Beta Diversity And Functional Diversity In An Evergreen Broad-leaved Forest Community In East China

The forming and maintenance of species diversity in space, which has been a crucial question in community ecology, has motivated much research. Beta diversity, as a fundamental macroecological pattern, is useful for understanding community assembly. This study evaluated the pattern of Beta diversity derived from species abundance and its environmental association in a 24 ha rugged subtropical evergreen broad-leaved forest plot (GTS plot) in East China. The 50 ha plot in Barro Colorado Island (BCI) was chosen as a comparison of different habitat topographies, and multi-scale approach was also adopted to detect scale sensitivity.The results showed that in GTS plot, species similarity had monotonic decline along the distance gradient, and was not sensitive to scales within the analyzed distance range. Both species similarities in plots with rougher and plainer topographies had the steepest decrease occurring in the first 100 m, and distance had independant effect on Beta diversity. Habitat heterogeneity, especially elevation and convexity differences, tend to be the key factors that influence Beta diverisity, and dispersal limitation also have have significant contribution in community assembly in GTS with rougher topography.Functional diversity, the extent of functional differences among the species in a community, has been widely emphasized in community and ecological researches, because of its exceptional angle which can engage in species coexistence, especially in evaluation of species-environment associations. The patterns of functional diversity, functional groups and their topographic association were evaluated in 24 ha GTS plot in this study. Vertical layers and multi-scale angles were also considered in the evaluation.The results showed that topographic explanations of functional diversity in the multi-scales were significantly greater than that of species diversity, which provided an evidence of that composition which based on phylogenetic classification has better association with ecosystem processes in the evergreen broad-leaved forest. This study also found that species in tree layer had better topographic association with their functional diversity, and functional traits tend to play different roles in species'interaction with habitat in different vertical layers in GTS plot. Species clustered with closer functional traits attributes tended to have tighter competition exclusions. The pattern of functional groups displayed strong aggregative distribution and seemed not provide support of the niche theory.