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

Public Deposited

Downloadable Content

Download PDF


Attribute NameValues
  • 1. The xylem pressure inducing 50% loss of hydraulic conductivity due to embolism widely used for comparisons of xylem vulnerability among species and across aridity However, despite its utility as an index of resistance to catastrophic xylem failure drought, P5o may have no special physiological relevance in the context of stomatal of daily minimum xylem pressure and avoidance of hydraulic failure under non- Moreover, few studies of hydraulic architecture have accounted for the buffering of tissue hydraulic capacitance on daily fluctuations in xylem pressure in intact plants. 2. We used data from 104 coniferous and angiosperm species representing a range growth forms and habitat types to evaluate trends in three alternative xylem margins based on features of their stem xylem vulnerability curves and regulation stem water potential (Ystem min) under non-extreme conditions: (i)Ystem min - Y stem min - Pe, the difference between Ystem min and the threshold xylem of conductivity begins to increase rapidly (Pe) and (iii) Pe - P50 an estimate of the the vulnerability curve between Pe and P50. Additionally, we assessed xylem capacitance, species-specific set-points for daily minimum stem water hydraulic safety margins in a subset of species for which relevant data were available. 3. The three types of hydraulic safety margin defined increased with decreasing set-points for Y stem min, suggesting a diminishing role of stem capacitance in in xylem pressure as Ystem min became more negative. The trends in hydraulic among coniferous and angiosperm species native to diverse habitat types. 4. Our results suggest that here is a continuum of relative reliance on different confer hydraulic safety under dynamic conditions. Species with low capacitance wood experience greater daily maximum xylem tension and appear to rely structural features to avoid embolism, whereas in species with high capacitance density avoidance of embolism appears to be achieved primarily via reliance on of stored water to constrain transpiration-induced fluctuations in xylem tension.
  • Keywords: hydraulic architecture, plant-water relations, xylem embolism, transpiration
Resource Type
Date Available
Date Issued
  • Meinzer, F. C., D. M. Johnson, B. Lachenbruch, K. A. McCulloh, and D. R. Woodruff. 2009. Xylem hydraulic safety margins in woody plants: coordination of stomatal control of xylem tension with hydraulic capacitance. Functional Ecology 23: 922-930
Journal Title
Journal Volume
  • 23
Journal Issue/Number
  • 5
Academic Affiliation
Rights Statement



This work has no parents.