Relationships between Crown Structure and Crowding in Quercus mongolica Forest of Xiaolong Mountains under Different Stand Densities
[Objective]This study explores the relationships between stand density,crown structure and crowding,in order to deeply clarify the structural characteristics of Quercus mongolica secondary forest for providing sufficient scientific basis for sustainable forest management in the future.[Method]In August 2020,typical plots with similar site conditions and different stand densities were selected from the second-ary mixed forest of Quercus mongolicus in Xiaolong Mountains to analyze the relationship between crown structure and crowding under different stand densities by using Pearson correlation analysis and structural equation model.[Result]There were differences in the crown structure characteristics of Quercus mon-golicus forest with different stand densities.The variation in crown volume was the strongest,followed by crown length and crown area.The variation in crown width,crown length ratio and crown shape ratio was the weakest.The variation trend in crown structure characteristics showed a unimodal distribution with changes in stand density.With the decrease of stand density,the correlation trends of crown width,crown area and crown volume with DBH were similar to"L"pattern,while the correlation between crown length and DBH were consistent with the change in stand density,and the effects of stand density on the correla-tion between crown length rate,crown shape rate and DBH was not significant.The crowding of the Quer-cus mongolica forest ranged from medium dense to very dense,but the crowding in different density stands was different.The dominant species of Quercus mongolica,Betula platyphylla,Pinus armandii and Tilia tuan dominated the crowding.The influence of stand density on the relationship between crown struc-ture and crowding in Quercus mongolicus forest could be divided into two ways:forest competition-indir-ect effects mediated by crown structure;The indirect impact mediated by forest competition,diameter at breast height,and crown structure.[Conclusion]The crown structures of Quercus mongolica forest vary with different stand densities.Crown structure is related to the DBH.The relationship between crown struc-ture and crowding of Quercus mongolicus forest is finally affected by stand density.In order to achieve sustainable management of the Quercus mongolicus secondary forest,we should not only consider the DBH,but also pay attention to the characteristics of the crown structure.By adjusting stand density,we can optimize the crown structure and improve the crowding state to promote forest regeneration and in-crease species diversity.
万方数据
维普
