Abstract: The study of species diversity and phylogenetic diversity of desert steppe community under different stocking rates is helpful to reveal the formation and maintenance mechanism of plant diversity. This study took Wulanqab desert steppe as the object to explore the effects of different stocking rates on species diversity and phylogenetic diversity of grassland community,and also explore the effects of environmental factors on species diversity and phylogenetic diversity. The results showed that grazing decreased the species and phylogenetic diversity of plant communities;The phylogenetic structure showed an aggregation state. Shannon-Wiener index,Simpson index,species richness index and Pielou index were significantly positively correlated with the phylogenetic diversity index,indicating that the higher the species diversity,the higher the phylogenetic diversity. Soil water content and soil organic carbon were the main factors affecting phylogenetic diversity,soil organic carbon content was the main factor affecting phylogenetic structure,and ammonium nitrogen was the main factor affecting Shannon-Wiener,Simpson,and Pielou index.

Key words: Desert steppe, Grazing, Phylogenetic diversity, Species diversity

摘要： 研究不同载畜率下荒漠草原群落物种多样性与系统发育多样性有助于揭示植物多样性的形成和维持机制。本研究以乌兰察布荒漠草原为对象，探究不同载畜率对草地群落物种多样性和系统发育多样性的影响，同时还探究了环境因子对物种多样性和系统发育的影响。研究结果显示放牧降低了植物群落的物种多样性和系统发育多样性，系统发育结构呈现聚集状态。Shannon-Wiener指数、Simpson指数、物种丰富度指数及Pielou指数均与系统发育多样性指数呈显著正相关，表明物种多样性越高，系统发育多样性也越高。土壤含水量和土壤有机碳含量是影响系统发育多样性指数的主要因素，土壤有机碳含量是影响系统发育结构的主要因素，铵态氮含量是影响Shannon-Wiener指数、Simpson指数、Pielou指数的主要因素。

关键词: 荒漠草原, 放牧, 系统发育多样性, 物种多样性