近35 a临泽县绿洲-荒漠土地变化及其景观响应

Spatiotemporal Change of Oasis/desert Land and Its Landscape Response in Linze County in Recent 35 Years

以黑河中游临泽县为例,基于5期多源Landsat影像数据,开展近35 a来乡镇尺度上绿洲和荒漠土地时空格局变化及景观格局响应研究。结果表明:临泽县绿洲与荒漠土地变化及景观呈现时空分布上的聚集和分异性,县域北部与沙漠毗邻乡镇的绿洲-荒漠土地变化相对平稳且逐渐放缓,绿洲斑块的扩张规模也小于中部乡镇,且荒漠景观主体较为稳定;中部乡镇的绿洲-荒漠土地的数量变化、趋势状态以及绿洲斑块的扩张规模均大于其他乡镇,荒漠景观趋于破碎化和被分割;与祁连山脉相接的南部乡镇无荒漠土地分布,其绿洲的规模和变化速率都最小。研究表明基于乡镇尺度的绿洲-荒漠土地时空变化存在明显的内部分异,应因地制宜地制定绿洲发展和荒漠化防治措施。

In this paper,a case study on the spatiotemporal change of the oasis/desert land and its landscape response in the townships and towns,Linze County,Gansu Province in the middle reaches of the Heihe River watershed in an arid area in northwest China,was carried out on the basis of interpretation and analysis of multi-source remote sensing images in 1977,1986,1993,2002 and 2012,landscape expansion index and GIS techniques. The results showed that there were both the aggregation and differentiation of spatiotemporal change of the oasis/desert land and its landscape response in Linze County on township/town scale. The change of the oasis/desert land in the north of the county and the townships and towns neighboring the sand desert was relatively stable and was gradually slowed down,where the expansion scale of the oasis patches was smaller than that in the townships and towns in the central part,and the desert landscapes were stable. In the townships and towns in the central part,the area of oasis/desert land change,trend and expansion scale of oasis patches were smaller than those in other townships and towns,and the desert landscapes were trended to fragmentization. There was no desert land in the townships and towns in the south neighboring the Qilian Mountains,and the scale and change rate of the oasis were small. The study results revealed that there was an internal differentiation of spatiotemporal change of oasis/desert land on the township scale,and the measures should be worked out for the oasis development and the desertification control based on the local conditions.