Abstract:

Objective: Quantitative analyses of the relative effects of habitat heterogeneity and dispersal limitation on species diversity of subtropical evergreen broad-leaved forest community in south China were conducted to provide a theoretical basis for further revealing the mechanism of diversity maintenance in the southern subtropical evergreen broad-leaved forest community in Dinghu Mountain. Method: Based on the information on spatial distribution of 71 333 plants and 195 species in a 20 hm² plot of the southern subtropical evergreen broad-leaved forest community of Dinghu Mountain, we systematically compared the mechanism of species diversity maintenance with an accurate and reliable spatial statistical simulation method. Four different models including homogeneous Poisson model, heterogeneous Poisson model, homogeneous Thomas model and heterogeneous Thomas model were used to test spatial processes of habitat association and seed dispersal, allowing us to evaluate the potential contribution of habitat heterogeneity and dispersal limitation to the formation of spatial patterns of tree species, and the combined effects on species-area relation (SAR) of species diversity pattern. Result: Most populations displayed a clustered spatial distribution, and both the habitat heterogeneity from the habitat diversity hypothesis and the dispersal limitation from the community neutral theory produced significant effects on species diversity pattern. The simulation of spatial point pattern model revealed that the combined effects of habitat heterogeneity and dispersal limitation provided a better explanation of the SAR compared with their separate effects. At the same time, the simulation of distribution process of species with Cox process showed that the proportion of species affected jointly by habitat heterogeneity and dispersal limitation was higher than that affected separately by them in the same community. The effect of habitat heterogeneity (31.12%) was higher than that of dispersal limitation (25.13%), however, 43.75% of the detected species were significantly affected by both processes. Conclusion: Both habitat heterogeneity and dispersal limitation were the main driving forces to maintain species diversity in the study area, none of them can be ignored. In terms of separate effects, the habitat heterogeneity was stronger than the dispersal limitation in south subtropical forest community in Dinghu Mountain. In order to further reveal the mechanism of diversity maintenance, further specific studies are needed on the mechanism and contribution of different species groups at different scales.

Key words: habitat heterogeneity, dispersal limitation, subtropical forest community, species diversity, maintenance mechanism