近20多年来石羊河流域景观格局演变特征

在RS和GIS的支持下,应用景观生态学理论和方法,通过对1986,1994,2000和2006年四期遥感影像,采用景观空间格局指标定量分析20多年来石羊河流域景观规模和空间格局演变。结果表明:在全流域草地和沙地占据优势,而武威绿洲以耕地占绝对优势,民勤绿洲则以耕地和沙地共同占主导地位,主要景观的变化则以民勤绿洲耕地、沙地的增加和林地、草地的减少最为显著;流域整体景观结构较为稳定,但流域小区域内,景观演变较为突出;流域景观变化主要发生在中下游的武威和民勤绿洲区,而各景观结构的变化主要集中在荒漠和绿洲的交错地带。尤其从2000年到2006年6年时间里,绿洲化趋势在武威绿洲发展明显,耕地增加显著,沙地大量减少。而在民勤绿洲,耕地虽有所增加,但沙漠化进程大于绿洲和农业化进程。

Landscape pattern evolution in Shiyang river basin based on GIS

Choosing four periods of Landsat/TM images of the arid region Shiyang River basin from 1986 to 2006,and using landscape ecological theory,we studied the landscape pattern changes of the area.The results show that grassland and sandy desert were the superiority in the whole basin,but farmland occupied overwhelming superiority in Wuwei oasis.In Minqin oasis,farmland and sandy desert dominated together.The main changes of the landscape were that farmland and sandy desert were increasing,but woodland and grassland were decreasing in Minqin oasis.Wholly,the landscape structure was stable,but in the basin of small region,the landscape evolved more prominently.The landscape change mainly occurred in the middle and lower reaches,such as Wuwei and Minqin oasis,while the changes of landscape structure mainly centralized in desert-oasis ecotone.Particularly from 2000 to 2006,the oasis development was obvious in Wuwei oasis,so farmland was increasing apparently,while sandy desert was decreasing massively.However,in Minqin oasis,farmland was increasing as well,but the desertification was faster than agriculturalization and the oasis development.