关键词: 环境异质性, 空间距离, 热带季节雨林, 大型森林动态样地, 西双版纳

Abstract: Functional beta diversity refers to the variation of functional composition between communities. Exploring the mechanisms underlying functional beta diversity is a central theme in community ecology. We measured 11 important functional traits of woody plant in a 20-ha tropical seasonal rainforest plot in Xishuangbanna and used abundance-weighted mean nearest neighbor trait distance to quantify the functional beta diversity at different sampling scales. We revealed the relative importance of canopy structure, environmental heterogeneity, and spatial distance on functional beta diversity using multiple regressions on distance matrices. Our results showed that, for all woody plant individuals with DBH ≥ 1 cm, the best model to explain the functional beta diversity was one including canopy structure, environment, and spatial distance. At each of the three sampling scales, canopy structure and environment had relatively large explanatory power and increased with increasing sampling scale, while the relative importance of spatial distance was negligible. Our findings corroborate that environmental heterogeneity and spatial distance are the two main factors driving functional beta diversity, and we provide new mechanistic insights by including the effects of canopy cover at local scales.

Key words: environmental heterogeneity, spatial distance, tropical seasonal rainforest, large forest dynamics plot, Xishuangbanna