Stem Architectural Effect on Leaf Size, Leaf Number, and Leaf Mass Fraction in Plant Twigs of Woody Species

Abstract

This study is to examine the effect of stem architecture on biomass allocation between leaf and stem and between leaf size and number in plant twigs of woody species. We investigated leaf size, leaf number, stem length, stem diameter, and mass for 282 woody species of subtropical evergreen broad‐leaved forests in southwest China. Both stem diameter and stem length were positively correlated with individual leaf mass and area but were negatively associated with leaf number per unit stem mass and leaf number per stem length. This suggests that these stem architecture traits can be a physiological mechanism underlying the leaf size versus leaf number trade‐off. The ratio of stem length to stem diameter (LDR) was negatively correlated with leaf size and leaf number per stem length, due to the difference in the strength of the effects of stem length and stem diameter on leaf size and leaf number. Similarly, both stem diameter and stem length were positively correlated with leaf mass and stem mass. LDR was negatively correlated with leaf biomass fraction (the ratio of leaf mass to twig mass), due to the difference in the strength of the effect of stem length and stem diameter on leaf mass and stem mass. This indicates that stem architecture can significantly influence biomass allocation between leaf and stem. These relationships were generally strong when expressed as correlated evolutionary divergences. In addition, LDR was generally larger in the high‐rainfall habitat than in the low‐rainfall site. Accordingly, LDR can be regarded as a functional trait and an important component of the leading dimension of leaf size–twig size spectrum in plants.