2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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6/05/2017  |   2:15 PM - 2:30 PM   |   GLOBAL BOUNDS ON GASEOUS NITROGEN LOSS FROM TROPICAL FOREST WATERSHEDS   |  306A

GLOBAL BOUNDS ON GASEOUS NITROGEN LOSS FROM TROPICAL FOREST WATERSHEDS

Humid tropical forests dominate denitrification from unmanaged lands, but there is large uncertainty about the range and drivers of N gas emissions across the biome. We combined pantropical measures of stream chemistry with ecosystem modeling to determine total N gas losses and associated uncertainty across tropical forest watersheds. We document a negative relationship between nitrate and dissolved organic carbon (DOC) across watersheds and find that the probability of a missing N sink was highest in watersheds with high DOC, consistent with the imprint of dissimilatory nitrate reduction. We find a large range in gaseous fluxes depending on whether denitrification is modeled occurring downstream of terrestrial plant uptake or competing with plant uptake. Combined, denitrification in soils and along soil-to-stream hydrologic flowpaths constitute >45% of total N losses. We place an upper bound on soil denitrification of ~80% of total N losses beyond which tropical plant growth would be compromised. Our simulations indicate that terrestrial soils dominate denitrification but also reveal globally significant levels of gaseous N loss from aquatic environments that are roughly equivalent to inputs via atmospheric deposition.

  • C28 Land-Water Interfaces
  • C31 Organic Matter Processing
  • C10 Biogeochemistry

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Presenters/Authors

Jack Brookshire (), Montana State University, jbrookshire@montana.edu;


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Stefan Gerber (), University of Florida, sgerber@ufl.edu;


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Steven Thomas (), School of Natural Resources, University of Nebraska-Lincoln, Lincoln, sthomas5@unl.edu;


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