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Harvard Forest REU Symposium Abstract 2005

  • Title: Why Does the Beaver Swamp at the Harvard Forest Appear to Release So Much CO2 into the Atmosphere?
  • Author: Jennifer P McInnis (Cornell University)
  • Abstract:

    Careful examination of CO2 exchange data from 1992 to 2003 at the Harvard Forest Environmental Measuring Site (EMS) shows consistently higher CO2 flux from the NW, where there is a beaver swamp. To better understand the CO2 budget of the swamp, I measured CO2 concentrations and CO2 fluxes from water to air in summer 2005. The stream entering the swamp contained 3000-4000 ppm dissolved CO2, much less than in the swamp (above 6000 ppm) suggesting that much of the CO2 in the swamp is produced by internal decomposition and respiration. Dissolved CO2 and O2 in the swamp were inversely related during mid-day, suggesting significant aquatic photosynthesis. Precipitation and increased wind speed were followed by lower dissolved CO2 levels. I measured CO2 flux from water to air in a floating wind tunnel attached to an infrared gas analyzer. Wind speed 3 cm above the water (in the range of 0.5 to 0.7m s-1) and wave height (0.32 to 0.95 mm) were positively correlated with CO2 flux from water to air (1.6 to 6.5 µmol m-2 s-1). The wind tunnel data suggests that water-to-air flux in the swamp could strongly influence CO2 flux measured at the EMS tower. The swamp may store CO2 and preferentially release it to the atmosphere during strong winds, generating very large surface-to-air fluxes, if the CO2 flux increases with wave height above 1 mm. Strong NW winds during the passage of cold fronts through New England could cause of large releases of CO2 from the beaver swamp.

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