Characteristics Of Plant Diversity And Community Structure In Daxing'anling Forests And Association Analysis

The protection of natural forest plant diversity was crucial to its ecological service function,and the contribution of stand size,community characteristics,and vertical structure to its change and the main influencing factors will help to improve the protection of plant diversity based on the adjustment of stand structure.Based on this,this paper chose the forests in Daxinganling Mts.(Huzhong,Nanweng River,Chuona River,Shuanghe and Dobucul Natural Reserve)as the research object.The characteristics of individual size(tree height,DBH,branch height,shrub height,etc.),the characteristics of arbor,shrub and herb-related communities(density and coverage)and species diversity(diversity,evenness and richness index)were investigated.Through redundancy analysis(RDA)and variation partition analysis,the following conclusions were drawn:In Daxinganling Mts.,the average richness of each plot was 3 arbor species,3 shrub species and 8 herb species.The diversity indices of arbor,shrub,and herb were 0.38,0.27,and 0.7,and the evenness were between 0.66 and 0.71.Plant diversity in Huzhong,Naweng River,Chuona River,Shuanghe,Dobucul nature reserves was different,and plant diversity in tree layer and herb layer in Huzhong was significantly lower than that in the remaining four nature reserves,while the richness and diversity of shrub layer were higher in Huzhong,and the evenness was significantly lower than Nanweng River,Chuona River,Shuanghe and Dobucul Natural reserve.Plants diversity of shrub layer in Huzhong Reserve fluctuated greatly among all plots,and the flutuation of arbor plant diversity in Dobkur Reserve was small,while the richness of herbs was the most fluctuant.Through the survey of community structure characteristics,and the average tree height in Daxinganling area was 13.7m,the height under branch averaged at 8.26m,and the diameter at breast height averaged at 14.38cm,and the average canopy density averaged at 0.69,and the average density averaged at 1400 trees/hm2.The individual size characteristics(tree height,height under brarnch,diameter at breast height)and coverage of the tree layers in the Nanweng River and ChuoNa River were significantly higher than those in the Huzhong(P<0.01),and the densities of the trees in the five protected areas were similar.The shrub height in Daxinganling area averaged at 0.66m,diameter averaged at 1.03cm,shrub crown width averaged at 52.6cm,coverage averaged at 29.18%,density averaged at 17.86 plants/m2,and grass height averaged at 33.61cm,coverage averaged at 44.49%.The shrubs were rich in resources and have large reserves,and the average density is significantly higher than that of other protected areas.The Dobucul nature reserves was flourishing,and the height and coverage were far higher than that in the Huzhong,Nanweng River,Chuona River and Shuanghe nature reserves.The characteristics of individual size of arbor and herbaceous in Dobukur Reserve largely vary among different plots,while the coefficient of variation of individual size characteristics in shrub layer was small.The dispersion of canopy density and canopy density distribution in various plots of Huzhong was the largest in the five nature reserves.The influence path of diversity in the 5 nature reserves was found to be inconsistent from the angle of individual size and community structure.The characteristics of the individual size of the Nanweng River,Chuona River and Dobucul nature reserve contributed greatly to the diversity,and the community characteristics of the Huzhong and the Shuanghe nature reserve contributed greatly to the diversity.The study of vertical structures found that the shrub layer characteristics of the Nanweng River and the Chuona River nature reserve had greater effects on diversity,and the diversity of Shuanghe and Dobucu nature reserve were influenced by the characteristics of herb and arbor layers,respectively.There were no obvious boundary between different forest types in each nature reserve,and the development of the community is continuous,but the species in Huzhong nature reserve were discontinuous with the other four nature reserves.The combination of community structure characteristics and natural-management factors were the main reasons for these variations,and establishment time contributes most to changes in plant diversity.To improve plant diversity in Daxinganling Mts.,the management of shrub resources,protection of herbaceous vegetation,the higher height of the trees and the height of the branches,and the interaction between different layers and different indexes should be taken into fully consideration so as to achieve the purpose of improving plant diversity.In summary,the future management of this five nature reserves should have specific strategy.Our research could provide guidance for the management of nature reserves.In future research about plant diversity,we should studythe effect of variation of structure factors of different stands on diversity by different levels and regions,so as to improve the "stand community structure-diversity" maintenance mechanism.