| Urban forest is an important part of urban ecosystem,which plays an important role in urban climate regulation,carbon sequestration,oxygen release,noise reduction and biodiversity protection.As an important part of urban forest,street trees have ecological functions such as air purification,noise reduction,dust retention and sterilization,as well as road beautification.Healthy and beautiful individual trees are important factors affecting the ecological benefits and landscape benefits of street trees.The health evaluation system and beauty evaluation system of street trees are important theoretical basis for the construction and maintenance of road vegetation landscape.At present,the health evaluation technology of street trees tends to be mature,but there are relatively few studies on scenic beauty evaluation,and the scenic beauty evaluation mostly uses photo evaluation method.The photo evaluation method is subject to more subjective influence of evaluators and complicated operation,while the single wood beauty evaluation method based on external morphological characteristics can quantitatively describe the external morphological characteristics of trees,and the data acquisition is more convenient and more operational in production practice.This study took Phellodendron amuranse in Changchun city as an example,through the investigation and analysis of leaf density,leaf color,leaf dying rate,dead crown proportion,primary branch health rate,secondary branch health rate,average length of primary branch,crown volume,branch point height,crown length rate,branch Angle,trunk inclination,crown extension,diameter to height ratio,crown skew degree and other 15 external morphological indicators affecting tree shape.The external form index was constructed to evaluate the beauty degree of a single tree by factor analysis method.The beauty degree of a single tree was divided into three levels by using the comprehensive score of external form and the system clustering method.At the same time,the beauty degree evaluation criteria based on the external form characteristics were determined.At the same time,considering the growth condition of trees,people’s aesthetic preference and the industry standard of street trees,a more scientific,comprehensive and convenient method for assessing the beauty degree of individual trees has been formed.The main research results are as follows:（1）The overall score of the external form index of barberry was used to divide the beauty degree of barberry.The results showed that the external form index and the constructed external form index had significant differences among different beauty degree levels.Crown health index（S1）,crown size index（S2）,crown expansion index（S5）,crown symmetry index（S7）were significantly different among all beauty degrees（p<0.001）.Leaf density（X1）,leaf color（X2）,dead leaf rate（X3）,dead crown ratio（X4）,primary branch health rate（X5）,secondary branch health rate（X6）,crown extension(X13)were significantly different among different beauty levels of individual trees（p<0.001）.（2）The beauty evaluation criteria of Berberis barberry based on external morphological characteristics were determined,and the comprehensive scores and value range of each grade were given respectively:superior single wood（0.24-0.37）,medium single wood（0.10-0.23）,inferior single wood（0.02-0.09）.Superior individual trees have the following morphological characteristics:vigorous crown growth,dense leaves and rich color,high branch health rate,small proportion of dead crown and low rate of dead leaves,high crown symmetry,long average length of primary branches,slightly inclined trunk,high branches under live branches.（3）Through the intraclass correlation coefficient（intraclasscorrelationcoefficient,ICC）method is verified using the method of external morphological characteristics and beauty degree evaluation method（Scenic Beauty Estimation,SBE）Chan Mu beauty degree of the evaluation results of consistency,The ICC internal phase relation value was 0.899,indicating that the two evaluation methods obtained the same beauty evaluation results of barberry wood.（4）The external morphological indicators investigated in the external morphological characteristics method can not only comprehensively cover the landscape elements decomposed in the SBE method,but also reflect the landscape elements in a more comprehensive and detailed way than that in the SBE method,and can quantitatively describe the external morphological characteristics.In summary,this study based on the external morphological characteristics of barberry beauty degree grade division is reasonable,and shows that the external morphological characteristics based on barberry beauty degree evaluation method can describe the external morphological characteristics of barberry quantitatively and in detail,can comprehensive,objective and comprehensive evaluation of barberry beauty degree,evaluation data is more convenient to obtain.The results are in good agreement with those of photo evaluation method.The results of this study can accurately reflect the external morphological characteristics of trees and evaluate the beauty rating of trees by investigating simple external morphological indexes of trees,and provide important theoretical basis for constructing the evaluation system of street trees and the beauty rating system of single trees of urban green space,as well as the basis and method for screening,maintenance and arch raising of excellent individuals in the construction of road vegetation landscape. |
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