Woodland Establishment Reduces Nutrient Losses to Waterbodies in Urban Catchments: A Review of the Evidence
Woodland Establishment Reduces Nutrient Losses to Waterbodies in Urban Catchments: A Review of the Evidence
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DOI：
10.1029/2022wr032626
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发表时间：
2023-05
影响因子：
5.4
通讯作者：
M. Hutchins;Yueming Qu;H. J. Baker
中科院分区：
文献类型：
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作者：
M. Hutchins;Yueming Qu;H. J. Baker
系统地回顾了同行评议的文献，以确定城市森林在降低邻近或下游水体的营养浓度方面的益处。在筛选之后，发现了少量相关的文章（40篇），这些文章代表了量化城市和城市周边环境中非点源营养损失的研究。证据分为地块尺度和集水区尺度。地块规模的研究通常包括对基于自然的工程解决方案的评估。在流域尺度上，对河流水质的研究通常是调查贡献流域营养源的影响。广泛的有益减少是显而易见的，在这两个尺度上，并非所有的研究都确定了显著的好处。综上所述，在地块（微）尺度林地，径流、土壤或地下水中总氮（TN）和总磷（TP）的平均浓度分别平均降低44.2%和47.0%。在流域（中）尺度上，有证据表明，以牺牲混合城市结构为代价增加20%的森林面积，可以使全氮和总磷的平均浓度分别降低15.7%和12.6%。此外，一些文章揭示了潜在的缺点，特别是减少了行道树和河岸林地提供的好处。落叶落在不透水表面会增加TP淋滤到溪流的风险，但对TN的影响很小。河岸林地对水质的影响较为复杂。林冠覆盖抑制了河流通道的生物氮吸收，从所有证据来看，这是相当大的。然而，未遮荫的源头可能会加速初级生产力，从而导致下游的不良后果。总的来说，考虑到目前的不确定性，特别是解决不透水、透水和河岸城市林地环境之间的差异，鼓励收集进一步的证据。
Systematic review of peer‐reviewed literature was undertaken to establish benefits of urban forests on reducing nutrient concentrations in adjacent or downstream waterbodies. Following screening, a small number of articles (40) were found relevant, representing studies quantifying non‐point source nutrient losses from urban and peri‐urban environments. Evidence was split between plot‐ and catchment‐scale. Plot‐scale studies often included evaluations of engineered nature‐based solutions. At catchment‐scale, studies of streamwater quality typically investigated influence of contributory catchment nutrient sources. Wide ranges of beneficial reductions were apparent, and at both scales not all studies identified significant benefits. Summarizing against this backdrop, at plot (micro‐) scale woodland reduces mean concentrations in runoff, soil or groundwater by an average of 44.2% for total nitrogen (TN) and 47.0% for total phosphorus (TP). At catchment (meso‐) scale, evidence suggests a 20% areal addition of forest at the expense of mixed urban fabric can reduce mean concentrations by 15.7% and 12.6% for TN and TP respectively. Additionally, some articles reveal potential drawbacks reducing benefits provided specifically by street trees and riparian woodland. Leaf litter falling on impervious surfaces can heighten risk of TP leaching to streams, but has little impact on TN. Riparian woodland was found to have complex water quality impacts. Canopy cover suppresses stream channel biological nitrogen uptake, which based on all evidence appears considerable. However, unshaded headwaters can foster accelerated primary productivity with undesirable downstream consequences. Overall, gathering further evidence is encouraged, given current uncertainties, especially to address differences between impervious, permeable and riparian urban woodland settings.