青岛市湿地生态网络评价与构建

在快速城市化背景下,城市社会经济发展与空间扩张不可避免,往往造成栖息地数量、面积、质量锐减、栖息地之间联系破碎等后果。此外,全球气候变化也加剧了栖息地恶化过程。生态网络通过保护恢复重点栖息地及构建栖息地之间物质、信息及能量传播的连接廊道,在整体上维持生态系统的动态平衡。青岛市位于东部沿海经济发达地区,地处海洋与陆地生态系统的交汇处,生态环境极为脆弱,易遭受外力破坏,且难以恢复。选取青岛地区湿地作为研究对象,在RS,GIS技术支持下,基于最小成本路径法构建青岛市湿地生态网络,并利用关联长度指数、介数指数对网络的整体结构及斑块重要程度进行评价。结果表明,不同路径成本阈值水平下,网络的连通性有很大差别;核心斑块中,胶州湾湿地、大沽河等具有较高重要程度;歇脚石斑块中,重要程度较高的斑块位于以胶州湾湿地为中心,以胶莱河、潍河河口,白马河、潮河河口及丁字湾为端点的连线上。在青岛市及周边地区划定"一心、二轴、一环"的湿地生态网络控制框架的策略,为青岛市湿地生态系统保护与城市发展空间选择提供科学方法与量化依据。

Evaluation and construction of wetland ecological network in Qingdao City

Urban socio-economic development and spatial urban expansion has led to the loss and fragmentation of habitat.Global climate change adds to the gravity of these effects.An ecological network describes a network of habitats and connecting corridors that is mapped using habitat suitability and land use/land cover data.Connectivity within a habitat network ensures a flow of material,energy and information among the various patches,and allows species′ movement from inappropriate to appropriate areas.This ensures the abundance of species reaches a dynamic equilibrium at the network level and also means that the disappearance of species from any particular patch does not change the function of the regional ecosystem network.Thus,management of ecological network is an effective measure to counter the loss of biodiversity caused by reductions in habitat quality and area,as well as habitat fragmentation,in the context of rapid urbanization and climate change.The least cost path method is a way to construct and analyze ecological networks based on landscape spatial structure and dynamic biological processes.Based on the understanding that the characteristic of the matrix is one of the important factors determining the movement of species between patches,the least cost path method gives different cost values to different landscape types,and generates a cost surface to substitute the Euclidean space.Therefore,the dispersal paths generated by the least cost method are similar to those of actual species movement.Qingdao city is located in the eastern coastal region of China where the economy is relatively well-developed.The region is also where marine and terrestrial ecosystems meet.In this paper,we propose a wetland ecological network in the Qingdao district based on remote sensing and geographic information systems technology.We evaluate the overall structure of the network and the importance of individual patches using the correlation length index and betweenness centrality index,and use the findings to identify optimal strategies and make recommendations.In this paper,we discuss the following five questions:(1) How to classify landscapes?(2) How to determine the cost value of each landscape type?(3) How to evaluate the importance of each core patch?(4) How to evaluate the importance of stepping stones?(5) What is optimal management strategy for the wetland systems in the study area? The result shows that the network connectivities are very different in terms of threshold levels of path cost.Core patches in Jiao Zhou bay wetlands and Da Gu river have a relatively high degree of importance.Stepping stone patches with a high degree of importance are found in two zones: one comprising Jiao Zhou bay,Jiao Lai river and Wei He river estuary,and the other comprising Jiao Zhou bay and Ding Zi bay.In this paper,we propose a wetland management plan based on an ecological network including one core area,two axes and a ring in Qingdao and its surrounding area,to provide a scientific and quantitative basis for the selection of urban development sites within Qingdao City that simultaneously achieves wetland ecosystem protection.These network construction and evaluation methods can be used for other ecological network analysis.