An ecophysiological approach of hydraulic performance for nine Mediterranean species.

The existence of an efficient but also safe hydraulic system seems to be essential for plant survival under water limiting conditions. To investigate any common pattern in this safety-efficiency trade-off, static (xylem anatomy and vulnerability to xylem cavitation) and dynamic (Kplant, soil to leaf hydraulic conductance and Psileaf, leaf water potential) hydraulic properties of nine Mediterranean species belonging to four functional groups (semi-deciduous malacophyllous, sclerophylls, deciduous and herbaceous) were studied across two altitude sites. Static parameters did not show any pattern, but a strong exponential relationship between Kplant and Psileaf was evident for all the studied species. Furthermore, each species is represented by a different part and/or range of the Kplant-Psileaf relationship, indicative of its adaptive mechanisms and capacity for survival under water stress conditions. The use of Kplant-Psileaf relationship as a tool for understanding the mechanisms of plant responses to water stress is discussed.