The Research Of Zhoushan Archipelago Ytpical Plant Communiyt Structure And Countermeasures Of Optimization

Zhoushan islands possess many typical island plant communities, which it is a natural gene bank of subtropics island plants in China. At present, there is short of detailed research on plant types construct by islands characteristic tree species of home and abroad. This paper bases on the Zhujiajian, Putuo and Luojiashan islands which own typical island vegetation for representatives as research objects, where they are located at the southeast of Zhoushan island. According to the study of communities of species composition and structure, biodiversity and trend of community succession from eighteen sample plots in the three islands, we came up with corresponding optimizing measures as a theory and technical support for guiding island ecological construction and the sustainable development. The results are follows:(1) The most common tree species in arbor layer include Machilus ergii, Cinnamomum japonicum var. chenii, Liquidambar formosana, Celtis tetrandra ssp. Sinensis; Cyclobalanopsis glauca, Albizia kalkora, Dalbergia hupeana, Symplocos setchuensis and Platycarya strobilacea, In shrub layer the common tree species conclude Ardisia crenata, Camellia sinensis and Eurya japonica; In herb layer the common plants are Dryopteris spp. and Arachniodes spp.. The three islands own many island and coastal special plants, such as Cinnamomum japonicum var. chenii, Eurya emarginata, Viburnum odoratissimum, Ilex integra and Neolitsea sericea and so on. This is also the most significant features in the species composition of island vegetation and can reflect the specificity and typicality of island plant communities. All in all, in the above three islands the arbor species have a low average height, low average diameter at breast height, a single dominant species and an relatively obvious dominance. This mentioned situations are positively correlated with strong wind and relatively poor site condition.(2) As the mentioned above islands the diversity index of broad-leaved evergreen forests is Machilus ergii, Cinnamomum japonicum var. Chenii forest> Cinnamomum camphora forest> Cyclobalanopsis glauca, Distylium racemosum forest; evergreen, deciduous broad-leaved mixed forest is on the succession process from the deciduous broad-leaved forest to evergreen broad-leaved forest, and the community is still not in a stable state, so the diversity of every level is very complex; In general, the species diversity index and Shannon-Wiener index in arbor layer and shrub layer of deciduous broad-leaved forest are lower than those of in the herb layer. As the Pielou index, shrub layer is evenly distributed, but there are obviously dominant species in arbor layer and herb layer and with an uneven distribution. On the whole, species richness and Shannon-Wiener index show order that evergreen, deciduous broad-leaved mixed forest> evergreen broad-leaved forest> deciduous broad-leaved forest and the diversity of evergreen broad-leaved forest is further small which becomes a very obvious trend. Pielou index shows the trait that broad-leaved forest with an obvious dominant species is relatively small, and other broad-leaved forest is relatively large.(3) There are26updated tree species among a variety of broad-leaved forest in Zhujiajian, Putuo and Luojiashan islands, with17evergreen species and9deciduous species. And compared with the number of species in the arbor layer, there are the same and similar species, which indicating a characteristic that there is a relatively single tree species in islands. The succession trend of stable zonal vegetation consist of dominant evergreen broad-leaved species such as Machilus ergii or Machilus ergii, Cinnamomum japonicum var. chenii or Cinnamomum japonicum var. Chenii, Neolitsea sericea or Cyclobalanopsis glauca in islands at the southeast of Zhoushan island. And this can be a direction to the succession of human intervention in forest stand.(4) Aim at the current situation of forest community in Zhoushan island, some advice are proposed as follows:enhancing public awareness and scientific planning, especially for a key protection of island zonal vegetation; closing hillside to facilitate afforestation and promoting a self-updating; strengthening the thinning and urging forest artificially; improving species and landscape diversity through supplementary afforestation.