巴中市丘陵山区土地利用在地形梯度上的分布特征

以巴中市2007年TM影像和1∶25万等高线为数据源,利用GIS空间分析功能,建立了巴中市土地利用数据库并生成了高程、坡度和地形位指数图。然后将高程梯度、坡度梯度和地形位梯度分别与土地利用景观数据进行分级叠加分析,并引入无量纲分布指数,探讨不同地形梯度下不同土地利用景观类型的分布特征。结果表明,林地主要分布在较高等级海拔,坡度较大,地形位较高的地形条件下;耕地和城乡居民用地受气候条件和水域分布的影响,多分布在低海拔,坡度平缓,地形位较低的地形条件下;未利用地中水域占绝大多数比例,其分布指数随着地形位指数、坡度等级、高程等级的增加逐渐趋近于0。草地对地形条件的选择性较强,主要分布在中等级高程、坡度和地形位的地形环境中。通过比较分析,可以看出综合了高程和坡度双重属性的地形位指数能更真实地反映不同土地利用景观类型空间特征及分布趋势。

Distribution Characteristics of Landuse Patterns at Different Terrain Gradients in Hills and Mountains of Bazhong City

By taking 2007 TM images and 1∶250 000 contour maps of Bazhong City as data sources and using GIS spatial analysis functions,landuse database of Bazhong City is established and the DEM,slope,and terrain niche index chart are produced.Then,slope gradient,elevation gradient,and terrain gradient are respectively overlaid with landuse landscape data.The distribution characteristics of different landuse landscapes at different terrain gradients are discussed by introducing the dimensionless distribution index.Results showed that the forest land mainly distributes in the place with higher elevation,steeper slope,and greater terrain niche.Farmland and rural residential land are located in the place with low altitude,gentle slope,and low terrain niche due to the effects of climatic conditions and water distribution.Unused land is in the vast majority of the waters and the distribution index of unused land gradually approaches zero as terrain niche index,slope class,and elevation increase.Lawn,which has stronger selectivity for topographical conditions,mainly distributes in the place with the medium elevation,slope and terrain niche.By comparison,terrain niche index,a dual attribute combining elevation with slope,can more truly reflect the different spatial characteristics and distribution trends of the landuse landscapes.