Study On Visual Simulation Of Multi-Objective Management Of Cunninghamia Lanceolata(Lamb.) Hook. Plantation

Multi-objective management of forest stands is an important part of forest management,which has guiding significance for forestry production practice.Tending thinning is the main method of managing forest stands.It is a method of artificially adjusting the density of forests based on the theory of reasonable density.It reduces the competition among trees in the stands,increases the nutritional space of trees,and improves plantations.The growth environment realizes the role of promoting the growth of artificial forest stands.Therefore,determining a reasonable management intensity and management plan can create a good growth environment for Chinese fir plantations,affecting the volume harvest of Chinese fir plantations,the output rate of large-diameter timber,and the dry type of trees.In view of this,this study aims to reflect the comprehensive situation of the spatial structure parameters and accumulation of Chinese fir stands by constructing a multi-objective management objective function for Chinese fir plantations,and to study a method of thinning simulation using Monte Carlo algorithm,combined with three-dimensional Visualization technology to realize visual simulation of multi-objective management of Chinese fir plantation.Based on the survey data of four Chinese fir plantations in the Huangfengqiao State-owned Forest Farm in Hunan,this study is guided by the idea of multi-objective management of forests,combining angle scale,Hegyi competition index,size ratio,openness,and stand volume.The objective is to construct the objective function of multi-objective management of Chinese fir plantation with the constraints of the improvement of the spatial structure of the stand and the increase of the stand volume.Monte Carlo algorithm was used to simulate thinning operation.Based on the Unity rendering engine,a visual simulation system for multi-objective management of Chinese fir plantations was developed,and based on this system,the spatial structure improvement and the growth of the volume of the stands under different operating intensities were compared,and the optimal Chinese fir plantation management intensity was studied.And get the optimal business plan that is not the same.The main results and conclusions are as follows:(1)Multi-objective management objective function of Chinese fir plantations constructed based on sub-objectives such as angular scale,Hegyi competition index,size ratio,openness,and stand volume can objectively reflect the spatial structure parameters and stand volume of stand The comprehensive situation of the thinning simulation algorithm developed based on the Monte Carlo algorithm can effectively screen out the suboptimal solution of the thinning scheme at a given thinning intensity,and it runs well in the visual simulation system.(2)By reading the data of 4 Chinese fir plantation plots in the multi-objective management visualization system of Chinese fir plantation,the thinning simulations were performed on 4 plots using 15%,25%,35%,and 40%of four thinning intensities.,We can get the optimal thinning plan for each of the four plots.Among them,sample A obtained the optimal thinning plan at 40%thinning intensity,and the multi-objective management objective function value Q(g)of Chinese fir plantation was 335.04.Sample B obtained the optimal thinning plan at 40%thinning intensity,Q(g)is 230.63;sample C gets the optimal thinning plan at 40%thinning intensity,Q(g)is 286.31;sample D also gets the optimal thinning plan at 40%thinning intensity,Q(g)It is 669.06.The highest Q(g)value of a single thinning simulation in 4 plots all appeared under the thinning intensity of 40%.Because the study object of this paper is a Chinese fir plantation,the change in angular scale is not large,and The range of the size ratio is also limited by the constraints of the objective function between 0..48-0.52,and neither of them has a large fluctuation range.The thinning management simulation results given in the multi-objective management visualization simulation system show that When the thinning intensity is increased,the growth space of the tree is greatly released,which has a direct positive impact on the two spatial structure indicators that describe the vegetative growth space and fierce competition of the tree,such as openness and competition index,making 4 plots Openness and competition at 40%high-intensity thinning The competition index has been greatly optimized,so the optimal management plan defined by the maximum Q(g)value will appear at a thinning intensity of 40%(3)In this study,a Unity3D engine was used as the development platform,and the Chinese fir plantation plot was used as the data support.Based on the Monte Carlo simulation algorithm and the Chinese fir plantation multi-objective objective function,a visual simulation system for the Chinese fir plantation multi-objective management was developed.The system can be run on the immersive virtual reality and visualization platform(CAVE2),which realizes the visual simulation of Chinese fir plantation forest management,stand spatial structure parameter analysis,stand volume growth estimation,and stand thinning scheme effect evaluation.Intuitive and smooth 3D visualization effects provide a visual simulation platform for forest management.