Seasonal variation in native hydraulic conductivity between two deciduous oak species

Aims Mechanisms of plant drought resistance include both tolerance and avoidance. Xylem vulnerability to embolism and turgor loss point are considered traits that confer tolerance, while leaf abscission and deciduousness characterizes the avoidance strategy. While these mechanisms are thought to trade-off expressing a continuum among species, little is known on how variation in the timing and duration of leaf shedding in response to drought affect the relationship between xylem and leaf tolerance. In the present study, we explored the extent to which drought tolerance differs between two oak (Quercus) species that exhibit different leaf shedding behaviours. Particularly, we predicted thatQ. deserticolaTrel., which loses leaves at the end of the dry season (late-deciduous) and is thus exposed to a greater risk of cavitation, would be more drought tolerant and more conservative in its water use thanQ. laetaLiebm., which loses its leaves for only a short period of time in the middle of the dry season (brevideciduous).