The Structural Analysis And Health Assessment Of Roadside Trees In Beijing

201 sections,378km various roads roadside trees of Beijing were investigated in this thesis.According to Ring Roads in Beijing,divided all the roads into different regions,different road types,and then did the field investigation, analysis and evaluation. Analysis of each region,different types of roadside trees in the species composition of the road, growth index structure, pest management and protection on the basis of other indicators in beijing, this thesis systematically for the first time evaluate the two scales from individuals and groups in different regions and different type roads of roadside trees ,and make recommendations about the heath management of roadside trees in Beijing. The main conclusions are as follows:1.There are 63 roadside tree species in Beijing which the arbor trees take up 24 families,31generas,50 kinds,the shrubs take up 8 families ,12 generas,13kinds.The formed tree is most abundant in The area inside 2^nd Ring Road and The area between 2^nd and 3^rd Ring Road,it is take up 72 persentage of the total of the formed tree,then The area between 3^rd and 4^th Ring Road and The area outside 6th Ring Road are take up 50%,The area between 4^th and 5^th Ring Road is 52%,the rent of the tree shrubs have a clear diffirences that it is priority to the formed trees.the change of the Diversity index and average index is consisitent,from the city to the suburbs have an increased trends.2.The average DBH of roadside trees throughout the City is 18.0cm. The area inside 2^nd Ring Road has the largest average DBH that is 24.3cm, The area between 4^th and 5^th Ring Road local minimum for the 11.4cm, DBH classs structure is more reasonable. Sub-region, in addition to regional Victoria to the rings, the diameter of left side show the trend of normal distribution. Sub-type of road run, expressways and Secondary roads of the structure is consistent with the number of paths for multi-level trees; and trunk roads and branch diameter classes in the scope of the second stage more of the small diameter and large diameter Relatively few trees. Planting the largest number of average diameter size of 10 species were Sophora japonica> Koelreuteria paniculata> Ginkgo biloba> Fraxinus chinensis> Sabina chinensis> Prunus cerasifera> Chinese arborvitae> Rosa xanthina. 3. The distribution of the roadside trees a height, the regional level in the second peak, that is, height 5-10m in the largest number of trees taller than 15m but not many, only 5% of the total number of trees. The area inside 2^nd Ring Road and the area between 2^nd and 3rd Ring Road's change is almost consistent; the area between 3rd and 4^th Ring Road,the area between 5^th and 6th Ring Road and the area outside 6th Ring Road consistent with the distribution of trends; tetracyclic to pentacyclic regional distribution of the performance of the first And second-level number of tree height or less, 94% of the trees, tree height is less than 10m. According to the distribution of road type, Main roads,Secondary roads and branch roads'distribution is more consistent for the 5-10m in diameter at breast height of trees was more than a small proportion of trees 10m; Expressway has 0-5m of the trees are mostly 48% of the total number of trees.4.Among the Roadside trees in Beijing City, the ratio of deciduous trees and evergreen trees is 14.5 :1. Evergreen trees is only 6.5% of the total number of trees. Comparing the different regions, the evergreen trees in the area inside 2^nd Ring Road and the area between 3rd and 4^th Ring Road are the least. In these two areas, the ratio of evergreen trees and deciduous trees is 1.7% and 1.4%. The number of evergreen trees in the area between 2^nd and 3rd Ring Road, the area between 5^th and 6th Ring Road and the area outside 6th Ring Road is above the average. There is little difference between different type roads, the ratio of evergreen trees is less than 10%.5.The ratio of native trees and exotic tree species among the roadside trees in Beijing is 5.4:1.As you can see,the richful exotic tree species only takes up a small proportion. Based on different areas,exotic tree species takes up the largest proportion between 5^th and 6th Ring Road which is 20.6%,while them takes up the smallest proportion inside 2^nd Ring Road which is 9.2%.The amount of native trees inside 4^th Ring Road is over the average amount in beijing.Based on different road types,native trees takes up the smallest room which is 77.5% on branch roads,secondary roads the largest which is 89%.Exotic tree species covers all kinds of road types,Expressways with 10 species,Main roads with 16 species,Secondary roads with 13 species,while branch roads with 11 species.6.The prune management,Tree-based coverage,diseases and insect pests ,mechanical demage reflects the case management and protection of Beijing roadside trees.The prune management when planting takes up 15%,while the prune management of management and protection takes up a large amount which is 70%.The average area of roadside trees is 1.53m2,while the projective area of crown is 23.5 m2,which makes the ration between them is 1:15.3.Among the roadside trees,tree-based takes up more than a half,while the green covered ones take up 35.19%,the rest of them are covered by other types of protections which takes up 5%.The organic compounds which are suitable for tree-based coverage only takes up 1.78%.The roadside trees suffered from various disease take up 5.5%,about 12% of them are affected by insect pest, the injured bark takes up 17.2%.the roadside trees which are procteced by fence,tree pond,whiten and irrigation measures takes up 1%,20% and 28%.7.Half of them blong to Sub-health state which make up 52.24%,the top quality roadside trees take up 4.8%,while the healthy ones take up 24.99%.the unhealthy ones take up 17.43%.0.24% of them are dying.According to different regions,the dying roadside trees and unhealthy ones inside 2^nd Ring Road take up the largest proportion,and there are few of them beteen 5^th and 6th Ring Road.Sub-healthy roadside trees take up a large proportion all over the area.The healthy ones take up the largest proportion outside 4^th Ring Road,while they take up the largest room between 5^th and 6th Ring Road.The farther they live from the downtown,the better their state is.It also implies the top-quality roadside trees exist less inside 2^nd Ring Road area.The state of the roadside trees show an approximate normal distribution skewed to the right among Expressways,Main roads and the Secondary roads, on the brach roads they show a left bias normal distribution.All in all, the amount of unhealthy level trees are over the healthy ones.8.The overall Health Evaluation score is 0.92 of roadside trees,which makes them belong to level III according to health score.It also suggests that the roadside trees in Beijing belong to Sub-health state,as well as medium level.The overall health index shows an extend trend from the inner area to the outer ring area.The unhealthy roadside trees within 2^nd ring road of which the healthy state is 0.56 belong to level II. And the sub-healthy roadside trees within 2^nd and 4^th ring road of which the index is 0.76 over the 2^nd ring road and 3rd ring road, 0.96 over the over the 3rd ring road and 4^th ring road area,which makes them belong to level III.The index is 1.04 over the 4^th ring road and 5^th ring road area,and 1.14 over the 5^th ring road and 6th ring road area,1.06 outside the 6^th ring road,whick makes them all belong to healthy state.Based on different roadtyes,the differences are quite obvious.Expressway roadside trees of which the index is 0.8 belong to Sub-healthy state.The overall state of the rest roadside trees is relatively healthy,their index are 1.07.1.11 and 1.06 which make them all belong to level IV.This study puts forward tree species selection, restructuring, management and protection measures three recommendations, in order to improving the health quality of roadside trees in Beijing.