Research On The Analysis And Multi-objective Intelligent Optimization Of Stand Structure Of Natural Secondary Forest

Aiming at solving the following problems existing in natural secondary forests such as irrational stand structure,poor stability and so on,the paper takes the south of Dongting Lake Mount Longhu forest secondary forests-Cyclobalanopsis myrsinaefolia mixed forest as the research object and uses modern forestry information engineering technology to thoroughly analyze the natural secondary forest structure,to optimize various elements of stand structure allocation,and to enhance its multiple benefits.The main contents are as follows:1.A forest Voronoi diagram and its dual structure Delaunay triangulation are established,and a plot edge correction method named distance determinant of Voronoi noda are also proposed based on the survey data of the plots.The results show that:? the forest Voronoi diagram could identify spatial adjacency relationship of neigbour trees which is helpful for extracting tree spatial information and digital features;? Voronoi node distance determination is more flexible,which can be regarded as a correction method that the actual distribution of forest boundary buffer distance would change adaptively.Besides,this method is of stronger power to correct,which could eliminate the extraterrestrial influence of edge forests to its greatest extent and could improve the accuracy of spatial structure index.2.Based on multiscale dynamic features in point pattern analyses,the paper puts forward Voronoi pattern analysis,a forest spatial pattern analysis method,to analyze the structure of secondary forest from two aspects:non-spatial structure and spatial structure.Non-spatial structure analytical results showed that in the Cyclobalanopsis myrsinaefolia mixed forest,Cyclobalanopsis myrsinaefolia was the dominant species,and Cinnamomum camphora,Cyclobalanopsis glauca,Quercusougla Hance and Liquidambar formosana Hance took the second place.Generally,the stand diameter distribution showed a reverse J curve,which was of typical different age forest.The research results of spatial structure were as follows:? in the spatial pattern,with the increase of spatial scale,the spatial pattern of stand had a trend of transition from aggregation distribution to random distribution.The spatial pattern of major tree species had a trend of transition from aggregation distribution to random distribution or uniform distribution.Compared with Uniform angle index and O-ring statistical method,the Voronoi pattern not only combined the multi-scale dynamic characteristics of point pattern analysis,but also highlighted the guiding role of forest management.? in the intraspecific and interspecific competition,intraspecific competition in Cyclobalanopsis myrsinaefolia population was very intense because of its aggregation distribution characteristics.? in the species spatial isolation,plot P1?P5 was less mixed,and P6?P7 was moderate mixed.These results showed that stands had poor spatial isolation of species,which needed replanting some native tree species.?in the vertical structures,the average Layer index value was generally low.The results showed that the vertical stratification was not ideal,the stand was relatively simple,and the space utilization in the vertical direction was not enough.3.The spatial heterogeneity was proposed to let the evaluation system and standards of forest spatial heterogeneity make sense,taking spatial isolation,competition and spatial pattern into consideration.Researches showed that plot P6 was in high ground,which was less disturbed by human or nature,and its spatial heterogeneity was 4.Other plots ranked 2?3 which showed that they were more influenced by some unreasonable factors,to be more exactly,the longtime man-made and natural disturbance had a profound impact on these plots.4.The paper constructed a multi-objective optimization model of swarm intelligence algorithm based on PSO,when considering the irrationality of stand structure,and then taking stand spatial structure as optimization objective.Later on,the model was applied to forest management practice.Researches showed that,the cutting scheme can optimize the stand structure,and can enhance structure stability,species diversity and structural complexity,when tree species and diameter distribution remained unchanged.Stand structure indices were improved to some extent.By the integrated GIS spatial analysis method,the artificial intelligence algorithm,the computer modeling and simulation technology,the paper tried to develop an intelligent decision-making and management system for secondary forest's structural analyses,optimization and adjustment.5.Key innovations:First,a new kind of spatial pattern method named Distance determinant of Voronoi nodal was proposed.The method provided a guarantee for the accurate analysis and evaluation of the spatial structure of forest stands.Second,a new kind of spatial pattern method named Voronoi pattern analysis was proposed,which enriched analysis method of stand spatial pattern.Third,the paper constructed a multi-objective optimization model of secondary forest structure based on swarm intelligence PSO algorithm.which improving the digitization,information and intelligence level of forest management and decision-making.