基于景观格局和网络分析法的崇明绿地系统现状和规划的评价

以崇明2005年卫星影像图、土地利用现状图为基础资料,结合崇明绿地系统规划,在地理信息系统支持下,选择崇明本岛面积大于10hm²的绿地作为节点,依照网络分析法,构建了不同的生态网络方案,通过α指数、β指数、γ指数以及成本比等网络结构指数进行不同网络方案的比较,从中选出最优的规划方案。然后在景观分析软件Fragstats支持下,运用景观格局分析方法,选用多种景观分析指数,在斑块类型层次上和景观层次上对崇明绿地系统现状、绿地系统规划以及优化后的生态网络规划方案从景观生态学角度进行了定量分析与评价,并针对现有的绿地系统规划提出了进一步完善的建议。研究结果表明崇明绿地系统规划有效地改善了绿地景观破碎化的问题,绿地斑块形状的复杂性程度增大,景观连接度得到提高,景观多样性和均匀性指数均得到较大幅度提升。而在现有绿地系统规划基础上做出的优化生态网络方案可进一步改善崇明本岛现有绿地系统的数量和质量。同时表明,生态网络分析结合景观格局分析是评价和改善绿地系统规划有效的途径。

Assessment of the current status & planning of the green space system of Chongming Island using landscape metrics and network analysis methods

Based on a land use map created from a satellite image from 2005,a map of agreenbelt system from 2005 and a map of a planned greenbelt system, a number of ecological networks of Chongming Island were designed using network analysis methods. Using network indices such as α,β,γ indices, cast ratio and corridor metrics, an optimal ecological network was selected among those ecological networks. The optimal ecological network was then overlaid on the existing plans for a greenbelt system on a GIS platform. Then we used landscape spatial pattern analysis and a series of landscape pattern metrics on Fragstats to assess the present situation, the planned greenbelt system and the optimal ecological network for Chongming Island. Our results showed that the greenbelt system plan for Chongming Island was an improvement which indicated by decrease in patch density and increase in edge density, mean patch fractal dimension on the patch level, landscape diversity, landscape evenness, and landscape connectivity. Compared to the existing greenbelt system plan, the optimal ecological network brought a further improvement to the greenbelt system both on quality and quantity of Chongming Island.