Plant chambers to measure shoot and root gas exchange of carbon dioxid and water.
Biomass sampling during an experiment on stress legacy in Scots pine. Pictures by KIT/Hanno Mueller.
In vivo visualization of drought-induced embolisms blocking water transport in pine saplings measured at the TOPO-TOMO beamline of the KIT-ANKA synchrotron.

Activities


The Plant Ecophysiology lab is a research group at the KIT-Campus Alpin in Garmisch-Partenkirchen, Germany. We receive funding by the Emmy Noether programme of the German Science Foundation (DFG) and by the German Federal Ministry of Education and Research (BMBF) through the Helmholtz Association and its research programme Changing Earth - Sustaining our Future.