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Soil Denitrification Fluxes from Three Northeastern North American Forests Across a Range of Nitrogen Deposition
Oecologia (2015)
  • Jennifer L Morse, Portland State University
  • Jorge Durán, University of Coimbra
  • Fred Beall
  • Eric M. Enanga, Western University
  • Irena F. Creed
  • Ivan Fernandez, University of Maine - Main
  • Peter M. Groffman

In northern forests, large amounts of missing N that dominate N balances at scales ranging from small watersheds to large regional drainage basins may be related to N-gas production by soil microbes. We measured denitrification rates in forest soils in northeastern North America along a N deposition gradient to determine whether N-gas fluxes were a significant fate for atmospheric N inputs and whether denitrification rates were correlated with N availability, soil O2 status, or forest type. We quantified N2 and N2O fluxes in the laboratory with an intact-core method and monitored soil O2, temperature and moisture in three forests differing in natural and anthropogenic N enrichment: Turkey Lakes Watershed, Ontario; Hubbard Brook Experimental Forest, New Hampshire; and Bear Brook Watershed, Maine (fertilized and reference plots in hardwood and softwood stands). Total N-gas flux estimates ranged from <1 in fertilized hardwood uplands at Bear Brook to>100 kg N ha(-1) year(-1) in hardwood wetlands at Turkey Lakes. N-gas flux increased systematically with natural N enrichment from soils with high nitrification rates (Bear Brook < Hubbard Brook < Turkey Lakes) but did not increase in the site where N fertilizer has been added since 1989 (Bear Brook). Our results show that denitrification is an important and underestimated term (1-24 % of atmospheric N inputs) in N budgets of upland forests in northeastern North America, but it does not appear to be an important sink for elevated anthropogenic atmospheric N deposition in this region.

  • Denitrification,
  • Forests & forestry,
  • Atmospheric nitrogen,
  • Watersheds,
  • Forest soils,
  • Soil microbiology
Publication Date
January, 2015
Publisher Statement
Electronic supplementary material The online version of this article (doi:10.​1007/​s00442-014-3117-1) contains supplementary material, which is available to authorized users.
Citation Information
Jennifer L Morse, Jorge Durán, Fred Beall, Eric M. Enanga, et al.. "Soil Denitrification Fluxes from Three Northeastern North American Forests Across a Range of Nitrogen Deposition" Oecologia Vol. 177 Iss. 1 (2015)
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