Analysis Of Characteristics Of Roadside Trees In Harbin,Changchun And Shenyang

As an important part of urban forest,the roadside trees provide important ecological service functions for human beings.The size,health and structure of the tree are the basis of providing the function of ecological service.In the past,field surveys were time-consuming and laborious,and could not be carried out in a large-scale and detailed investigation.This paper investigates the size,structure and health of the roadside trees in the provincial capital cities of Northeast China(2896 plots of Harbin,Changchun and Shenyang)through the StreetView platform.A total of 4 tree size indices(Diameter at breast height,tree height,Canopy size,Under branch height)were measured,and 4 health indicators(Stents,Dieback,Non-greenness leaf color,Death)and vertical structure indicators were measured.According to the administrative area and the loop,we analyze the statistical difference of the characteristics of roadside trees in the city and form a spatial distribution map.Based on the urbanization gradient and social natural factors,the reasons for the differences between cities and cities are discussed.The main conclusions of this paper are as follows:1.Comparison of size,stereoscopic structure and health status of roadside trees.The trees in Shenyang are healthier.Shenyang is 2 times less dead and dead than other cities,but its stents are as high as 20%,which is 1.3-2 times that of other two cities.The three layer complex in Harbin is only 35%,which is 50-70%of Changchun and Shenyang.The proportion of bare land in Harbin is 28%,while that in Shenyang and Changchun is only 9%and 17%.The average value of roadside trees in Shenyang is relatively small,but the size distribution of trees is even,and the health condition is good.And the proportion of three layer structure is high.In Shenyang,16%of the trees have stents,which is 1.8-5.3 times that of Changchun and Harbin.2.The characteristic spatial distribution of the tree tree.Three the larger roadside trees in the city are mainly located near the center of the city,and the small trees are mainly located near the suburbs of the city.Three the unhealthy roadside trees of urban roadside trees are mainly distributed in the suburbs of cities.The proportion of three layer structure in Harbin center and suburb is less.The proportion of three layer structure structure in Changchun city center and northeast of the city is less.The proportion of three layer structure in Shenyang center and southeastern city is less.3.The relationship between the tree size,the stereoscopic structure and the health index in the city.Redundancy analysis in all three cities shows that,the bigger the tree,the better it is.In Harbin,along with the increase of the three layer structure structure of roadside trees,the stand of roadside trees increased.Along with the increase of the three layer structure of in Changchun,the proportion of unhealthy roadside trees has increased.In Shenyang,along with the increase of three layer structure,the proportion of healthy roadside trees increased.4.A correlation analysis of social natural factors among cities.The size and health condition of roadside trees were affected by different natural and social factors.The size of roadside trees is positively correlated with gross industrial output and per capita GDP,and negatively correlated with bus volume.The proportion of unhealthy roadside trees is significantly positively correlated with the amount of water falling down,the actual area of roads at the end of the year,and the emission of industrial smoke and dust.Besides,it has a significant negative correlation with air temperature.The three layer structure of roadside trees is positively correlated with the growth rate of gross domestic product,and negatively related to the urban construction land area.From the comprehensive health score analysis,we can see that the greater the wind speed and altitude,the higher the proportion of unhealthy roadside trees.The greater the average annual population,the total gas supply,the relative humidity,and the four indexes in the bus,the higher the discrete coefficient of the road tree’s comprehensive health score,that is,the more uneven distribution.