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Effects of elevated carbon dioxide and increased temperature on methane and nitrous oxide fluxes: evidence from field experiments

Dijkstra, Feike A., Prior, Stephen A., Runion, G. Brett, Torbert, H. Allen, Tian, Hanqin, Lu, Chaoqun, Venterea, Rodney T.
Frontiers in ecology and the environment 2012 v.10 no.10 pp. 520
air temperature, atmospheric circulation, carbon dioxide, clay soils, ecosystems, fertilizer application, field experimentation, global warming, greenhouse gas emissions, greenhouse gases, methane, methane production, nitrous oxide, paddies, peatlands, sandy soils, soil ecology, wetland soils
Climate change could alter terrestrial ecosystems, which are important sources and sinks of the potent greenhouse gases (GHGs) nitrous oxide (N2O) and methane (CH4), in ways that either stimulate or decrease the magnitude and duration of global warming. Using manipulative field experiments, we assessed how N2O and CH4 soil fluxes responded to a rise in atmospheric carbon dioxide (CO2) concentration and to increased air temperature. Nitrous oxide and CH4 responses varied greatly among studied ecosystems. Elevated CO2 often stimulated N2O emissions in fertilized systems and CH4 emissions in wetlands, peatlands, and rice paddy fields; both effects were stronger in clayey soils than in sandy upland soils. Elevated temperature, however, impacted N2O and CH4 emissions inconsistently. Thus, the effects of elevated CO2 concentrations on N2O and CH4 emissions may further enhance global warming, but it remains unclear whether increased temperature generates positive or negative feedbacks on these GHGs in terrestrial ecosystems.