Characteristics of spatial- temporal changes in vegetation coverage in Yan'an region during 2000- 2013

Because ecological environment is fragile in Yan'an region,the main objectives were to improve the vegetation coverage. This research calculated and analyzed the vegetation coverage from 2000 to 2013 in Yan'an region by the data of MODIS and two sub- pixel model. The results were as follows: Form the time scale,the vegetation coverage had a slight fluctuation growth. The peak and valley were similar to the interannual change of precipitation. The growth trend was mainly due to the factors such as national policy. For spatial scale,the areas of relatively high vegetation coverage was distributed in southwest and southeast,however,the vegetation coverage was small in west,north and northeast. The vegetation coverage was consistent with the natural geographical characteristics and contrary to the terrain trend in Yan'an region,moreover,it was also significantly correlated to the distribution of water resources. It reflected the effects of altitude,topography and water resources on the vegetation coverage.