Study On Urbanized Island Ecosystem Health Assessment

With the constant urbanization process and intensive island exploitation activities, ecosystem health of the islands is faced with serious threats. Island ecosystem health assessment is the foundation of the ecological protection, planning and management of island.To meet the demand of the Chinese island ecosystem assessment and management, assessment method of island ecosystem health was constructed and applied to Xiamen Island, which included the index selection, assessment standards and indicator weight establishment, island ecosystem deterioration analysis and island ecosystems protection suggestion. The main contents and results are as follows:(1) Based on the review of studies on the ecosystem assessment and island ecosystem,"Driving Force-pressure-state-impact-reponse"(DPSIR) framework was selected and assessment indexes for island ecosystem health was established in terms of five factors: socio-economics, environmental management, environmental quality, bio-ecology, landscape patterns,and the meaning of each indicator and the way to get it were analyzed respectively. Then the criteria and corresponding weights for these indicators were determined.(2) The assessment method was applied to Xiamen Island. The results showed that the IEHI of Xiamen Island was 6.99, 6.77 and 5.33 in 1980's, 1990's and 2000's respectively, which means that the island ecosystem was healthy in 1980's and 1990's, while it was sub-healthy in 2000's. The ecosystem was degraded gradually, which was mainly due to decline of surface water quality, intensification of sea water eutrophication, reduction in the benthos species in the intertidal zone, decline in landscape's naturalness, increase in landscape fragmentation, and so on.(3) Correlation analysis was applied to analyze alteration mechanism of ecosystem health in Xiamen Island under the cooperative influences of the driving force, pressure and response, especially for sea water quality. The results showed that there was a dynamic relationship of cause and effect among the driving force, pressure, response and state. In the past 20 years, The driving force and pressure on island ecosystem exceeded government's investment in environmental protection, which might be the cause for ecosystem deterioration in Xiamen Island.