Quantifying the impact of single-tree morphological characteristics on the vertical gradient cooling effect and human thermal comfort during summer

IF 6 2区环境科学与生态学 Q1 ENVIRONMENTAL STUDIES

Urban Forestry & Urban Greening Pub Date : 2025-03-20 DOI:10.1016/j.ufug.2025.128789

Yue Cai , Chong Li , Chunyu Pan , Guangyu Wang , Jianxiang Xu , Wenyan Cui , Yufeng Zhou , Guomo Zhou

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引用次数: 0

Abstract

Urban forests are crucial in improving the urban environment, relieving the heat island effect, and regulating microclimates. Urban areas encompass a diverse range of tree species exhibiting varying morphological characteristics. Nevertheless, there is limited quantitative research investigating the factors influencing the thermal regulation effectiveness of urban tree morphology during summer. In this study, we utilized a portable meteorological station, a thermal infrared camera mounted on an unmanned aerial vehicle (UAV), and a handheld thermal camera to measure air temperature (AT), canopy temperature (CT), and ground surface temperature (GST) of individual trees, respectively. The results revealed a significant correlation between AT, CT, and GST across four canopy morphologies. ΔAT decreased with increasing height and reached its maximum at 1.5 m (ΔAT_1.5). The ΔAT_1.5 values for the different canopy shapes were as follows: pyramidal (2.99 ± 0.75℃); spherical (3.93 ± 0.61℃); pileate (4.03 ± 0.60℃); and ellipsoidal (3.27 ± 0.48℃). The corresponding ΔGST values were determined as: pyramidal (3.92 ± 0.48℃); spherical (8.68 ± 2.13℃); pileate (13.08 ± 1.08℃); and ellipsoidal (6.15 ± 0.7℃). The ΔAT values under pileate and ellipsoidal canopy shapes exhibited statistically significant differences among the four heights (P ˂ 0.05). In terms of human thermal comfort, the ΔPhysiological equivalent temperature (PET)_1.5 values for the pyramidal, spherical, pileate, and ellipsoidal canopy shapes were observed as 11.01℃, 18.01℃, 18.7℃, and 16.04℃ respectively. Therefore, we recommend using species with pileate, spherical, and ellipsoidal canopies with a high leaf area index for urban trees. Our study quantified the vertical gradient cooling effects of individual trees and demonstrates how tree morphological characteristics influence the microclimate and human thermal comfort, providing a valuable reference for urban forestry planning.

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单树形态特征对夏季垂直梯度降温效果和人体热舒适影响的量化研究

城市森林在改善城市环境、缓解热岛效应、调节小气候等方面具有重要作用。城市地区包含各种各样的树种，表现出不同的形态特征。然而，对夏季城市树木形态热调节效果影响因素的定量研究有限。在本研究中，我们利用便携式气象站、安装在无人机（UAV）上的热红外相机和手持式热像仪分别测量了单株树木的空气温度（AT）、冠层温度（CT）和地表温度（GST）。结果显示，在四种冠层形态中，AT、CT和GST之间存在显著的相关性。ΔAT随高度的增加而减小，在1.5 m处达到最大值（ΔAT1.5）。不同冠层形态的ΔAT1.5值分别为：金字塔形（2.99 ± 0.75℃）；球形(3.93 ± 0.61℃); pileate(4.03±0.60℃ );椭球面（3.27 ± 0.48℃）。相应的ΔGST值为：金字塔形（3.92 ± 0.48℃）；球形(8.68 ± 2.13℃); pileate(13.08±1.08℃ );和椭球面（6.15 ± 0.7℃）。冠状和椭球状冠层形态下的ΔAT值在4个高度间差异有统计学意义（P小于0.05）。在人体热舒适方面，金字塔形、球形、毛线形和椭球形冠层的ΔPhysiological等效温度（PET）1.5值分别为11.01℃、18.01℃、18.7℃和16.04℃。因此，我们建议在城市树木中使用具有高叶面积指数的冠层、球形和椭球形的树种。本研究量化了单株树木的垂直梯度降温效应，揭示了树木形态特征对小气候和人体热舒适的影响，为城市林业规划提供了有价值的参考。

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来源期刊

Urban Forestry & Urban Greening FORESTRY-

CiteScore

11.70

自引率

12.50%

发文量

289

审稿时长

70 days

期刊介绍： Urban Forestry and Urban Greening is a refereed, international journal aimed at presenting high-quality research with urban and peri-urban woody and non-woody vegetation and its use, planning, design, establishment and management as its main topics. Urban Forestry and Urban Greening concentrates on all tree-dominated (as joint together in the urban forest) as well as other green resources in and around urban areas, such as woodlands, public and private urban parks and gardens, urban nature areas, street tree and square plantations, botanical gardens and cemeteries. The journal welcomes basic and applied research papers, as well as review papers and short communications. Contributions should focus on one or more of the following aspects: -Form and functions of urban forests and other vegetation, including aspects of urban ecology. -Policy-making, planning and design related to urban forests and other vegetation. -Selection and establishment of tree resources and other vegetation for urban environments. -Management of urban forests and other vegetation. Original contributions of a high academic standard are invited from a wide range of disciplines and fields, including forestry, biology, horticulture, arboriculture, landscape ecology, pathology, soil science, hydrology, landscape architecture, landscape planning, urban planning and design, economics, sociology, environmental psychology, public health, and education.