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Harvard Forest Symposium Abstract 2011

  • Title: Soil respiration under snowpack in a temperate forest in Massachusetts: steady state vs. transient state
  • Primary Author: Jim Tang (Marine Biological Laboratory)
  • Additional Authors: Skyler Hackley (Marine Biological Laboratory); Tim Savas (Marine Biological Laboratory)
  • Abstract:

    Soil respiration plays a major role in global carbon cycling. However, the magnitude and process of soil respiration under snowpack is not well understood due to the difficulty in measuring soil respiration in temperate forests under snowpack through the winter. As a result, when the annual cumulative flux of soil respiration is estimated, soil respiration during the winter is either neglected or modeled solely from a temperature function that is derived from the growing season respiration measurement. The traditional chamber method does not work well on snowpack. The eddy covariance method in winter covers total ecosystem respiration that includes both aboveground plant respiration and belowground soil respiration. Here we used a belowground soil CO2 profile system to measure soil respiration under snowpack. The measurement system functioned when the forest floor was covered by snow. Three CO2 sensors were buried vertically, at different depths, in the soil to obtain a CO2 profile. The surface CO2 efflux was calculated based on Fick’s law of diffusion. The snowpack depth was also measured with an automated sonic ranging sensor.





    Under the steady state, the snowpack did not physically change the soil CO2 efflux, but it increased soil temperature and thus indirectly increased soil CO2 efflux. During the transient period (snowfall or melting), the snowpack changed soil CO2 efflux. The temperature sensitivity, Q10, was higher in the low temperature range than in the high temperature range in winter. Our results suggest that winter soil respiration is more complicated than non-snow covered seasons and should not be neglected in estimating the annual carbon budget.


  • Research Category: Soil Carbon and Nitrogen Dynamics