Research On Ecosystem Characteristics And Evaluation Of Current Situation Of Island

Islands are important components of the nation maritime territory, and play important roles in the national economy, politic and military. Islands are geographically away from the land, and their ecosystems are mainly influenced by the ocean, so the ecosystems on the islands are very vulnerable to the damages from human and the natural disasters. In the prosperity stage of the islands exploit, islands brought human considerable economic benefits. However, as economy of the island cities developed rapidly, the vulnerability of the islands emerged. Unlimited exploits combined with the loss of effective regulations have brought great threat to the mineral and ecological resources of the islands. Islands ecosystems have already one of the ocean protection research hotspots.The islands conservation is based on their ecosystems, so conducting ecosystems evaluating skill study would help to identify the status of the ecosystems and provide basis for the ocean ecological division, ecological recovery and conservation. Currently, there are no unified index system and evaluation model for islands ecosystems evaluation both at home and abroad. The paper studies the methods and approaches on islands ecosystems evaluation, analysis the Zhejiang coastal typical islands, and tries to builds the islands ecosystems evaluation system and model.The contents of the paper are as follows:（1）According to the results of the ecological regionalization of the islands in Zhejiang province, the Qixing islands are chosen as a typical case in the IV₂ ecological subregion to make ecological status evaluation, and are regarded as the unified model and indexes system for the same type islands. Using the islands survey data to study the ecological system features of the Qixing islands, the results indicate: the islands retain original ecology features, and are important in the ecology and should be conserved; despite of the limited area, they have single vegetative cover; influenced by the warm Taiwan and the Zhejiang and Fujiang coastal currents, the population are characterised both temperate and tropical feature, they are the most typical ocean ecosystem in Cangnan.（2）establishing the comprehensive evaluating model. The paper focuses on a islands-intertidal zone-inshore area sub-ecosystem "3 in 1" evaluating model. The three sub-ecosystems should be considered together to make an objective evaluation.（3）the islands, intertidal zones and inshore areas sub-ecosystems are evaluated respectively. The islands and inshore areas sub-ecosystems are evaluated by indexes; the intertidal zones are evaluated by indicator organism, and the organism in intertidal zones sensitive to specific pollutions are chosen as indicators. The evaluating results indicate: the current ecosystem quality of the Qixing islands is generally fine, but the environments of the intertidal zones are moderately polluted, and balance of the ecosystem in the sea area is subjected to certain damage.（4）The comprehensive evaluation of the islands ecosystem. Following the evaluations of the three sub-ecosystems, the weight is distributed to the three sub-ecosystem. The weight is based on the vulnerability, and the more vulnerable the larger weight. The evaluation results show: the current comprehensive evaluating index is 0.719, the current status of the islands ecosystem is "fine", and it is certain that the Qixing ocean conservation ecosystem is subjected to certain damage, and it is promised to focus on improving the ecological quality in the future.