Grassland Sandification Dynamic Monitoring And Landscape Pattern Analysis Of Maqu County In Source Region Of Yellow River

Grassland sandy desertification is one of the main reasons that the grassland ecosystem degradation and productivity decline continuously. Under many synthetical factors, the area of desertification grassland extended quickly and the degrees of desertification turn worse continuously in the last five decades in Maqu County. The special geographical position and ecological function makes the grassland desertification of this district have the typical features and important research significance. Based on the data of TM images, the historical data and investigated results through the GPS Land-based positioning, the present situation of natural grassland desertification of Maqu County was investigated and contrasted with the Monitoring result of the last 14 years. The result showed that:(1) The area of the desertification grassland increased evidently in this region. The total area of the desertification grassland in Maqu County is 7136.77hm2. Contrasted with the 1999, it had increased 1056.77hm2, the total growth rate is 17.38% and the Annual mean growth rate is 4.35%. Mobile dune and semi-fixed sand land are the main causes of desertification land increase.(2) The degrees of regional desertification were serious. The area of mobile dune, semi-mobile sand land and fixed sand land of the current desertification area occupies respectively 35.5%, 12% and 52.5% of total. The percentage of the severe and very severe degrees is 41.4% of the total area. The slight degrees and moderate degrees is 31.4% and 27.2%.(3) The desertification land distributions show the certain orderliness. The desertification land distribute mainly in fluvial terrace and alluvion. Fixed sand lands and semi-fixed sand lands are the main type of the desertification grassland, their distribution concentrate correspondingly in the alluvion and the overgrazing grassland, while the mobile dune intersperse on the fluvial terrace and alluvion of river bend.(4) The range of desertification extended gradually. The distribution range of desertification extends to the upper stream and lower reaches of the Yellow River, and the drainage area of desertification land reached 186.12km long, which occupies 43% of the Yellow River basin in Maqu County. The desertification grassland extends its distribution area, from the fluvial terrace and alluvion to part of the degenerate grassland and the marsh margin.(5) The development of the regional desertification shows a wide potential range. Fixed sand lands and semi-fixed sand lands have large percentage of the current desertification land types, they are the main type of mobile dune is converted. In addition,potential sand land of 3616.07hm2 is main source of desertification land in the future. If the potential sand land is...