PI: Dr. Anna Sala, University of Montana Biological Sciences

Climate change is predicted to increase the frequency and severity of drought in many areas of the world with profound consequences on drought-induced mortality (DIM), global carbon cycles and subsequent vegetation-climate feedbacks. For large scale monitoring and adaptive management purposes, a critical need is the ability to identify early warning signals of DIM that can be remotely sensed. That is, to identify critical threshold-like indicators beyond which the risk of mortality increases. Remote sensing approaches have successfully detected declines in vegetation water content under severe drought which have been followed by DIM. However, these observations remain correlative and critical thresholds have not been identified. Despite intense physiological research, to date, direct experimental evidence that water content is a good threshold-type predictor of DIM is missing. Here, I propose to obtain such critically needed experimental evidence and relate it to remotely sensed variables. Specifically, I propose to conduct greenhouse experiments to test whether decreases of water content in different species and plant tissues are reliable and consistent threshold-type indicators of mortality risk across species and whether these thresholds can be detected with hyperspectral signals. This project will help pave the way to use remotely sensed indicators of vegetation water content to predict the risk of DIM and devise a priori management strategies to mitigate such risk. This proposal directly contributes to the ECOSTRESS NASA mission aimed at identifying critical thresholds of water use and water stress in key climate-sensitive biomes.