Analysis Of Changes Of Tree Species Composition Over The Last Ten Years In Different Urban Forest Type Within The Fifth Ring In Beijing

Based on the investigation of the tree species composition of 18 parks,23 residential areas,34 industries,174 roads and 7 waterfront forests within the Fifth Ring in Beijing,I analyzed the changes in the number of applications,frequency,coverage and important value of the main tree species in different types of urban forest from 2006 to 2016,and summarized the changing characteristics of the tree species composition structure of different types of urban forest,and put forward suggestions for the improvement of different types of urban forest.The main conclusions were as follows:1.From 2006 to 2016,the composition of tree species in different types of urban forest changed,but the variation of different types of research areas was different.The change of residential area and enterprise was larger,and the change of park,road and waterfront forest belt was relatively slight.2.From the change of the composition structure of the tree species in the residential area,the overall greening status of the residential area was obviously improved,the tree density and the tree species were significantly increased,and the tree species structure was more reasonable,such as Populus tomentosa,Ailanthus altissima and Platycladus orientalis.The growth of poor adaptability of the number of trees gradually reduced,and toon,ginkgo,floating Suzuki,West House Begonia and other popular tree species are increasing.Sophora japonica,white wax,Sabina chinensis,Populus tomentosa,Platanus orientalis,and asparagus have become the most important backbone in the current residential area.However,the green area of residential area was not effectively improved.The overall coverage decreased by 4.73%,and green space can not meet the needs of people's livelihood because site environmental conditions are still poor.3.From the change of the composition of tree species in the enterprise area,the overall greening condition improved significantly,and the forest density and species increased obviously,increased by 1.19 times and 1.53 times of that of the previous year.The main tree species changed significantly,and the ornamental trees of Cotinus coggygatum,Koelreuteria glauca,Jinyin wood,Yuyemei,Bizhu,peach and walnut were gradually replaced by the poor growth of Platycladus orientalis,Poplar,Persimmon,Dry Willow,Cypress,Ailanthus.These tree species became the main species.Among these species,Sophora japonica,Populus alba,Sabina chinensis,Ginkgo biloba,Cedar and Pinus tabulaeformis are the most important key species in the enterprise.In addition,the phenomenon of tree truncation increased by27.81% over a decade ago,while the new tree species were mainly small-sized landscape trees,and the overall green coverage decreased by 4.15%,which was difficult to meet the needs of the citizens;however,these tree speceis have great potential.4.There was no significant change in the structure of the tree species in the park.The density,frequency,type and proportion of the trees were almost the same as those of a decade ago.But the main species of tree species experienced a certain change.Ten years ago,as the main tree species of Platycladus orientalis,Forsythia,yellow thorns,spring were replaced by Atshibin,magnolia,dry willow,peach.Sophora japonica,Sauce,Populus,Sabina,Begonia,Begonia,which are the most important backbone of the tree species in the current park.In addition,the overall green volume of the park has improved over a decade ago,the overall coverage increased by 3.78%.However,there are still some park tree species configuration is relatively simple,low degree of forest landscape.5.From the changes in the structure of the tree species and the waterfront forest,the overall degree of change is small,tree density,species,and shrubs are almost the same as those of a decade ago.Only a small number of tree species replacement occurred in some sections of the 44 roads.The main tree species changed little,Sophora japonica,Populus alba,Ginkgo biloba,Platanus orientalis,Koelreuteria paniculata and Koelreuteria paniculata are the most important tree species in the present road and waterfront forest belt.Peach,walnut,magnolia instead of Platycladus orientalis,cedar,green tung,became the new main tree species.In addition,the truncated phenomenon of street trees is the most serious,an increase of 30.48%over a decade ago.And tree species structure is simple,commonly used species is only 10 species,uneven distribution of the number.The formation of the road to the main Sophora japonica,the other several species of vegetation supplemented by the composition of the model,the waterfront forest belt is formed with the main incense,other species embellishment of the composition of the structure model.6.In the past 10 years,urban forests are still in the stage of frequent changes in tree species,especially in residential areas and enterprise.A large number of tall trees were cut off or cut down,and the forest site conditions are poor.The overall green is not high,and plant configuration mode is still relatively simple.In the current urban green area is limited,it is recommended to properly fill the tall broad-leaved tree species,and the rational use of irrigation,teng,grass formation of multi-layer structure,strengthen the forest conservation management and forest surface environment improvement,comprehensive enhancement of urban forest ecological benefits And plant landscape level,the formation of a good urban ecological environment.Rational use of irrigation,teng,grass formation of multi-layer structure,strengthen the forest conservation management and forest surface environment improvement,comprehensive enhancement of urban forest ecological benefits and plant landscape level,the formation of a good urban ecological environment.