绿洲化-荒漠化土地时空格局变化对比研究——以黑河中游临泽县为例

Analysis on the Spatio-Temporal Evolution of Oasis Formation and Desertification: A Case Study of Linze County in the Middle Reaches of Heihe River,Gansu

利用临泽县近35 a共5期Landsat影像,得到该区绿洲-荒漠土地变化数据,结合自然景观特征和绿洲初始范围进行分区,开展土地利用变化指数和时空变化指数对比研究,结果表明:1绿洲化-荒漠化土地从整体到局部的变化特点为绿洲扩张而荒漠退缩,但自北向南空间上表现出整体有序到离散无序的变化以及土地变化的热点区域随时间迁移的现象。2绿洲化-荒漠化土地变化的主导因素是人文,制度政策成为阶段性变化的根本原因,个人意愿与响应是变化的直接原因,导致区域差异的主要原因是自然条件和移民。3临泽县绿洲-荒漠土地变化可分为生计驱动、经济驱动和生态-经济驱动3个阶段,在生态资源压力增大的背景下,未来的绿洲开发更需因地制宜,以防治土地沙漠化逆转和盐碱化扩张。

Taking Linze County in the middle reaches of Heihe River as example,5 periods Landsat remote sensing images including MSS（ 1977）,TM（ 1986,1993,2002） and ETM ＋（ 2012） were used to extract the spatialtemporal pattern change of oasis-desertification in this region,combined with the feature of the natural landscape and oasis initial scope,Linze County was divided into 4 sub-regions（ Ⅰ,Ⅱ,Ⅲ,Ⅳ） from north to south for comparison research. After that,we using the land use dynamic index and spatial-temporal variation index model to study the spatial-temporal pattern change processes of oasis-desertification land and their interactions in different regions,and the results showed that： 1 Oasis-desertification land change behaved as oasis expansion and desert retreat from local to overall region,but the characteristic of oasis-desert land change and the degree of desertification in different regions was disparate. Regional Ⅰ and are Ⅱ dominated by extremely severe desertification land,and they changed fast in 1986-1993 and 2002-2012 respectively,region Ⅲ changed fast in 1986-2002,and its degree of desertification was getting worse,from light desertification to severe and extremely severe desertification land,while region Ⅳ only distributed oasis and haven＇t changed much. 2 The spatial variation of oasis-desertification land from north to south were oasis-desertification ecotone change,spatial imbalance change in oasis fringe and internal of desertification land,fragmentation of desertification land respectively,the changes in region Ⅳ is mainly city expansion in the north. 3 The human factors were the dominant factor of oasis-desertification land change in Linze County,institution and policies become the root causes of the periodic change,while the personal wishes and the responses were the direct cause,the main reason of the regional differences was the natural conditions and immigration. 4 Oasis-desertification land change can be divided into three stages： the livelihoods drive,the economic drive and the ecological-economic drive,in the context of the ecological resource pressures,the future development of oasis needs to adjust to local conditions and pay more attention to reversing of desertification and expansion of salinization.