Study on the Dynamically Monitoring and Simulating the Vegetation Cover in Northwest China in the Past 21 Years
MA Ming guo 1 , DONG Li xin 2 , WANG Xue mei 3 (1. State Key Laboratory of Frozen Soil Engineering, CAREERI, CAS, Lanzhou Gansu 730000,China; 2. Qinghai MeteorologicalInstitute, Xining Qinghai 810001, China; 3. Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences, Lanzhou Gansu 730000,China)
The study area of this paper is Northwest China. The data is 8 km AVHRR from 1981 to 2001. The average value method, difference value method were used to analyze the annual and interannual changes. The linear regression of one variable was used to simulate the change trend of the maximal NDVI values and calculate the change quantity. As a result, the vegetation cover reaches the best condition between July and August in each year. During the last 21 years, the vegetation degradation is popular in most of Northwest China. However, there are some regions where vegetation cover is increasing. But the increasing range is smaller than the decreasing range on the whole. The simulating results indicate that the improved regions of vegetation cover mainly appear in west and north parts of Uygur Autonomous Region of Xinjiang.