Plants mitigate ecosystem nitrous oxide emissions primarily through reductions in soil nitrate content: Evidence from a meta-analysis.

Nitrous oxide (N ₂ O) is a potent greenhouse gas (GHG) and an ozone-depleting substance. The presence of plants in an ecosystem can either increase or decrease N ₂ O emissions, or play a negligible role in driving N ₂ O emissions. Here, we conducted a meta-analysis comparing ecosystem N ₂ O emissions from planted and unplanted systems to evaluate how plant presence influences N ₂ O emissions and examined the mechanisms driving observed responses. Our results indicate that plant presence reduces N ₂ O emissions while it increases dinitrogen (N ₂ ) emissions from ecosystems through decreases in soil nitrate concentration as well as increases in complete denitrification and mineral N immobilization. The response of N ₂ O emissions to plant presence was universal across major terrestrial ecosystems - including forests, grassland and cropland - and it did not vary with N fertilization. Further, in light of the potential mechanisms of N ₂ O formation in plant cells, we discussed how plant presence could enhance the emission of N ₂ O from plants themselves. Improving our understanding of the mechanisms driving N ₂ O emissions in response to plant presence could be beneficial for enhancing the robustness for predictions of our GHG sinks and sources and for developing strategies to minimize emissions at the ecosystem scale.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests that could appear to influence the work of this paper.
(Copyright © 2024 Elsevier B.V. All rights reserved.)