Vegetation Dynamics in Arid and Semi-Arid Ecotone - A Case Study in Yanchi County

Land degradation and, its extremes, desertification continue to be the most significant environmental issues in arid and semi-arid area of China, especially in transition regions where the vegetation is more sensitive to climate change and human activities. Desertification is mainly resulted from climatic variations and human activities. Vegetation coverage and its changes are easy to be interpreted from satellite images and are often considered as preferred indicators of desertification in arid, semiarid, dry subhumid areas. In the paper, we explored the vegetation dynamics with SPOT/Vegetation data from 1999 to 2006 and its relation to precipitation. The vegetation wasn´t suffering extensive deterioration during the drought bagun in 2004. The desertification speed has been decelerated after 1999. Land use change data visual-interpreted from Landsat and CRERS indicates the eco-friend policies and actions, such as grain-for-green, reforestation, and fixation of sand dunes, affected the regional land use change processes with grain-for-green land and vegetation restoration area increased 4.7% and 3.1% from 2000 to 2005 respectively. The positive human activities are the crucial cause in alleviating and decelerating desertification.