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Title: Dinitrogen Emissions Dominate Nitrogen Gas Emissions From Soils With Low Oxygen Availability in a Moist Tropical Forest
Abstract Lowland tropical forest soils are relatively N rich and are the largest global source of N2O (a powerful greenhouse gas) to the atmosphere. Despite the importance of tropical N cycling, there have been few direct measurements of N2(an inert gas that can serve as an alternate fate for N2O) in tropical soils, limiting our ability to characterize N budgets, manage soils to reduce N2O production, or predict the future role that N limitation to primary productivity will play in buffering against climate change. We collected soils from across macro‐ and micro‐topographic gradients that have previously been shown to differ in O2availability and trace gas emissions. We then incubated these soils under oxic and anoxic headspaces to explore the relative effect of soil location versus transient redox conditions. No matter where the soils came from, or what headspace O2was used in the incubation, N2emissions dominated the flux of N gas losses. In the macrotopography plots, production of N2and N2O were higher in low O2valleys than on more aerated ridges and slopes. In the microtopography plots, N2emissions from plots with lower mean soil O2(5%–10%) were greater than in plots with higher mean soil O2(10%–20%). We estimate an N gas flux of ∼37 kg N/ha/yr from this forest, 99% as N2. These results suggest that N2fluxes may have been systematically underestimated in these landscapes, and that the measurements we present call for a reevaluation of the N budgets in lowland tropical forest ecosystems.  more » « less
Award ID(s):
1831952
PAR ID:
10567674
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
American Geophysical Union
Date Published:
Journal Name:
Journal of Geophysical Research: Biogeosciences
Volume:
128
Issue:
1
ISSN:
2169-8953
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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