A Study On Environmental Effects Of Common Greening Tree Species In Urban Greenland Of Nanning

In this thesis,the common greening tree species of park green space,square green space,community green space and green road in Nanning city are taken as the research object,the photosynthetic rate and transpiration rate of the tested plants were measured by ECA-PB0402 photosynthesis analyzer.The indexes of plant leaf area and dust retention were calculated by the amount of dust and leaf area.The carbon sequestration of common green trees Release oxygen,cooling,dampness and dust retention,and draw the following conclusions:(1)Based on the measurement and calculation of the carbon fixation capacity of 10 common greening species in winter and summer,the results show that: The diurnal variation curves of photosynthetic rate of five kinds of shrubs and five kinds of trees showed a single peak curve in winter and summer,and no photosynthetic midday depression,and peak at around 12:00or 14:00.The changes in photosynthetic rate of shrubs and trees were different in the morning and afternoon,and the photosynthetic rate of trees was larger than that of shrubs.Based on the measured data,the assimilation amount,carbon sequestration and oxygen release were calculated.The three indexes were proportional to the photosynthetic rate of the plant,and the order of carbon sequestration and oxygen release were Dracontomelon duperreanum Pierre>Bauhinia purourea>Mangifera indica>Ficus microcarpa>Bougainvillea glabra>Schefflera octophylla>Mangifera persiciforma>Buxus sinica>Hibiscus rosa-sinensis>Nerium indicum;Carbon fixation and oxygen release of the two seasons of winter and summer order basically unchanged.The value of summer is higher than that of winter.(2)Through the measurement and calculation we found,the diurnal variation curves of summer transpiration rate of five kinds of trees showed a bimodal curve,and the peak values were around 10:00 and 16:00 respectively;The diurnal variation curve of transpiration rate of shrub in summer showed a single peak curve,the peak appeared between 12:00-14: 00.In winter,the transpiration rate of shrubs and trees decreased,but the daily transpiration rate of shrubs was similar,while the diurnal variation curve of transpiration rate of trees in winter became a single peak curve,and the peak concentration appeared at 14:00 about.Transpiration rate determines the amount of plant evaporation of water vapor,which is the degree of humidification,which also determines the rate of plant cooling,the three were proportional relationship.Stomatal conductance,leaf temperature and air relative humidity are the main factors that affect the transpiration rate of plants,which interact with each other and change by the internal and external factors such as their own stomatal characteristics,light,air temperature and wind speed.The order of summer cooling capacity of 10 kinds of plants was Hibiscus rosa-sinensis >Dracontomelon duperreanum Pierre>Bougainvillea glabra>Bauhinia purourea>Buxus sinica> Nerium indicum > Schefflera octophylla > Mangifera persiciforma > Ficus microcarpa >Mangifera indica,in the winter is slightly different.Summer temperature range between 1?-3?,Hibiscus rosa-sinensis unit leaf area transpiration cooling the largest,reaching 2.89 ?,the smallest Mangifera indica,only 1.01?.In the winter temperature range between 0.8?-2?,Hibiscus rosa-sinensis unit leaf area transpiration cooling the largest,reaching 1.8 ?,thesmallest Mangifera indica,only 0.88?.In winter,only considering the effect of humidification and cooling effect is not considered.(3)The total amount of leaves of each sample was calculated by punching and weighing,and the amount of dust in each unit area was calculated.The order of the amount of dust in the unit was Hibiscus rosa-sinensis > Dracontomelon duperreanum Pierre > Nerium indicum >Bauhinia purourea > Mangifera persiciforma > Bougainvillea glabra > Mangifera indica >Buxus sinica>Schefflera octophylla>Ficus microcarpa.According to the unit leaf area of dust retention size of 10 kinds of plants will be divided into three categories: the first category is Schefflera octophylla,Buxus sinica,Mangifera indicaand Ficus microcarpa,dust retention capacity were Schefflera octophylla(10.13g/m~2)?Buxus sinica(10.43g/m~2)?Mangifera indica(12.05g/m~2)?Ficus microcarpa(8.98g/m~2);The second category includes Bougainvillea glabra(17.84g/m~2)? Nerium indicum(30.86g/m~2)? Mangifera persiciforma(19.83g/m~2)?Dracontomelon duperreanum Pierre(33.28g/m~2)?Bauhinia purourea(22.33g/m~2);The third category is only hibiscus(52.35g/m~2).Through the comparative analysis of the characteristics of the leaves of the plants,the papery leaves the ability of dust retention better than the leathery,leaf with or without fine hair,wrinkles,glands and other factors also affect the amount of dust.Although some of the tree dust retention capacity is not as good as shrubs,but the advantages of the tree is high,large,the total amount of dust to be more;Shrubs are dense,helping to prevent secondary dust.In order to better analyze the dust catching ability of each plant,the unit can be obtained by manual methods of dust the dust amount of leaf area is an ideal numerical condition,more than the amount of dust in the natural state,is closer to the maximum amount of dust species.