基于遥感的山区县域土地覆被变化的驱动力因子和生态环境效应分析——以重庆市忠县为例

Driving Factors of Land Cover Changes and Their Ecological and Environmental Effects Based on RS in Mountainous Counties--A case study of Zhongxian County of Chongqing City

在对重庆市忠县区域TM遥感数据进行波谱信息特征实验分析的基础上,建立了土地覆被信息提取的渡段组合方案;通过人机交互目视解译和野外数据检验工作。实现利用遥感影像数据对重要生态安全指标因子之一——土地覆被因子的数据提取,并用GIS技术对其时空变化的驱动力因子和生态环境效应进行分析,效果和效率令人非常满意。这不仅在一定程度上解决了中尺度山区县域的土地覆被数据提取与地学分析的技术和方法难题,而且揭示了忠县土地覆被的时空分异特征。这是用常规与传统的技术方法与研究手段难以实现的,也为山区县域生态环境退化评价和生态恢复研究提供了一种新的方法尝试。 通过GIS空间分析,揭示了忠县土地覆被和水土流失的时空分异特征。忠县土地覆被动态变化的生态环境效应表现为耕地与林地在“制高地”上(海拔500 m以上)的大互换,在平川坝地地区建设用地大量占用优质耕地、林地等土地覆被类型;水土流失发生的坡度分异不明显,主要分布在200～800 m间,与坡耕旱地分布密切相关。从总体上,这种变化使区域生态环境系统的功能发生退化。分析发现,忠县土地覆被变化的驱动力主要有:(1)人口压力和经济发展落后是生态环境系统安全状态恶化的社会经济背景因素;(2)

Based on spectrum information analysis of TM images of Zhongxian County of Chongqing City, a band combined program about the extraction of land cover information was developed in this paper. Land cover information, which is an important index of ecological security, was obtained from remote sensing image by contact interpretation and then tested by investigation data. The analysis of the driving factors of the temporal and spatial land cover changes and their ecological and environmental effects were also carried out by GIS. Both the analysis effect and efficiency are agreeable. It not only resolved the problems of land cover information extraction in mountainous counties on middle scale and the technique and methods in geographical analysis,but also presented the temporal and spatial differentiated features of land cover in Zhongxian County,which are difficult to accomplish by traditional techniques and methods. This paper provides an attempt of new method for evaluation of ecological and environmental degradation and ecological restoration in mountainous counties. The temporal and spatial differentiated features of land cover in Zhongxian County was presented by GIS. The Eco-environmental effects caused by the land cover changes in Zhongxian County are: the cultivated land is in exchange with the forest land largely at the high-land(over 500 meter above sea level), lots of the high quality cultivated land and forest land are occupied by construction land at the low-land such as small plain and basin; the emergence of the soil erosion is not correlated closely with the slopes of landform but the altitudes(most between 200 and 800 m) and sloping dry land. These changes conduce to the function degeneration of regional eco-environment system. It was found that the driving factors of land cover changes that caused the deterioration of ecological environment are as follows, (1) population pressure and backward of economic development are the social economic background factors. (2) excessive use and unreasonable development of the natural resources are the direct human factors; (3)fragile ecological environment is the natural environmental background factor. Thus, it was necessary to adopt the countermeasure including ecological immigrate, ecological construction and protection to control the regional ecological security in ZhongXian County.