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N supply mediates the radiative balance of N 2 O emissions and CO 2 sequestration driven by N‐fixing vs. non‐fixing trees
Author(s) -
KouGiesbrecht Sian,
Funk Jennifer L.,
Perakis Steven S.,
Wolf Amelia A.,
Menge Duncan N. L.
Publication year - 2021
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1002/ecy.3414
Subject(s) - reforestation , environmental science , climate change , soil water , greenhouse gas , nitrous oxide , agroforestry , agronomy , ecology , soil science , biology
Forests are a significant CO 2 sink. However, CO 2 sequestration in forests is radiatively offset by emissions of nitrous oxide (N 2 O), a potent greenhouse gas, from forest soils. Reforestation, an important strategy for mitigating climate change, has focused on maximizing CO 2 sequestration in plant biomass without integrating N 2 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 2 O emissions from soils. Here, we first used a field experiment to show that a N‐fixing tree ( Robinia pseudoacacia ) initially mitigated climate change more than a non‐fixing tree ( Betula nigra ). 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 2 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.