开都孔雀河流域近20年土地利用／覆被变化及景观破碎化研究

摘要

根据开都孔雀河流域1990、2000和2010年Landsat⁃TM影像数据和中巴资源卫星数据，结合GIS技术，研究其近20 a土地利用／覆被及景观格局的动态变化特征及变化原因。结果表明，1990—2010年开都孔雀河流域土地利用类型变化最明显的是耕地、建设用地和水域湿地，年均变化率分别为4�76％、－1�61％和1�45％，而未利用地年均变化率最小，为－0�29％。草地面积的8�71％和未利用地面积的1�73％均转变为耕地，草地面积的2�41％转变为水域湿地，建设用地的54�74％转变为未利用地；林地面积在2000年前减少，主要转变为耕地，而在2000年后耕地和草地转变为林地，又使其面积增加。整个研究时段耕地、水域湿地分布趋于集中，逐渐成为研究区的优势景观类型；在2000年前林地分布破碎化明显，在2000年后趋于集中；1990—2010年，草地面积减少，景观优势度下降，景观形状趋于简单。认为人口的不断增加以及经济利益的驱动使得流域内耕地面积不断扩大，从而严重危及流域的生态环境安全。%Based on Landsat⁃TM and CBERS images of the Kaidu⁃Kongque River valley in 1990, 2000 and 2010, and with the aid of the GIS technology, dynamic changes in land use/cover and landscape pattern of the valley and causes of the changes in the recent 20 years were analyzed. Results show:In 1990—2010, the changes in farmland, construction land and water wetlands were the most obvious, being at a rate of 4�76%, -1�61% and 1�45%, respectively, in annual mean, while the change in virgin land, the least, being at a rate of-0�29%;8�71% of the grassland area and 1�73% of the virgin land transformed into farmland, 2�41% of the grassland into water surface or wetland and 54�74% of the con⁃struction land into waste land;Before the year of 2000 forest land decreased in area, being mainly transformed into farm⁃land, while after that year, farmland and grassland were turned back into forest land, increasing the forest land in area;During the time period covered by the study, cultivated land and water surface/wetland tended to be concentrated in distri⁃bution and gradually became the dominant types of landscape in the study area;Before 2000 forest land distributed in frag⁃ments, but after 2000 it began to tend to be concentrated;during the period, grassland decreased in area and in landscape dominance as well;and as a result, the landscape pattern tended to be simple. It is believed that it is mainly the continu⁃ous growing population and their activities for seeking economic profits that has caused farmland steadily diminishing in ar⁃ea in the valley, thus seriously threatening the eco⁃environment safety of the valley.