Research Of Vegetation Coverage Distribution Changes Of Alpine Grassland Based On 3S Technology

Vegetation coverage is important eco-climatic parameters, it is also an important characterization of surface vegetation status. Vegetation cover change has great significance on alpine grassland ecosystem change, change in grassland communities, regional hydrology and the whole structure of alpine ecosystem.In this study, we estimated the vegetation coverage of alpine grasland by use improved second sub-pixcel model of remote sensing and NDVI vegetation index. We also discussed dynamic changes in vegetation cover of research area by using methods of GIS spatial statiastical analysis and multivarable statitical analysis in detail. The main conclusions of the research are as follows:1. We took the Maqu county as an example, by using improved second sub-pixcel model of remote sensing, estimated the vegetation coverage of the year 2000,2002,2004,2006 and 2008 in alpine grassland. The results indicate the average vegetation coverage of research area was 66.17% in 2000, 56.41% in 2002, 57.34% in 2004, 77.38% in 2006, and 58.93% in 2008.2. Based on the estimation of 5 years' (2000, 2002, 2004, 2006 and 2008) vegetation coverage, the mean vegetation coverage of these 5 years was analyzed with GIS spatial statistical analysis, and then achieve a estimation for the dynamic process of space and trends in vegetation coverage of Maqu County from year 2000 to 2008. The results shows that from year 2000 to 2008, the alpine grassland vegetation coverage is overall downward, level1 vegetation resulted in more serious degradation. Grassland vegetation mainly transferred from excellent to low-grade, which further verified the degradation trend of grassland in Maqu County.3. The change of vegetation coverage in spatial dynamic process resulted from desertification and degradation of grassland was also analyzed. The result showed that from 2000 to 2008, grassland desertification was developing to be more severe, and alpine meadow is the most serious degradation type in a variety of grassland types.4. Various factors leading to the vegetation coverage change in Maqu County were analyzed with PCA, and the results showed that under conditions of low productivity animal husbandry and animal husbandry output value labor factor is the main human factor that leading to the change in vegetation coverage in Maqu, growing season precipitation and temperature changes are a result of grassland vegetation cover changes in the main natural factors. which further indicates human activity is enormous in change of alpine grassland ecological environment.