Studies On Rodent Communities In Desert Under Different Disturbances And Scales In Inner Mongolia

Based on overall investigation upon fauna and species distribution characteristics of rodents in Alashan Desert, the four kinds of study areas under different human disturbance were selected in typical region in Alashan Desert of Inner Mongolia from 2002 to 2004, i.e. farmland, rotational grazing, over-grazing and forbidden grazing areas.The rodent communities in the four kinds of study areas were investigated by using trap-day and mark-recapture methods on three principal scales: 1hm~2, 10hm~2 and 40hm~2. The data on the above-mentioned scales was analyzed on composition pattern and dynamics, characteristics of diversity and evenness, similarity, niche characteristics, the correspondence between rodent species and disturbance, the correspondence between rodent species and scale, the relationship between rodent species and habitat, the relationship between rodent communities and climate factors, the sensitive response of dominant populations.At the same time, the rodent communities were studied by fractal analysis and wavelet analysis on five spatial scales. Based on, which, the sampling reasonable scales in four different disturbances areas were defined, and then the concept of"manifestation scale"was advanced. In addition, in this paper, the pattern-process-scale of rodent communities in different disturbances was analyzed, and then the characteristic of ecological process of rodent communities was definite under different disturbances in during the course of desert ecosystem fragmented. The results are as follows:(1) The rodents in Alashan Desert belong to 2 orders, 6 families and 24 species, and were as 44.4% to all of recorded rodents in Inner Mongolia. Especially, the rodents of Dipodidae in the region were as 87.5% to those of Inner Mongolia, and the region is the concentrate region of rodents of Dipodidae distributed in Inner Mongolia. The rodents also belong to 9 distribution patterns of 3 types. The arido-tolerent distribution pattern was the principal part in the region.(2) Comparing to three methods of measuring niche breadth indices, Shannon-Wiener Index was more suitable to measure niche breadth of desert rodents than others. Compared to three different measuring methods of the niche overlap indices by Principal Component Analysis, Pianka Index was more applicable to measure the niche overlap of desert rodents than others.(3) The niches were highly overlap that the desert rodents under different disturbances in different season. The Pianka niche overlap indices of 17 species-paired were highest and varied from 0.9 to 1.0, and even reached 1 that was overlap completely. The results about it in this paper support the viewpoint that many species could occupy the same niche.