基于地形梯度的河北省太行山区土地利用时空变异研究

地形在一定程度上影响着土地利用变化, 对土地利用空间格局的形成具有重要影响。利用GIS空间分析功能, 结合地形位指数、分布指数和土地利用程度综合指数, 系统分析了1990-2008年间河北省太行山区土地利用变化的地形梯度特征, 探讨地形因素对土地利用方式选择及空间格局的影响, 并定量分析了地形梯度上的土地利用程度状况。结果表明: 各种土地利用类型空间分布及其变化明显受到地形因子的影响和制约, 总的分布特征为: 随着地形位的升高, 耕地的分布指数呈现降低趋势, 草地、建设用地、水域和未利用地先升后降, 而林地则升高; 研究期间林地的优势地形位的上限增加了2个地形位, 草地已失去高地形位上的分布优势, 在中地形位上的优势分布区间增加了3个地形位, 水体的优势地形位在低地形位上有所扩展, 未利用地的优势地形位明显收缩, 而耕地、建设用地优势地形位基本保持稳定; 土地利用程度综合指数随着地形位的增加而不断下降。根据地形梯度上土地利用程度的定量表达, 将研究区地形位划分为3个区段: 耕地、水域、建设用地和未利用地的优势地形位区域、草地和林地的优势分布区、林地的优势地形位区域, 其面积分别占研究区总面积的45.79%、41.30%和12.91%。在此基础上对河北省太行山区土地资源的合理利用和生态环境恢复提出了相应建议和措施。

Spatial-temporal variability of land use with terrain gradient in Taihang Mountain, Hebei Province

Terrain significantly influences land use change and spatial pattern. Compared with the single terrain factor (elevation, slope) method, terrain niche index, combination of elevation and slope, can reflect detailed spatial variability of terrains. Distribution index can describe the differences between actual and standard distribution of different land use types, excluding the disturbances of the area. The comprehensive index of land use degree can reflect regional land use intensity and is suitable for comprehensive evaluation of land use degree. Taking advantage of GIS spatial capabilities along with terrain niche index, distribution index and comprehensive index of land use degree, this study analyzed land use patterns and changes in Taihang Mountain in Hebei Province from 1990 to 2008. Also the land use degree on terrain gradient was quantitatively analyzed and terrain influence on land use selection pattern was explored. The results showed that the spatial distributions and changes in various land use types were considerably influenced by terrain factors. Arable land, construction land, water and unused land were mainly in areas with 0° 15° slope and <500 m altitude. Also the changing areas of land use on these terrains were highest. Arable land, construction land, water and unused land were mainly in areas with low terrain niche index. Then grassland was mainly in areas with medium terrain niche index and woodland in areas with medium-to-high terrain niche index. With increasing terrain niche index, the distribution index of arable land decreased, that of grassland, construction land, water and unused land decreased followed by an increase, while that of woodland increased. From 1990 to 2008, predominant distribution terrain niche index scale of woodland increased by two units. That of grassland expanded by three units in the middle terrain niche section but reduced the sections with high terrain niche. That of water expanded in low terrain niche section, and that of unused lands reduced significantly. Then those of arable land and construction land generally remained stable during the study period. Additionally, the comprehensive index of land use degree reduced with increasing terrain niche index. Based on quantitative analysis of the land use degree on terrain gradients, terrain niche was divided into three sections. They were dominant terrain niche section of arable land, water, construction land and unused land; dominant terrain niche sections of grassland and woodland; and dominant terrain niche section of woodland. The areas of the three sections were 45.79%, 41.30% and 12.91% of the study area. Finally, suggestions were put forward for rational use of land resources and ecological environment restoration in Taihang Mountain in Hebei Province.