Most global and regional "greenhouse gas" budgets have neglected beaver ponds, but they have been found to be relatively high emitters of methane (CH$ sb4$) (Roulet et. al., 1992). Static chambers, bubble traps, benthic chambers. piezometers, and water column and sediment profiles were used to determine the dynamics of CH$ sb4$ production, oxidation, storage, and emissions from a northern boreal beaver pond, as part of the Boreal Forest Ecosystem-Atmosphere Study (BOREAS) from May 1 to September 15, 1994. Samples were analysed by gas chromatography, and isotopic analyses were performed by mass spectrometry. / The mean flux of CH$ sb4$ from the beaver pond (155 and 320 mg CH$ sb4$ m$ sp{-2}$ d$ sp{-1}$ for vegetated and open water sites, respectively) was greater than the flux from most other northern boreal wetlands (Bubier et. al., 1995). CH$ sb4$ availability was primarily controlled by sediment temperature, and CH$ sb4$ transport was controlled by windspeed (diffusion) and atmospheric pressure (bubbles). Bubbles comprised 20 to 52% of the net annual flux comprising the remainder. A large difference in bubble flux was observed between open water (15.7 g CH$ sb4$ m$ sp{-2}$ yr$ sp{-1}$) and vegetated sites (2.9 g CH$ sb4$ m$ sp{-2}$ yr$ sp{-1}$), and isotopic analyses indicate that this difference is due, in part, to a difference in CH$ sb4$ production pathways between sites. Greater oxidation also reduced the CH$ sb4$ flux from shallow, vegetated sites. / A preliminary CH$ sb4$ budget for the BOREAS northern study area indicates that beaver ponds contribute significantly (6% to 30%) to the regional CH$ sb4$ flux. The areal extent of beaver ponds needs to be determined for inclusion in regional and global CH$ sb4$ budgets.

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