Dominant woody plant population niche characteristics in secondary succession stage of degraded artificial Picea asperata forest
[Objective]To study the community structure and ecological status of the secondary succession stage in the degraded artificial spruce forest in the Bailongjiang forest area and predict the community's development trends.[Method]Using sample plots to represent the comprehensive state of various resources and based on community survey data,we calculated species'importance values as niche measurement indices.We determined the niche width for dominant species using Levins'method,calculated Pianka's niche overlap,and analyzed overall species associations.[Result]The results indicate that there were a total of 11 tree species in the secondary community's canopy layer.Artificial P.asperata trees had experienced significant mortality.The importance values and niche breadths of Betula albo-sinensis,Betula utilis,and Abies faxoniana were much larger than those of other species,establishing them as dominant species in the secondary community.A.faxoniana had the widest niche breadth in both the canopy and shrub layers,while Betula species were dominant in the canopy layer but not in the shrub layer.The secondary plant communities,there was generally a significant degree of niche overlap in the tree layer,which was greater than that in the shrub layer.Shrub communities exhibit niche differentiation.Overall,there was no significant positive correlation among species in both the canopy and shrub layers.[Conclusion]This study indicates that the secondary community is a Betula-Abies faxoniana forest community,currently in the mid-successional stage of positive dynamics and competitive equilibrium.The dominance and niche of various populations are still undergoing mutual adaptive changes,rendering the community relatively unstable.There is no clear correlation between species importance values and niche breadth,nor is there a definite pattern between niche overlap and niche breadth.Niche overlap further reflects the community's stability.The degree of dominance and niche breadth among coexisting species in the canopy and shrub layers reflect species growth potential.Therefore,the tree layer's stability in this secondary community is greater than that of the shrub layer.The A.faxoniana population is showing a further growth trend,while the birch population is restricted in its regeneration and is gradually being replaced by shade-tolerant tree species.Therefore,management in this secondary forest area should create favorable conditions for the growth of A.faxoniana.
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