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A moderate increase in the annual CH 4 efflux by raised CO 2 or NH 4 NO 3 supply in a boreal oligotrophic mire
Author(s) -
Saarnio Sanna,
Saarinen T.I.M.O.,
Vasander Harri,
Silvola Jouko
Publication year - 2000
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 - 10.1046/j.1365-2486.2000.00294.x
Subject(s) - mire , environmental science , radiative forcing , temperate climate , greenhouse gas , peat , trace gas , boreal , wetland , atmospheric sciences , environmental chemistry , carbon cycle , carbon dioxide , permafrost , climate change , chemistry , ecosystem , ecology , biology , geology
Summary Natural wetlands release about 20% of global emissions of CH 4 , an effective greenhouse gas contributing to the total radiative forcing. Thus, changes in the carbon cycle in wetlands could have significant impacts on climate. The effect of raised supply of CO 2 or NH 4 NO 3 on the annual CH 4 efflux from the lawn of a boreal oligotrophic mire was investigated over two years. Ten study plots were enclosed with mini‐FACE rings, five vented with CO 2 ‐enriched air and the other five with ambient air. In addition, five plots were sprayed with NH 4 NO 3 so that the cumulative addition of N was 3 g m −2 y −1 ; and five plots were controls. The CO 2 enrichment (target concentration 560 ppm v ) increased CH 4 efflux about 30–40%, but half of this increase seemed to be caused by the air‐blowing system. The increasing atmospheric concentration of CO 2 would promote CH 4 release in boreal mires, but the increase in CH 4 efflux would be clearly smaller than that reported in studies made in temperate or subtropical temperature conditions. Addition of N enhanced the annual release of CH 4 only slightly. At least over the short‐term, the increase in N deposition would have little effect on CH 4 effluxes. The increase in CH 4 release would probably increase radiative forcing and thus accelerate climate change. However, CH 4 effluxes are only a small part in the whole matter balance in mires and thus further studies are needed to define the net effects of raised supply of CO 2 or N for carbon accumulation, trace gas fluxes and radiative forcing.