四十年来嘉陵江中下游土地利用/覆被动态变化研究

运用GIS空间分析方法,以1960年1:5万地形图、1972年、1986年和2000年LandsatTM/MSS影像数据为基础,分析了1960─2000年40年来嘉陵江中下游地区各土地利用类型数量变化和空间变化特征。结果表明:1960─2000年间土地利用/覆被变化的总趋势是林地和草地减少,减少量分别为27087.0hm2和37696.5hm2,建设用地和耕地增加,分别增加15252.3hm2和14871.8hm2;但以1986年为界分为两个时期:1960─1986年土地利用的总趋势是林地大面积地转化为草地和耕地,林地面积减少;而1986─2000年间耕地向林地转化加快,导致林地面积有所增加,而耕地面积相对减少。在40年中建筑用地一直在增加。同时结合历史资料分析了自然和人文特别是政策因素在动态变化中所起的作用。

Dynamic Change in Land Use/Cover in Middle and Lower Reaches of the Jialing River

Based on Landsat TM/MSS images of the middle and lower reaches of the Jialing River in 1972, 1986 and 2000, and a relif map (1:50000 in scale) of the region in 1960, temporal-spatial changes in land use were analyzed, with the aid of GIS. The results indicated that from 1960 to 2000 a general declining trend was observed with forest land and grassland, which decreased by 27087.0 hm2 and by 37696.5 hm2 respecively, and a rising trend with built-up land and farmland, which increased by 15252.3 hm2 and by 14871.8 hm2, respectively. Before 1986, the dominant trend of the change was forestland being turned into grassland and farmland, so forestland dropped rapidly in area during the period from 1960 to 1986. However, since 1986, the trend has been reversed. Large areas of farmland have been yielded to forestland and grassland, leading to decrease in farmland and increase in forestland. And in the past 40 years, the area of built-up land has been expanding. Besides, the paper also analyzed driving forces of the change based on available historical documents.