阴山中段山地土地利用类型转换格局分析

利用1990年TM数据和2000年ETM数据，以农牧交错带的阴山山地中段为研究区，分析1990～2000年土地利用类型的空间分异规律，重点探讨各土地利用类型中耕地、林地和草地的变化过程。研究表明，耕地的转移流向主要集中于草地，而草地的转移流向又集中于耕地，林地消失区主要转变为草地。阴山北麓为草地向耕地转变的集中区域；阴山南部是林地向草地转变最为集中的区域；阴山中部土地利用类型相互转化相对较少。在土地利用的垂向变化上，耕地减少区域集中分布于海拔1500～1600m及1700～1850m；而其他土地利用类型向耕地转变的集中分布区域大致在海拔1700～1900m范围；海拔1600-1800m为草地-耕地相互转移变化最为集中的区域；草地面积主要在海拔1450-1600m范围增加，在1650-1800m范围内减少；林地除在海拔2000～2200m范围内与非林地相互转变大致持平外，在其余地区均发生退化。海拔1800m和海拔2100左右是本农牧交错带山地土地利用类型波动最为集中的两个分布区。

Land-use Conversion Patterns in the Middle of the Yinshan Mountains

Taking the middle Yinshan Mts. as an example, this paper analyzes land-use patterns in mountains of faming-pastoral region with Landsat-TM and ETM images for 1990 and 2000. The emphasis is put on the spatio-temporal changes of farmland, grassland and woodland. It is found that the main land use change is the mutual conversion of farmland and grassland. The main conversion of woodland is also toward grassland. The conversion of grassland to farmland chiefly occurs in the northern foot of Yinshan Mts, and that of woodland to grassland in the southern parts of Yinshan Mts. Land use changes little in the upper parts of the Yinshan Mts. Farmland conversion to other types appears largely on elevations of 1 500 m to 1 600 m and 1 700 m to 1 850 m, while the conversion of non-farmland to farmland occurs mainly on elevations of 1 700 m and 1 900 m. Between 1 600 m and 1 800 m are the altitudes where most of the conversion of grassland to farmland happens. Grassland area increases on elevations of 1 450 m to 1 600 m and decreases between 1 650 m and 1 800 m. Woodland declines almost in all the mountain areas except the altitudes between 2 000 m and 2 200 m where the conversion of woodland to other types and other types to woodland is just the same. Near the altitudes of 1 800 m and 2 100 m are the areas where the most intensive land use change can be seen in the mountain regions of farming-pastoral zone.