The Research Of Community Assembly Along A Slope Aspect Gradient In An Alpine Meadow Based On Community Phylogeny

Species co-existence, for a long time, had been one of the main problems. This paper attempts to reveal the coexistence mechanism of plant community on the South-North-facing slope gradient based on community phylogeny and functions traits. In the research, we calculated separately phylogenetic signal for SLA(specific leaf area) and ?13C(stable carbon isotope ratio), and used phylogenetic index to quantify community phylogenetic structure. For exploring the community assembly along slope aspects gradient, we calculated two biodiversity index(Simpson and Shannon).We found SLA and ?13C showed no phylogenetic signal. Meanwhile, in south-facing and southwest-facing, these communities had a tendency to be phylogenetically over-dispersed; while they exhibit random or clustered phylogenetic structure in north-facing. Moreover, the species coexisted in south-facing slope have no close relationship. On the contrary, in north-facing slope aspect the species show closer relationship. Species diversity along the slope gradient shows unimodal change and dissimilarity become increasing large.We conclude that Plant communities in different slope aspects do exhibit different phylogenetic structure. In south facing slope, those communities are structured by habitat filtering, and convergent evolution creates analogous structures that have similar form or function. In north-facing slope, what drives community assembly in north-facing is interspecies interaction, and competition(niche overlap) in ecological communities often leads to niche differentiation. However, in westfacing and northwest-facing two indexes showed different consequence. This means the process of community assembly in west-facing and northwest-facing is more complicated. This problem need further study to explain.