Analysis On The Types And Species Diversity Of Urban Forest Remnants-Cinnamomum Camphora Community

In recent years,the development of urbanization had made a significant change in the environment of the city.And it also changed plants in the city.Wuhan is one of the important distribution areas of evergreen broad leaved forest in subtropical zone of China.In the process of urban construction,the original vegetation is inevitably destroyed.And plantation gradually replaces the natural vegetation and the vegetation of fragmentation phenomenon was very serious.It is of great significance to understand the composition of the local natural vegetation and the structure of the zonal vegetation.At the same time,it is instructive to study the urban remnant forest for the restoration of urban vegetation in the future.In this paper,We investigated the camphor community with residual forest and relatively few human disturbance in Wuhan urban area by the quadrat method and the theory of potential natural vegetation.We had analyzed its community composition and community structure and community types and species diversity.Comprehensive the above research results,this paper draw the following conclusions:(1)Based on the study of the important values of the species in the 15 quad rats of the sample plots and according to the method of group connection,the re maining camphor communities in the study area were divided into 6 association.There are Association 1:Ass.Cinnamomum camphora-Ligustrum lucidum-Dryopt eris championii;Association 2:Ass.Cinnamomum camphora-Ligustrum lucidum+T rachycarpus fortunei-Parathelypteris nipponica+Dryopteris fuscipes;Association 3:Ass.Cinnamomum camphora-Pittosporum tobira+rachycarpus fortunei-Paederia s candens;Association 4:Ass.Cinnamomum camphor a-Pittosporum tobira-Trachel ospermum jasminoides+Dryopteris championii;Association 5:Ass.Cinnamomum ca mphora-Trachycarpus fortunei+Ilex chinensis-Dryopteris championii;Association 6:Ass.Cinnamomum camphora-Quercus variabilis-Pteridium aquilinum.Among them,Association 1 is the most common,accounting for 40%of the total number of the total community.According to the different site conditions,the species co mposition of the community and the dominant species,the results of the cluster c lassification are in accordance with the actual situation.(2)According to different community types and different structure level,the remaining camphor tree community types were divided,we also analy the Patrick richness index,Shannon-Wiener diversity index,Simpson diversity index and Pielou evenness index of each.Patrick richness index of Association 1:Ass.Cinnamomum camphora-Ligustrum lucidum-Dryopteris championii is the highest.The Shannon-Wiener diversity index(H),Pielou evenness index(J)and Simpson diversity index(D)of Association 4:Ass.Cinnamomum camphora-Pittosporum tobira-Trachelospermum jasminoides+Dryopteris championii is the highest.The remained camphor communities in the study area were divided into three layers:tree layer,shrub layer and herb layer.In terms of the diversity index of each layer,it showed the herb layer>shrub layer>tree layer but Association 4 is an exception because shrub layer>herb layer>tree layer.Each index of tree layer was significantly the lowest than shrub layer and herb layer.This may be due to a large number of herbaceous species and a lot of trees and shrubs seedlings in the herb layer,similarly shrub layer is not only a lot of shrub species,but also some young trees;In addition,association 4 is a mixed forest of Cinnamomum camphora and Pinus massonianas,there is fewer species in herb layer because the light is not sufficient,and the decomposition of pine litter is slower than camphor tree litter,it has a great influence of the germination and growth of plants.Therefore,the diversity index of association 4 is slightly different from that of other association.(3)15 communities of the study area were recorded 63 families,95 genera and 119 species,Among them,9 families,10 genera and 12 species of fern;2 families,2 genera and 2 species of gymnosperms;52 families,83 genera and 98 species of angiosperms including 45 families,75 genera and 86 species of dicotyledon;7 families,8 genera and 12 species of monocotyledon.The flora analysis of families and genera showed that the remained camphor community in Wuhan plant flora showed significant tropical and it has a close relationship with temperate,reflects the transitional nature of residual vascular flora of Wuhan.