Linking vein properties to leaf biomechanics across 58 woody species from a subtropical forest.

Leaf venations have elements with relatively lower elasticity than other leaf tissue components, which are thought to contribute to leaf biomechanics. A better mechanistic understanding of relationships between vein traits and leaf mechanical properties is essential for ecologically relevant interpretation of leaf structural variations. We investigated 13 major (first to third order) and minor (>third order) vein traits, six leaf mechanical properties and other structural traits across 58 woody species from a subtropical forest to elucidate how vein traits contribute to leaf biomechanics. Across species, vein dry mass density (ρv ), total vein dry mass per leaf area (VMA) and minor vein diameter (VDmin ), but not the lower-order vein density (VLA1•2 ), were positively correlated with leaf force to punch (Fp ) and force to tear (Ft ). Structural equation models showed that ρv and VDmin not only contribute to leaf mechanical properties directly (direct pathway), but also had impacts on leaf biomechanics by influencing leaf thickness and leaf dry mass per area (indirect pathway). Our study demonstrated that vein dry mass density and minor vein diameter are the key vein properties for leaf biomechanics. We also suggest that the mechanical characteristics of venations are potential factors influencing leaf mechanical resistance, structure and leaf economics spectrum.