Changes of land use and landscape pattern in Xichang city based on RS and GIS

Based on the three periods of remote sensing images (TM in 1989, ETM in 1998, ASTER in 2008), the temporal and spatial variation of land use and landscape pattern in the recent 19 years in Xichang city in Sichuan province were analyzed by using RS,GIS technology and landscape ecological methods. The results showed that the main landscape types were forestland, grassland and cultivated land in the study area. And the area of forestland was largest, which accounted for more than 50% of the whole study area. During the recent two decades, the areas of cultivated land, grassland, unused land and water decreased continuously. Among them, the area of cultivated land decreased most, which decreased by 20.01%. The construction land and forestland increased obviously, of which the construction land increased by 64.55%. The changes of land use mainly concentrated in the Anning valley and the Qionghai basin, where the terrain was low and flat, the industry and agriculture distribution were centralized, and human-land conflict was intense. The mutual conversion among land use types was frequently due to the intervention of human activities. And the major patterns of 1and use change were the conversions of cultivated land to construction land and forestland, grassland to forestland and cultivated land, unused land to cultivated land and grassland, and water to cultivated land and construction land. From 1989 to 2008, the landscape diversity index decreased from 1.323 to 1.256, the landscape evenness index decreased from 0.738 to 0.701, and the dominance index increased from 0.469 to 0.536, which indicated that landscape heterogeneity reduced in the study area.