Preliminary Study On Fixing Carbon Dioxide Releasing Oxygen And Retention Of Dust Of Street Trees In Beijing

This paper study on the main tree species on the Xue Qing Road in Beijing,taking the scientific quantitative measurement and analysis as tools;and taking the effective measures of improving road green as target, to study the quantity of fixing carbon and releasing oxygen and dust-retention ability of 16 different tree species, including carbon sequestration and oxygen release of plant and leaf dust and species physiological changes under dust stress, as well as to provide a reasonable basis for urban tree species selection, configuration, and ecological benefits.The results are as follows.(1) The seasonal trend common tree species in photosynthetic rate on the road is summer> spring> autumn, the same species in different seasons of fixing carbon and releasing oxygen is also different. Different species in the same season has different carbon sequestration and oxygen release, the same species in different seasons of fixing carbon and releasing oxygen is also different. Per leaf area and oxygen release of 16 tree species at 3.62 g·m-2d-1(ginkgo)-6.87g·m-2d-1(Sophora japonica), with per land area is in 13.74g of oxygen release 13.74g·m-2d-1 (Salix)-27.69g·m-2d-1 (Euonymus japonicus).(2) Annual carbon sequestration benefits per leaf area was 16.39 yuan, and oxygen release efficiency is 11.68 yuan; the least effective species of fixing carbon and releasing oxygen is ginkgo, Annual carbon sequestration benefits per leaf area was 8.46 yuan, releasing oxygen efficiency is 6.04 yuan. Euonymus japonicas has the maximum utilization of land, Annual carbon sequestration benefits per land area was 103.28 yuan, releaseing oxygen efficiency is 73.6 yuan; the lowest effective carbon sequestration and oxygen release is Salix species, Annual carbon sequestration benefits per land area was 33.13 yuan, releaseing oxygen efficiency is 23.59 yuan.(3) Dust-retention ability of 16 different tree species increases over time, while weekly increation is nonlinear, with increasing degree improved in decreasing trend before dust-retention had reached saturation point. After that, dust-retention no longer increases or unobviously until a new round of dust-retention begins with the next heavy rain.(4) Dust-retention ability of different tree species along the road is more stronger than the ones on campus, and there are differences between them. In the greenland of road system, Euonymus japonicus have the strongest dust-retention ability with its total dust 27.33g.m-2 within 3 weeks and Populus the weakest with its total dust just 9.74g.m-2. Weekly average and annual dust-retention of singleBroussonetia is 570.31g and 17.11kg respectively, which is the most effective dust-retention specie. comparatively, Of Purple is the worst one with its weekly average and annual dust-retention 570.31g and 17.11kg respectively. Among arbor species, Fraxinus is the most effective one with its annual dust-retention 10.73kg and Salix the least one with its annual dust-retention 3.76kg.(5) Among the 16 different tree species, the ones along the road have the bigger photosynthetic feature parameters than the ones on campus. Dust-retention ability is related with net photosynthetic rate(Pn) loss and transportation loss, the relativity between them are 0.8287 and 0.9799 respectively.