Response of vegetation to variation in climate and groundwater in the Qaidam Basin

The vegetation cover fraction in the Qaidam Basin was estimated by MODIS NDVI in the period of2000—2013 and its dynamic variation was also discussed in this paper. The results indicate that the areas of bare soil and low-density vegetation presented rate decrease with time. On the other hand,the areas of medium,medium-high and high density vegetation show increasing trends with year. The climate variables,elevation,water table depth and total dissolved solid( TDS) were the main impact factors for the vegetation change. The vegetation change has positive correlation with the air temperature and precipitation. The dependence of vegetation on groundwater is more complicated: shrubs of Phragmites australis,Artemisia desertorum and Tamarix ramossissima Ledeb are sensitive to water table depth and the vegetation growth is well when the water table depth is shallower than 2 m. Nitraria Schoberi L. reflects less dependent on water table depth. Vegetation can develop well when TDS is smaller than 3 g / L.