Trees are considered to be an effective tool for improving human thermal comfort in hot climates and have been widely used in landscape architecture. However, it is not always clear how trees affect human-environment energy fluxes. In this study, an in-depth analysis of four common tree species was undertaken based on comprehensive field measurements, in terms of how each tree and its characteristics affected the energy fluxes of a person in a humid subtropical climate region. Results showed that the largest effect of trees was on radiation fluxes, with a much smaller effect on the convective and evaporative fluxes. For a person standing in shade, a tree can reduce approximately 25% of the absorbed radiation compared with an open reference point. Moreover, the cooling effect on radiation components was found to be greater in the solar radiation domain than in the terrestrial radiation domain. Solar radiation and ground surface temperature had the largest effect on a human energy budget, which was affected by characteristics of the trees and the thermophysical properties of ground surfaces. The effect from relative humidity and wind speed was quite minimal. For the four common tree species in this study, Ficus microcarpa had the best thermal performance by reducing the most absorbed solar radiation flux. This study shows a detailed empirical research about the thermal effects of trees on a person, providing recommendations for tree species selection in urban design.

中文翻译：

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亚热带湿润气候区树木对人体能量通量的影响

树木被认为是在炎热气候下提高人体热舒适度的有效工具，并已广泛应用于景观设计。然而，树木如何影响人类-环境能量通量并不总是很清楚。在这项研究中，在综合实地测量的基础上，对四种常见树种进行了深入分析，了解每棵树及其特征如何影响亚热带湿润气候地区人的能量通量。结果表明，树木对辐射通量的影响最大，对对流和蒸发通量的影响要小得多。对于站在阴凉处的人来说，与开放的参考点相比，一棵树可以减少大约 25% 的吸收辐射。而且，发现在太阳辐射域中对辐射分量的冷却效果比在陆地辐射域中更大。太阳辐射和地表温度对人类能量收支的影响最大，受树木特性和地表热物理性质的影响。相对湿度和风速的影响非常小。对于本研究中的四种常见树种，小果榕通过减少吸收最多的太阳辐射通量而具有最佳的热性能。本研究展示了关于树木对人的热效应的详细实证研究，为城市设计中的树种选择提供了建议。太阳辐射和地表温度对人类能量收支的影响最大，受树木特性和地表热物理性质的影响。相对湿度和风速的影响非常小。对于本研究中的四种常见树种，小果榕通过减少吸收最多的太阳辐射通量而具有最佳的热性能。本研究展示了关于树木对人的热效应的详细实证研究，为城市设计中的树种选择提供了建议。太阳辐射和地表温度对人类能量收支的影响最大，受树木特性和地表热物理性质的影响。相对湿度和风速的影响非常小。对于本研究中的四种常见树种，小果榕通过减少吸收最多的太阳辐射通量而具有最佳的热性能。本研究展示了关于树木对人的热效应的详细实证研究，为城市设计中的树种选择提供了建议。小果榕通过减少吸收最多的太阳辐射通量而具有最佳的热性能。本研究展示了关于树木对人的热效应的详细实证研究，为城市设计中的树种选择提供了建议。小果榕通过减少吸收最多的太阳辐射通量而具有最佳的热性能。本研究展示了关于树木对人的热效应的详细实证研究，为城市设计中的树种选择提供了建议。