Impact of water table depth on forest soil methane turnover in laboratory soil cores deduced from natural abundance and tracer C-13 stable isotope experiments

McNamara, Niall P. ORCID: https://orcid.org/0000-0002-5143-5819; Chamberlain, Paul M.; Pierce, Trevor G.; Sleep, Darren ORCID: https://orcid.org/0009-0002-1128-1883; Black, Helaina I. J.; Reay, David S.; Ineson, Phil. 2006 Impact of water table depth on forest soil methane turnover in laboratory soil cores deduced from natural abundance and tracer C-13 stable isotope experiments. Isotopes in Environmental and Health Studies, 42. 379-390. 10.1080/10256010600990765

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Abstract/Summary

We investigated turnover of methane (CH4) in soils from a poorly drained UK forest. In situ, this forest exhibited a negligible soil-atmosphere CH4 flux, whereas adjacent grassland plots were sources of CH4. We hypothesised that the forest plots exhibited reduced anaerobic CH4 production through water-table draw down. Consequently, we exposed soil cores from under oak to high and low water-table conditions in the laboratory. Methane fluxes increased significantly in the high water-table (1925±1702 μg CH4 m-2 h-1) compared to the low one (-3.5±6.8 μg CH4 m-2 h-1). Natural abundance δ13C values of CH4 showed a strong depletion in high water-table cores (-56.7±2.9 ‰) compared to methane in ambient air (-46.0 ‰) indicative of methanogenic processes. The δ13C values of CH4 from low water-table cores (δ13C-46.8±0.2 ‰) was similar to ambient air and suggested little alteration of headspace CH4 by the soil microbial community. In order to assess the CH4 oxidizing activity of the two treatments conclusively, a 13CH4 spike was added to the cores and 13CO2 production was measured as the by-product of CH4 oxidation. 13CH4 oxidation rates were 57.5 (±12.7) and 0.5 (±0.1) μg CH4 m-2 h-1 for high and low water-tables, respectively. These data show that the lower water-table hydrology treatment impacted methanogenic processes without stimulating methanotrophy.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1080/10256010600990765
Programmes:	CEH Programmes pre-2009 publications > Biogeochemistry
UKCEH and CEH Sections/Science Areas:	_ Environmental Chemistry & Pollution _ Ecological Processes in Freshwater & Soils
ISSN:	1025-6016
Additional Keywords:	carbon-13, forest, methane, soil, turnover, water table
NORA Subject Terms:	Agriculture and Soil Science Hydrology Chemistry
Date made live:	09 May 2008 07:36 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/2893

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