Analysis of vegetation time-space dynamics and its effect factor in northwestern China

The vegetation's variation is very sensitive to climatic change and Human activates in Northwestern China. The vegetation distribution in Northwest of China since 1981 to 2003 is assessed with Normalized Difference Vegetation Index (NDVI) data. The vegetation season change is in accord with change of surface energy. And most of vegetation in Northwest China is related to rainfall. The value of drought index is in accord with the change of NDVI in Northwest China. More rainfall in spring or summer resulted in the increase of NDVI values in Shanxi, Inner Mongolia, Gansu, Ningxia, and Qinghai. But the NDVI in arid region, such as Xinjiang, has been little influenced by rainfall. The conclusion is that precipitation, melted snow or ice water, and irrigation are all the factors affecting vegetation growth.