Jennifer L. Funk Steven S. Perakis Amelia A. Wolf Duncan Menge Sian Kou-Giesbrecht 2021 <p><span>Forests are a significant CO</span>₂<span>&nbsp;sink. However, CO</span>₂<span>&nbsp;sequestration in forests is radiatively offset by emissions of nitrous oxide (N</span>₂<span>O), a potent greenhouse gas, from forest soils. Reforestation, an important strategy for mitigating climate change, has focused on maximizing CO</span>₂<span>&nbsp;sequestration in plant biomass without integrating N</span>₂<span>O emissions from soils. Although nitrogen (N)-fixing trees are often recommended for reforestation because of their rapid growth on N-poor soil, they can stimulate significant N</span>₂<span>O emissions from soils. Here, we first used a field experiment to show that a N-fixing tree (</span><i>Robinia pseudoacacia</i><span>) initially mitigated climate change more than a non-fixing tree (</span><i>Betula nigra</i><span>). We then used our field data to parameterize a theoretical model to investigate these effects over time. Under lower N supply, N-fixers continued to mitigate climate change more than non-fixers by overcoming N limitation of plant growth. However, under higher N supply, N-fixers ultimately mitigated climate change less than non-fixers by enriching soil N and stimulating N</span>₂<span>O emissions from soils. These results have implications for reforestation, suggesting that N-fixing trees are more effective at mitigating climate change at lower N supply, whereas non-fixing trees are more effective at mitigating climate change at higher N supply.</span></p> application/pdf 10.1002/ecy.3414 en Wiley N supply mediates the radiative balance of N2O emissions and CO2 sequestration driven by N-fixing vs. non-fixing trees article