城市行道树对交通环境的响应

以远离交通环境的公园作为相对清洁区,研究了位于广东佛山种植最普遍的8种城市行道树树黄葛榕(FicusvirensAit.var.sublanceolata(Miq.)Corner),大叶紫薇(Lagerstroemiaspeciosa(L.)Pers.),芒果(MangiferaindicaL.),细叶榕(FicusmicrocarpaL.),阴香(Cinnamomumburmanii(Nees)Bl.),垂叶榕(FicusbenjaminaL.),白兰(MicheliaalbaDC.),红花羊蹄甲(BauhiniablakeanaDunn)在交通密集区生长在不同方位的植物器官对交通环境的响应。结果表明,交通密集区的城市行道树的叶片和树皮器官吸收重金属铅和镉、硫含量、电导率和pH值等指标在不同的方位呈现显著的差别,即城市行道树位于快车道一侧生长的植物的器官(以下简称P1)、位于面向人行道一侧生长的植物的器官(以下简称P2)及相对清洁区采集的植物样品(以下简称P0)各指标测定值的分析结果为:其叶片和树皮硫、重金属铅和镉、电导率等特征值基本呈现P1>P2>P0的大小规律,在显著度为0.05时差异显著;而pH值基本呈现P1

Responses of the urban roadside trees to traffic environment

Ficus virens Ait. var. sublanceolata (Miq.) Corner, Lagerstroemia speciosa (L.) Pers., Mangifera indica L., Ficus microcarpa L. Cinnamomum burmanii (Nees) Bl., Ficus benjamina L.Michelia alba DC., and Bauhinia blakeana (Dunn) are common urban roadside trees in Foshan, Guangdong. They are subjected to many pollutants from automobile emissions, such as SO_2 and the heavy metals Pb and Cd. The comparatively pollution-free parks far from the traffic environment were used as a control site to study the responses of urban roadside trees to the traffic environment. The results are as follows: The eight roadside trees differed from park trees in their absorption of the heavy metals Pb and Cd, sulfur content, electric conductivity, pH value in the leaves and bark, and stomatal density. There were three sampling sites: next to the automobile lane (P_1), the pavement (P_2), and in the comparatively pollution-free parks away from traffic (P_0). Pb, Cd, and sulfur content and electric conductivity in the leaves and bark of the urban roadside trees demonstrated significant differences (5% level) following the trend of P_1>P_2>P_0. The pH value was also significant (5% level); however, it showed the reverse results: P_1P_2>P_0. However, the stomata density of the lower epidermis in leaves of Michelia alba DC showed no significant difference at the 5% level. For the other tree varieties (Lagerstroemia speciosa (L.) Pers., Mangifera indica L., and Cinnamomum burmanii (Nees) Bl.), the stomata density of the lower epidermis of leaves decreased closer to the traffic lanes (i.e., they were significantly different (5% level) with the opposite trend: P_1