Distribution patterns and driving factors of grassland plant diversity along a precipitation gradient on the Qinghai-Tibet Plateau
The distribution patterns of plant diversity in the Qinghai-Tibet Plateau vary across spatial scales.How-ever,the factors that drive these patterns are still unclear.We investigated plant community and soils in 33 grass-land sites along a precipitation gradient from Qinghai-Tibet Plateau,and elucidated the patterns of plant species di-versity from three aspects:α,β,and γ diversity.Linear regression and structural equation modeling(SEM)were used to explore the direct or indirect factors affecting the distribution patterns of plant diversity.We found that α di-versity and γ diversity increased,while β diversity decreased with increasing precipitation.Increased precipitation enhanced α diversity directly by changing soil moisture and indirectly by increasing soil inorganic nitrogen content.Moreover,increased precipitation indirectly increased γ diversity by increasing soil N/P ratio and decreasing soil pH.In summary,changes of precipitation can alter soil physicochemical properties,and thus affect plant diversity at different spatial scales.