Role of street trees in mitigating effects of heat and drought at highly sealed urban sites
Role of street trees in mitigating effects of heat and drought at highly sealed urban sites
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DOI：
10.1016/j.landurbplan.2015.06.005
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发表时间：
2015-11-01
影响因子：
9.1
通讯作者：
Roloff, Andreas
中科院分区：
文献类型：
--
作者：
Gillner, Sten;Vogt, Juliane;Roloff, Andreas
在减轻城市地区的热负荷方面，植被和树木尤其发挥着关键作用。这项研究的目的是分析特定物种的小气候效应，并确定叶面积密度、蒸腾作用和气孔导度在城市站点降温效应中的作用。以气温、相对湿度和地表温度为指标，在立地条件相近的居民区，研究了6个树种年龄结构相似的影响。在2013年夏季测定了蒸腾作用、气孔导度和叶面积密度。每条街道每隔一小时监测四棵树的气温和相对湿度，并在下午记录树下有阴影和无阴影的沥青表面连续三天的表面温度。不同物种降低空气和表面温度以及增加相对湿度的能力存在显著差异。同时具有高叶面积密度和高蒸腾速率的树木在冷却空气温度方面更有效。与气温相比，树荫区域表面温度的差异更加明显。因此，全日照区域的表面温度比树荫区域高出15.2K。研究结果为选择具有较高降温潜力的树种，降低城市热负荷，为今后的植树提供参考。测得的冷却潜势最高的是平贝和紫檀‘Greenspire’，最低的是榆树和荷兰的‘Lobel’。(C)2015爱思唯尔B.V.保留所有权利。
Vegetation and trees in particular play a key role in mitigating thermal load in urban areas. The goals of this study were to analyse species-specific microclimatic effects and to identify the role of leaf-area-density, transpiration, and stomatal conductance for cooling effects at urban sites. Air temperature, relative humidity and surface temperature were used to study the effects of six tree species with similar age structure in a residential area with comparable site conditions. Transpiration, stomatal conductance and leaf-area density were measured during the summer months in 2013. Air temperatures and relative humidity were monitored for four trees per street in hourly intervals, and surface temperatures were recorded in the afternoon for three hot days on the shaded and unshaded asphalt surfaces beneath the trees.Species differ significantly in their ability to reduce air and surface temperatures, as well as to increase relative humidity. Trees showing both a high leaf-area density and a high rate of transpiration are more effective in cooling the air temperatures. Differences in the surface temperatures of the tree shaded areas are more pronounced compared to the air temperatures. Thus, the surface temperatures of the full sun exposed areas are up to 15.2 K warmer than that in the tree shaded areas. The results provide information to decrease thermal load in urban areas for future tree planting by choosing species with high cooling potential. The highest cooling potential was measured for Corylus colurna and Tilia cordata 'Greenspire' and the lowest for Ulmus x hollandica 'Lobel'. (C) 2015 Elsevier B.V. All rights reserved.