The grey correlative degree analysis of rodent population number and annual precipitation

Rotational grazing is a main utilization types in the Alxa desert grasslands. The live trap method was used to investigate the rodent population in the rotational grazing grassland area of Jiaergelesaihan town during 2002 to 2008. The field survey was carried out at the beginning of April, July, and October in every year. Four sample plots with the size of 10 ha were randomly chosen every time. 500 clips were put in the each plot with 100 clips in a line, and the distance between clips was 5 m and the distance between lines was 50 m. The grey correlative degree was applied to determine the relationship between the capture rate of main rodent species and annual precipitation. This study showed that total capture rate of rodent was significant positive correlation with annual precipitation (r=0.390 5, P0.05), and the order of correlative degree between main species and annual precipitation was Dipus sagitta＞Allactaga sibirica＞Phodopus roborovskii＞Spermophilus alaschanicus＞Meriones meridianus＞Cricetulus barabensis. The response of Jerboa to the precipitation was more obvious than other species. The grey incidence coefficient of D. sagitta and A. sibirica with precipitation was 0.855 6 and 0.818 9, respectively. The response of M. meridianus and C. barabensis to the precipitation was weak, indicating that the grey incidence coefficient of them was 0.706 7 and 0.706 4.