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Proc Natl Acad Sci U S A. 2018 Jan 16;115(3):549-554. doi: 10.1073/pnas.1714597115. Epub 2018 Jan 2.

High fire-derived nitrogen deposition on central African forests.

Author information

1
Isotope Bioscience Laboratory-ISOFYS, Ghent University, 9000 Gent, Belgium; Marijn.Bauters@UGent.be.
2
CAVElab, Computational and Applied Vegetation Ecology, Ghent University, 9000 Ghent, Belgium.
3
National High Magnetic Field Laboratory Geochemistry Group, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306.
4
Isotope Bioscience Laboratory-ISOFYS, Ghent University, 9000 Gent, Belgium.
5
Laboratory of Hydrology and Water Management, Ghent University, 9000 Gent, Belgium.
6
Plant Department, Faculty of Science, Université de Kisangani, Kisangani, Democratic Republic of Congo.
7
Faculty of Agronomy, Université Catholique de Bukavu, BP 285 Bukavu, Democratic Republic of Congo.

Abstract

Atmospheric nitrogen (N) deposition is an important determinant of N availability for natural ecosystems worldwide. Increased anthropogenic N deposition shifts the stoichiometric equilibrium of ecosystems, with direct and indirect impacts on ecosystem functioning and biogeochemical cycles. Current simulation data suggest that remote tropical forests still receive low atmospheric N deposition due to a lack of proximate industry, low rates of fossil fuel combustion, and absence of intensive agriculture. We present field-based N deposition data for forests of the central Congo Basin, and use ultrahigh-resolution mass spectrometry to characterize the organic N fraction. Additionally, we use satellite data and modeling for atmospheric N source apportionment. Our results indicate that these forests receive 18.2 kg N hectare-1 years-1 as wet deposition, with dry deposition via canopy interception adding considerably to this flux. We also show that roughly half of the N deposition is organic, which is often ignored in N deposition measurements and simulations. The source of atmospheric N is predominantly derived from intensive seasonal burning of biomass on the continent. This high N deposition has important implications for the ecology of the Congo Basin and for global biogeochemical cycles more broadly.

KEYWORDS:

Congo Basin; FT-ICR-MS; biomass burning; central Africa; nitrogen deposition

PMID:
29295919
PMCID:
PMC5776982
DOI:
10.1073/pnas.1714597115
[Indexed for MEDLINE]
Free PMC Article

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