黑河流域中游张掖绿洲景观格局研究

Research on the Landscape Pattern of Zhangye Oasis in the Middle Reaches of Heihe River

在解译的张掖绿洲土地利用 /土地覆盖图的基础上 ,进行相关的景观类型综合处理 ,计算了绿洲景观格局的多个指数 .结果表明 ,绿洲景观的组成以戈壁、沙地、耕地和草地为主 ,体现了荒漠基质受人工影响而形成的典型农业型绿洲的特点 .绿洲内居民点众多 ,仅与少数类型邻接并且比较分散 ,戈壁、平原旱地和沙地分布则比较集中 .盐碱地和裸岩石砾地的形状最复杂 ,戈壁的形状则最简单 ;同时 ,平原旱地、戈壁和裸岩石砾地的连接性均较好 ,在景观中占有较大比重 ,类型间的物质和能量迁移比较通畅 .

In this paper, Zhangye Oasis, a famous agricultural base located in the alluvion of Heihe River in Northwest China is selected as study area. Landscape maps are compiled based on the landuse maps interpreted from Landsat TM images in 1995. Various landscape metrics are calculated by using the landscape structure analysis software-FRAGSTATS Version 3 at class and landscape levels, including total area of landscape, percentage of landscape types, patch density, edge density, largest patch indices, perimeter-area fractal dimension, interspersion & juxtaposition index, aggregation index, percentage of like adjacencies, patch cohesion index, Shannon's diversity index, Shannon's evenness index, patch richness and contagion. The results indicate that: desert, grassland, field and gobi are the major components in the oasis. The landscape patterns of the oasis are heterogeneous mosaics embedded in desert and gobi landscape matrix. Patches number of rural villages is the largest, which indicates the important influence of human beings. They are scattered in the whole landscapes and the cohesion indices is the lowest, because they are unconnected each other. The shape of bare rock and grassland are the most complex, which reflected the human-induced fragmentation of these types. In addition, the better connection of dry field, Gobi and bare rock indicate that the energy and mass can be transferred within the same types easily. At last, the caution of scale dependent of grid and classification was discussed.