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Production and oxidation of methane in a boreal mire after a decade of increased temperature and nitrogen and sulfur deposition
Author(s) -
ERIKSSON TOBIAS,
ÖQUIST MATS G.,
NILSSON MATS B.
Publication year - 2010
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2009.02097.x
Subject(s) - mire , amendment , sulfur , sulfate , environmental chemistry , nitrogen , peat , chemistry , sphagnum , deposition (geology) , agronomy , ecology , biology , organic chemistry , political science , law , paleontology , sediment
Natural wetlands are the single largest source of atmospheric methane (CH 4 ). Both a changed climate and deposition of anthropogenic nitrogen and sulfur can alter the production and oxidation of CH 4 respectively and thereby also CH 4 exchange. We used a long‐term (12 years) factorial field experiment in a boreal oligotrophic mire to evaluate the effects of greenhouse cover and addition of ammonium nitrate and sodium sulfate on the production and oxidation of CH 4 by applying laboratory incubations of samples from five depths in the mire. The rates of CH 4 production were measured without amendments and after the addition of either glucose or sulfate. Twelve years of increased nitrogen deposition has changed the mire from a Sphagnum ‐dominated plant community to one dominated by sedges and dwarf shrubs. The deposition of nitrogen to the field plots caused increased production of CH 4 in incubations without amendments (34%), and also after amendments with glucose (40%) or sulfate (42%). This indicates increased substrate availability (without amendments) but also a greater abundance of methanogens (glucose amendment). The greenhouse cover caused a decrease in CH 4 production in incubations without amendments (34%), after glucose amendment (20%) and after sulfate amendment (31%). These responses indicate decreased substrate availability (without amendment) accompanied by the reduced abundance of methanogens (glucose amendment). The field application of sulfur had no effect on CH 4 production at the depth where maximal CH 4 production occurred. Closer to the mire surface, however, the rate of CH 4 production was significantly reduced by 32–45%. These results suggest that the deposition of sulfate has altered the vertical distribution of methanogens and sulfate‐reducing bacteria. The oxidation of CH 4 was not significantly affected by any of the long‐term field treatments.