关键词: 荒漠, 景观破碎化, 啮齿动物群落, β, 多样性

Abstract: This study was conducted in four different habitats of the Alax desert of Inner Mongolia including a grazing-prohibited site,a rotational-grazing site,an over-grazing site and farmland. Rodent communities were sampled using snaptraps for a single day each month during April,July and October from 2002 to 2010,and beta diversity of rodent communities in
the different habitats was analyzed. The characteristics of shrub communities also were analyzed to investigate landscape fragmentation under different disturbance conditions. The variation of the four habitats along with gradient were divided into six classes based on the amount of landscape fragmentation. The Jaccard’s diversity index,Sorenson’s diversity index and Cody diversity index were used to analyze the variation in the beta diversity of the rodent communities. The results showed that the three beta diversity indices differed significantly among all gradients between habitats (P < 0.05),and the variance was the most obvious between grazing-prohibited areas and the over-grazing site in the gradient. The Shannon-Wiener index, Simpson index and the species number in the shrub communities were significantly different among studies sites (P <0. 01),and showed the following trends:rotational-grazing site > over-grazing site > grazing-prohibited site > farmland. The region was considered a fragmented landscape if the degree of variation for environment conditions and the beta diversity was similar. In addition,the main reason for the landscape fragmentation in the region was the human-caused disturbance,
particularly the grazing activities,which drove the heterogeneity of environment significantly. The beta diversity increase along with the increase of environment gradient lead to heterogeneity,which was caused by the increase in difference and variation of the species composition between rodent communities rather than the increase of species in arid desert region.

Key words: Beta diversity, Desert, Landscape fragmentation, Rodent community