A Study On Phylogenetic Biodiversity-area Relationship Of Sub-alpine Meadow Plant Community In Qinghai-Tibetan Plateau

With the rapid development of molecular technology, a new research area named phylogenetic community ecology emerged based on the merging of phylogenetic biology and community ecology. Phylogenetic diversity (PD) is a measurement of biodiversity taking the phylogenetic relationship between taxa (evolutionary history) into account, hence contains information of species phylogenetic relatedness. In recent years, there are many researches using phylogenetic diversity to investigate the community assembly rules and the relationship between biodiversity and ecosystem functioning and stability. However, few studies have examined the spatial variation of phylogenetic diversity in natural communities. Yet the relationships between PD and area (termed PDAR) is analogous to species-area relationship (SAR), which characterizes the variation in the observed values of the phylogenetic diversity with increased sample area. Here I integrate phylogenetic diversity-area relationship with species-area relationship to study the mechanisms of community assembly.In this paper, based on the point patterns of plant species of the sub-alpine meadows in the Qinghai-Tibetan Plateau in two different habitats (natural and grazing), I simulated the PDAR and SAR according to different spatial point process, and then compare the simulation results to those observed in natural communities. I used three spatial point process models including homogeneous Poisson distribution, heterogeneous Poisson distribution, and homogeneous Thomas distribution which represents ecological process of random placement, habitat filtering, and limited dispersal respectively. We found that the limited dispersal hypothesis is the best in fitting the observed PDARs and SARs. Hence, we conclude that the limited dispersal hypothesis may be the main drivers of plant community assembly of sub-alpine meadows in Qinghai-Tibetan Plateau. Finally by examining the spatial distribution of Elymus nutans Griseb, we found that it is gathered on the space distribution and homogeneous Thomas distribution can very good fitting of the spatial distribution pattern.Also verify the limited dispersal hypothesis can explain very well species distribution pattern at the population level.