【摘要】 通过面向对象的模糊分类方法对汶川地震前后两期的Landsat-TM影像数据进行土地覆盖类型解译,结合应用统计学法、景观指数法分析研究区土地覆盖的时空格局和演变趋势。结果表明:(1)使用面向对象的分类方法对研究区域土地覆盖类型进行提取,地震前后两期遥感数据分类总精度分别达到0.90和0.92,Kappa系数达到0.88和0.90,取得了较好的精度效果,适用于区域覆被的提取。(2)"5.12"汶川地震后,区域林地退化显著,较地震前面积减少35679.76hm2,减少幅度达7.66%。土地退化明显,不透水面由地震前的24558.61hm2增加到67935.41hm2,相对动态度达到176.62%。水体面积增加了近40%,相对动态度为35.82%。(3)地震前后土地覆盖破碎度呈增加趋势。斑块数大量增加,其中,不透水面增加最多,由震前的240块增加到539块。区域蔓延度指数(CONTAG)由震前的40.89下降到31.09,散布与并列指数(IJI)由65.10上升到了73.99,均匀度指数(SHEI)从1.04上升到了1.35。以上指数均反映地震使研究区斑块破碎度加剧,斑块间的离散程度增高,植被景观退化及其空间格局演变导致了生态退化以及区域生态系统服务功能衰退。更多还原

【Abstract】 Interpretation of land cover types by using two Landsat-TM image data before and after the Wenchuan Earthquake through the fuzzy object-oriented classification,at the same time,analysis the land cover temporal-spatial patterns and the changing tendency of the study area by using applied statistics methods and the index of landscape.Results show:① Extracting land cover types of research field by object-oriented classification;precision is comparatively exactitude and efficiency.The total precision of Post-quake and pre-earthquake respectively are 0.90 and 0.92,while Kappa factor are 0.88 and 0.90.② Forest in research field degenerated dramatically.The area of forest reduced 35679.76hm2,accounting to 7.66% of the total area.Desertification trends are obvious,After the earthquake impervious surface increased to 67935.41hm2 from 24558.61hm2.And relative dynamic degree reached 35.82%.③ After the earthquake,land cover fragmentation tends to rise and number of patch largely increased.Impervious surface which changes the most severely among all the land cover types increase to 539 from 240 in Post-quake;forest have also been doubled to 335.CONTAG of the research areas is 31.09 and comparing to Post-quake’s data decrease 9.80.The results show that earthquake intensifies the patch fragmentation of the research areas and leads to the degree of dispersion between patches expand.Accordingly,landscape degradation and spatial patterns evolution result in ecological deterioration and regional ecosystem service function decline.更多还原