Coupling Relationships Between Stand Structure And Soil And Water Conservation Functionin Based On Structural Equation Model

This study focused on the two kinds of typical Pinus tabulaeformis and Larix gmelinii plantations in the upper Liaohe River,Western Liaoning Province.Characteristic analysis,correlation analysis and factor analysis of the influencing factors of forest structure and soil and water conservation functions were studied.Quantitatively analyze the coupling relationship between forest structure and soil and water conservation functions of Pinus tabulaeformis and Larix gmelinii with the help of structural equation model.And based on the results of model analysis,put forward function-oriented stand structure optimization goals and measures,which can provide reference for the adjustment of plantation stand structure and the improvement of soil and water conservation function in the upper Liaohe River.As concluded:(1)About stand structure,the DBH growth of Pinus tabulaeformis was better than that of Larix gmelinii,but the tree height,s was opposite.The distribution of tree height and DBH of Pinus tabulaeformis and Larix gmelinii showed fluctuation and bimodal,respectively.The distribution crown width of Pinus tabulaeformis was more concentrated than that of Larix gmelinii,and the light transmittance of the forest stands was better.Both stands were evenly distributed,intra-species competition within Pinus tabulaeformis forests was more intense.(2)In terms of soil and water conservation functions,Larix gmelinii had better water conservation,soil conservation and biodiversity protection functions than Pinus tabulaeformis,so Larix gmelinii had stronger soil and water conservation functions.(3)The structural equation model was used to analyze the coupling relationship between stand structure and soil and water conservation function.The order of water and soil conservation function of the two plantations is water conservation > soil conservation > biodiversity protection.Stand density,competition index,tree height and forest layer index have the most significant effects on the stand structure of Pinus tabulaeformis plantation.Canopy density,stand density,competition index,breast diameter,crown width,tree height and forest layer Index and other indicators have the most significant influence on the stand structure of Larix gmelinii plantation.(4)Aiming at the key indicators that control forest structure,putting forward control objectives.Stand density is about 800~1000trees/hm2,competition index < 1.50-2.00,canopy is about 0.80,openness > 0.30,size ratio is stable at 0.40,and forest layer indexda > 0.40,increasing stand mixed degree.Through forest adjustment measures such as thinning,selective cutting and replanting,adjusting stand structure.Pinus tabulaeformis and Larix gmelinii plantation are gradually transformed into multi-layer and mixed forest of different ages combined with shrubs,shrubs and grass,thereby improving the soil and water conservation.The conclusion of this paper has certain reference value for the stand structural optimization and quantitative control of Pinus tabulaeformis and Larix gmelinii and other plantations in the upper Liaohe River,and is of great significance for improving soil and water conservation function of forest stands in the entire region,and it has great significance for improving soil and water conservation function in the region.