1991-2006年无锡市土地利用变化动态度及转换参数分析

Analysis on dynamic degree and transition parameters of land-use type changes in Wuxi city,Jiangsu during 1991-2006

在RS和GIS技术支持下,以3期TM/ETM+影像为数据源,提取无锡市土地利用变化信息,分析了区域土地利用变化的动态度;挖掘土地利用转移矩阵中的净变化量、交换变化量以及变化持续性等隐藏属性;在此基础上,通过随机转换和系统转换判别15 a间不同地类间转换的优势度,进一步探讨其对太湖流域生态环境的影响。结果表明:1991—2006年间无锡市建设用地面积呈现较快增长,而林地的流失速率最高;耕地主导了交换变化量,主要表现为空间位置转移;建设用地变化主导了净变化,其变化以建设用地新增为主;从期望新增量和期望流失量角度分析可知,林地转化为新增耕地具有明显的转换优势,同时又存在部分耕地转回林地的现象,两种地类间存在剧烈的空间位移,加剧了林地景观的破碎化程度。保护好现存林地和建设环太湖森林植被缓冲带有利于减轻农地面源污染和改善湖泊水质。

With the support of the remote sensing（RS） and geographical information system（GIS） techniques,land use change information was extracted by taking the Landsat TM/ETM＋images of Wuxi city as the data source.The dynamic degree method was utilized to analyze the integrated rate of land use change,and according to the land use transition matrix,we digged hidden information about the net change,swap,persistence of changes,etc.Systematic transitions and random transitions were used to determine intensity of different class switch,which intend to discuss its effects on ecological environment around Taihu Lake basin.The research results showed that during 1991—2006,the area of construction land in Wuxi city grew rapidly,accompanied with high loss rate of forestland;the amount of net change for construction land was the largest,and the change in cropland was nearly a pure swap-type of change;according to excepted gains and excepted losses,there was an obvious advantage for the forestland to transform into cropland.Meanwhile,part of the cropland were turning back to forestland.It should be considered that spatial location conversion varied intensely between forestland and cropland,which might aggravated forestland landscape fragmentation.It is beneficial for the control of non-point pollution from cropland and the improvement of lake water quality to protect the present forestlands and establish vegetation buffer zones surrounding Taihu Lake.