| Green spaces are a harbour of biodiversity,which has played a great role in the ecological functions.Dust-retention is one of the most important ecological functions of green spaces.Many researchers have carried out studies on dust-retention in the green spaces.There are few studies on the relationship between vegetation structure,biodiversity,and airborne particulate concentration.The study took the main urban area of Baoji City in the Guanzhong region as a study area and selected a variety of green spaces along both sides of the Weihe River.9 types of urban green spaces with various horizontal structures,vertical structures and plant compositions as samples were selected based on a urban biotope map of Baoji city.Each structural type of green space was replicated three times and a one-year field survey and testing was conducted(2017 April-March 2018).The study analyze the impact of factors such as monitoring location,time,wind speed,temperature,humidity,and green area on the PM2.5 and PM10 concentration(based on mass concentration,the same below)"local effect" of airborne particulate matter in the urban green spaces.Minitab 16 statistical software was used to establish a generalized regression model for multivariate analysis to explore the differences in the effects of different vegetation structure and biodiversity on airborne particulate concentration reduction.The main findings of this study are as follows:(1)As the temperature gradually increased in the range of-3.7-47.4°C,the wind speed gradually increased in the range of 0-4.4m/s,the concentration of PM2.5 and PM10 decreased significantly,while the humidity gradually increased in the range of 19.7-84.9RH,the concentration of PM2.5 gradually increased,while the concentration of PM10 gradually decreased.(2)Different vegetation structures had a significant effect on the reduction of PM2.5 and PM10.The dust retention capacity of the one layered closed broad-leaved mixed conifer forest,one layered partly closed conifer forest,one layered partly closed broad-leaved forest,one layered closed broad-leaved forest,multi-layered partly closed broad-leaved mixed conifer forest,open shrub are better than that of multi-layered partly closed broad-leaved forest,one layered partly closed broad-leaved forest and open grass.(3)With the increase of species diversity,the concentrations of PM2.5 and PM10 showed a downward trend.The higher the species richness,the lower the concentration of particles matters.(4)The overall PM2.5 and PM10 concentrations were lower in May,June,July,August,and September,however,the PM2.5 and PM10 concentrations were higher in October,November,December,and January.For different time periods during the day,the experimental data showed that the concentration of airborne particles was higher in the morning,decreased at noon,and gradually recovered in the evening.(5)Multi-green types of green space were most effective in reducing PM2.5 and PM10.There was no source of pollution in the surrounding environment of urban green spaces,and the level of plant conservation and management had a certain degree of impact on the reduction of airborne particulate matter.As the area gradually increased from 0.09 to 2.4 hectares,the concentration of PM2.5 gradually decreased,while the concentration of PM10 did not increase or decrease significantly.The above research results will provide theoretical basis for the air quality regulation oriented urban-rural green space planning and design.We should demonstrate the advantages of the discipline of landscape architecture,integrating environmental protection into the landscape design,exploring new models of plant dust retention for beautifying the living environment,and enhancing urban landscape in the future. |
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