滇西北高原湿地区土地利用变化特征

湿地景观格局的动态变化与区域土地利用/覆盖格局的变化有着十分紧密的联系。以纳帕海、碧塔海和属都湖三块高原湿地所在的云南省香格里拉县建塘镇为例,在遥感和GIS技术的支持下,对该区域1974、1987和2000三期Landsat TM(ETM)影像进行了解译,分析了26 a间的土地利用/覆盖变化规律,并结合景观格局动态分析的方法,借助FRAGSTATS软件定量分析了该区景观格局特征及其动态变化。结果表明:该区土地利用/覆盖状况变化显著,主要土地利用/覆盖类型有林地以822 hm2/a的速度在大面积减少,并主要转为灌木林地,使得后者在26 a间扩大高达17倍,变化幅度最大。建设用地和耕地的面积分别扩大了6倍和2倍,而草地和雪地面积持续减少。相应地,该区景观格局定量分析显示,有林地的斑块密度增大而平均斑块面积减小迅速,呈破碎化趋势,灌木林地的斑块密度、平均斑块面积均增加,草地则与之相反均减小,耕地的斑块密度降低而平均斑块面积增加,在不断融合成大斑块,其余各景观单元斑块密度增大平均斑块面积减小,同时各斑块几何形状在1987年变化最剧烈,景观格局趋于复杂。

Regional Land Use Dynamics of Plateau Wetlands in the Northwest of Yunnan Province,China

There's a close relationship between landscape dynamics and land use/land cover change.This study analyzed spatial and temporal changes of land use/land cover in Jiantang Township of Shangri-La County,where three plateau wetlands(Napahai Lake,Bitahai Lake and Shudu Lake) located,by comparing classified Landsat TM(ETM) images from 1974,1987 and 2000 coupled by GIS analysis,and patterns of landscape dynamics by using the spatial pattern analysis software(FRAGSTATS). The results indicated that the land use/land cover in this area has changed significantly during 1974 and 2000.The most obvious change was the decrease in dominant cover of forest(annual deforestation rate of 822 hm2/a) and an increase in shrublands.Shrublands expanded more than 17 times in the past 26 years and mainly came from forest.The built-up and farmland increased more than 6 and 2 times respectively while the grassland and snow-land substantially deceased in area.The water surface shrank markedly near the Napahai Lake.Accordingly, the landscape pattern quantitative analysis showed increasing landscape fragmentation,particularly during the 1974~1987.There was markedly increase in patch density(0.61~1.93 km2) of shrublands and mean patch area(2 ~11 hm2),while grassland made an opposite change.Furthermore,increase in the patch density(0.17~0.52 km2) of forest was association with decrease in the mean patch size(454~117 hm2).However,the decrease in patch density of the farmland and increase in mean patch area exhibited aggregation.The patch shape of the landscape types changed most distinctly in 1987 and the landscape pattern tend to be more complicated.