乌兰布和沙漠地区土地利用动态变化分析

以乌兰布和沙漠为研究靶区,以GIS和RS技术为手段,利用解译的1986,1995,2000年和2004年的土地利用现状图,对该区域的土地利用动态变化过程及其驱动因素进行分析.结果表明:不同年份其景观基质差异较大,1986年为沙漠和其他未利用土地,1995年为沙漠和草地共同构成,呈现出复合型特点;而2000年之后,沙漠以其57%以上的面积而成为唯一的景观基质.从土地利用类型的稳定性来看,耕地、建设用地和沙漠的稳定性最强,在不同时间段内,其保持自身面积不变的比例均在85%以上.从土地利用类型的变化方向来看,最重要的转化方向有两个,一是林地、草地、水体、建设用地向耕地的转化;一是耕地、林地、水体和建设用地向草地的转化;另外盐碱地、沙漠和其他未利用土地之间的相互转化也非常重要.从不同时期土地图斑随时间的双向变化分析发现,该区域既有退耕还林还草、积极治理沙漠、改造盐碱地的事实,也同时存在着毁林毁草开垦荒地,以及荒漠化土地扩展的现实.该区域土地利用变化的驱动因素主要为降水、人口和牲畜数量,以及农牧业经济地位变动,同时大的政策因素影响也不容忽视.

Analysis on the Dynamic Land Use Change in the Ulanbuh Desert Region

Land use/cover change(LUCC) is a key field in global change research.In China,the area of arid regions occupies 21.4% of the total area of terrestrial land,and the Ulanbuh Desert is one of the largest deserts in China,so it is very important to research LUCC in this region.By applying GIS and RS means,in this paper the process of dynamic LUCC and its driving factors in the Ulanbuh desert region are analyzed using the maps of LUCC in 1986,1995,2000 and 2004,interpreted from the Landsat TM images.The results reveal that the landscape substrates were quite different from different years,the region was covered by sand desert and other unused land types in 1986,it was covered by both sand desert and steppes in 1995,but the area of sand desert after 2000 occupied over 57% of the total area of the region.The stability of cultivated lands,building lands and desert was the highest in all the land use types,and the proportion of the unchangeable land use types was over 85% during the different periods.The study results also reveal that there are two shifting directions of land use types: one is that some woodlands,steppes,waters and building lands are shifted towards cultivated lands,and another is that some cultivated lands,woodlands,waters and building lands are shifted towards steppes.The reciprocal transformation between saline or alkaline land,desert and other unused land types is also important.After analyzing the temporal change of land use patches in the study area during different periods,it is found that there is not only a benign trend of LUCC,such as implementing the projects of returning land for farming to forestry and grass planting,desertification control and improvement of saline or alkaline soil,but also an inverse trend,such as deforestation,steppe degeneration and land reclamation.The driving factors bringing about LUCC in the study area are mainly the precipitation,population and livestock as well as the change of economic position of agriculture and animal husbandry,and the effect of policy can not be neglected.