Abstract: Biodiversity is crucial to maintaining ecosystem functions and services. Combining species,phylogenetic and functional diversity to understand the mechanism of community assembly are necessary. This study took the Inner Mongolia Stipa breviflora desert steppe community as the object,and analyzed the response of different dimensions of biodiversity to different stocking rates (control,light,moderate and heavy grazing). The results showed that each grazing treatment significantly reduced species richness,Simpson,Shannon-Wiener and Pielou index. Furthermore,both moderate and heavy grazing treatments reduced phylogenetic diversity. Each grazing treatment significantly reduced community functional richness (FRic),functional differentiation (FDiv),functional dispersion index (FDis) and Rao quadratic entropy index (RaoQ). Both moderate and heavy grazing treatments significantly reduced functional evenness (FEve). Overall,functional diversity showed a gradually decreasing trend with the increase of grazing intensity. In addition,there were significant or extremely significant correlations between species,phylogenetic,and functional diversity. In conclusion,the study of biodiversity in different dimensions is conducive to understanding the mechanism of plant community assembly,and provides a theoretical basis for rational utilization and sustainability of grassland.

Key words: Desert steppe, Grazing, Functional traits, Phylogenetic structure

摘要： 生物多样性对维持生态系统功能与服务至关重要,结合物种、谱系及功能多样性理解群落构建十分必要。本研究以内蒙古短花针茅(Stipa breviflora)荒漠草原植物群落为对象,研究了对照、轻度、中度及重度放牧下不同维度生物多样性对不同载畜率的响应。研究结果表明:各放牧处理均显著降低物种丰富度、Simpson、Shannon-Wiener及Pielou指数。此外,中度和重度放牧处理均降低了谱系多样性。各放牧处理均显著降低了群落功能丰富度(FRic)、功能分异度(FDiv)、功能分散指数(FDis)及Rao二次熵指数(RaoQ);中度和重度放牧处理显著降低了群落功能均匀度(FEve)。总体而言,随放牧强度的增大,群落功能多样性呈现出逐渐降低的趋势。此外,物种、谱系及功能多样性之间存在显著或极显著的相关性。总之,对不同维度生物多样性的分析有利于理解植物群落构建机制,为草地合理利用及可持续性提供一定的理论基础。

关键词: 荒漠草原, 放牧, 功能性状, 谱系结构