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.
Tree recovery following stress release depends on critical stress impacts Ruehr et al (2019) Tree Physiology
In this joined DFG-funded project (2015-2019) 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. 2021). 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. 2020).
Stress-induced BVOC emissions
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 (2019-2021), emissions of volatile organic compounds from trees under heat and drought stress were investigated. In addition, the atmospheric oxidation of stress-related BVOC emissions was quantified in a cooperation with colleagues from the Forschungszentrum Juelich using the Saphir-PLUS chamber.
Nadine Ruehr - Professor
Nadine received her PhD from ETH Zurich with a focus on soil-plant-atmosphere interactions. She was awarded an Emmy Noether research group and became Professor of Climatic Ecophysiology at the Institute of Geography and Geoecology in 2022. She strives to understand mechanisms of tree and forest responses to climate change with the aim to increase forest resilience to extreme events and integrates physiological, biogeochemical and ecological methods and modelling approaches.
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.
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.
Rocco Pace - Postdoctoral researcher
Rocco studied Forestry and Environmental Sciences and received a PhD in Natural Sciences from the Technical University of Munich. His research interests are in urban forest modeling and tree ecophysiology, with a focus on assessing ecosystem services to improve air quality and microclimate. He is integrating morphological and physiological traits of trees into model parameterization to provide appropriate tools for supporting urban forest management and planning.
Peter Petrík - Postdoctoral researcher
Peter studied Forestry and received a PhD in Forest Phytology from Technical University in Zvolen. His research revolves around forest ecosystems under climate change with a focus on abiotic stresses on tree physiology. He applies sapflow and eddy-covariance methods to analyse carbon and water fluxes of forest ecosystems, and uses a process-based model to to estimate forest water demand under changing climate and management scenarios.
Selina Schwarz - PhD student |
Selina 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 studied Geoecology at the University of Tübingen and is pursuing his PhD at the University of Innsbruck. His research addresses the drought recovery potential of Norway spruce and European beech trees. He studies drought hydraulic responses in mature trees and applies experiments under controlled conditions.
Andreas Gast - Engineer |
Andreas 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 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 in the greenhouse and plant cultivation.
|Dr. Ines Bamberger||Postdoc – now at BayCEER|
|Dr. Elizabeth Gaona||Postdoc – now in Cordoba|
|Benjamin Birami||PhD Student – now at University of Bayreuth|
|Marielle Gattmann||PhD Student – now Climate Change Manager|
|Romy Rehschuh||PhD Student – now at TU Dresden|
|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|
Examples of controlled experiments. Shown are saplings of black locust in temperature-controlled pots (left) and our custom-designed tree chamber system (right).
Conceptual scheme of new hydraulic process description within PSIM to model drought stress impacts on tree physiology.
Gattmann M, McAdam S, Birami B, Link R, Nadal-Sala D, Schuldt B, Yakir D, Ruehr N (accepted) Anatomical adjustments of the tree hydraulic pathway decrease canopy conductance under long-term elevated CO2 in Aleppo pine Plant Physiology
Pace R, Chiocchini F, Sarti M, Endreny TA, Calfapietra C, Ciolfi M (2022) Integrating Copernicus land cover data into the i-Tree Cool Air model to evaluate and map urban heat mitigation by tree cover European Journal of Remote Sensing
Hikino K, Danzberger J, Riedel VP, Hesse BD, Hafner BD, Gebhardt T, Rehschuh R, Ruehr NK, Brunn M, Bauerle TL, Landhäusser SM, Lehmann MM, Rötzer T, Pretzsch H, Buegger F, Weikl F, Pritsch K, Grams TEE (2022) Dynamics of initial C allocation after drought release in mature Norway spruce - Increased belowground allocation of current photoassimilates covers only half of the C used for fine-root growth. Global Change Biology
Mahnken M, Cailleret M, Collalti A, Trotta C, Biondo C, D’Andrea E, Dalmonech D, Marano G, Mäkelä A, Minunno F, Peltoniemi M, Trotsiuk V, Nadal-Sala D, Sabaté S, Vallet P, Aussenac R, Cameron DR, Bohn FJ, Grote R, Augustynczik ALD, Yousefpour R, Huber N, Bugmann H, Merganicova K, Merganic J, Valent P, Lasch-Born P, Hartig F, Vega del Valle ID, Volkholz J, Gutsch M, Matteucci G, Krejza J, Ibrom A, Meesenburg H, Rötzer T, van der Maaten-Theunissen M, van der Maaten E, Reyer CPO (accepted) Accuracy, realism and general applicability of European forest models. Global Change Biology Global Change Biology
Gaglio M, Pace R, Muresan AN, Grote R, Castaldelli G, Calfapietra C, Fano EA (2022) Species-specific efficiency in PM2.5 removal by urban trees: From leaf measurements to improved modeling estimates. Science of The Total Environment
Pretzsch H, del Río M, Grote R, Klemmt H-J, Ordóñez C, Oviedo FB (2022) Tracing drought effects from the tree to the stand growth in temperate and Mediterranean forests: insights and consequences for forest ecology and management. European Journal of Forest Research
Rehschuh R, Rehschuh S, Gast A, Jakab A-L, Lehmann MM, Saurer M, Gessler A, Ruehr NK (2022) Tree allocation dynamics beyond heat and hot drought stress reveal changes in carbon storage, belowground translocation and growth. New Phytologist
Hikino K, Danzberger J, Riedel VP, Rehschuh R, Ruehr NK, Hesse BD, Lehmann MM, Buegger F, Weikl F, Pritsch K, Grams TEE (2022) High resilience of carbon transport in long-term drought stressed mature Norway spruce trees within two weeks after drought release. Global Change Biology
Ghirardo A, Blande JD, Ruehr NK, Balestrini R, Külheim C (2022) Editorial: Adaptation of Trees to Climate Change: Mechanisms Behind Physiological and Ecological Resilience and Vulnerability. Frontiers in Forests and Global Change
Havermann F, Ghirardo A, Schnitzler J-P, Nendel C, Hoffmann M, Kraus D, Grote R (2022) Modeling intra- and interannual variability of BVOC emissions from maize, oil-seed rape, and ryegrass. Journal of Advances in Modeling Earth Systems
Brunn M, Hafner BD, Zwetsloot MJ, Weikl F, Pritsch K, Hikino K, Ruehr NK, Sayer EJ, Bauerle TL (2022) Carbon allocation to root exudates is maintained in mature temperate tree species under drought. New Phytologist
Rehschuh R, Ruehr NK (2021) Diverging responses of water and carbon relations during and after heat and hot drought stress in Pinus sylvestris. Tree Physiology
Preisler Y, Hölttä T, Grünzweig JM, Oz I, Tatarinov F, Ruehr NK, Rotenberg E, Yakir D (2021) The importance of tree internal water storage under drought conditions. Tree Physiology
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.
*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
The Plant Ecophysiology lab is a research group at the KIT-Campus Alpin in Garmisch-Partenkirchen, Germany. We receive base funding in part by the Helmholtz Impulse and Networking Fund and the German Federal Ministry of Education and Research (BMBF) through the Helmholtz Association and its research programme Changing Earth - Sustaining our Future.