Context:
Hot droughts, characterized by higher air temperatures combined with water deficit, are becoming increasingly frequent and severe due to global warming. These phenomena have devastating impacts on forest ecosystems. One of the main challenges for trees subjected to these conditions is to maintain their optimal physiological functions (e.g. carbon exchange, canopy temperature regulation and evapotranspiration). In the context of global warming, we are studying the physiological responses of trees to hotter and drier conditions, from the leaf to the forest level.
Study and methods:
Main question: how are ecophysiological characteristics, heat tolerance and canopy temperature regulation determined in ecosystems acclimatized to contrasting soil moisture conditions?
Hypothesis: long-term acclimatization to reduced soil moisture will lead to sparser tree canopies with smaller leaves and increased wind flow. During the growing season, trees growing under chronically dry soil conditions will have weakened evapotranspiration, leading to warmer canopies.
Restoration of normal evapotranspiration values after periods of heatwave will be faster for trees that have not been subjected to severe soil drought. Trees at warmer, drier sites (in Spain) are expected to show better acclimatization to reduced soil moisture, and a greater capacity to maintain high evapotranspiration.
Methods: the project involves several measurement campaigns at research sites in France and Spain, from May to September. The candidate will join a team of researchers using advanced tools to assess a wide range of plant physiological functions. After the fieldwork, laboratory activities and data analysis will complete the study.
Prerequisites: commitment and motivation. Interest in plant ecophysiology. Good knowledge of English. Driving licence.
Collaboration and contacts:
Charlotte Grossiord ([email protected]), tenure track assistant professor; Alyssa Kullberg ([email protected]), scientific collaborator; Arianna Milano ([email protected]), research assistant.
Key words: climate change, drought, forest, tree ecophysiology.
Place of work: PERL – EPFL/ WSL Lausanne site, to be moved to experimental sites in Puéchabon (FR) and Prades (ES) in summer 2025.
