Xylem hydraulic safety margins in woody plants: coordination of stomatal control of xylem tension with hydraulic capacitance

Summary 1. The xylem pressure inducing 50% loss of hydraulic conductivity due to embolism ( P 50 ) is widely used for comparisons of xylem vulnerability among species and across aridity gradients. However, despite its utility as an index of resistance to catastrophic xylem failure under extreme drought, P 50 may have no special physiological relevance in the context of stomatal regulation of daily minimum xylem pressure and avoidance of hydraulic failure under non‐extreme conditions. Moreover, few studies of hydraulic architecture have accounted for the buffering influence of tissue hydraulic capacitance on daily fluctuations in xylem pressure in intact plants. 2. We used data from 104 coniferous and…

• NS
  National Science Foundation