Tree Ecophysiology

Almost 90% of the global biomass is stored in trees. Knowing the reactions of trees and forests to the ongoing increase in atmospheric CO₂ concentrations and other global climate changes is thus of major importance to predict the future of the earth's biosphere and its feedback with the atmosphere. Together with my research group, I investigate carbon relations of trees with special emphasis on the effects of environmental stress.

A core research topic is the clarification of the physiological controls for the storage of carbon reserves (e.g. starch or storage lipids). While there is detailed knowledge about the regulation of carbon storage and re-mobilization at the level of individual leaves, these mechanisms are still largely unknown for sapwood, which resembles the largest carbon storage pool in trees. By combining experimental studies with field observations, we aim to identify how carbon reserves storage is controlled at the whole tree level, how climatic and biotic stress influences carbon storage, and how tissue concentrations of carbon storage compounds can be used as a proxy for the net tree carbon balance. In addition, we experimentally test the functional significance of a tree's carbon storage pool for its resilience under climatic stress, like drought and cold temperatures.

• Mechanisms of woody-plant mortality under rising drought, CO2 and vapour pressure deficit
  McDowell, Nate G.; Sapes, Gerard; Pivovaroff, Alexandria; Adams, Henry D.; Allen, Craig D.; et al.
  Nature Reviews Earth & Environment  10.1038/s43017-022-00272-1  MAY 2022
• Lack of hydraulic recovery as a cause of post-drought foliage reduction and canopy decline in European beech
  Arend, Matthias; Link, Roman Mathias; Zahnd, Cedric; Hoch, Guenter; Schuldt, Bernhard; et al.
  New Phytologist   10.1111/nph.18065  MAY 2022
• TreeNet – The Biological Drought and Growth Indicator Network
  Zweifel, R; Etzold, S; Basler, D; Bischoff, R; Braun, S; Buchmann, N; Conedera, M; Fonti, P; Gessler, A; Haeni, M; Hoch, G; Kahmen, A; Kochli, R; Maeder, M; Nievergelt, D; Peter, M; Peters, RL; Schaub, M; Trotsiuk, V; Walthert, L; Wilhelm, M; Eugster, W
  Frontiers In Forests And Global Change  10.3389/ffgc.2021.776905  NOV 4 2021
• Dynamic H-2 irrigation pulse labelling reveals rapid infiltration and mixing of precipitation in the soil and species-specific water uptake depths of trees in a temperate forest
  Kahmen, Ansgar; Buser, Till; Hoch, Guenter; Grun, Georges; Dietrich, Lars
  Ecohydrology 10.1002/eco.2322  SEP 2021
• Soil nutrient availability alters tree carbon allocation dynamics during drought
  Schonbeck, Leonie; Li, Mai-He; Lehmann, Marco M.; Rigling, Andreas; Schaub, Marcus; Hoch, Gunter; Kahmen, Ansgar; Gessler, Arthur
  Tree Physiology 10.1093/treephys/tpaa139  MAY 2021
• Climate Change Modulates Multitrophic Interactions Between Maize, A Root Herbivore, and Its Enemies
  Guyer, Anouk; van Doan, Cong; Maurer, Corina; Machado, Ricardo A. R.; Mateo, Pierre; Steinauer, Katja; Kesner, Luci; Hoch, Guenter; Kahmen, Ansgar; Erb, Matthias; Robert, Christelle A. M.
  Journal Of Chemical Ecology, 10.1007/s10886-021-01303-9, NOV 2021
• Effect of Asynchronous Light and Temperature Fluctuations on Plant Traits in Indoor Growth Facilities
  Chiang, Camilo; Bankestad, Daniel; Hoch, Gunter
  Agronomy-basel  10.3390/agronomy11040755 Published: APR 2021
• A bottom-up quantification of foliar mercury uptake fluxes across Europe
  Wohlgemuth, Lena; Osterwalder, Stefan; Joseph, Carl; Kahmen, Ansgar; Hoch, Gunter; et al.
  Biogeosciences, 10.5194/bg-17-6441-2020  DEC 21 2020
• Reaching Natural Growth: The Significance of Light and Temperature Fluctuations in Plant Performance in Indoor Growth Facilities
  Chiang, Camilo; Bankestad, Daniel; Hoch, Gunter
  Plants-Basel   DOI: 10.3390/plants9101312  OCT 2020
• Reaching Natural Growth: Light Quality Effects on Plant Performance in Indoor Growth Facilities
  Chiang, Camilo; Bankestad, Daniel; Hoch, Gunter
  Plants-Basel  DOI: 10.3390/plants9101273  OCT 2020
• Rhizosphere activity in an old-growth forest reacts rapidly to changes in soil moisture and shapes whole-tree carbon allocation
  Joseph, Jobin; Gao, Decai; Backes, Bernhard; Bloch, Corinne; Brunner, Ivano; et al.
  Proceedings Of The National Academy Of Sciences Of The United States Of America  DOI: 10.1073/pnas.2014084117  OCT 2020
• A first assessment of the impact of the extreme 2018 summer drought on Central European forests
  Schuldt B; Buras A; Arend M; Vitasse Y; Beierkuhnlein, C; Damm, A; Gharun, M; Grams, TEE; Hauck, M; Hajek, P; Hartmann, H; Hiltbrunner, E; Hoch, G; Holloway-Phillips, M; Koerner, C; Larysch, E; Lubbe, T; Nelson, DB; Rammig, A; Rigling, A; Rose, L; Ruehr, NK; Schumann, K; Weiser, F; Werner, C; Wohlgemuth, T; Zang, CS; Kahmen, A
  Basic And Applied Ecology 2020, 10.1016/j.baae.2020.04.003
• Soil nutrients and lowered source:sink ratio mitigate effects of mild but not of extreme drought in trees
  Schoenbeck, Leonie; Gessler, Arthur; Schaub, Marcus; Rigling, Andreas; Hoch, Guenter; Kahmen A, Li MH
  Environmental And Experimental Botany,  DOI: 10.1016/j.envexpbot.2019.103905  JAN 2020
• Plant respiration: Controlled by photosynthesis or biomass?
  Collalti, Alessio; Tjoelker, Mark G.; Hoch, Guenter; Makela, Annikki; Guidolotti, Gabriele; et al.
  Global Change Biology 2020 DOI: 10.1111/gcb.14857 
• High carbon storage in carbon-limited trees
  Weber, R; Gessler, A; Hoch, G
  NEW PHYTOLOGIST, 222 (1):171-182; 10.1111/nph.15599 APR 2019
• No role for xylem embolism or carbohydrate shortage in temperate trees during the severe 2015 drought
  Dietrich, L; Delzon, S; Hoch, G; Kahmen, A
  JOURNAL OF ECOLOGY, 107 (1):334-349; 10.1111/1365-2745.13051 JAN 2019
• Standardized protocols and procedures can precisely and accurately quantify non-structural carbohydrates
  Landhausser, SM; Chow, PS; Dickman, LT; Furze, ME; Kuhlman, I; Schmid, S; Wiesenbauer, J; Wild, B; Gleixner, G; Hartmann, H; Hoch, G; McDowell, NG; Richardson, AD; Richter, A; Adams, HD
  TREE PHYSIOLOGY, 38 (12):1764-1778; 10.1093/treephys/tpy118 DEC 2018
• Losing half the conductive area hardly impacts the water status of mature trees
  Dietrich, L; Hoch, G; Kahmen, A; Korner, C
  SCIENTIFIC REPORTS, 8 10.1038/s41598-018-33465-0 OCT 9 2018
• …

• Carbon storage of trees exposed to carbon limitation
• Identifying the functions of different carbon storage compounds
• Drought effects on carbon- and water-relations of plants
• Tree growth and carbon-storage at cold climates

• Upscaling from trees to ecosystem processes (biogeochemistry)
• Tree water-carbon relations (biophysics)
• Applications for forest management (forestry)