科尔沁沙地典型地区土地利用景观格局变化分析

Change of Landscape Pattern of Typicsl Area in Horqin Sand Land

在3S技术的支持下,以奈曼旗1975,1985,1995和2005年的遥感影像为信息源,分析了研究区近30 a土地利用景观格局变化。结果表明,该沙漠化土地景观类型面积持续减少,以固定沙丘景观类型面积减少幅度尤为明显,面积比重由1975年的44.79%减少到2005年的6.18%;林地和耕地景观类型面积显著增加,其中以林地景观类型增加幅度尤为显著,净增量为29.72%,其它景观类型面积变化较小。从主要斑块类型之间的转化来看,主要表现为流动沙丘、半固定沙丘景观类型向固定沙丘、林地和耕地景观类型的转化,固定沙丘、草地景观类型向林地和耕地景观类型的转化,林地向耕地的转化以及耕地向林地的转化。从景观空间格局变化来看,林地斑块数最多,出现在2005年,为191;农田最大斑块指数最大,出现在2005年,为43.12;固定沙丘平均斑块面积最大,出现在1975年,为1 896.50 hm2;连通性指数呈现出持续下降的变化趋势,由1975年的2.62降至2005年的2.13,而斑块密度呈现出与之相反的持续增加的变化趋势,由1975年的0.15增加至2005年的0.44;Shannon多样性指数和Shannon均匀度指数呈现出相似的先增后减的变化趋势。

The images of Naimanqi in the year 1975, 1985, 1995, and 2005 were interpreted and the land use change in typical area of Horqin sand land during recent 30 years was analyzed by using 3S technology. Results showed that the area of landscape types of sandy land was reduced obviously. The reduced extent of fixed dune was significant, decreasing from 44. 790/00 in 1975 to 6.18% in 2005. The areas of cultivated land and woodland increased prominently, especially the woodland with the net increase of 29.72%. The areas of other landscape types did not change obviously. The transfers among the main land use types were from mobile dune and semi-fixed dune to fixed dune, cultivated land, and woodland; from fixed dune and pasture to cultivated land and woodland; from cultivated land to woodland; and from woodland to cultivated land. In view of the change space pattern, the number of woodland patches was the most, being 191 in 2005. Theindex of the largest patch of cultivated land was the greatest and its numerical value was 43. 12 in 2005. The mean patch area of fixed dune was more than other landscape types, being 1 896.50 hme in 2005. The connect index was reduced continually from 2.62 in 1975 to 2.13 in 2005, However, the patchdensity（PD） index changedoppositely, increasing continually from0.15 in 1975 to 0.44 in 2005. The Shaanon＇s diversity index （SHDI） and Shannon＇s evenness index（SHEI） presented the similar changing trend of increasing first and then decreasing.