Structural Characteristics Of Natural Oak Forests And Their Effects On Forest Growth In Hunan Province

The main factors that affecting stand growth are stand structure and site condition.Compared to planted forest,the stand structure of natural forest is more complex,the way in which affects the succession and growth of natural forest is the research basis of scientific and reasonable management of natural forest.In order to solve this scientific question in this study.Based on this scientific problem,this paper took Hunan Quercus natural forest as the research object,set up 49 fixed plots,and used 22 stand structure indicators and 4 stand growth indicators(average diameter at breast height,average tree height,sectional area at breast height,K-means cluster analysis was used to divide the stand types,and the stand structure and stand growth characteristics of different stand types were compared;Pearson correlation analysis and redundancy analysis were used to screen the affected forests.On this basis,a structural equation model was constructed to explore the influence of stand structure on stand growth,in order to provide a reference for the scientific management of natural forests.The main research results are as follows:(1)The stand structure characteristics of oak natural forest in Hunan are as following:a.The community is mainly composed with middle-young aged forest,which is in the preliminary stage of growth and development;b.The canopy is relatively dense,and the density of tree growth is general;c.The mixed degree of tree species with medium and high intensity,and the horizontal structure shows a low aggregation distribution pattern;d.The forest layer is dominated by multi-layer forest,and the degree of differentiation is general;e.Species composition is rich;f.The overall competition situation of the community is relatively mild,but the size differentiation of single trees is quite different.(2)The total average growth of oak natural forest in Hunan is low as a whole.The average increment of stand volume,sectional area,mean height and mean DBH are 87.23 m3·hm-2·a-1、12.66 m2·hm-2·a-1、0.38 m·a-1、0.0045 m· a-1 respectively.There is no significant difference between total mean growth and mean DBH in different forest types(P>0.05),but there are significant differences among other three factors(P<0.05).(3)Pearson correlation analysis,redundancy analysis and structural equation model show that the main stand structure factors affecting the growth of oak natural forest in Hunan are as follows:Mingling(0.515)>variation coefficient of DBH(0.443)>stand age(-0.359)>stand density(0.253)>species composition(0.189).It will be beneficial for stand increment by reasonable regulation of these factors.is conducive to stand growth.