Leaf Traits of Drought Tolerance for 37 Shrub Species Originating from a Moisture Gradient

Identifying the drought-tolerance traits of plant species originating from a moisture gradient will increase our understanding of the differences and similarities in plant drought tolerance. However, which traits can be used to evaluate drought tolerance remain an open question. Here, we conducted a common-garden experiment on 37 shrub species originating from desert to humid regions. The correlations between plant traits and the native environmental conditions were studied. Leaf sizes and Huber values were significantly correlated with most climate variables of the shrubs' origins. The osmotic potentials at full turgor (pi(100)), turgor loss point (psi(TLP)), and midday leaf water potential (psi(mid)) were significantly correlated with most climate variables of their origins. We proposed using leaf sizes, Huber values, and psi(TLP)as predictors of drought tolerance across shrub species and shrub biomes. Statistically significant correlations were found between pi(100),psi(TLP), and specific leaf area (SLA). However, owing to the weak correlations between SLA and the climate variables of the shrubs origins and between Huber values and leaf size and turgor loss traits, it was difficult to integrate leaf morphological traits with physiological traits to find a simple way to accurately quantify drought-tolerance-related differences among these shrub species.