干旱区生态环境知识资源中心

As an important factor of ecology, vegetation is not only enduring the climate change but also has a feedback on climate change positively. It is a sensitive indicator for environment change. Climate is the uppermost factor deciding vegetation type and distributing on the earth, while vegetation is the brightest reflection and integration symbol about climate. Using the distribution of arid and humid regions of China, the typical semi-arid/semi-humid region(Xilamulun river) as a study areas. Xilamulun river has important ecological significance because it is ecological conservation and water source protection area of Northern china. As an index of denoting basin's vegetation cover,NDVI is influenced by many climatic factors such as precipitation and average air temperature.The influence of precipitation on vegetation coverage of xilamulun river basin was qualitatively analyzed using multi-temporal Landsat TM (MSS) image during the recent 10 years,and analyze the vegetation dynamic changes in xilamulun river basin and its relationship with human activities. Firstly, the influence of exterior factor, such as phonology and relative radiometric correction, on NDVI was removed by normalization of different period remote sensing image. Preliminary Comparison of coverage in Xilamulun river,The coverage appeared to have a increase trend from 2000 to 2010. Therefore, Through protracted efforts the basin has made great achievements in the protection and nurturing of the ecological environment, of which afforestation is an outstanding example. Analysis of dynamic changes of the vegetation covers in two phases from 2000 to 2005, 2005 to 2010, respectively. The vegetation cover showed an 1 increased trend from 2000 to 2010, which increased significantly in 2000 to 2005.The spring and winter showed in the opposite direction change in 2000 to 2005, but the same direction change trend in 2005 to 2010 by synthesized analysis of relationship of precipitation and vegetation cover. There are also an opposite direction change trend in spring and fall in two phases. The main factors influencing the vegetation cover change is human activity rather than climate factors in 2000 to 2010. According to the comprehensive analysis of precipitation and related data of the protection of the ecological environment in BalM right banner, human activities were proven as the main reason of vegetation fraction change during 2000-2010, such as conversion of cropland to forest, ecological migration, afforestation by the BalM right banner. Finally, the residual analysis of NDVI indicates that human activities have promoted or destroyed the vegetation cover in some areas of xilamulun river basin.