滇南热带雨林区土地利用/覆盖变化分析——以西双版纳勐仑地区为例

Land Use and Land Cover Change in the Tropical Rainforest Region of Southern Yunnan ——A Case Study of Menglun, Xishuangbanna

根据1988年和2003年两期卫星遥感影像的解译结果,采用GIS空间分析技术,对以勐仑为代表的滇南热带雨林区的土地利用/覆盖变化(LUCC)规律及趋势进行了研究,初步探讨了其驱动力机制和环境资源效应。结果表明,15a间该区土地利用/覆盖状况发生了很大变化,橡胶园以604 12hm2/a的平均速度递增,而有林地则以431 17hm2/a的平均速度递减。橡胶园取代有林地成为优势的土地利用/覆盖类型,耕地也有较大幅度减少。结合地形因子进一步分析发现,变化最为强烈的区域正处于热带雨林适宜分布的海拔范围(900m以下),橡胶园的增加与有林地和轮歇地的减少在15°～25°坡度范围内最大,灌木林在陡坡地带有明显增加;在北向坡,有林地减少和橡胶园增加的幅度均大于其他坡向。上述变化导致了有林地的破碎化和生态环境综合服务功能的下降,反映出地形等自然条件是该区LUCC的限制因子,受市场和政策影响的人类活动在此基础上对其起着显著的驱动作用。土地利用/趋势指数结合未来10a的驱动力变化分析表明,目前该区土地利用/覆盖变化仍处于活跃的态势。

With the pressures of population growth and economic development, the forest coverage of Xishuangbanna, has been reduced significantly, and the ecological issues are emerging. Menglun township, one of the nature reserves of Xishuangbanna, is undergoing the same process. We took it as the case study area to give an insight into the land use and land cover change(LUCC). Based on the interpretation of Landsat TM (ETM) images (1988 and 2003) and spatial analyses with GIS technology, we summarized the transition regularities among different types of land use and land cover, and concluded that the dramatic decreases of forest (431.17 hm^2/a)and fallow were mainly attributable to the expansion of rubber plantation(604.12 hm^2/a), and the urbanization took the main responsibility for the decrease of farmland. Spatial analysis of LUCC data with digital elevation model (DEM) revealed that the most intensive changes occurred in those areas under the latitude of 900 m where the tropical rain forest most possibly distributes. The increase of rubber plantation and the decrease of forest and fallow got the maximum on the slope of 15° to 25°, and both of them were more obvious on the north-facing slopes than on the others. The trend analysis shows that the LUCC is still in an active status.