| The relationship between species in plant communities is a hot topic and the core issue of modern ecology which mainly includes resource competition of different populations and stable coexistence mechanism.While exploring interspecific association and niche is an important method for interspecies relationship.Interspecific association was defined as the interconnectedness of space distributionof the different species in the community,which could reflect the effect of interspecific interactions and habitat differences on species distribution.Niche should be used for spatial and temporal location and functional status of species in the community.which could reflect the species utilization and the stability of their communities.If interspecific association and niche were combined to carry out research,it is of great significance to understand the interspecific relationship,community structure and function,time and space position,function of contact in the community species,populationevolution,community succession,natural vegetation restoration,biodiversity conservation and forest management.The typical plots were surveyed in Pinus taiwanensis community of Daiyunshan.Based on the ecological niche space compartmentalization,18 populations from the arbor,11 from the shrub of more than 1 important value were chosen to research their three dimensional multidimensional niche characteristics formed soil total N,total P,total K.And A series of parameters including variance ratio method(VR),?~2-test,association coefficient(AC),Percentage of co-occurrence(PC)and the Spearman rank correlation were used to analyze the interspecific ralationship.The main results and conclusions of this paper are as follows:(1)Three are 56 families,102 genera and 189 species of vascular bundlespants in Pinus taiwanensis community,and mainly distributed Rosaceae,Liliaceae,Theaceae,Fagaceae,Lauraceae Anacardiaceae.(2)Resources availability influenced niche matrices greatly.And Yu Shixiao multidimensional niches measure was more consistent with the actual situation.There was no significant correlation between niche breadth values and importance values.(3)153 species pairs were constituted in the mainarbor species,whose the niche overlap values below 0.5 was 105,accounting for 68.6%;55 species pairs were constituted in the mainshrub species,whose the niche overlap values below 0.5 was 25,accounting for 45.5%.It indicated that the niche overlap values was generally low and weak interspecific competition ofmain woody plant populations in Pinus taiwanensis.Niche breadth of pinus taiwanensis,Schima superba,Toxicodendron succedaneum,Machilus thunbergii,castanopsis faberi,Castanopsis eyrei,Rhododendron latoucheae,whose niche overlaps were 0.532,0.527,0.334,0.491,0.467,0.348,0.463,respectively.It showed that the average value of niche overlap of pinus taiwanensis and other species was higher relatively.Thus,more speciesoccupied the same resource position with fierce interspecific competition.(4)The expression of the relationbetween nichebreadth,overlap and similarity was as follows:the niche overlap values and niche similarity of between the species with larger niche width and other species not necessarily large,but the consistency of variation trend between niche similarity and overlapping values of all major species were basically confirmed with significant positive correlation(arbors:P<0.01,r=0.890;shrubs:P<0.01,r=0.909).It showed that the similarity of the resource utilization of populations was greater,the more similar the ecological characteristics of the population.The populations occupied the same position,often niche overlap.Therefore,the similarity of resource utilization of populations could be reflected by niche overlap among species.(5)In the study of interspecific association,the reliable results of interspecific association degree could be given only that multiple indicators(interspecific association coefficient,Percentage of co-occurrence,the Spearman rank correlation,and other indicators determination)should be used together.(6)The variance ratio method(VR)of Pinus taiwanensis communitywas above 1,which showed a sinificant positive correlation among the main woody plant populations.It indicated that the community structure was stable with weak competition.The?~2-test,association coefficient(AC),the Spearman rank correlation showed positive correlations of majority of species-pairs in the the layers of arbor and shrub.The positive association pairs of arbor layer accounted for 58.2%,49.7%,56.9%,respectively;followed by negative correlations of species-pairs for 41.2%,38.6%,42.5%,respectively;Only few species-pairs displayed no correlations.The positive association pairs of shrub layer accounted for 65.5%,70.9%,56.4%,respectively;followed by negative correlations of species-pairs for 29.1%,29.1%,43.6%,respectively;Also,only few species-pairs displayed no correlations.It indicated the existence of a certain degree of independence among the main woody plant populations.(7)There was a significant positive correlation between the?~2-test,association coefficient(AC),Percentage of co-occurrencethe,Spearman rank correlation and niche overlap in main woody plants populations of Pinus taiwanensis community(P<0.01).(8)Combined with species composition,the important value and age structure of Pinus taiwanensis community,the population changes were analyzed.Pinus taiwanensis occupied the dominant position with higher important value in the arbor,but fewer seedlings and saplings by investigation.Thus,Pinus taiwanensis was a typical kind of recession.The niche overlap values of between Pinus taiwanensis and other species were higher and resource sharing was relatively obvious.As increasing species occupied the same resource position and environmental resources decreased continuously,the species could develop into competition.Pinus taiwanensis would be threatened greatly.Those results demonstrated that the status of Pinus taiwanensis,Schima superba,Rhododendron latoucheae,Machilus thunbergii and Castanopsis eyrei would probably be dominant in coming community structure.However,the dominance of Pinus taiwanensis tend to decline gradually. |
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