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Harvard Forest Symposium Abstract 2007

  • Title: Autochamber soil CO2 efflux measurements at Harvard Forest
  • Primary Author: Steve Phillips (University of New Hampshire - Main Campus)
  • Additional Authors: Patrick Crill (University of New Hampshire - Main Campus); J. William Munger (Harvard University); Steve Phillips (University of New Hampshire - Main Campus); Ruth Varner (University of New Hampshire - Main Campus); Steven Wofsy (Harvard University)
  • Abstract:

    Soil CO2 efflux is an important component of the terrestrial carbon budget. To determine the seasonal controls on soil CO2 efflux, we measured the temporal and spatial patterns of soil CO2 flux across a hydrological gradient from wetland to upland. A transect of 10 automated chambers were installed across a gradient of depth to ground water on the northeast margin of the "Beaver Swamp" north of the EMS tower (+42.5378,-72.1715). The first eight are opaque chambers and were installed in April 2003. Two additional transparent chambers were installed in the beaver swamp itself in April 2006. Each automated chamber closes for a measurement every three and a half hours. The resulting semi-continuous data provides a high temporal density characterization of soil flux across a moisture gradient.



    These automatic chamber measurements provide a database of upland soil CO2 efflux, wetland net ecosystem exchange, soil and peat temperature, and soil moisture with both high temporal resolution, across multiple cover types and ground water levels. Our analysis to date has resulted in two questions regarding soil CO2 efflux:



    What factors other than temperature (i.e. phenology of root activity and photosynthate transport) control the seasonal variation in flux?



    Why do the mid-slope chambers exhibit a higher seasonality and higher overall fluxes than the upland chambers?

  • Research Category: Soil Carbon and Nitrogen Dynamics