关键词: 系统发育多样性, 结构方程模型, 森林生产力, 物种多样性, 空间尺度

Abstract: Community dynamics could reveal current status and future tendency of alien invasive species. Tithonia diversifolia, an alien invasive shrub species that is widely distributed in the tropical and subtropical regions of China was examined to understand the establishment and dynamics of T. diversifolia communities. We investigated the community characters with random survey of plots in the typical distribution area of T. diversifolia and analyzed the relationships between community characters and time span of establishment. The results showed that: (1) Old branches suppressed the production of young branches and controlled the community development after the community had developed to certain stage. (2) The mean stembase diameter of branches negatively correlated with cluster density and branch density (P<0.01) and positively correlated with aboveground biomass (P<0.01). The infructescence density did not correlate with mean stem-base diameter of branches (P>0.1). (3) Soil total K and available P concentrations were significantly increased (P<0.05) with the development of T. diversifolia community, whereas the concentrations of soil organic matter, total N, and hydrolysableN showed an insignificant decreasing trend (P>0.1). In conclusion, with the increases of colonization time, cluster density and branch density decreased, community aboveground biomass increased, and community infructescence amount per unit area unchanged. T. diversifolia community could occupy the invaded area in the long term, with consistent influence on soil nutrient composition.

Key words: spatial scale, forest productivity, phylogenetic diversity, species diversity, structural equation modeling.