Department of Geography, University of Aberdeen, Aberdeen, UK.
Northern Rivers Institute, University of Aberdeen, Aberdeen, UK.
Environ Monit Assess. 2023 Mar 15;195(4):468. doi: 10.1007/s10661-023-11055-6.
Urban green spaces (UGS) can help mitigate hydrological impacts of urbanisation and climate change through precipitation infiltration, evapotranspiration and groundwater recharge. However, there is a need to understand how precipitation is partitioned by contrasting vegetation types in order to target UGS management for specific ecosystem services. We monitored, over one growing season, hydrometeorology, soil moisture, sapflux and isotopic variability of soil water under contrasting vegetation (evergreen shrub, evergreen conifer, grassland, larger and smaller deciduous trees), focussed around a 150-m transect of UGS in northern Scotland. We further used the data to develop a one-dimensional model, calibrated to soil moisture observations (KGE's generally > 0.65), to estimate evapotranspiration and groundwater recharge. Our results evidenced clear inter-site differences, with grassland soils experiencing rapid drying at the start of summer, resulting in more fractionated soil water isotopes. Contrastingly, the larger deciduous site saw gradual drying, whilst deeper sandy upslope soils beneath the evergreen shrub drained rapidly. Soils beneath the denser canopied evergreen conifer were overall least responsive to precipitation. Modelled ecohydrological fluxes showed similar diversity, with median evapotranspiration estimates increasing in the order grassland (193 mm) < evergreen shrub (214 mm) < larger deciduous tree (224 mm) < evergreen conifer tree (265 mm). The evergreen shrub had similar estimated median transpiration totals as the larger deciduous tree (155 mm and 128 mm, respectively), though timing of water uptake was different. Median groundwater recharge was greatest beneath grassland (232 mm) and lowest beneath the evergreen conifer (128 mm). The study showed how integrating observational data and simple modelling can quantify heterogeneities in ecohydrological partitioning and help guide UGS management.
城市绿地（UGS）可以通过降水入渗、蒸散和地下水补给来帮助减轻城市化和气候变化的水文影响。然而，需要了解不同植被类型如何分配降水，以便针对特定生态系统服务目标进行 UGS 管理。我们在苏格兰北部一个 150 米长的 UGS 沿线的不同植被（常绿灌木、常绿针叶树、草地、大小不同的落叶树）下，监测了一个生长季节的水文气象、土壤湿度、树干液流和土壤水同位素变化。我们进一步利用这些数据开发了一个一维模型，该模型通过土壤湿度观测进行了校准（KGE 值通常大于 0.65），以估算蒸散量和地下水补给量。我们的研究结果表明存在明显的站点间差异，夏季开始时草地土壤迅速干燥，导致土壤水同位素更具分馏性。相比之下，较大的落叶树种土壤逐渐干燥，而常绿灌木下较深的沙质上坡土壤排水迅速。较密树冠的常绿针叶树下的土壤对降水的反应总体上最小。模拟的生态水文通量也表现出类似的多样性，平均蒸散量估计值按草地（193 毫米）<常绿灌木（214 毫米）<较大的落叶树（224 毫米）<常绿针叶树（265 毫米）的顺序递增。常绿灌木的估计平均蒸腾总量与较大的落叶树相似（分别为 155 毫米和 128 毫米），尽管水分吸收的时间不同。地下水补给量以草地（232 毫米）最大，常绿针叶树（128 毫米）最小。该研究表明，如何整合观测数据和简单模型可以量化生态水文分配的异质性，并有助于指导 UGS 管理。
