Significant effects of ecological context on urban trees' cooling efficiency
Significant effects of ecological context on urban trees' cooling efficiency
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生态环境对城市树木降温效率的显着影响
DOI：
10.1016/j.isprsjprs.2019.11.001
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发表时间：
2020
影响因子：
12.7
通讯作者：
Zhang Qiming
中科院分区：
文献类型：
--
作者：
Wang Jia;Zhou Weiqi;Jiao Min;Zheng Zhong;Ren Tian;Zhang Qiming
由于城市化和全球气候变化的协同作用，大多数城市的城市热岛效应在未来几年可能会加剧。许多研究表明，城市植被的冷却效果。然而，温度降低一个单位的幅度（例如，1%的树木覆盖）的植被丰富度的增加，这里定义为冷却效率（CE），在不同的研究中差异很大，但对这种变化的了解很少。本研究旨在通过调查美国大陆生物群落CE的空间变化，以及它如何受到生态环境，特别是气候条件的影响来填补这一空白。我们使用普通最小二乘法（OLS）线性回归模型计算了118个城市的CE，从10个不同的生物群落，城市树木的百分比（Ptree）作为自变量，地表温度（LST）作为因变量。结果表明，CE的平均值为0.168 °C（0.040-0.574 °C），Ptree可以解释LST平均40.3%的变化。CE是较高的西南部城市，特别是在炎热和干燥的生物群落，但没有显着不同的其他剩余的生物群落，其中CE通常是更大的生物群落为主的阔叶树相比，占主导地位的针叶树或稀疏的树木。气候背景，包括空气温度，湿度和风速强烈影响CE，但并不总是以线性的方式。另外，在潮湿城市，气温对CE的影响比湿度更大，而在干燥城市则相反。了解不同城市间城市树木碳当量的变化及其气候驱动因素，可以为城市热缓解和适应提供重要的见解。
Urban heat island effect in most cities is likely to be exacerbated in future years due to the synergetic effects of urbanization and global climate change. Numerous studies have shown cooling effects of urban vegetation. However, the magnitude of temperature reduction by one-unit (e.g., 1% of tree cover) increase of vegetation abundance, defined as cooling efficiency (CE) here, varies greatly by different studies, but with little understanding on such variation. This study aims to fill this gap by investigating the spatial variation of CE across biomes in the continental USA, and how it is affected by ecological context, especially climatic conditions. We calculated CE for 118 cities from 10 different biomes using Ordinary Least Squares (OLS) linear regression models with percent of urban trees (Ptree) as the independent variable, and land surface temperature (LST) as the dependent variable. The results revealed that the average value of CE was 0.168 °C (0.040–0.574 °C), and Ptree could explain an average of 40.3% of LST's variation. CE was higher in southwestern cities especially in hot and dry biomes but not significantly different among other remaining biomes, within which CE was typically greater in biomes dominated by broadleaf trees compared to those dominated by coniferous or sparse trees. Climatic context including air temperature, humidity and wind speed strongly affected CE but not always in a linear way. In addition, air temperature played a more important role in affecting CE than humidity in humid cities, but the opposite in dry cities. Understanding the variation of CE of urban trees among different cities and its climatic drivers can provide important insights for urban heat mitigation and adaptation.