title: Soil Methane Sink Capacity Response to a Long-Term Wildfire Chronosequence in Northern Sweden.
abstract: Boreal forests occupy nearly one fifth of the terrestrial land surface and are recognised as globally important regulators of carbon (C) cycling and greenhouse gas emissions. Carbon sequestration processes in these forests include assimilation of CO2 into biomass and subsequently into soil organic matter, and soil microbial oxidation of methane (CH4). In this study we explored how ecosystem retrogression, which drives vegetation change, regulates the important process of soil CH4 oxidation in boreal forests. We measured soil CH4 oxidation processes on a group of 30 forested islands in northern Sweden differing greatly in fire history, and collectively representing a retrogressive chronosequence, spanning 5000 years. Across these islands the build-up of soil organic matter was observed to increase with time since fire disturbance, with a significant correlation between greater humus depth and increased net soil CH4 oxidation rates. We suggest that this increase in net CH4 oxidation rates, in the absence of disturbance, results as deeper humus stores accumulate and provide niches for methanotrophs to thrive. By using this gradient we have discovered important regulatory controls on the stability of soil CH4 oxidation processes that could not have not been explored through shorter-term experiments. Our findings indicate that in the absence of human interventions such as fire suppression, and with increased wildfire frequency, the globally important boreal CH4 sink could be diminished.
authors.affiliation: Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster, United Kingdom.
authors.forename: Niall P
authors.initials: NP
authors.lastname: McNamara
authors.affiliation: Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster, United Kingdom; Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom.
authors.forename: Ruth
authors.initials: R
authors.lastname: Gregg
authors.affiliation: Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Oakley
authors.affiliation: NERC Life Sciences Stable Isotope Facility, Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster, United Kingdom.
authors.forename: Andy
authors.initials: A
authors.lastname: Stott
authors.affiliation: Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh, Bangladesh.
authors.forename: Md Tanvir
authors.initials: MT
authors.lastname: Rahman
authors.affiliation: School of Environmental Science, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.
authors.forename: J Colin
authors.initials: JC
authors.lastname: Murrell
authors.affiliation: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
authors.forename: David A
authors.initials: DA
authors.lastname: Wardle
authors.affiliation: Faculty of Life Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, United Kingdom; Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Bardgett
authors.affiliation: Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster, United Kingdom; Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom.
authors.forename: Nick J
authors.initials: NJ
authors.lastname: Ostle
mesh_terms: D005390:Fires; D065928:Forests; D006801:Humans; D008697:Methane / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D012987:Soil / Q000737:chemistry*; D013548:Sweden
chemical_list: D012987:Soil; D008697:Methane