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 I 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.
Results/Conclusions
Snowpack changes both CO2 production and soil CO2 efflux. CO2 production in soils was affected by the snowpack by changing soil temperature. Soil efflux was affected by snowpack by altering the diffusivity of CO2 from soils through the snowpack to the atmosphere. My results show that winter soil respiration should not be neglected in estimating the annual carbon budget.