Abstract: Based on NDVI from MODIS during the time period from 2000 to 2014, the spatial and temporal variation of vegetation in Shaanxi Province, China was analyzed using the methods of raster pixel trend analysis and stability evaluation. The vegetation change trends in the future were forecasted by R/S (Rescaled range analysis) method in Shaanxi Province. The correlation analysis was applied between annual temperature, precipitation and NDVI in Shaanxi Province. The results showed that the mean values of NDVI in 2000 and 2014 were 0.427 3 and 0.494 2, respectively, which indicated an NDVI increase of 0.067, or 16 % equivalently. The NDVI was increased significantly in northern region of Shaanxi and there was a negative growth in some parts of Guanzhong area, while the NDVI in southern region of Shaanxi was still maintained at a higher level and changed a little. The vegetation variation in Shaanxi Province has obvious spatial regularity. The areas with vegetation of little change accounted for 52.0 % in the whole province, while the areas with improved vegetation coverage accounted for 44.27 %, and the areas where the vegetation was degraded accounted for 3.73 %. It explained that the overall vegetation coverage in Shaanxi Province was improved in the past 15 years. The stability region of vegetation in Shaanxi Province accounted for more than 50% and the Cv value was between 0 and 0.1. The moderate area of vegetation accounted for 28% and the Cv value was between 0.1 and 0.2. The unstable area of vegetation in Shaanxi Province was less than 2% and the Cv value was greater than 0.2. It shows that vegetation condition was relatively stable in Shanxi Province in the past 15 years. The vegetation status was most stable in southern area of Shaanxi Province, southern area of Yan'an City while vegetation status varied greatly in some part of Yulin City, Xi 'an City and the southern part of Weinan City. The analysis of Hurst index showed that 44.54% area of vegetation in Shaanxi Province may face degradation of vegetation in the future. It is possibly distributed mainly in the northern area and the Guanzhong area. 49.78% area of vegetation in Shaanxi Province may face improving or degrading in the future which is mainly distributed in Yan’an City and southern area of Shaanxi Province. The annual temperature and precipitation showed an increasing trend in Shaanxi Province in the past 15 years and the increasing rates were 0.48 ℃·(10 a)-1 and 69.5 mm·a-1 respectively. The correlation analysis results showed that the annual precipitation was the main meteorological factors affecting the NDVI. The changes of vegetation in Shanxi Province had also been influenced by artificial factors such as the project of returning farmland to forest and grass, sand prevention and ecological politics.

Key words: vegetation, MODIS, NDVI, trend analysis, stability evaluation, Hurst, Shaanxi