期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 116, 期 6, 页码 2138-2145出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1814632116
关键词
nitrification; deciduous forests; soil emissions; nitric oxide; nitrous acid
资金
- Agriculture and Food Research Initiative Competitive Grant from the US Department of Agriculture National Institute of Food and Agriculture [2013-67011-21095]
- US Department of Energy, Office of Science, Early Career Research Program from Subsurface Biogeochemical Research Program Award [DE-SC0014443]
- Indiana University's Integrated Program in the Environment
- Indiana University's School of Public and Environmental Affairs
- NSF [AGS-1352375]
- U.S. Department of Energy (DOE) [DE-SC0014443] Funding Source: U.S. Department of Energy (DOE)
- NIFA [577739, 2013-67011-21095] Funding Source: Federal RePORTER
Reactive nitrogen oxides (NOy; NOy = NO + NO2 + HONO) decrease air quality and impact radiative forcing, yet the factors responsible for their emission from nonpoint sources (i.e., soils) remain poorly understood. We investigated the factors that control the production of aerobic NOy in forest soils using molecular techniques, process-based assays, and inhibitor experiments. We subsequently used these data to identify hotspots for gas emissions across forests of the eastern United States. Here, we show that nitrogen oxide soil emissions are mediated by microbial community structure (e.g., ammonium oxidizer abundances), soil chemical characteristics (pH and C:N), and nitrogen (N) transformation rates (net nitrification). We find that, while nitrification rates are controlled primarily by chemoautotrophic ammonia-oxidizing archaea (AOA), the production of NOy is mediated in large part by chemoautotrophic ammonia-oxidizing bacteria (AOB). Variation in nitrification rates and nitrogen oxide emissions tracked variation in forest communities, as stands dominated by arbuscular mycorrhizal (AM) trees had greater N transformation rates and NOy fluxes than stands dominated by ectomycorrhizal (ECM) trees. Given mapped distributions of AM and ECM trees from 78,000 forest inventory plots, we estimate that broadleaf forests of the Midwest and the eastern United States as well as the Mississippi River corridor may be considered hotspots of biogenic NOy emissions. Together, our results greatly improve our understanding of NOy fluxes from forests, which should lead to improved predictions about the atmospheric consequences of tree species shifts owing to land management and climate change.
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