关键词: 土壤养分, 酶活性, 高寒草地, 植被演替, 放牧胁迫

Abstract: As twigs are important components of woody plants, studying the twig’s biomass allocation strategy is beneficial to understand the optimal growth strategies of plants. In this study, we sampled twigs from 19 woody  species in an evergreen broad-leaf forest, Wuyi Mountain National Natural Reserve, Jiangxi, China. We analyzed the scaling relationships among twig’s leaf mass, leaf area, petiole mass, stem mass and leaf number of woody plants by standardized major axis (SMA) to explore the biomass allocation patterns at community scale and synusia scale. Model Type II regression was used to determine the numerical values of scaling exponents and normalization constants of scaling relationships. Isometric relationships were found among the twig mass, total leaf mass and stem mass at the community scale. Stem mass and total leaf mass in the tree layer and shrub layer also showed invariant isometric scaling. In contrary, the twig mass showed allometric relationship with stem mass at tree layer, but showed isometric relationship at shrub layer. Additionally, negative isometric relationships were found between individual leaf mass and leafing intensity. The negative relationship between leafing intensity and individual leaf mass does not hold in different life forms of plant classification in the analysis. The total petiole mass scaled allometrically (i.e.,α<1.0) with respect to total leaf mass and twig mass on twig level, which indicated that twigs need to allocate more biomass for the construction of transport tissues and support structures with the increase of leaf mass. Therefore, the petiole investment plays a key role in limiting the growth of twigs and leaves, with important influence on the optimum selection of twig and leaf size.

Key words: vegetation succession, enzyme activity, grazing stress, alpine grassland, soil nutrient.