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The Stand Structure Of Pinus Thunbergii Forest After The Invasion Of Bursaphenchus Xylophilus In Zhoushan Zhejiang

Posted on:2015-09-25Degree:MasterType:Thesis
Country:ChinaCandidate:J H YeFull Text:PDF
GTID:2283330470977345Subject:Forestry
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The Bursaphelenchus xylophilus invasion on Zhoushan island resulted in a large number of Japanese black pine(Pinus thunbergii) tree deaths in 1992. With a plot investigation(plot size 100 m x 100 m) in Changgang Mountain, the stand structure of P. thunbergii forest was researched. The results show that:(1)The past P. thunbergii forest now take evolution to mixed conifer and broadleaved forest with an increasing species richness and plant diversity;(2)deciduous broadleaf trees are the majority and occupy a relatively large advantage in the forest canopy, however evergreen broadleaved trees are the minority and mainly distributed in the middle and lower layer;(3)The forest stands, lack of dominant species, was aggregation distribution with low mixed degree. The above results show that the forest is still in the early succession and needs a long-term process for the development of evergreen broadleaved forest. In order to speed up the forest succession and restore the local forest ecological system as soon as possible, we suggest that it is important to replant some island zonal vegetation selected from the native tree species.And the 3 type forests of small, medium, large rage affected by pine wilt disease were selected and respectively five sample plots of size 20 m ×20m were set for each in the same forest. The effects of different density of Pinus thunbergii on the niche of main associated tree species were researched after statistical analysis by niche breadth formula. The results show that:(1)The larger of forest area affected by pine wilt disease, the less of the residual P. thunbergii, which made the deciduous trees become the subject stand;(2)In the 3 type forests, the niche breadth of Liquidambar formosana, Quercus fabri and Dalbergia hupeana are relatively large, because of the increasing area affected by pine wilt disease, The niche breadths increase for such species as Machilus thunbergii, Lagerstroemia indica, Symplocos caudata, Mallotus japonicus and Albizia kalkora;(3) In the small area forest affected by pine wilt disease, the resources are relative adequacy, however with the decrease of P. thunbergii and community succession, the forest community environment is improved and more and more species was invaded, which leads to increasingly fierce of the interspecific competition. The conclusion can be drawn that with the reduction of P. thunbergii, the species number and population density of the community will gradually increase.
Keywords/Search Tags:Pinus thunbergii forest, pine wilt disease, stand structure, niche breadth, Zhoushan islan
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