Quantifying landscape structure of the Heihe River Basin, north-west China using FRAGSTATS

We have compiled landscape map of the Heihe River Basin based on the land-use map using geographic information systems. A total of six ecoregions was delineated. Various landscape metrics of each zone, including area, patch density and size, edge, shape, nearest-neighbor, diversity, and contagion and interspersion metrics were calculated using the landscape structure analysis program FRAGSTATS. The results indicated that the landscape pattern of the Heihe River Basin is mainly controlled by the distribution of water resources. The landscape structure in the mountainous area of the Heihe River Basin shows a high continuity and complex patch shapes. The landscape structure of the oasis area shows the most complex landscape structure, the richest patch types, and the highest diversity. The oases are distributed along rivers and artificial channels, and are heterogeneous mosaics embedded in the desert landscape matrix. The landscape structures of oases in different zones vary greatly. In the oasis zone in the Hexi Corridor, the artificial oasis, dominated by irrigated farmland, is one of the most important landscape elements. Conversely, in the Ruoshui River Delta zone, the patches are fragmented and the landscape is easily disturbed. In the transitional belt between oasis and desert, the patch types are meadow, salinized meadow, salt desert, and marsh, which are fragmented and distributed in clusters. These patch types reflect the biodiversity in the and region and play an important role in resisting the desertification in the area, suggesting they must be protected carefully. In the desert area, such as the northern Alxa High Plain, the bare gobi is a landscape matrix with absolute dominance and very high contagion, while other landscape types in the zone are heterogeneous mosaics embedded in the matrix with very small percentage. (C) 2001 Academic Press.