The Study On Common Street Trees Fixing Carbon And Releasing Oxygen Sluggish Dust Benefits In Changsha

This paper with changsha landscape commonly used street trees, such as Cinnamomum camphora,Platanus orientalis,magnolia grandiflora linn, eight kinds of plants as the research object, through the determination of the leaf area index, photosynthesis rate index, quantitative research of eight plants living vegetation volume, carbon fixation and oxygen release and the dust-retention ability, comprehensive evaluation the ecological benefits of street trees commonly used in Changsha, to improve plant ecological benefits related indicators, improve the level of changsha city greening, science of the green space structure adjustment, the unit area of green ecological benefit maximization, improve people living environment for the purpose of the research and significance, for the choice of the urban street trees and ecological benefit provide reasonable references. The results were as follows:(1) The leaf area index order of street trees commonly used in changsha city is: Platanus orientalis> Magnolia grandiflora Linn> Cinnamomum camphora> Elaeocarpus sylvestris (Lour.) Poir> Koelreuteria paniculata>Ginkgo biloda Linn. Mant> Osmanthus fragrans> Zelkova schneideriana Hand.-Mazz. From the leaf area index to see, P. orientalis,M. grandiflora and C. camphora belong to the finest road greening tree species, either from the landscape effect or ecological benefit angles, has the unique advantages, in the future urban road greening should be more use.(2) By comparing that individual plant leaf area namely living vegetation volume the amount of total arrange order is P. orientalis> C. camphora> M. grandiflora> K. paniculata> G. biloda> Z. schneideriana> E. sylvestris> O. fragrans E. sylvestris. Green quantity is a important index to reflect the ecological benefits of plants, form the determination of the eight kinds of street trees from the green quantity to see, P. orientalis,M. grandiflora and C. camphora not only large amount of living vegetation volume, and leaf area index also explain, the three is the best city greening tree species.(3) Eight kinds of street trees light response parameters have significant differences, LCP value between in the10~40μmol·m-2·s-1, the LSP value between in300-1300μmol· m-2·s-1. Eight kinds of street trees net photosynthetic rate scope in5~18μmol· m-2·s-1, and the difference is bigger, P. orientalis have largest Amax,for17.03μmol μ m-2μs-1the minimum Amax is O. fragrans, for5.68μmol· m-2·s=1, the net photosynthetic rate order of eight kinds street trees is:P. orientalis> M. grandiflora linn> E. sylvestris> K. paniculata> Z. schneideriana> C. camphora> G. biloda> O. fragrans.(4) The photosynthetic rate of seasonal change trend of Changsha common street trees is summer> spring> autumn. The same plant in different seasons, in accord with the change trend, different plants in the same season, have great differences curve. The same tree species in different seasons of fixing carbon and releasing oxygen amount is different. Eight kinds of street trees unit leaf area releasing oxygen between in2.81g·m-2·d-1(G biloda)-5.43g-m-2·d-1(C. camphora), unit land area of fixing carbon and releasing oxygen amount in11.58g·m-2·d-1(G. biloda)-46.21g·m-2·d-1(P orientalis)(5) By the determination results, it is known that the annual unit leaf area fixing carbon and releasing oxygen efficiency is highest is Z. schneideriana., solid carbon benefit year-round is (?)13.91, releasing oxygen benefit for (?)9.92; Annual unit leaf area fixing carbon and releasing oxygen benefit is the lowest G. biloda, solid carbon benefit is (?)6.95, releasing oxygen benefit is (?)5.37. Of these, the P. orientalis have highest land utilization, unit land area fixing carbon and releasing oxygen best benefit each year, solid carbon unit of land benefit is (?)114.81, releasing oxygen benefit for (?)81.84; Unit of land every year fixing carbon and releasing oxygen benefit the lowest street trees is G. biloda, each year solid carbon benefit for (?)28.64, each year releasing oxygen benefit for (?)20.42.(6) Eight kinds of street trees sluggish dust capacity and is not always linear increase, but as time gradually reduce cumulative growth, sluggish dust capacity after saturation, leaf will no longer lag dust, until after the heavy rain again plant leaves sluggish dust, completing a sluggish dust cycle. The sluggish of street trees dust capacity are presenting more than the rule of the urban road campus, between different species there exist great sluggish dust difference, in urban road green space system, the P. orientalis dust detentions of the strongest,the O. fragrans dust detentions of the weakest.According to the above, we think that the P. orientalis,Z. schneideriana,C. camphora and M. grandiflora comprehensive ecological benefit is the best. K. paniculata,E. sylvestris.take second place, G. biloda and O. fragrans ecological benefit is poor.