| With the rapid development of urbanization,the deterioration of the ecological environment and climate change has become the most important problem in the period of urban development today.Under the background of low-carbon,the ecological construction of urban green space is placed in an important position,and the quantitative research on green volume and eco-efficiency has become a significant topic.In this study,adopting the total leaf area as green volume,the green volume is calculated based on the LAI.Taking five types of green space(road green space,affiliated green space,park green space,campus green space,residential green space)in Xianlin area of Nanjing City as the research object,it analyzed the structure of typical plant communities based on the 60 typical plots investigation.And then classify the plant community factors into different grades,analyzing the distribution of green volume,as a result,studying on the effects of different community factors on green volume and eco-efficiency.According to the quantitative study,the research has explored the method of enhancing green volume and eco-efficiency of green space,in order to provide reference for the study of green volume and plant arrangement of Xianlin area in the future.The main results of the study are including the following aspects.(1)Through the analysis of the structure characteristics of typical plant communities,it found that the rich layer of plant community structure can improve the per unit area amount of green volume and eco-efficiency.In contrast,the green volume in per unit area decreased due to the high plant density.In plant community,the tree layer has the best eco-efficiency.(2)By classifying the plant community factors,it found that the distribution of DBH concentrated in the range of 10-15cm,and the average DBH of road green space was maximum;the tree height mainly distributed in the range of 5-8m,and park green space was the most concentrated,while the road green space was the highest;plant density mostly distributed in range of>2000/hm2,and affiliated space was the biggest,while the smallest was road green space.There was a positive correlation between DBH,tree height and green volume in per unit area,but the plant density was opposite to a certain value.(3)The distribution of green volume has differences in the horizontal and vertical structure of five types of green space.The distribution of green volume on DBH was mainly affected by the numbers of plants,and park green space’s was the most stable and balanced with the DBH 17.5～20cm plant making the most contribution to green volume;while on height,it was mainly affected by the size of plant.The green volume of large size trees is superior in abundant plant structure.It was common in road green space and green volume was mainly from the 6-8m height plant.(4)Through the quantitative study on green volume in Xianlin area of Nanjing,it found the average green volume in per unit area was 8.52×104 m2/hm2,when it mainly distributed within the range from 5×104 m2/hm2to 10×104m2/hm2.Among five types of green space,green volume in per unit area of park gree1 space was maximum with 9.54×104 m2/hm2,while the residential green space’s was minimum,1nly 7.10×104 m2/hm2.In contrast to Beijing and Wuhan,it found that park green space’s was maximum,and the residential green space’s or road green space’s was minimum.Among three cities,the green volume in per unit area of five types of green space in Beijing was maximum,which of road green space in Xianlin area of Nanjing is relatively higher.As a whole,there is a broad space of improvement.(5)Taking the abilities of carbon sequestration,oxygen-releasing,cooling and humidifying as the main indexes of eco-efficiency,it found the average value of eco-efficiency of five types of green space in Xianlin area of Nanjing City,in per unit area,56.66 g·m-2·d-1 for the carbon sequestration,41.02 g·m-2·d-1for oxygen-releasing amount,1.54℃·m-2·d-1 for cooling amount,9919.71g·m-2·d-1 for humidifying amount,respectively.In five types of green space,the eco-efficiency of park green space was maximum while the residential green space’s was minimum.(6)According to the study on green volume and eco-efficiency of seven kinds of ordinary tree species(Koelreuteria integrifolia,Cinnamomum camphora,Magnolia grandiflora,Zelkova serrata,Albizia julibrissin,Celtis sinensis,Acer palmatum)in Xianlin area of Nanjing City,it found that Albizia julibrissin has the best comprehensive efficiency with the highest green volume and eco-efficiency.Albizia julibrissin and Acer palmatum has the maximum correlation between DBH,height and green volume,and the green volume was a marked change with the DBH and height of plant. |
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