Study On Dynamic Change Of Vegetation And Desertification Assessment In Plain Of Qitai County

Vegetation is the main component of ecosystems, there is the basis of the ecosystem, but also link the soil, air and water to naturally "bond." In arid and semi arid areas of minor changes in vegetation are likely to cause wind erosion, reduced vegetation cover and vegetation species change is a sensitive indicator of desertification, vegetation reflects the arid and semi arid areas of hydrology. Vegetation degradation is both the causes of desertification is the result of desertification occurs, but also the most visible signs of desertification. Based on TM image, investigation and statisties data, the paper has studied the dynamic change of the vegetation coverage, the stutus of desertifieation in Qitai County of Xinjiang Uygur Autonomous Region with the methods of integrated TM image proeessing, quantitative analysis, the advices of desertifieation controlling also has been given in the paper.This study is to use as Transfer Model and NDVI derived density models such as the decomposition study area to estimate vegetation coverage,to estimate the Qi tai plain area vegetation cover from TM images, a model is set up using pixel decompose density model.The area and spatial charaeteristics of vegetation cover change over study area in l986 and 2006 are studied on the basis of above approach, and the results indicate that the main transformation of vegetation coverage change is reclaimation, which accounts for 39.04% of the conversion of land. Two charaeteristics of vegetation cover change in study area are: the area of natural vegetation coverage is decreasing, however, the area of cropland increases ruptly, and human activity is the main factor which inducing the change of vegetation coverage.Applied the rain-use efficiency of vegetation as a key assessment indicator, regarded the situations in1986 as a benchmark, the desertifieation degree over Qi tai plain area in 2006 is assessed. Results show that desertifieation area is 37.64% of the assessment area in 2006, however, the area of less desertifieation area is 98.41% of the desertifieation area, it is implied that desertification degree of the assessment area is not serious in 2006, the difficulty to control desertifieation is relatively small.