海南生态环境现状评价与变化分析

遥感和地理信息系统技术的发展为研究区域生态环境变化提供了有效手段，以1987年海南植被类型分布图、1988年河南省土壤侵蚀图和1998年的TM遥感资料为信息源，综合GIS参与监督分类及目视判读的方法，以GIS为工具提取生态因子信息并按景观生态类型进行了评价和分析对比，并以海南西部部分地区为例，进行了海南西部地区土地沙化／土地退化研究，表明海南生态环境质量由中部向外依次降低，森林生态环境好，部分园林和农田生态环境质量较差，土地沙化／土地退化在向着恢复逆转的方向发展。

Evaluation and Change Analysis of Eco?environment on Hainan Island

RS is at present a primary and effective means of measurement for ecological situation. GIS provides an efficient tool to analyze the status and the changes of ecological environment. In the study, we use 1987 vegetation distributing map,1988 soil erosion map and 1998 TM Landsat data to construct an ecological map and to evaluate the landscape ecological forms on Hainan Island according to landscape ecology with the integration of visual interpretation and supervised classification with GIS. The detail steps as follows: Firstly, we overlap the topography, soil and vegetation types based on the vegetation type spot and divide them into different eco?landscape types, which are considered as the basic units of the assessment cartography of eco?environment. Secondly, we put the related TM Landsat data and others such as DEM into ERDAS, which is a kind of software processing the remote sensing image, to have the classification with maximum likelihood of the supervised classification, and then verify the supervised classification results by visual interpretation to extract the thematic information. Then, the topography map, soil map and vegetation types map are made by ARC/INFO. Finally, we build the assessment index system of eco?landscape factors and then the index value is processed for normalization to compute the single factor assessment maps to get the synthetic assessment map by ARC/INFO spatial overlapping analysis. During the overlapping, the single factor assessment indexes are processed with weight function to get the synthetic assessment index, then the eco?landscape type units are assigned. On the basis of those mentioned above, the eco?landscape type units are evaluated one by one. Then we have a study on the land desertification and land degradation in the west of Hainan Island. The result shows that the quality of ecological environment gradually declines from the central part of Hainan Island to its border The area of rain forest and seasonal rainforest changes comparatively less. Factors of human disturbance take deep effects on the forests's ecosystem. There is an evident change to the man?made vegetation as a whole, but it is not well distributed. And the area of the natural vegetation has decreased. The area of land desertification and land degradation is decreasing and most of the grievous area has been harnessed.