Abstract: The rodent densities were investigated by rectilinear trap-day method in fenced pasture (667ha) and natural pasture in Zhengxiangbai County,Inner Mongolia in the middle ten days of May to September of 1987-1992.3486 rodents which belong to 6 species,3 families were captured by 16350 trap days.The results showed that there were significant changes of rodent composition among years.The brandt’s vole(Microtus brandti) was the dominant species,which took up 90% of all the rodent species,in both fenced pasture and natural pasture in 1987 and 1988.Then,the density of brandt’s vole decreased sharply from 1989,and only one brandt’s vole was captured in 1990 and 1992 respectively.The composition of rodent species changed greatly from a community composed of mainly brandt’s vole to a community composed of mainly striped hairy-footed hamster (Phodopus sungorus) and ground squirrel (Citellus dauricus).The seasonal changes of rodent composition was also obvious.The causes of composition and dynamics of rodents were analysed also in this paper.

Key words: Typical steppe, Rodent composition, Dynamics

摘要： 1987－1992年5～9月,每月中下旬作者在内蒙古正镶白旗天然草场和10000亩围栏草场上,利用直线法调查鼠的种类组成和密度,共调查16350个夹日,捕获鼠3486只,隶属3科6种;鼠类组成年度差异较大,1987和1988年围栏内外,布氏田鼠为优势种,在鼠类中所占比例均在90%以上,1988年之后该鼠显著减少,到1990、1992年每年仅能捕到1只。经过6年调查,鼠种组成发生了变化,由布氏田鼠为主的群落演替成以黑线毛足鼠和达乌尔黄鼠为主的群落;种群数量的季节和年度变化明显;文中就各种变动的原因进行了初步分析。

关键词: 典型草原, 鼠类组成, 数量变动