| In this research,three types of typical roadside trees were selected as sample in Fuzhou city, including low vegetation coverage of roadside trees(Ficus microcarpa L.f.) in road A;high vegetation coverage of roadside trees(Cinnamomum camphora(L.) Presl) in road B;low vegetation coverage of roadside trees(Ficus microcarpa L.f.) in road C of residence.PM and concentration of CO was recorded in street and sidewalk by using CO as a vehicular pollutant tracer,for the aim of how influence of urban roadside trees on vehicular pollutant diffusion,the variation of PM and concentration of CO between street and sidewalk was analyzed at the different height.Some results are as fellows:1.Concentration of CO of sidewalk and traffic density was extremely significant correlation. Correlation of concentration of CO in road B and road C is greater than road A.It can be think that the traffic density is the main factor affecting the concentration of CO.The PM concentration of sidewalk and traffic density was less relevant,not with regularity.2.Concentration of CO is not significantly between three seasons in road A and B,the other way round road C.The PM concentration of three roads has clear seasonal variation.The highest PM concentration is in spring,PM concentration of three roads was significantly higher than the other two seasons,PM concentration was no significant differences in summer and autumn.PM concentration beside trees is no significant difference in the same road.3.The vegetation coverage and shelterbelt porosity of roadside trees in road A is lower,benefit to the spreading of vehicular pollutant.The effect of spreading CO is very obvious in road A.PM concentration in road A is significant difference to the others,and the concentration of PM in the three seasons is the lowest;In road B the vegetation coverage is higher and shelterbelt porosity is lower,the effect of spreading vehicular pollutant between road A and road B.Dense "cap" blocked the spreading of vehicular pollutant o some extent.The PM concentration in road B is higher,and has no significant difference with road C;In road C the vegetation coverage is higher and shelterbelt porosity is lower,its effect of spreading CO is bad.Road C located in a narrow residence,although the traffic was lower, because of sheltering from the roadside trees,the spreading of vehicular pollutant was hindered,and it was harmful to pedestrians.The concentration of PM in road C is higher,and has no significant difference with road B.4.The correlation between temperature and the concentration of CO is weak,during 12:00～14:00 in the negative correlation.Air temperature and the concentration of PM were negatively correlated, especially more obvious during 12:00～14:00,at night air temperature and the concentration of PM is more consistent trends.The correlation between humidity and the concentration of CO is weak,in a positive correlation during 12:00～14:00.Humidity and PM showing a certain degree of correlation,and their variation trends is basically accordant.Considering the influence of urban roadside trees on vehicular pollutant diffusion,The vegetation coverage and shelterbelt porosity of roadside trees is lower,benefit to the spreading of vehicular pollutant from the road surface,it can reduce the the harm caused of vehicular pollutant on pedestrians and residents.All this provides evidence of theoretics on the roadside trees species and the way of trees disposition.
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