Influence of transient flooding on methane fluxes from subtropical pastures

Samuel D. Chamberlain, Nuria Gomez-Casanovas, M. Todd Walter, Elizabeth H. Boughton, Carl Bernacchi, Evan H Delucia, Peter M. Groffman, Earl W. Keel, Jed P. Sparks

Research output: Contribution to journalArticle

Abstract

Seasonally flooded subtropical pastures are major methane (CH 4 ) sources, where transient flooding drives episodic and high-magnitude emissions from the underlying landscape. Understanding the mechanisms that drive these patterns is needed to better understand pasture CH 4 emissions and their response to global change. We investigated belowground CH 4 dynamics in relation to surface fluxes using laboratory water table manipulations and compared these results to field-based eddy covariance measurements to link within-soil CH 4 dynamics to ecosystem fluxes. Ecosystem CH 4 fluxes lag flooding events, and this dynamic was replicated in laboratory experiments. In both cases, peak emissions were observed during water table recession. Flooding of surface organic soils and precipitation driven oxygen pulses best explained the observed time lags. Precipitation oxygen pulses likely delay CH 4 emissions until groundwater dissolved oxygen is consumed, and emissions were temporally linked to CH 4 production in surface soil horizons. Methane accumulating in deep soils did not contribute to surface fluxes and is likely oxidized within the soil profile. Methane production rates in surface organic soils were also orders of magnitude higher than in deep mineral soils, suggesting that over longer flooding regimes CH 4 produced in deep horizons is not a significant component of surface emissions. Our results demonstrate that distinct CH 4 dynamics may be stratified by depth and flooding of surface organic soils drives CH 4 fluxes from subtropical pastures. These results suggest that small changes in pasture water table dynamics can drive large changes in CH 4 emissions if surface soils remain saturated over longer time scales.

Original languageEnglish (US)
Pages (from-to)965-977
Number of pages13
JournalJournal of Geophysical Research G: Biogeosciences
Volume121
Issue number3
DOIs
StatePublished - Mar 1 2016

Fingerprint

tropical pastures
Methane
methane production
pasture
methane
flooding
methylidyne
Fluxes
soils
Soils
organic soils
organic soil
water table
water tables
surface flux
pastures
Ecosystems
ecosystems
Water
oxygen

Keywords

  • eddy covariance
  • mesocosm
  • methane
  • pastureland
  • precipitation
  • subtropical

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology

Cite this

Influence of transient flooding on methane fluxes from subtropical pastures. / Chamberlain, Samuel D.; Gomez-Casanovas, Nuria; Walter, M. Todd; Boughton, Elizabeth H.; Bernacchi, Carl; Delucia, Evan H; Groffman, Peter M.; Keel, Earl W.; Sparks, Jed P.

In: Journal of Geophysical Research G: Biogeosciences, Vol. 121, No. 3, 01.03.2016, p. 965-977.

Research output: Contribution to journalArticle

Chamberlain, SD, Gomez-Casanovas, N, Walter, MT, Boughton, EH, Bernacchi, C, Delucia, EH, Groffman, PM, Keel, EW & Sparks, JP 2016, 'Influence of transient flooding on methane fluxes from subtropical pastures', Journal of Geophysical Research G: Biogeosciences, vol. 121, no. 3, pp. 965-977. https://doi.org/10.1002/2015JG003283
Chamberlain, Samuel D. ; Gomez-Casanovas, Nuria ; Walter, M. Todd ; Boughton, Elizabeth H. ; Bernacchi, Carl ; Delucia, Evan H ; Groffman, Peter M. ; Keel, Earl W. ; Sparks, Jed P. / Influence of transient flooding on methane fluxes from subtropical pastures. In: Journal of Geophysical Research G: Biogeosciences. 2016 ; Vol. 121, No. 3. pp. 965-977.
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