秦岭土石山区土地利用程度对生态恢复力的影响评价

Effects of Landuse on Ecological Restoring Force in Qinling Mountainous Region

以秦岭典型土石山区陕西省商洛市为例,探讨了土地利用程度对生态恢复力的影响,旨在为保护生态环境以及制定土地利用政策提供建议。根据土地利用对生态环境的影响程度,将土地利用分为未利用土地、生态用地、农业用地和建设用地4大类;以粒度单元为统计量,以乡镇为粒度单元,从全局及局部分析了人类活动对土地的影响,计算其土地利用度;生态恢复力评价采用植被指数(NDVI);Moran′s I指数等进行空间聚类,分析了土地利用度与NDVI值的相关程度。结果表明,近1/2的乡镇NDVI值变化快于土地利用度变化,说明生态环境改善速度快于土地退化速度。一个乡镇NDVI值变化慢于土地利用度变化,说明其土地利用退化速度快于生态环境改善速度。研究区9a间生态恢复力较高,说明9a间国家政策上对经济发展与环境保护矛盾处理较好。但对一些土地利用程度仍在提高的乡镇,应进一步重视该区域生态环境变化,提出相应的对策。

Shangluo City is a typical area of Qinling mountainous region, which is an ecologically sensitive area where ecological protection is of great significance, using ETM＋ images and NDVI of MODIS, the study investigated the different influence of land use degree on vegetation coverage. The influences of human activi- ties on lands were analyzed throughout and locally. Statistical analysis was conducted on the ＂cells＂, which was the towns and districts of the city. The land use degrees were then calculated globally over the whole study area and locally on the cells. After the spatial autocorrelation being computed, the land use degrees were found closely correlated with the cumulative percentages of NDVI. A formula was proposed using both the land use degrees and NDVIs, and was then applied to analyze the impacts of land use change on the envi- ronment during the past 9 years. The results show that in most of the region, the ecological environment was improving faster than or nearly equal to the land use degradation. This is a remarkable achievement made by ecological restoration efforts in study area. The ecological restoring forces were strong in most towns during the 9 years, which means that the related policies were enforced well in both economic development and envi- ronmental protection. However, the land use degrees in some towns still need to be improved, and more at- tention should be paid to the regional ecological environment.