石羊河流域及其典型绿洲景观动态变化研究

根据1986年和2000年的TM影像数据,利用GIS技术和景观结构分析软件FRAGSTATS,分别在类型和景观两个水平上分析了石羊河流域及武威和民勤两个典型绿洲近15a来的景观结构变化.结果表明:在整个流域水平上,虽然发生了景观结构的空间变化,但总体上相对稳定.在典型绿洲区,特别是民勤绿洲景观格局的变化较大,表现为景观的破碎化,形状的简单化和景观多样性的降低,以及耕地、沙地的增加和林地、草地的显著减少,沙漠化趋势加剧.

Studies on the Landscape Dynamics of the Shiyang River Watershed and Its Typical Oases

Using GIS and landscape structure analysis program FRAGSTATES, based on the TM image of Shiyang River watershed in 1986 and 2000, in this paper the landscape metrics of the watershed in 1986 and 2000 are calculated and analyzed at class metrics level and landscape metrics level respectively. The transformation matrix of the landscape mosaics is also got, which is the base for spatial change analysis of the landscape patterns. The results show that: although the landscape patterns have changed at the whole watershed level, the landscape is at a relatively stable status; but at the typical oases level, landscape patterns have changed remarkably. In Minqin oasis, desertification develops evidently, as a result the area of farmland and sandy land increases observably, and the area of woodland and grassland decreases markedly. The sequent of these changes is fragmentation of landscape, simplification of landscape mosaics and decrease in landscape diversity. The reason is over use of the limited water resources in the middle reaches, shortage of surface water, and over pumping groundwater. But in Wuwei oasis, the development trend is different; the result is decrease in sandy land and increase in farmland.