The Study On Urban Forest Structure And Eco-service In The Sixth Ring Road Of Beijing

Urban forest is an important part of urban ecosystem.Its main body is trees.It is of great significance to promote urban ecological protection and improve the close relationship between man and nature.In recent years,with the rapid increase of population,excessive consumption of resources and deterioration of the environment,scholars have carried out research on the service function of urban forest ecosystem.How to fully understand and properly estimate the service function of urban forest ecosystem has become one of the research hotspots.Beijing is a mega-city city in China.It puts high requirements on ecological construction in the new urban master plan,and it is of great significance to evaluate its urban forest structure and ecological service functionThis paper takes the study area within 1 km out of Beijing's 6th Rd,and investigates 771 sample squares and 638 168.09 m samples randomly sampled by different types and different region line,comprehensively assessed the urban forest structure.And based on the ECO and Street modules of the software,the ecological service functions and values are estimated for the sample and sample data respectively.According to the research results of forest structure and ecosystem service function,the relationship between them was further found,and the corresponding countermeasures and suggestions were put forward(1)The survey recorded 50 families,106 genera and 159 species of forest woody plants in Beijing,and the average richness index was 5.25.There are 120 species of native species,accounting for 75%of the total species.The average DBH of trees is 19.79 cm,the average crown is 5.38 m,and the average tree height is 9.37 m.The difference in the size of the trees is small.Most of the top 20 trees of the important value were in the 15.2-30.5 cm adolescent plant,and lacked the juvenile and strong tree species.Sophora japonica is the most widely used species in Beijing.It is more widely used in road accessory green space than other types,accounting for 27.2%of the total number of this type..Sophora japonica is a long-lived tree species with strong pollution-adsorption capacity.The use of this tree species in urban street trees helps to form stable canopy cover and reduce pollutant emissions caused by planting and removal.(2)The estimated value of the ecological service in Beijing was 104.778 billion ?/yr,with an average of 424900?/hm2/yr.Including energy saving of 24.816 billion?/yr;CO2 sequestration 14 776136.1 t/yr,value of 10.788 billion?/yr,carbon sequestration per unit area 59.93 t/hm2/yr,net carbon sequestration 26 838 370.36 t/yr;avoide runoff 407 337 788.56 m3/yr,value of 2.519 billion?/yr,on average avoide runoff per hectare 1652.04 m3/yr;pollution removal of 100 376.56 t/yr,valued at 22.45 billion?/yr,an average of 0.41 t/yr of pollution per hectare;aesthetic and other benefits of 64.409 billion?/yr.In addition,trees(including trees and shrubs)in the study area produced a total of O2158 648.80 t/yr,with a unit area of 0.64 t/hm2/yr;a total of 1758.29 t/yr of volatile organic compounds;a carbon storage of 104366504t,valued at 76.478 billion ?,with an average storage of 423.28 t/hm2(3)Sophora japonica has the highest ecological service function and total value.The total carbon sequestration of this specie is 4 571 940.6 t/yr,accounting for 30.94%of the total carbon sequestration,with a value of 3.34 billion?/yr,and a net carbon sequestration of 8017994.9 t/yr.The the highest carbon sequestration of individual plant is Populus ×canadensis Moench(154.75 t/plant/yr);Sophora japonica has a total carbon storage of 310.007 million tons,accounting for 29.70%of the total carbon storage,with a value of 22.620 billion yuan.The highest carbon storage of per plant is Populus ×canadensis Moench,which average carbon storage of per plant is 144.41 kg.The annual avoide runoff of Sophora japonica is118 986 900 m3/yr,with a value of 736 010 400?/yr.The highest avoide runoff of per plant is Populus×canadensis Moench(4.45 m3/plant/yr).Sophora japonica has removal a total of 26 094.34 t/yr,accounting for 25.70%of the total,with a value of 523 371 200 ?t/yr.The highest pollution removal of per plant is Juglans regia,with an average of 2.71 kg of air pollution removal per plant(4)Beijing urban forests showed obvious gradient changes along the direction of urbanization.From the city inside to the outside,the total number of species gradually increased,but the diversity gradually decreased.The number of trees has gradually increased,and the specifications of trees have gradually decreased.The proportion of juvenile and maturing trees has gradually increased with the gradient of the ring road,and the semi-mature and mature trees has decreased.The function and value of ecological services gradually increased from inside to the outside of the city.The ecological services benefit of 1 km out from 5th-6th ring road was 83.516 billion ?/yr.The highest value,followed by 4-5 rings,and the ecological service value of 2-3 rings was the lowest(5)There are large differences in the different type of forests from various structures to ecological services.As the most widely distributed forest type,road-affiliated green land has the largest number of plants,with the largest average arbor specification and the highest ecological service function,with a value of 112.76 billion yuan.The garden has the largest plaque area,and its ecological service function ranks second,with a value of 736 547 600 yuan The number of species in subsidiary green space of schools and hospitals is the highes,and the ecological service function ranks third,with a value of 51.643 million yuan.Green areas in residential areas and units have the highest biodiversity,but the contribution of ecological service functions is the least(6)There is a strong correlation between DBH,canopy cover,leaf area,basal area and Eco-service function.The most relevant to carbon storage and carbon sequestration is the basal area and DBH;the highest correlation between aviod runoff and pollution removal is the leaf area,followed by canopy cover,in which the leaf area and air pollution removal show extreme strong correlationThis study is the first time in China to use the i-Tree model ECO,Street two modules to evaluate the urban forest ecological service function of the completed built-up area and the suburbs of large cities.The urban forest according to the different types and regions,A detailed analysis of further ecological service functions of the urban forest according to the different types and regions is the first example of the assessment of urban forest ecosystem services in China.The worldview-2 satellite image data based on 0.5m resolution in the study area is used as the basic data for estimating the urban ecological service function,which makes the actual situation of the estimation result closer.The relationship between goals and countermeasures is established since the correlation between the forest structure and its ecological service function is analyzed.