Leaf hydraulic safety margin and safety-efficiency trade-off across angiosperm woody species.

Leaf hydraulic conductance and the vulnerability to water deficits have profound effects on plant distribution and mortality. In this study, we compiled a leaf hydraulic trait dataset with 311 species-at-site combinations from biomes worldwide. These traits included maximum leaf hydraulic conductance (), water potential at 50% loss of (P50), and minimum leaf water potential (). Leaf hydraulic safety margin (HSM) was calculated as the difference between and P50. Our results indicated that 70% of the studied species had a narrow HSM (less than 1 MPa), which was consistent with the global pattern of stem hydraulic safety margin. There was a positive relationship between HSM and aridity index (the ratio of mean annual precipitation to potential evapotranspiration), as species from humid sites tended to have larger HSM. We found a significant relationship between and P50 across global angiosperm woody species and within each of the different plant groups. This global analysis of leaf hydraulic traits improves our understanding of plant hydraulic response to environmental change.