Spatial Distribution Patterns And The Underlying Mechanisins Of The Alpine Meadow Veaetation In Tibetan Plateau

The spatial distribution of a species arises from interactions among various endogenous and exogenous processes. Determining the processes influencing these patterns can help describe the mechanisms of species diversity maintenance at different temporal and spatial scales. We investigated the spatial structure of herbaceous vegetation and the processes maintaining their patterns in a species-rich alpine meadow of the eastern Tibetan Plateau using quadrat sampling at two spatial scales (0.25and1.0m2). Measured species were highly spatially aggregated. At both spatial scales, biomass and density explained the majority of variation in aggregation, whereas there was no evidence for an effect of mean seed mass on aggregation intensity. The effects of soil nutrients (C, N and P) at different depths affected plant abundance most at the broader spatial scale. Point pattern analysis of30plants in a spatial scale of10×10m showed that except by abundance, species cluster size was also determined by its dispersal mode and reproductive mode. Our results demonstrate that self-thinning, local dispersal and habitat heterogeneity all contribute to determine the spatial aggregation patterns in alpine meadow vegetation in the eastern Tibetan Plateau.