Study On Optimization Method Of Large Diameter Grade Poplar Clones In Guanzhong Industry Based On Airborne LiDAR Data

The lack of large diameter grade resources in China seriously restricts the sustainable development of plywood and other related industries.At present,our country is constantly increasing investment in large scale industrial forest,in order to improve the situation of the serious shortage of large scale resource materials in order to realize the inner cycle of self-sufficiency of timber resources.There is a relatively mature system for the study of large-diameter industrial forest in terms of forest management techniques and tree species selection,but there is a lack of research on the selection of large-diameter clones in specific areas.Due to the time,effort,high risk and lack of rapid and accurate collection and analysis ability of phenotype,especially some basic parameters of large-diameter clones that are difficult to be measured,traditional forest survey methods limit the efficiency of selecting large-diameter clones in different areas and are difficult to meet the increasing demand for large-diameter wood.Airborne Lidar technology is characterized by convenience,high efficiency and accuracy.It can obtain the basic parameters involved in the optimization of large-diameter class clones,which provides a large-range,fast and accurate method of single wood parameter acquisition for large-diameter class clones.This study aims to select poplar clones suitable for large-diameter scale planting in Guanzhong area,and discuss the application of Lidar technology in the selection of large-diameter wood clones of poplar.In this paper,24 Populus tomentoides clones in Guanzhong area were studied.According to the requirements of large-diameter class resource wood,the optimal selection system of large-diameter wood clones was determined by referring to the comparative analysis method in forest cultivation and literature review.Based on the tree height and tree crown parameters extracted from airborne laser radar scanning data,the correlation between tree height,tree crown structure and trunk properties of populus tomentosa clones was analyzed,and the unary and binary linear regression inversion models of tree crown parameters to trunk parameters were constructed.Based on the evaluation parameters obtained by airborne radar data,TOPSIS comprehensive evaluation was used to select the most suitable for large-diameter wood planting in Guanzhong area.Compared with the survey evaluation,the reasonableness and accuracy of rapid acquisition of forest parameters and evaluation selection by Lidar were determined.In order to provide support for the selection of large diameter scale industrial forest clones in Guanzhong area and rapid selection of large diameter scale clones in the future.The main conclusions are as follows:(1)Analysis of variance showed that there were significant differences in growth characteristics among the 24 populus tomentosa clones.The volume growth ranged from0.34cm~3to 1.25cm~3.The volume growth of poplar No.85 was the largest,which was 0.34m~3(41.92%)and 0.57m~3(96.0%)higher than that of Yixian and Jianzhu,respectively,which was significant for evaluating the measured clones.Combined with the requirements of large-diameter timber stand,Pearson correlation analysis was used to determine the correlation between the difference factor and the key factors such as volume,and the evaluation indexes were determined with diameter at breast height,volume,height-diameter ratio,sharpness,branch number and branch Angle.(2)Correlation analysis of tree height,crown structure and trunk traits extracted based on Lidar scanning showed that except tree height,DBH and diameter of each relative height were significantly correlated with crown structure.The linear regression model of crown structure to trunk character was constructed.On the whole,the inverse model of tree trunk character based on crown area is the best among the unary linear regression models.In the binary linear regression model,canopy area and canopy volume have the best effect on the inversion model of trunk traits.The fitting effect and root mean square error of the binary linear regression model are significantly better than that of the single linear regression model.The average error rate of tree height extraction and clonal trunk parameters based on inversion model were both below 5%.It conforms to the class A forest resource survey error and can be directly applied to the actual survey.(3)Using diameter at breast height,volume,ratio of height to diameter,sharpness,branch number and base diameter as the key variables,the TOPSIS method was used to comprehensively evaluate 24 populus tomentosa clones based on the measured survey data,and compared with the evaluation results of lidar inversion results,the optimal results were consistent.Among them,No.85,86,87,83,60,90 and the control line Yixian Populus tomentoides clones are suitable for the cultivation of large-diameter class timber stands in Guanzhong area or further study and analysis.