Abstract: Structure of rodent community reflects the characteristics of ecological environment. This study systematically analyses species distribution patterns and community diversity of the rodents in the Mt. Helan National Nature Reserve, Inner Mongolia, an "isolated island" in Alashan desert area. The reserve is divided into five habitat types, with a total of 18,748 effective clip days in spring, summer and autumn in 2013. Our project captured two hundred-thirty-five rodents, belonging to 13 species, 11 genera, 5 families in 2 orders, in the area, among them Spermophilus alashanicus is the dominant species. The results indicate that the taxa favored for moisture environment and habitat are the main composition of the community, accounting for 54% of the rodents captured, echoing the unique geographical location and environment of the Mt. Helan, where proportion of moisture environment and habitat increases following increased altitude in the middle and low elevations. According to indices of "edge effect", rodents in the deserts of mountain and grassland, and mountain grassland shrub exhibit a higher density of the community than those in other habitats. In addition to environmental factors, such diversity pattern may have been shaped by the two factors: the increasing number of species, and the evenness of species distribution. The results of redundancy analysis show that vegetation height and coverage, shrub (tree) height and altitude, are the most important environmental factors driving the formation of rodent community. Interestingly, different from the others, vegetation coverage is negatively correlated with community diversity index decreases following the increased vegetation coverage.

Key words: Mt. Helan, Inner Mongolia, Rodents, Distribution type, Community diversity, Environmental factors

摘要： 啮齿动物群落结构可以反映生态环境特征。本研究对处于阿拉善荒漠区呈“孤岛”状态的内蒙古贺兰山国家级自然保护区内啮齿动物的种类、分布型及群落多样性进行系统研究。将内蒙古贺兰山划分为五种生境类型，于2013年春、夏、秋3季共布设有效铗日18748个，捕获啮齿动物235只，分属2目5科11属13种。在整体研究区域，阿拉善黄鼠（Spermophilus alashanicus）为优势种。明确了喜湿型是本研究区域的主要分布型，占捕获啮齿动物的54%，并且在中低海拔区域，随着海拔的升高，喜湿型所占比例增加。受“边缘效应”的影响，山地荒漠和荒漠草原生境以及山地草原灌丛生境的啮齿动物群落多样性指数高于其他生境，除环境因素外，啮齿动物群落的多样性受两种因素的影响，既可随群落内物种数量的增加而增大，同时又受制于群落内部物种分布的均匀程度。冗余分析结果表明，植被高度、植被盖度、灌木（乔木）高度和海拔4个环境因子是决定啮齿动物群落结构最主要的环境因子，其中植被盖度与群落多样性呈负相关，随着植被盖度的增加，多样性指数随之减低。

关键词: 内蒙古贺兰山, 啮齿动物, 分布型, 群落多样性, 环境因子