Plant water use and plant water status during protracted and seasonal droughts: A link between hydrological fluxes and ecological disturbance

Hydrologic Feedbacks with Ecosystems
Chair: Gretchen Miller (Texas A&M University)
Advancements in ecohydrology have highlighted the importance of feedbacks between vegetation and the hydroclimate, with their subsequent impacts on water and food supplies. In this session, we discuss these feedbacks across a range of ecosystems and scales, highlighting recent and developing improvements in their modeling.

\"Plant water use and plant water status during protracted and seasonal droughts: A link between hydrological fluxes and ecological disturbance\"
Speaker: Sally Thompson (University of California Berkeley)

Ecohydrology has two important, related insights to offer the study of global change: (i) prediction of plant vulnerability to changes in the water cycle, and (ii) descriptions of the water cycle that account for the role of plants in regulating water fluxes. The link between these issues is the internal water status of plants, which controls water uptake and the physiological experience of stress. The relationship between water status and water uptake, however, is strongly mediated by plant physiological characteristics and a plant’s environmental setting. Here I will draw on a combination of modeling and observational studies of Californian vegetation during seasonal and multi-year drought to (i) show how different physiological characteristics can de-couple trajectories of plant water potential and transpiration, (ii) illustrate how different landscape and hydrological settings influence the crossing of water potential thresholds, xylem recovery and ultimately plant health during multi-year drought, and (iii) highlight some challenges associated with reconciling the ecohydrological and ecophysiological communities’ approaches to describing plants and plant water fluxes during drought.