基于人体健康的 3种城市森林夏季林内紫外线照射环境特征比较研究

Ultraviolet(UV)radiation has multiple biological effects on human health,and urban forests can provide a moderate UV radiation environment for residents.In order to understand whether there are inter-species differences in the characteristics of UV environment in canopy shade,the UV intensity,the ratio of UV radiation in shade and in the open(Shade Ratio,SR),the proportion of UVB in total UV radiation(UVB/UV),and the intensity of two types of human-acting effective radiation for vitamin D synthesis and erythema effect(UVVD and UVer)in shade of three groves were measured in Beijing in summer.The results showed that:(1)The total amount of UV radiation in the three groves was 3%-10%of that in the open.There were significant differences in UV intensity between different groves.Mono maple had the strongest UV screening effect,followed by golden raintree and pagoda tree;(2)Similarity in effectiveness of screening UV radiation at different wavelengths in each grove was found.The screening effectiveness of the canopy in UVB band is not as strong and stable as which in the UVA band,and the UVB/UV values in shade were generally higher than that in the open;(3)The canopy significantly changed the curves of daylight UVVD and UVer spectrum,but the spectral curves in different grove shades were similar.In terms of intensity,the UVVD/UVer values in each shade and in the open were close to 1,and there was no significant difference between different groves;(4)The diameter at breast height(DBH),diffuse non-interceptance(DIFN),mean tilt angle of the leaves(MTA),leaf area index(LAI),leaf transmission,and other features of tree species or canopy structure,could affect the intensity of UV in tree shade,but no inter-species differences in the characteristics of UV light quality or spectral distribution were found.