Vegetation characteristics and plant diversity of Waimalangshan Island, Zhoushan.
The vegetation characteristics and the α, β biodiversity of plant communities were investigated at the desert island of Waimalangshan Island, Zhoushan Archipelago, Zhejiang Province. In order to discuss the difference of vegetation characteristics and plant diversity between Waimalangshan Island and nearly mainland, we analyzed the vegetation characteristics, life form of island plants, geographical elements, similarity of six plant communities, the structure and diversity of community. Firstly, there were 55 species of seed plants belonging to 33 families 51 genera in Waimalangshan Island. The area of Waimalangshan Island is small, but there existed some autochthonal strand plants such as Heteropappus arenarius, Eurya emarginata, Rhaphiolepis umbellata, which had great development potentials in landscape use. Secondly, the tropical types of genera were distinct similar to nearly islands, Dongfushan Island and Dajinshan Island. The families of dominant species in communities were Theacea, Pinaceae Euphorbiaceae, nevertheless, it was different from the zonal vegetation's dominant families in island forest. The major life form was phanerophytes plants of island plants and the proportion in plant life form were lower than that in the life form of subtropical vegetation. Thirdly, the richness and structure of plant population were simple and contained less diversity than the nearly mainland due to small area and special circumstance. Margalef richness, Simpson diversity, Shannon-Wiener diversity, Pielou evenness of tree layers were higher than that cf shrub's layer. The dominant species of tree and shrub' s layer was single. Similarity of six plant communities were low ranging from different habitats because of high level of landscape fragmentation. Because of the difference of ecological adaptability and stage of plant succession, the plant population would take a long time to be climax community. Lastly, the proportion of introduced plants of Waimalangshan Island plants was 9.09%. Pinus thunbergii and Phyllostachys mannii which were introduced species for landscape use had a distinct dominance in plant communities for several decades. Native plants loss, introduced plants increased and native plants disappeared. It should be treated with caution that introduced plants may caused eco-disturb to native plants for competitive relationship in habitat fragmentation.