Estimation And Optimization Study On Carbon Sink Benefits Of Plant Communities In Mingyue Park Of Jingzhou City

Under the current climate background,reducing greenhouse gas emissions is undoubtedly a major issue facing mankind.With the proposal of China ’s carbon neutrality goal,the research on carbon sinks has become increasingly urgent.As the only natural carbon sink in the urban area,urban green space plays an important role in neutralizing urban carbon emissions and maintaining urban carbon and oxygen balance.At present,there is a lack of unified standards for the estimation of green space carbon sinks in China,and there is a lack of systematic quantitative research on the improvement of carbon sink benefits of park green space.The plant community of Mingyue Park in Jingzhou City was taken as the research object.Through field investigation,all arbor,shrub and grass vegetation in the park were counted and measured.Through the summary of the survey data,the community analysis charts were drawn,and the plant community composition structure of urban parks was analyzed.The i-Tree model was used to estimate the carbon sink benefits of plant communities in the park,and the SPSS model was used to analyze the effects of community characteristics such as tree species composition,diameter structure,community type structure,and species diversity index on carbon sink benefits.The optimization strategy is summarized and put forward,and the carbon sink benefit optimization and transformation practice of typical plant community nodes in the park is carried out.The analysis and comparison before and after the transformation are carried out to explore the improvement and optimization ways and high carbon sequestration development space of plant community in park green space under the background of climate change,so as to provide reference for the follow-up research on carbon sink benefit of urban parks.The main results are as follows :(1)A total of 159 species of plants belonging to 71 families and 135 genera were investigated in 40 community samples of Mingyue Park.There are 3317 trees in the park,and the DBH is mainly distributed in 10-30 cm.There are 3618 shrubs,and the DBH is concentrated in 0-20 cm.The proportion of deciduous and evergreen trees was4.86 : 1,and the proportion of broad-leaved and coniferous trees was 6.66 : 1.The Margalef index was 5.001,the Simpson index was 0.810,the Shannon-Wiener index was 2.323,and the Pielou ’s index was 0.712.(2)The total carbon storage of plant communities in Mingyue Park was 777.15 t,the total annual carbon sequestration was 140.69 t,and the average annual economic benefits of carbon sinks were 146,900 yuan.The economic benefits of trees,shrubs and ground cover herbs accounted for 45.90 %,27.67 % and 26.43 % respectively.The average carbon storage of 40 community samples in the park was 19.43 t,and the average carbon sink benefit was 3671.9 ￥ / a.Among the 77 tree species in Mingyue Park,the average carbon storage of Taxodium distichum var.imbricatum was the highest,which was 403.5 kg / plant.The average annual carbon sequestration of Salix babylonica was the highest,which was 28.0 kg / plant · a.(3)According to the cluster analysis of carbon sink benefits of each tree species,the carbon sequestration capacity of different tree species is divided into three grades.One type of tree species are Salix babylonica,Cinnamomum camphora,Populus tomentosa,Ulmus pumila,Taxodium distichum var.imbricatum,Ulmus parvifolia,and Glyptostrobus pensilis,Michelia figo,a total of 8 species.The second type of tree species are Acer buergerianum,Koelreuteria paniculata,Sapindus saponaria,Citrus maxima,Elaeocarpus decipiens,Chimonanthus praecox,Prunus persica,Citrus japonica,a total of 27 species.The third type has 42 tree species.The diameter structure of trees has a very significant positive correlation with its carbon storage and annual carbon sequestration.When the DBH of trees is in the range of 16-36 cm and the DBH of shrubs is in the range of 8-13 cm,the carbon sink capacity of plant communities is relatively stable at a high level.Among the various types of communities,the average annual carbon sequestration of the conifer-broadleaf mixed community was the highest;among the communities with different vertical structures,the tree-shrub-grass multi-layer model community had the highest carbon sink benefit.In terms of species diversity index,the carbon sink benefit of plant community has a greater correlation with community complexity and species richness,and is relatively less affected by community stability and plant individual evenness.(4)The main problems of plant communities in Mingyue Parks are as follows :(1)The plant community structure in some areas is single and the landscape effect is poor.(2)Community density is not suitable for vegetation growth in some areas.(3)Some tree species selection needs to be optimized.(4)Some vegetations are in poor health.According to the existing problems,the corresponding carbon sink benefit optimization principles are as follows :(1)Planning high carbon sequestration backbone tree species,scientifically arranging communities,grasping landscape nodes,and taking into account aesthetic values.(2)Adjusting the hierarchical structure of the community,creating a mixed community,enriching the vertical structure of the community and improving its carbon sink capacity.(3)Fully consider the use function of different plant communities.(4)In the process of tree species configuration,while satisfying the ornamental and practical functions,priority should be given to the selection of middle-aged and low-aged native trees with DBH specifications of 16-36 cm and shrubs with DBH specifications of 8-13 cm and high carbon fixation level.After optimization,the average number of trees per hectare increased by 80,the carbon storage per hectare increased by12.0 t,the annual carbon sequestration per hectare increased by 2.2 t,the annual carbon sink benefit per hectare increased by 2314.8 yuan,and the average carbon sink benefit increased by 34.4 % on the original basis.