Nitrogen-fixing trees are an important nitrogen source to terrestrial ecosystems. While they can fuel primary production and drive carbon dioxide sequestration, they can also potentially stimulate soil emissions of nitrous oxide, a potent greenhouse gas. However, studies on the influence of nitrogen-fixing trees on soil nitrous oxide emissions have not been quantitatively synthesized. Here, we show in a meta-analysis that nitrogen-fixing trees more than double soil nitrous oxide emissions relative to non-fixing trees and soils. If planted in reforestation projects at the global scale, nitrogen-fixing trees could increase global soil nitrous oxide emissions from natural terrestrial ecosystems by up to 4.1%, offsetting climate change mitigation via reforestation by up to 4.4%.

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固氮树木增加土壤一氧化二氮排放：荟萃分析

固氮树木是陆地生态系统的重要氮源。虽然它们可以为初级生产提供燃料并推动二氧化碳封存，但它们还可能刺激土壤排放一氧化二氮，一种强效温室气体。然而，关于固氮树木对土壤一氧化二氮排放影响的研究尚未定量综合。在这里，我们在一项荟萃分析中表明，与非固氮树木和土壤相比，固氮树木的土壤一氧化二氮排放量增加了一倍以上。如果在全球范围内的重新造林项目中种植，固氮树木可以使全球自然陆地生态系统的土壤一氧化二氮排放量增加高达 4.1%，从而抵消通过重新造林缓解气候变化的影响高达 4.4%。