A Study On Urban Ecological Network

The urban greenpace system is a natural element which composes and supports urban environment and provides an important base for sustainable development of urban society and economy. Urbanization is arguably the most dramatic form of land transformation that profoundly influences natural environment, biological diversity and human life. Therefore, it is becoming increasingly important for large-scale ecological research and applications (e.g., urban landscape planning, land use planning, and biodiversity conservation) to consider these most dramatic land transformations and their ecological consequences. Based on the land use map created from a Landsat-TM satellite image of year 2000, a map of greenbelt system of year 2002 and a planning of greenbelt system, this dissertation assessed the present situation and the existing planning of greenbelt system for Xiamen Island, using landscape spatial pattern analysis and a series of landscape pattern metrics on a GIS platform. On the basis of these analyses, a number of new planning scenarios were designed by using network analysis methods for optimizing the ecological network of Xiamen Island.Firstly, this dissertation reviewed the development and evolution of ecological network concepts and practices, which could be summarized as three phases: the era of urban park planning in the 19^th century, the period of open space planning in the 20 century and the era of comprehensive ecological network planning since 1980s. The main functions of ecological network (e.g. ecology, recreation, history and culture protection, economy and education) as well as planning theory and method of ecological network (e.g. questionnaire, network analysis, landscape metrics assessment, multi-objective planning, multi-scale planning, vision plan and landscape assessment model based GIS) have been introduced. Some issues of ecological network planning in China, such as considering less recreation, lacking participant from public, lacking scientific research as the base of planning decision and faultiness in long-term management mode have been discussed.As a case study, this dissertation carried out an ecological network planning indetail for Xiamen Island. Based on the landscape pattern analysis of present situation of greenspace system in 2002 and planning of greenspace system in 2002 using FRAGSTATS3.3 software, five ecological network scenarios (ecological A-E) using network analysis were proposed. Then, an ecological network with higher connectivity was selected as an optimized ecological network among the five scenarios, using corridor structure analysis (by corridor length and corridor density) and network structure analysis(by α index ,β index,γ index and cost radio). The improvement of the optimized ecological network on urban landscape was quantitatively assessed through a comparison between the optimized ecological network and planning of greenspace system for Xiamen Island in 2002. Finally, some advices were listed for the planning implement. The research results showed that: (1) Through the comparison of landscape metrics at patch class level between the present situation of greenspace system in 2002 and a planning of greenspace system in 2002, a decrease in patch density and an increase in mean patch size of cultivated greenspace patches indicated an improvement of fragmentation in cultivated greenspace patches. A decrease in patch density and an increase in mean patch size of landscape patch at landscape level indicated also that fragmentation of the whole landscape had been reduced. Increases in diversity index and connectance index, and a decrease in Euclidean nearest neighbor distance implied an improvement in landscape fragmentation and connectivity. (2) Among the five ecological network scenarios, the ecological network D and ecological network E had higher corridor length, corridor density, α index, β index and γ index, which could, therefore, be considered as the better designs. The ecological network E could be considered as an optimized one with the lowest cost radi...