Water is an essential resource that determines the form and function of plants and ecosystems. In turn, plants are a critical link in the soil-plant-atmosphere continuum and take an active role in regulating terrestrial water fluxes at local, regional and continental scales. In our research, we are interested in different aspects of plant and ecosystem water relations.
One focus is to understand how water in temperate ecosystems circulates along the soil, plant, atmosphere continuum, what the residence times of water in terrestrial ecosystems are and from where plants in particular trees take up their water. Here we often use stable oxygen and hydrogen isotopes to trace the flow of water from precipitation to the soil and into plants.
Another focus is to characterize the physiological vulnerability of different temperate forest tree species to extreme drought events and to reveal the biological mechanisms that determine these differences in the drought vulnerability. We then use this information to understand the larger effects of drought events on biogeochemical processes in temperate forest ecosystems.
In addition, we address the effects of drought on the productivity of temperate and alpine grasslands. Specifically, we test if grasslands respond differently to drought events that occur in different times of the growing season and what the legacy of drought events is for biogeochemical processes in these systems.
Recent key publications:
Brinkmann N, Eugster W, Buchmann N, Kahmen A (in press) Species-specific differences in water uptake depth of mature temperate trees vary with water availability in the soil. Plant Biology.
Dietrich L, Delzon S, Hoch G, Kahmen A (in press) No role for xylem embolism or carbohydrate shortage in temperate trees during the severe 2015 drought. Journal of Ecology.
Brinkmann N, Seeger S, Weiler M, Buchmann N, Eugster W, Kahmen A (2018) Employing δ2H and δ 18O values to estimate mean residence time and temporal origin of soil and xylem water in a temperate forest. New Phytologist 219: 1300-1313.
Peters RL, Fonti P, Frank DC, Poyatos R, Pappas C, Kahmen A, Carraro V, Prendin AL, Schneider L, Baltzer JL, Baron-Gafford GA, Dietrich L, Heinrich I, Minor RL, Sonnentag O, Ashley M, Wightman M, Steppe K (2018) Quantification of uncertainties in conifer sap flow measured with the thermal dissipation method. New Phytologist 219: 1283-1299.
Dietrich L, Zweifel R, Kahmen A (2018) Daily stem diameter variations can predict the canopy water status of mature temperate trees.Tree Physiology 38: 941-952.
Newberry SL, Nelson DB, Kahmen A (2017) Cryogenic vacuum artefacts do not affect plant water-uptake studies using stable isotope analysis. Ecohydrology 10:e1892.
Brinkmann N, Eugster W, Zweifel R, Buchmann N, Kahmen A (2016) Temperate tree species show identical response in tree water deficit but different sensitivities in sap flow to summer soil drying. Tree Physiology 36: 1508-1519.
Prechsl UE, Burri S, Gilgen AK, Kahmen A, Buchmann N (2015) No shift to deeper water uptake depth in response to summer drought of two lowland and sub-alpine C3 grasslands in Switzerland. Oecologia, 177: 97-111.