Abstract: The vegetation is important to maintain the ecological environment in northwest region,and it is affected by climate factors significantly.Dynamic monitoring of the vegetation variation could reflect the trend of climate change to some extent.In this paper,NDVI data and the corresponding temperature and precipitation data during 1981-2001 were used to analyze the temporal and spatial changes in vegetation coverage and the corresponding factors.The results showed that vegetation coverage in the Northwest region appeared a clear seasonal variation.The vegetation coverage reached its maximum in July and August with the rising temperature and increasing precipitation.From the inter-annual change in point of view,the growth of vegetation was also significantly different in dry years and wet years.It was poorer in dry year than that in wet year,and the difference in summer was larger than that in spring.Meanwhile,from 1981 to 1995 the vegetation coverage appeared improvement as a whole area but degeneration in some local areas from 1996 to 2001.

Key words: Northwestern region, Northwestern region, Vegetation coverage, Temperature, Precipitation