乌鲁木齐市快速路绿化树种滞尘量与叶片结构特性分析

Dust Retention Amount and Leaf Micro Morphological Structure of the Greening Species in the Frostbelt Along the Expressway in Urumqi

为深入了解城市快速路林带不同绿化树种的滞尘能力,选择乌鲁木齐市河滩快速路林带落叶乔木、常绿乔木和灌木等12个树种为试验对象,分别从树冠向车道和背车道方向上不同高度处采集叶片,通过测定其滞尘量和采用Hitachi台式TM3000电镜观测叶片显微结构,探讨树冠不同位置叶片的滞尘量及叶表面显微结构的差异及其相关性。结果表明,1)不同树种叶片滞尘量具有显著差异(P<0.01),12个树种滞尘能力由大到小排序为:樟子松、云杉、榆树、刺槐、黄金树、山桃、水蜡、山楂、丁香、白蜡、红瑞木、火炬树;2)各树种叶面滞尘量在不同生活型之间差异极其显著(P<0.01),平均单位叶面积滞尘量由大到小排序为常绿乔木(201.71μg/cm^(2))、灌木(83.68μg/cm^(2))、落叶乔木(58.97μg/cm^(2));3)常绿、落叶乔木树种向车道方向的叶片滞尘量均大于背车道方向的叶片滞尘量,而灌木则相反,对树冠高度而言,12个树种叶片滞尘量在树冠高度由大到小均呈现为:1、2、4 m;4)不同树种叶片微结构的差异均表现在叶面气孔大小、密度、数量、蜡质结构和周围细胞的褶皱度等指标,而这些差异对滞尘量的排序影响较大;气孔分布不规则、粗糙或平滑、有无叶毛等指标对叶片滞尘量的影响不明显。研究结果可为揭示城市林带对颗粒污染物的阻滞规律、干旱区绿洲城市绿化方案的优化和城市绿化树种的科学选培提供参考。

In order to explore the particulate retention capacity of the tree species in the shelterbelt along the city expressway,12 plant species were selected as the experimental objects,including deciduous arbors,evergreen arbors and shrubs.The leaf samples were collected from different positions of a tree/bush canopy.The dust retention amounts the plant leaves were measured.The microstructures of the leaves were observed to examine the differences in dust retention amounts among different leaves and the relationship between microstructure and dust retention capacity.The results showed that 1)there were significant differences in the dust retention amounts of the leaves among 12 plant species(P<0.01),and the dust retention capacity of different tree species was in the order of Pinus sylvestris,Picea asperata,Ulmus pumila,Robinia pseudoacacia,Catalpa speciosa,Prunus davidiana,Ligustrum obtusifolium,Crataegus pinnatifida,Syringa oblata,Fraxinus chinensis,Swida alba,Rhus typhina.2)The dust retention amounts of the trees with different life forms were also significantly different,which was in the order of evergreen arbor species(201.71μg/cm^(2)),shrub(83.68μg/cm^(2)),deciduous arbors(58.97μg/cm^(2)).3)For the evergreen and deciduous arbors,the dust retention amounts of the leaves in the backwards direction to the expressway was higher than those in the towards direction,and the shrub species showed the opposite results.All the selected tree species showed the same order in the differences of dust retention amounts at height of the canopy,i.e.,1 m,2 m,4 m.4)There were differences in leaf microstructures,including the density,number and size of stomata,wax structure,and the folding degree of surrounding cells on the leaf surface,and these differences had great influences on the dust retention capacity.However,no significant relationships were found between the dust retention capacity and the stomata irregularity,quantity of leaf hairs,and roughness of leaf surface.The results could provide a reference for the optimization of greening and management scheme and rational tree species selection in oasis cities in the arid area.