RESEARCH ABOUT ANALYSIS OF THE CAUSES OF ECOLOGICAL DEGRADATION OF THE PASTORAL AREAS IN QINGHAI—WITH THE CASE STUDY OF THE GRASSLAND DEGRADATION IN THE THREE RIVES

To analyzes the reasons for grassland degradation by the principal components of SPAA and studies.The result showed that.All the human factors and natural factors had impact on grassland in the region of study,but,The human factors are main reason for grassland degradation in all impact factors,especially the overloud of grassland,and plus the influence of the rat insect of nature disaster,for which most areas of grassland were turned into degradation and desertification more seriously.