Global Change Could Amplify Fire Effects on Soil Greenhouse Gas Emissions

PLoS One

Bruce A. Hungate¹  Joseph C. Blankinship¹  Paul Dijkstra¹  Jamie R. Brown¹  Christopher B. Field²  Romain L. Barnard³  Audrey Niboyet⁴  Paul W. Leadley⁴  Laure Barthes⁴  Xavier Le Roux⁵ 

[1] Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, Arizona, United States of America;Department of Global Ecology, Carnegie Institution for Science, Stanford, California, United States of America;Institute of Plant Sciences, ETH Zürich, Zürich, Switzerland;Laboratoire Ecologie, Systématique et Evolution, UMR 8079 Université Paris-Sud 11/CNRS/AgroParisTech, Université Paris-Sud 11, Orsay, France;Laboratoire d'Ecologie Microbienne, UMR 5557 CNRS, USC 1193 INRA, Université Lyon 1, Villeurbanne, France

关键词: Carbon dioxide;    Nitrification;    Wildfires;    Ecosystem functioning;    Ecosystems;    Fire suppression technology;    Grasslands;    Oxidation;   

DOI  :  10.1371/journal.pone.0020105

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

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.

【 授权许可】

CC BY