Soil sealing and a decrease in vegetation cover in urban areas increase the likelihood and frequency of localised flooding. Populating the remaining green areas with vegetation, which can efficiently capture excess rainfall, is therefore important. We argue that urban hedges can be a useful tool in mitigating rainfall, so the understanding of optimal plant choice, and underlying traits which enable most rain attenuation, is needed. We tested the hypothesis that higher plant evapo-transpiration rates and larger canopy size can be linked with reduced rainfall runoff in urban hedge species. We first characterised seven hedge species grown in individual containers. These were both deciduous and evergreen species, with a range of inherent canopy sizes and water requirements. We assessed their plant water use, leaf stomatal conductance, canopy rainfall retention, and runoff delay and reduction capacity. The species showing highest and lowest potential for runoff reduction were then investigated for their outdoor performance, when planted in a hedge-like form. Our findings suggest that—after 3 days between rainfall events—species such as Cotoneaster and Crataegus with larger and wide canopies, and with high evapo-transpiration/water use rates, delayed the start of runoff (by as much to 10–15 min compared to bare substrate) as well reduced the volume of rainfall runoff. For example, < 5% of the applied rainfall had runoff with Cotoneaster and Crataegus, compared with > 40% in bare substrate. Substrate moisture content at the time of rainfall (which is linked to plants’ ET rate) was the key explanatory variable.

中文翻译：

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植物选择对降雨径流延迟和树篱物种减少的影响

城市地区的土壤封闭和植被覆盖率的下降增加了局部洪灾的可能性和发生频率。因此，重要的是要在剩余的绿地上种植植被，以有效地捕获过多的降雨。我们认为，城市绿篱可以作为缓解降雨的有用工具，因此需要了解最佳植物选择以及能够最大程度地减少降雨的潜在性状。我们检验了以下假设：较高的植物蒸发蒸腾速率和较大的树冠尺寸可以与城市树篱物种的降雨径流减少相关。我们首先对在单个容器中生长的七个树篱物种进行了表征。它们都是落叶和常绿树种，具有一定的固有冠层大小和需水量。我们评估了它们的植物耗水量，叶片气孔导度，冠层降雨保持力，径流延迟和减少能力。然后，当以树篱状种植时，研究显示出最高和最低的减少径流潜力的物种的室外性能。我们的发现表明，在两次降雨事件之间的三天后，诸如Cotoneaste r和Crataegus的冠层较大且较宽，且蒸发蒸腾/水的使用率很高，因此延迟了径流的开始（与裸露的基质相比，缩短了10-15分钟），并减少了径流的量。例如，Cotoneaste r和Crataegus的径流中<5％径流，而裸露的土壤中> 40％。降雨时的基质含水量（与植物的ET率有关）是关键的解释变量。