Vertical distribution pattern of small mammal community diversity in the middle section of northern slope of Qilian Mountain,China

A survey of the elevational distribution of small mammal communities in the middle section of the northern slopes of Mt.Qilian,northwestern China was conducted from July to August 2001.Removal trapping was conducted using standard sampling techniques at 7 sites within an elevation of 1600～3900m in the study area.A total of 254 samples of 10 rodent species are collected during 6720 trap nights.The mammals are composed of 2 species of lagomorphs and 8 species of rodents.Of the species,Allactaga sibirica(23.27%) is most abundant.Next is Dipus sagitta(17.96%),followed by Cricetulus barabensis(15.10%)and C.longicaudatus(13.88%).They are the most commonly trapped species in the region,accounting for 70.20% of the total catch.Correlation,regression and graphical analyses show diversity of the mammals along elevational gradient to be unevenly distributed.The results further show humped-shape relationships between species richness and diversity,and elevation;and a transect is noted between diversity peaks and middle elevations.A negative correlation is also noted between relative abundance of the mammals and elevation.Maximum diversity of rodent species occurs at mid-elevations where plant diversity and primary productivity are at maximum.