Ecological change of the source region of Three Rivers during last 30 years based on satellite and ground observations

The source region of Yangtze River, Yellow River and Lancang River is the most important surface water origin of China. With recent serious regional events (i.e. 1998 Yangtze flood, flow cutoff of Yellow River), the ecological conservation of this region has aroused more attention and practical measures. To examine the ecological change of the region after national strategy of ecological conservation there, the satellite and ground-based observations are adopted to analyze the spatial and temporal change of vegetation covers during 1981~2007. The results indicate that during 2000-2007, the spatial vegetation expanding trend is obvious in the Source Region of Three Rivers, which results in about three fourths of total region with the vegetation density above 60%. This ecologically positive vegetation variation in this region can be attributed to both the favorable trend of heat/water climate conditions and the strong protecting measure within the conservation area.