A study on vegetation coverage change in Korla City based on the TM NDVI

The vegetation coverage changes in Korla region have crucial impacts on local and regional climate, agriculture and economy. This study uses the Landsat TM data to investigate the vegetation coverage changes in this region from 1990 to 2011 (four periods in 1990, 1998, 2006, and 2011). The vegetation coverage is calculated using the NDVI data, derived from raw TM images, and a mixed pixel model. We further classify the vegetation coverage into four categories and analyze the main characteristics of its changes using transpose matrices of each vegetation coverage category and land use data. The results show that, overall, the vegetation coverage has improved from 1990 to 2011 in the Korla City region. The area with increased vegetation is 23.8% higher than that with decreased vegetation. The vegetation coverage in southeastern sector oasis plain greatly increased, while vegetation degraded in the north and south region.