近20a三峡库区农林地利用变化图谱特征分析

土地利用变化图谱单元能够把表示"空间单元特征的图"与表示"时间发展之起点与过程的谱"合为一体,并建立起空间—属性—过程一体化数据信息。论文以TM/ETM影像为空间数据源,构建三峡库区1990—2000年和2000—2010年两个阶段农林地利用变化信息图谱,以及融合1990、2000、2010年这三个时期土地利用现状的变化模式图谱,以探讨库区近20 a来的农林用地变化轨迹和特征规律。结果表明:1 1990—2000年阶段的农林地利用变化图谱主要以农林地间及其和草地互换、建设用地占用农林地的图谱单元类型为主。空间差异上最为显著的是"耕地→建设用地(编码15)"、"草地→林地(编码32)"和"林地→草地(编码23)",空间分离度较低。2 2000—2010年阶段的农林地利用变化图谱单元分离度增大,农林地利用发生转换空间进一步扩张。最显著变化的是"耕地→林地(编码12)"和"耕地→建设用地(编码15)"图谱单元类型,其次是农林地转换为水域图谱类型(编码14和24)的面积增大。3库区农林地利用变化模式以前期变化型和后期变化型为主,反复变化型和持续变化型发生概率较小,库区农林地利用的转换具有明显的时间阶段性特征。

Geo-Spectrum Based Analysis of Crop and Forest Land Use Change in the Recent 20 Years in the Three Gorges Reservoir Area

The Geo-spectrum unit of land use change can unify "the map expressing the spatial cells" and "the spectrum expressing the starting point and the process of phenomena" , and can establish the integrated space-property-process information. Supported by 3S technology, this paper built Geo-spectrum information of crop and forest land use change in the Three Gorges Reservoir Area at two stages (1990-2000, 2000-2010) based on TM/ETM images and auxiliary image interpretation, and also built Geo-spectrum of crop and forest land use change model which combined land use information of three periods (1990, 2000, 2010). Then the change trajectories, characteristics and laws of crop and forest land use in the Three Gorges Reservoir Ar-ea are discussed. The results showed that: 1) The interchange among crop land, forest land, and grass land, the crop land and forest land occupied by building land were the main ways of cropforest land use conversion throughout the 1990-2000 phases in the Three Gorges Reservoir Area. The change of crop land to building land (code 15)" , "grassland to forest land (code 32)" and "forest land to grassland (code 23)" were the most marked types in spatial differences, and the spatial isolation of them were low. 2) The isolation of Geo-spectrum unit of crop and forest land use change increased during 2000-2010, and the spatial scale of Geo-spectrum unit of crop and forest land use change further enlarged during 2000-2010. The most marked types were the change of "crop land to forest land (code 12)" and "crop land to building land (code 15)" . The second marked types were that of crop and forest land use flooded by water body (code 14 and 24). The area of this type enlarged. 3) The change in earlier stage and later stage were the main ways of crop and forest land use change in the Three Gorges Reservoir Area, so the transformation of crop and forest land use have obvious characteristics of stages.