南四湖流域土地利用及其景观格局变化分析

以1987年、2000年、2014年的Landsat影像数据为基础,借助ENVI,ArcGIS,Fragstats等软件,提取了土地利用信息,计算了景观指数,定量分析了流域土地利用变化及其对景观格局的影响。结果表明:(1)近30年来,南四湖流域土地利用变化突出表现为耕地向建设用地的转化,耕地面积减少1 069.15km2,建设用地面积增加1 573.26km~2。2000—2014年,土地利用综合动态度为0.461%,是1987—2000年的4倍。(2)景观结构上,耕地是流域的主导斑块,面积约占70%,30年来占景观面积的比例降低了3.85%,斑块形状趋于复杂;建设用地日益发展为优势斑块,占景观面积的比例指数增加了6.1%。耕地与建设用地斑块在景观中的变迁,使得流域自然生态功能受到较为严重的干扰。(3)流域总体的景观特征表现为优势斑块明显,景观比较完整,但空间异质性较高而连通性较低。近30年来景观结构由较完整的大斑块主导、演化成小斑块圈点状穿孔于大斑块的格局,景观破碎化较为严重。

Analysis on Landscape Pattern Change and Land Use in Nansi Lake Basin

Based on three sets of Landsat data (1987,2000 and 2014),the land use information was extracted by using the software of ENVI,ArcGIS.The landscape indexes were figured out by analyzing the attribute data of the landscape classification map with the Fragstats software.The land use change and its impact on the landscape pattern were quantitatively analyzed in the Nansi Lake Basin.The results show that:(1) during the 30 years,the change of the land use in Nansi Lake Basin performed distinctly for the transformation of farmland to construction land.The areas of farmland decreased by 1 069.15 km2 and construction land increased by 1 573.26 km2.The comprehensive land use dynamic degree was 0.461％ from 2000 to 2014,which is 4 times of that from 1987 to 2000;(2) on the landscape structure,farmland,as a dominated patch in basin,accounted for about 70％,percentage of landscape is reduced by 3.85 ％,and shape was complicated in 30 years;construction land was developed increasingly as an advantage patch,of which percentage of landscape was increased by 6.1％;the changes of farmland and construction land patches in landscape made the natural ecological function suffer more severe disturbance in basin;(3) the whole basin landscape was relatively integrated and the dominant patches were obvious,however,the spatial heterogeneity was higher and landscape connectivity was low.In the recent 30 years,the landscape structure dominated by relatively complete large patches,evolved into the pattern of the small circle patch perforated in large patches,and the landscape fragmentation was relatively severe.