近10年宁夏盐池县生态景观格局动态变化研究

Studies on the Landscape Pattern Dynamic Change of Yanchi in Ningxia in Recent 10 Years

以Landsat TM/ETM卫星数据为基本信息源,运用景观生态学原理和地理信息系统(GIS)技术,通过对景观斑块面积、分离度、破碎度、分形维数、多样性指数、均匀度指数的计算,对我国典型农牧交错生态脆弱区宁夏盐池县1991—2000年生态景观格局的动态变化进行了研究.结果表明,盐池县生态景观的基质是草地,景观格局始终呈农牧交错结构;耕地斑块面积减少,但分离度和破碎度增加;草地斑块面积增加,但中高盖度草地斑块面积大幅度减少,低盖度草地斑块面积大幅度增加,草地质量退化严重;林地斑块面积增加,但连通性不够明显,防护林廊道尚未形成;沙荒地斑块面积有所减少;居民工矿建设用地略有增加;各类型景观斑块面积增减变化量由大到小的顺序为中高盖度草地、低盖度草地、耕地、林地、极低盖度草地、沙荒地、居民工矿建设用地.总体看来,景观多样性和均匀性有所改进,但改进幅度不大,政策引导和人为活动是本地区生态景观格局变化的重要因素.

Based on the data of Landsat TM/ETM, the principles of Landscape Ecology and the techniques of GIS, this paper uses some landscape indices, such as patch areas, isolation, fragmentation, fractal dimension, diversity, evenness, etc. to study the dynamic change of landscape pattern of Yanchi in Ningxia, one of typical farming pasture ecotonal areas in China from 1991 to 2000. The findings were： in Yanchi, pastures were the matrix, farming pasture ecotone were the principal landscape pattern; crop farming land was in the decreasing, yet, the isolation and fragmentation of this kind of patch were in the increase; the pasture increased, but, of which, the high and mediumcovered decreased greatly and the lower-covered increased considerably, the pasture degraded to a great extent; forest land was in the increase, while its connectivity increased slightly, the corridor of shelter belt had not formed; the desertified land decreased and the residential and industrial construction land increased slightly; in term of variation of patch area, high and medium-covered pasture, lower-covered pasture crop farming land, forestry land, lowest-covered pasture, desertified land, residential and industrial land. On the whole, the landscape＇s diversity and evenness improved gradually to a small extent. The implementation of policies and human activities were the main factors of the landscape pattern＇ s changes.