Carbon balance under dual droughts: Disentangling the effects of soil and atmospheric moisture on tree sink and source dynamics in European forests.
Datasets
Atmospheric drought (high vapor pressure deficit, VPD) and soil drought frequently co-occur, yet plants respond to these stressors through partially distinct physiological pathways, potentially altering source (photosynthesis) and sink (growth and respiration) activities. Despite significant advances in understanding drought impacts on photosynthesis and plant hydraulics, the independent and interactive effects of soil vs. atmospheric drought on whole-tree carbon balance, including non-structural carbohydrate (NSC) dynamics, allocation priorities, and growth, remain insufficiently understood. This project aims to disentangle the effects of soil and atmospheric droughts on tree sink and source dynamics in European forests, by studying leaf-to-whole-tree ecophysiological processes that drive growth, carbon sequestration and tree mortality. Research will primarily be conducted in Pfynwald (Valais, Switzerland), as part of the VPDrought experiment, where mature Scots pines (Pinus sylvestris) are exposed to increased soil drought and reduced VPD. Our study addresses the research question: how do soil and atmospheric droughts differentially affect tree carbon uptake and allocation to gro