Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, U.K.
Max-Planck Odense Center, Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
Sci Rep. 2016 Sep 19;6:33708. doi: 10.1038/srep33708.
Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface temperature extremes, but their effects have not been investigated at a city-wide scale. Across a mid-sized UK city we buried temperature loggers at the surface of greenspace soils at 100 sites, stratified by proximity to city centre, vegetation cover and land-use. Mean daily soil surface temperature over 11 months increased by 0.6 °C over the 5 km from the city outskirts to the centre. Trees and shrubs in non-domestic greenspace reduced mean maximum daily soil surface temperatures in the summer by 5.7 °C compared to herbaceous vegetation, but tended to maintain slightly higher temperatures in winter. Trees in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce the adverse impacts of urbanization on microclimate, soil processes and human health.
城市是空气污染和气候变化的主要贡献者，通过城市热岛（UHI）效应，建筑物和灰色基础设施的微气候效应放大了对人类健康的影响。城市绿地对于降低地表极端温度可能很重要，但它们的影响尚未在全市范围内进行调查。在英国的一个中等城市，我们在 100 个绿地土壤表面埋藏了温度记录仪，按距市中心的距离、植被覆盖和土地利用进行分层。在 11 个月的时间里，从城市郊区到市中心的 5 公里范围内，平均每日土壤表面温度上升了 0.6°C。与草本植被相比，非住宅绿地中的树木和灌木在夏季将平均最高每日土壤表面温度降低了 5.7°C，但在冬季往往保持略高的温度。在家庭花园中的树木往往较小，在降低夏季土壤表面温度方面效果较差。我们的研究结果表明，城市热岛效应会影响全市范围内的土壤温度，而树木和灌木在调节城市土壤表面极端温度方面，可能有助于减少城市化对小气候、土壤过程和人类健康的不利影响。
