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HERO ID
3292052
Reference Type
Journal Article
Title
Elevated CO2 promotes long-term nitrogen accumulation only in combination with nitrogen addition
Author(s)
Pastore, MA; Megonigal, JP; Langley, JA
Year
2016
Is Peer Reviewed?
Yes
Journal
Global Change Biology
ISSN:
1354-1013
EISSN:
1365-2486
Volume
22
Issue
1
Page Numbers
391-403
Language
English
PMID
26577708
DOI
10.1111/gcb.13112
Web of Science Id
WOS:000367982900031
Abstract
Biogeochemical models that incorporate nitrogen (N) limitation indicate that N availability will control the magnitude of ecosystem carbon uptake in response to rising CO2. Some models, however, suggest that elevated CO2 may promote ecosystem N accumulation, a feedback that in the long term could circumvent N limitation of the CO2 response while mitigating N pollution. We tested this prediction using a nine-year CO(2)xN experiment in a tidal marsh. Although the effects of CO2 are similar between uplands and wetlands in many respects, this experiment offers a greater likelihood of detecting CO2 effects on N retention on a decadal timescale because tidal marshes have a relatively open N cycle and can accrue soil organic matter rapidly. To determine how elevated CO2 affects N dynamics, we assessed the three primary fates of N in a tidal marsh: (1) retention in plants and soil, (2) denitrification to the atmosphere, and (3) tidal export. We assessed changes in N pools and tracked the fate of a N-15 tracer added to each plot in 2006 to quantify the fraction of added N retained in vegetation and soil, and to estimate lateral N movement. Elevated CO2 alone did not increase plant N mass, soil N mass, or N-15 label retention. Unexpectedly, CO2 and N interacted such that the combined N+CO2 treatment increased ecosystem N accumulation despite the stimulation in N losses indicated by reduced N-15 label retention. These findings suggest that in N-limited ecosystems, elevated CO2 is unlikely to increase long-term N accumulation and circumvent progressive N limitation without additional N inputs, which may relieve plant-microbe competition and allow for increased plant N uptake.
Keywords
brackish marsh; CO2 enrichment; denitrification; isotopic biogeochemistry; nitrogen pollution; nitrogen retention and loss
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NAAQS
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ISA NOxSOxPM Ecology (2018)
Cited in the Second Draft
Appendix 11
•
ISA NOxSOxPM Ecology (2020- Final Project Page)
Cited
Appendix 11
•
ISA-Ozone (2020 Final Project Page)
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