Global change could amplify fire effects on soil greenhouse gas emissions

Niboyet, Audrey and Brown, Jamie R. and Dijkstra, Paul and Blankinship, Joseph C. and Leadley, Paul W. and Le Roux, Xavier and Barthes, Laure and Barnard, Romain L. and Field, Christopher B. and Hungate, Bruce A (2011) Global change could amplify fire effects on soil greenhouse gas emissions. PLoS ONE, 6 (6). e20105. ISSN 1932-6203

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Abstract

Background: Little is known about the combined impacts of global environmental changes and ecological disturbances on ecosystem functioning, even though such combined impacts might play critical roles in shaping ecosystem processes that can in turn feed back to climate change, such as soil emissions of greenhouse gases. Methodology/Principal Findings: We took advantage of an accidental, low-severity wildfire that burned part of a long-term global change experiment to investigate the interactive effects of a fire disturbance and increases in CO2 concentration, precipitation and nitrogen supply on soil nitrous oxide (N2O) emissions in a grassland ecosystem. We examined the responses of soil N2O emissions, as well as the responses of the two main microbial processes contributing to soil N2O production – nitrification and denitrification – and of their main drivers. We show that the fire disturbance greatly increased soil N2O emissions over a three-year period, and that elevated CO2 and enhanced nitrogen supply amplified fire effects on soil N2O emissions: emissions increased by a factor of two with fire alone and by a factor of six under the combined influence of fire, elevated CO2 and nitrogen. We also provide evidence that this response was caused by increased microbial denitrification, resulting from increased soil moisture and soil carbon and nitrogen availability in the burned and fertilized plots. Conclusions/Significance: Our results indicate that the combined effects of fire and global environmental changes can exceed their effects in isolation, thereby creating unexpected feedbacks to soil greenhouse gas emissions. These findings highlight the need to further explore the impacts of ecological disturbances on ecosystem functioning in the context of global change if we wish to be able to model future soil greenhouse gas emissions with greater confidence.

Item Type:	Article
ID number or DOI:	10.1371/journal.pone.0020105
Keywords:	carbon-dioxide; Climatic changes; Denitrification; deposition; Ecological disturbances; Ecosystem dynamics; elevated atmospheric co2; environmental-changes; fire ecology; Fluxes; global environmental change; Grassland ecology; grassland responses; Greenhouse gases; Nitrification; nitrifier denitrification; nitrous-oxide; plant; precipitation; Wildfires
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QH Natural history > QH301 Biology
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > Biological Sciences Research Centers > Merriam-Powell Center for Environmental Research
Date Deposited:	16 Oct 2015 19:55
URI:	http://openknowledge.nau.edu/id/eprint/1706

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