Research On The Carbon Sink Capacity Of Urban Street Trees Based On The Perspective Of Carbon Neutrality

In 2020,China proposed the "double carbon" goal of "carbon neutral" and "carbon peak".As the main output source of carbon emissions,cities should be the most direct and effective way to fix carbon at the source.Under this background,the carbon sink effect of urban greening is increasingly significant.As an important part of the urban green space system,urban road greening has a very important contribution to the realization of the goal of "carbon neutrality" in the city.In order to analyze its practical role,the author takes the street trees on the urban trunk roads in Haikou as the research object to investigate their growth and estimate the carbon sink of the street trees.The author selected Haikou’s urban primary roads as the scope of investigation,and selected 13 main roads within the urban built-up area of Haikou to carry out the investigation,including Binhai Avenue,Guoxing Avenue,Nanhai Avenue,Yehai Avenue,Wuxi Road,Heping Avenue,Qiuhai Avenue,Xiuying Avenue,Bailong Road,Haifu Road,Longkun Road,and Changtong Road.The sampling site is selected by sampling survey method,and the plant growth indicators of current and past years are calculated by outdoor field measurement and graphic simulation calculation of street trees,and the data is verified by the "DBH-tree height" model of arbor plants.The carbon storage and carbon sink rate are calculated by using the binary wood volume formula,and the accuracy of the calculation results is verified by using I-Trees software.According to the statistical investigation,there are 40932 roadside trees in the study area,belonging to 17 species,13 genera and 10 families.Among them,there are 1 genus and 1 species of Euphorbiaceae,1 genus and 1 species of Leguminosae,1 genus and 1species of Apocynaceae,1 genus and 1 species of Meliaceae,1 genus and 1 species of Kapiaceae,1 genus and 2 species of Moriaceae,1 genus and 2 species of Juniperidae,1genus and 1 species of Myricaceae,1 genus and 1 species of Bignoniaceae,and 4 genera and 3 species of Palmae.After calculating the survey results,it is found that the three roads with the highest carbon sink efficiency among the main roads are Longkun Road,Guoxing Avenue and Haifu Road.The three roads with the lowest carbon sink efficiency are Wuxi Road,Changtong Road and Xiuying Avenue.The tree species with high carbon sink capacity include African Melia azedarach,Ficus microcarpa,and Olivia microphylla,while the tree species with low carbon sink capacity include Olivia macrophylla,Prunus hainanensis,and Flamethree.It is analyzed that this is closely related to the greening layout structure of the road.The large greening area of the road and the high planting density of trees can effectively improve the overall carbon sink efficiency of the road.Finally,according to the calculation,the average annual carbon sequestration of street trees on the urban trunk roads in Haikou is 156.39 t C,and the carbon sequestration capacity per kilometer is 1.4t C.The estimated annual carbon sink of street trees on urban trunk roads in Haikou is 132.55 t C.According to the above conclusions,it can effectively provide guidance factors based on the perspective of carbon neutrality in the design process of street trees,and also make a basic estimate of the carbon sequestration capacity of urban roads in Haikou.