The leaf size-twig size spectrum in evergreen broad-leaved forest of subtropical China.

Abstract

Plant twig characters for 82 woody species including individual leaf and total leaf mass, stem mass, individual leaf area, total leaf area and stem cross-sectional area were investigated at the twig level in different altitudes and life forms on Meihuashan Mountain in Southeastern China. The results showed that twig cross-sectional area of plant twigs were found to allometrically scale to individual leaf area and total leaf area that the twig supported, all with the common SMA (standardized major axis) slope being significantly larger than 1.0. However, the spectrum of twig leaf mass–stem mass was found to be mostly isometric and the slope had no significant deviation from 1.0, the same as the spectrum of twig total leaf area–twig leaf mass. The allometric constants (y-intercepts) of the relationships between the stem cross-sectional area and leaf area (both total leaf area and individual leaf area) were found to decrease significantly along the altitudinal gradient. Compared to deciduous broad-leaved species, the evergreen broad-leaved species were smaller in total leaf area for a given cross-sectional area or stem mass. This suggests that the species would support less leaf area at a given twig cross-sectional area with increasing environmental stress. And the life form can modify leaf-stem scaling relationship because of the difference of function.