西双版纳主干公路沿线森林景观格局动态

Dynamics of Forest Landscape Patterns along the Main Roads in Xishuangbanna,Yunnan,China

根据西双版纳地区1976、1988和2003年3期LandsatMSS/TM/ETM影像的解译结果,借助于地理信息系统技术,运用景观生态学的基本理论分析了该区主干公路沿线的森林景观格局动态。主要结果为3个时期,与整个西双版纳州相比,公路沿线10km范围内的人工林景观百分比更大,增长更快,天然林景观则表现出相反的特征和趋势;且距公路越近,天然林的景观百分比越小,人工林的景观百分比越大,表现出明显的公路效应。公路沿线景观格局朝着多样化、均匀化、破碎化的方向发展。样区内的质心偏移分析表明,1976年至2003年,橡胶林、热带季节雨林、灌木林、山地雨林和非林地景观的分布都在向远离公路的方向偏移。

In this paper, we investigated dynamics of forest landscape along the main roads in Xishuangbanna, Yunnan, China from 1976 to 1988, and from 1988 to 2003, using FRAGSTATS software and the GIS technology, based on the results interpreted from the Landsat MSS/TM/ETM images in 1976, 1988, 2003. Some representative quantitative indices of landscape diversity, including mean patch area, percent of landscape, perimeter-area fractal dimension, aggregation, Shannon＇s diversity index, and Shannon＇s evenness index were used to describe the changes in the spatial pattern of landscape elements. Comparing with whole region of Xishuangbanna during last 27 years, the results showed that the manmade landscape （rubber plantation） and non-forested landscape along the main roads expanded faster and their percentage were greater, whereas the natural landscape （ primary forest patches） reduced faster and its percentage was smaller. There were obvious effects of mad on landscape which the forest coverage was decreased, and rubber plantation landscape was increased with the distance from the road. The natural forest landscape had been fragmented. Especially, the tropical seasonal rain forest was affected severely, while the area and contagion of rubber plantation and shrub increased. The whole landscape pattern along the main road tended to be diversifonn, equal and fragmented. The landscape was still dominated by natural landscapes but this dominance was weakening. A case study about the displacement of landscape patch centroids showed that the spatial centroids of many types of landscape, including rubber plantation, tropical seasonal rain forest, mountain rain forest, shrub and non-forested land had moved away from the road. All of these changes in landscape pattem would lead the deterioration of these region environments.