Vegetation Coverage Change and Its Relationship with Climate Factors in Northwest China

【Objective】 This article aims to analyze the change of vegetation coverage and its relationship with climate factors in northwest China,to provide reference for the improvement of regional ecological environment.【Method】 Based on GIMMS/NDVI data,the spatial and temporal change of vegetation coverage and its relationship with temperature and precipitation by using mean NDVI,difference analysis,and correlation analysis were analyzed.【Result】 The increased regions of vegetation coverage mainly include: Xinjiang Tianshan,Tarim river basin,the southeast of Qinghai Province,the central and eastern of Gansu,Ningxia and Shaanxi.The decreased areas are mainly distributed in Xinjiang Tarim basin,Kunlun mountains,northwest of Gansu,and the edge of Ningxia and Gansu.Vegetation NDVI is strongly positively related to annual temperature,and significantly correlated to month average temperature,precipitation and accumulated temperature,and the correlation coefficients are 0.890,0.900 and 0.442.【Conclusion】Vegetation NDVI increased in northwest during 1982-2006 with a growth rate of 0.4%/10 a,vegetation coverage change is significantly correlated to the month average temperature and precipitation,and the response of vegetation change to temperature and precipitation have time lag.