A Preliminary Study On The Canopy Of Main Tree Species In Urban Forest And Its Growing Space Demand

Due to the particularity of the urban environment,the initial distribution of tree species structure of urban green space is completely controlled by artificial selection.Many urban green areas in the early construction did not build a reasonable plant community structure from the perspective of planning and construction,blindly by increasing the density of plant planting,the pursuit of landscape effects,so that with the plant growth,urbanization process,human disturbance and other factors.The green space gradually shows the problems such as the single structure of community,the decline of landscape quality and the decline of tree health and the low ecological efficiency,which makes the demand of reasonable growth space of urban greenbelt become very important.The size of the canopy directly affects the ecological value of the trees,but the large canopy in the community will affect the growth of other trees,so the trees in the urban forest need to be properly configured.In order to increase the amount of green for trees,trees should be considered to choose the suitable site environment for the trees,and there is a suitable growth space in the plant community.In this paper,we try to apply the allometric growth method to the study of individual trees in urban forest.By constructing the optimal model of crown width,tree height and DBH of ten main tree species in Ring Park around Hefei city,in the crown,tree,the most suitable for the growth of the size of the space prediction.So as to provide reference for the future planning and construction of urban green space in Hefei,and provide scientific basis for the renewal,conservation,management and decision-making of trees in the park.Study on location selection of the typical characteristics of the Hefei City Forest Park City,selectParkPlatycladusorientalis,Robiniapseudoacacia,Broussonetia papyrifera,Koelreuteriapaniculata,Ligustrumlucidum,Photiniadavidsoniae,Cedrus deodara,Ginkgo biloba,Prunus Cerasifera Ehrhar f.atropurpurea,Trachycarpus fortunei and other major tree species dominance on the ten as the research object.Based on the investigation of crown,DBH and tree height,linear regression method,allometric growth method and R language software were used to analyze the Crown height,height and diameter of the tree were analyzed and calculated.Using the box plot;inspection of outliers,excluding outliers after each of the tree crown,tree height and DBH were analyzed and compared,finally construct ten optimal model of tree crown diameter,tree height and dbh.The main conclusions are as follows:(1)This study investigated a total of 57 plots,including Ligustrum lucidum,Robinia pseudoacacia,Broussonetia papyrifera,Cedrus deodara,Photinia davidsoniae etc.both the frequency or number plots are located in the top 5.The diameter and height distribution of trees are more reasonable,and the characteristics of urban forest are obvious.(2)The main tree species in Ring Park around Hefei City-crown DBH,tree height diameter correlation analysis,the scatter analysis of different species and crown diameter,tree height and DBH are positively correlated;on this basis,establish a regression and allometric model,the coefficient of determination R~2,RMSE(Root mean squared error),F statistic,standard error(Standard Error)4 indicators to evaluate the accuracy of the model.In comparison,a regression model can explain the tree crown,tree height and DBH of the relationship to a certain extent,but comprehensive allometric model is better than regression model.(3)Selection of quantile regression of allometric growth were studied,95%quantile regression represents the same DBH of trees under the canopy more representative in the environment of the site of growth free trees,trees is the most suitable for the growth of space;50%and 5%quantile regression represent the average value and inhibited the growth of trees.The allometric growth model are discussed in the 95%quantile regression,so the model can not only explain the ten kinds of trees,tree height and DBH crown diameter relationship,can also predict the most suitable growth space quantization on ten kinds of trees.(4)Not all species of tree crown and height and DBH have high correlation,in the study of the optimal model of ten species constructed in Ginkgo biloba,Ligustrum lucidum,Photinia davidsoniae crown diameter model fitting degree is high,and the crown diameter of Platycladus orientalis Koelreuteria paniculata,Ginkgo biloba,correlation is not high;Koelreuteria paniculata,cedar tree height diameter model better fit,Broussonetia papyrifera,Robinia pseudoacacia,palm tree height diameter model fitting.(5)The optimal model parameter estimation values are significant,shows significantly changed the tree crown and height variables and around the city of Hefei Park,DBH,crown diameter model fitting precision of the fitting accuracy is slightly higher than the tree height diameter model.