Effects Of Snow Disaster On Community Structure And Dynamic Of Evergreen Broad-Leaved Forest In The Middle Part Of Wuyi Mountains

Based on the evergreen broad-leaved forest in Yashi Mountain in the middle part of Wuyi Mountains,this paper carried out a community survey which affected by the severe snow disaster.The effects of severe snow disaster on the community structure and community dynamics of evergreen broadleaved forest were discussed.Attempt to analyze the plant function group,niche,species diversity,community stability,species regeneration composition and so on.The main conclusions are as follows:1.According to the analysis results of interspecific association and the determination of species ecological groups,the main species in the study area were divided into four PFTs:PFTsl:Castanopsis fargesii,Castanopsis fabri,Daphniphyllum oldnami,Ternstroemia gymnanthera,Adinandra milletii,Eurya nitida,Ardisia crenata,Alpinia japonica.PFTs2:Alniphyllum fortune,Styrax odoratissima,Itea chinensis,Toxicodendron succedaneum,Rhus chinensis,Schima superb,Millettia nitida,Rubus corchorifolius.Dicranopteris dichotoma.PFTs3:Castanopsis eyrei,Machilus grijsii,Cyclobalanopsis glauca,Cinnamomum porrectum,Symplocos stellaris,Dendropanax dentiger,Maesa japonica,Morus wittiorum.Liriope platyphylla,Woodwardia japonica.PFTs4:Sapium discolor,Elaeocarpus japonicas,Pieris japonica,Loropetalum chinense,Litsea cubeba,Mallotus apelta,Ampelopsis grossedentata,Lophatherum gracile.2.In the analysis of niche,the species with higher niche breadth are the dominant species of community.The dominance of disturbed forest is less significant than closed forest.In addition,the niche breadth of heliophilous plants in the closed forest and the shade-tolerant species in the disturbed forest were lower.The species pairs with high niche overlap were that species with similar ecological characteristics or they had complementary use of habitat factors each other.The average niche overlap of closed forest is lower than that of disturbed forest.It also indicated that niche differentiation appeared among different species in closed forest gradually.3.The comparison of species diversity and community dominance showed that the four diversity indices of disturbed forest were higher than those of closed forest respectively.But the distinction of shrub layer and herbaceous layer was more pronounced.However,the community dominance of closed forest was higher than that of disturbed forest.The increase of species diversity is a response of ecosystem to external disturbance and it is a countermeasure to restore ecosystem stability.4.The similarity between communities showed a decreasing trend at the level of genera.Due to the heterogeneity of community habitats and geographical location,the similarity between communities belonging to closed forest(disturbance forest)was greater than that of closed forest&disturbed forest assemblage.In communities with closed forest&disturbed forest assemblage,the communities with more closer geographical locations were more similar to their communities.5.In the analysis of community stability,from the calculation method selected in this paper,the relative stability of each community was in sequence:Castanopsis fargesii community>Castanopsis eyrei community>Alpine leaf&Castanopsis fargesii community>Sapium sebifera&Castanopsis eyrei community.That is,the overall stability of closed forest is higher than that of disturbed forest.6.The trend of species regeneration was roughly as follows:as time goes on,the first invasive heliophilous and deciduous pioneer species were gradually replaced by shade or shade tolerant evergreen species,and these species were mostly the construction or co-construction species of evergreen broad-leaved forest.