基于一级水生态分区辽河流域景观格局时空动态分析

以辽河流域四个一级水生态分区为研究区,基于1990、2000、2005年TM影像,应用GIS技术,采用转移矩阵和景观指数方法,对辽河流域1990～2000年和2000～2005年期间土地利用和景观格局的变化进行了综合分析。结果表明:1990～2000年间水生态Ⅰ区耕地减少显著,减少的耕地主要转变为林地,而2000～2005年间草地面积大幅度减少,减少的草地主要转变为耕地;1990～2000年间水生态Ⅱ区耕地面积大幅度减少,耕地主要转变为草地和林地,2000～2005期间耕地大幅度增加,主要来源于草地;1990到2000年间水生态Ⅲ区耕地面积大幅减少,耕地主要转变为林地,2000～2005年大量林地转变为耕地和建设用地;水生态Ⅳ区包括浑河和太子河流域,其中浑河流域在1990～2000年时期景观格局的变化类型主要是由耕地转变为林地和建设用地,太子河流域耕地主要转变为林地。2000～2005年时期浑太河流域景观格局变化类型主要由减少的林地流向耕地。景观指数分析得到辽河流域景观变化的总体趋势是:形状更加复杂,异质性增加,破碎化程度加剧,尤其以建设用地的破碎度最高,并且有逐年增加的趋势。Ⅰ区和Ⅱ区景观连通性和聚合度在1990～2005年时期呈上升趋势,而在Ⅲ区和Ⅳ区在2000年景观结合度和连通度最低。研究时间内Ⅰ、Ⅱ、Ⅳ区景观多样性和均匀性指数在前期变化不显著,后期显著上升,Ⅲ区多样性和均匀度最高时期是2000年,1990年和2005年差别不显著。

A Spatial-Temporal Dynamic Analysis of Landscape Pattern for Ecoregions Level I in the Liao River Basin

On the basis of TM remote sensing images in 1990,2000 and 2005,the landscape pattern changes of four aquatic ecoregions(level I)in the Liao River Basin from 1990 to 2005 were analyzed by using GIS technology,as well as the methods of transfer matrix,and landscape metrics.The results indicated that the area decreasing most significantly is cropland in aquatic ecoregions I and Ⅱ,and most of the croplands were changed to woodland and grassland from 1990 to 2000,the area decreasing most significantly is grassland,and most of the grasslands were changed to cropland from 2000 to 2005 in the same region.The area decreasing most significantly is cropland in aquatic ecoregion Ⅲ,Most of the croplands were changed to woodland from 1990 to 2000,and ?most of the woodlands were changed to cropland and construction land from 2000 to 2005.The Hun and Tai River basins are included in aquatic ecoregion Ⅳ,the area decreasing most significantly is cropland in the Hun River and Tai River basins.Most of the croplands were changed to woodland and construction land in the Hun River Basin and to woodland from 1990 to 2000,the area decreasing most significantly is woodland,and most of the woodlands were changed to cropland.The landscape shape,heterogeneity and fragmentation in the Liao River Basin were enhanced to some extent,the fragmentation of the land for construction was largest and increased from 1990 to 2005,Cohension and AI tended to be improved from 1990 to 2005 in ecoregionsⅠand Ⅱ,Patch Cohesion Index(COHESION) and Aggregation Index(AI) in 2000 were largest in ecoregions Ⅲ and Ⅳ,SHDI and SHEI did not change obviously from 1990 to 2000 and increased from 2000 to 2005 in ecoregionsⅠ,Ⅱ and Ⅳ,Shannon's Diversity Index(SHDI) and Shannon's Evenness Index(SHEI) in 2000 were largest,there were not obvious difference in SHDI and SHEI between 1990 and 2005.