千岛湖生态保护与建设对景观格局的影响研究

Effects of ecological protection and development on landscape pattern in the Thousand-Island Lake region, Zhejiang Province

生态保护和生态建设过程对景观格局产生影响并使之发生变化 ,这种变化又会影响景观的生态过程。应用3S技术和景观指数分析了 39年 (196 4 - 2 0 0 3年 )内千岛湖库区土地利用和土地覆盖格局的变化。结果显示 ,斑块总数和景观破碎度基本保持不变 ,但是各斑块类型的斑块数量、面积和优势度变化非常显著。最优势斑块类型由荒山 (占陆地面积的 4 7.4 4 % )演变为马尾松 (Pinusmassoniana)林 (占陆地面积的 5 2 .81% ) ,研究区域内森林植被覆盖率增加。研究还发现景观多样性指数略微下降。景观多样性是对土地利用和覆盖类型丰富度和均匀度的概要度量 ,并不一定总是和景观功能呈正相关关系。上述变化归因于多项生态保护措施的实施使得自然演替得以实现。景观格局的优化使生态系统的生态功能得到提高 ,包括生境恢复、生物多样性增加、水土流失减少。森林植被恢复以后 ,马尾松林斑块的单一化趋势应在今后的生物多样性保护。

Actions of ecological protection and development shape the pattern of a landscape, which in turn affects ecological processes in the landscape. Changes of the fragmented Thousand-Island Lake landscape, formed by the construction of a large dam in 1959, provide an outstanding example. We analyzed the changes in land use and land cover pattern in this region for a period of 39 years (1964-2003) using landscape metrics and 3S technology. Our results showed that the total number of patches and the degree of fragmentation basically remained the same, whereas the patch number, patch area, and dominance of each patch type changed significantly. The most dominant patch type changed from treeless barrens (47.44% of the terrestrial land) in 1964 to the Pinus massoniana forest (52.81% of the terrestrial land) in 2003. We also found that the value of landscape diversity decreased slightly. It is important to note that landscape diversity, a synoptic measure of the richness and evenness of all land use and land cover types, is not always positively related to landscape functioning. The slight decrease in landscape diversity was a result of the dynamics of all existing patches in the study region. Our results suggest that the forest vegetation on the area has improved in terms of coverage since 1964 (i.e., 5 years after the dam construction). These changes may be attributed to the many measures of ecological protection in this region which allowed natural succession to take its course. The improved landscape pattern enhanced ecological functioning of the island ecosystems, including restoration of habitats, increased biodiversity, and reduction in soil erosion. While the forest vegetation has been recovering, the increasing dominance by the structurally simple Pinus massoniana forest in this region should be considered in future efforts of biodiversity conservation, ecological planning, and sustainable development.