| Based on the preciption and temperature data of 12 weather stations of the northeastern Qinghai-Xizang plateau from 1961～2000,the climate varieties of agro-pastoral zone in the northeastern Qinghai-Xizang Plateau and their impact on vegetation were analised.The results show that from the end of 1980s the climate changing character shows a warm-drying trend in this area.Because of the climatic warm-drying,over pasturing,damage by wild rat,inscet pest and over exploiting,the yield of grassland and the average density of pasturing grass has apparently decreased,the grass land vegetaion is sparsing and degeneration trend is severe. |