中文摘要：

这研究从 2000～2007 用规范的差别植被索引( NDVI )数据在西藏区域调查植被的最近的分发变化趋势 .It 也在典型区域讨论植被降级的原因(例如 Nagqu )基于气候的条件，人的活动，并且有最好的植被的区域盖住的另外的影响 factors.Results 表演在 Nyingchi 和 Shannan 的南部的部分，由 Chamdo ，拉萨区域，和 Nagq 的东方部分列在后面

英文摘要：

This research investigates the recent distribution variation trends of vegetation in the Tibet region using Normalized Difference Vegetation Index （NDVI） data from 2000 to 2007. It also discusses the causes of vegetation degradation in typical regions （such as Nagqu） based on climatic conditions, human activity, and other influencing factors. Results show that the areas with the best vegetation cover are in Nyingchi and the southern part of Shannan, followed by Chamdo, the Lhasa area, and the eastern part of Nagqu. Vegetation in various regions exhibits significant seasonal differences. The vegetation status has improved in some parts of the Tibet region in the past few years, while the areas with the most serious degradation are in the middle and southem parts of the Nagqu region. On average, distinct vegetation degradation occurred between 2003 and 2006 in the whole Tibet region but vegetation has been increasing since 2006. The vegetation cover in summer basically determines the annual vegetation status. An increase in precipitation and decrease in wind speed generally corresponds to an increase in vegetation cover. The reverse is also true： a decrease in precipitation and increase in wind speed correspond to the decrease in vegetation cover. NDVI is thus positively related to temperature and precipitation but has a negative relation with wind speed. Increasing temperature and decreasing precipitation have led to the present vegetation degradation in Nagqu, and vegetation in all of these regions has been affected by growth of human population, intensified urbanization, livestock overgrazing leading to the proliferation of noxious plants, extraction of underground minerals and alluvial gold, extensive harvesting of traditional Chinese medicinal plants [e.g., Cordyceps sinensis, Caladium spp., and saffron crocus （Crocus sativus）], and serious rodent and other pest damage.