The Neighborhood Structure Characteristics Of Evergreen Broad-Leaved Forest In Guanshan,Jiangxi Province

Evergreen broad-leaved forest is the typical vegetation of subtropical area in China.It plays an indispensable role in forest resource cultivation and ecological environment protection in this area.Therefore,our study based on Jiangxi Guanshan Evergreen BroadLeaved Forest Monitoring Plot which large in 12 hectares as platform and took the individual as a research unit.Firstly,The index of mingling,neighborhood pattern,dominance and so on of each neighborhood unit were calculated.And then the difference of neighborhood structure characteristics of different species,functional groups and stands were compared.Lastly,the spatial autocorrelation of stand neighborhood structure was analyzed.The main results were as follow:(1)Among the 25 major tree species,except for Phyllostachys edulis and Cunninghamia lanceolata showed moderate mixed state,all the other 23 species showed intense or extremely intense mixed state.Pinus massoniana,Quercus acutissima,Liquidambar formosana and Choerospondias axillaris all took the lead in dominance and maturity.And Machilus thunbergii,Ilex ficoidea and Phoebe bournei were relatively low.(2)The neighborhood structural indexes of deciduous tree species were all greater than evergreen tree species.Bamboo species,broad-leaved tree species and coniferous tree species were all showed aggregated distribution pattern.And the mingling,base openness and treetop openness of broad-leaved tree species were significantly greater than the coniferous trees species and bamboo species.The neighborhood pattern of sun-loving,neutral and shade-tolerant tree species were all aggregated.The mingling and base openness of shade-tolerant tree species were greater than that of sun-loving tree species,and sun-loving tree species were greater than that of neutral tree species.(3)The average mingling of Jiangxi Guanshan Evergreen Broad-Leaved Forest Monitoring Plot community was 0.77,which indicated that this community was in a extremely intense mixed state.The neighborhood pattern of this community was 0.54,which means that the tree species was in a crowded state.The dominance was 0.50,which indicated that the size of trees was in the medium state.The treetop openness was 0.68,it means that the light access and growth space of canopy were sufficient.The base openness was 0.08,which indicated that the light access and growth space under the trees were insufficient.The maturity was 0.28,it means that the community was in a young state.(4)We found that the neighborhood indexes showed obvious spatial heterogeneity and spatial autocorrelation if the large plot was divided into 300 stands which large in 400 square meters.In the global spatial autocorrelation,the Moran’s index of mingling,neighborhood pattern,maturity,base openness and treetop openness was 0.3515,0.1331,0.4405,0.3520 and 0.1787,respectively.It means that these indexes showed significant spatial positive correlation.And the Moran’s index of dominance was-0.0374,which showed no significant negative correlation in space.In the local spatial autocorrelation,the mingling,maturity and base openness showed a strong aggregation phenomenon in space.These results indicated the following conclusions.In terms of species level,the early succession tree species,such as Pinus massoniana,Quercus acutissima and Liquidambar formosana still occupied a dominant position in the Guanshan large plot.From the perspective of functional group level,the age of deciduous tree species was generally higher than that of evergreen tree species.In terms of stand level,the age of Guanshan large plot community was relatively low,the distribution showed aggregated pattern,which indicated that this community was in a succession stage between early stage and climax stage.The spatial heterogeneity and spatial autocorrelation of the stand neighborhood indexes were obvious,but the distribution of the neighborhood indexes of the stand had its own rules in some place.It was because of that the Guanshan large plot community was a complex community with large area,therefore,this community could not be uniform.And the community would become more and more uniform in the process from early stage to climax stage.In the future.The results of this study are beneficial to understanding the ecological habits of tree species,and provide references for the study of community construction,species coexistence,community succession and biodiversity conservation in subtropical forests.