基于SPOT4数据的黄土高原植被动态变化研究

Study on the Dynamic Changes of Vegetation in the Loess Plateau Based on Data from SPOT4

以SPOT4／VEGETATION数据为基础，以NDVI变化率和年均NDVI值作为植被覆盖动态变化的指标，分析了1998～2005年黄土高原植被覆盖的时空动态变化特征。结果表明黄土高原地区植被动态变化显著增强，1998～2001年黄土高原的植被覆盖有所减少，幅度约为10．5％，2001年后，植被活动显著增强，植被覆盖面积呈增加趋势，2004年后稍有回落。植被生长季的延长和生长加速是该区域NDVI值增加的主要原因，黄土高原地区植被增加和减少的区域相互交错，这一特性是由农业生产活动、城市建设、政府决策及植被对气候变化的响应等综合因素作用的结果。

Changes in vegetation distribution of Loess Plateau during 1998-2005 are discussed in this paper based on SPOT4/VEGETATION data. The ratio of NDVI and the annual mean NDVI were used as the indices to show the dynamic changes. The conclusion is that those changes have been greatly enhanced during the past few years. The vegetation cover had decreased since 1998, however, after 2001 it has been increased significantly, for the Grain for Green Project, even though a little rebound in 2004. Both growth rate and growth period have a great impact on NDVI. Changes in vegetation distribution have taken place in so many different areas. This phenomenon is caused by a variety of factors such as farming, urban planning and weather changing.