WINTER FLUXES OF METHANE FROM MINNESOTA PEATLANDS

Winter fluxes of methane were investigated in northern Minnesota during 1988-89 and 1989-90. Two bogs and a fen emitted methane throughout the snow-covered season (November through March). Fluxes decreased to a low level of 3-16 mg CH4 m-2 d-1 in late March, reflecting decreasing peat temperatures and (in 1989-90) increasing depth of frost in the peat. Winter fluxes calculated by integration for an open poor fen, an open bog, a forested bog hollow, and a hummock site in the forested bog averaged 49, 12, 13, and 5 mg m-2 d-1, respectively, in 1989-90 (the year most measurements were made). These comprised 11%, 4%,15%, and 21% of total annual flux.