基于RS和GIS的西昌市土地利用及景观格局变化

为了解西昌市土地利用及景观格局时空变化特征，以3期遥感影像（1989年TM、1998年ETM和2008年ASTER）为数据源像，利用RS、GIS技术和景观生态学方法，对研究区1989－2008年土地利用和景观格局时空变化特征进行分析研究。结果表明，研究区景观要素类型以林地、草地和耕地为主，其中林地面积最大，占50%以上。近20年来，耕地、草地、未利用地和水域面积持续减少，其中耕地减少幅度最大，减少了20.01%；建设用地和林地显著增加，分别增加4?861.31和7?609.46 hm2，其中建设用地增加了64.55%。景观要素明显变化的区域主要集中在地势低平，工、农业集中，人地矛盾异常突出的中部安宁河谷和东部邛海盆地。由于人类活动的干预，研究区景观要素类型相互转化较为频繁，主要表现为耕地转为建设用地和林地，草地转为林地和耕地，未利用地转为耕地和草地，水域转为耕地和建设用地。1989－2008年研究区多样性指数和均匀度指数分别从1.323和0.738下降到1.256和0.701，优势度从0.469上升到0.536，表明景观异质性程度有所降低。

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.