Continuous estimates of CO₂ efflux from brown forest soil under seasonal snowpack on Rishiri Island, Japan

Abstract

An automated sampling system was built to estimate soil CO₂ efflux through the snowpack at Rishiri Island, northernmost Japan. CO₂ concentrations at 5 layers of the snowpack spanning from the soil surface to the ambient air were measured. Based on the gas diffusion approach, an average apparent soil CO₂ flux of 0.27 micro-mol m^-2 s^-1 was estimated in the snow season from December to April. A general increasing trend, interrupted by several sharp decreasing events, characterized the seasonal dynamics of CO₂ flux. Air temperature had a significant influence on the estimation of CO₂ efflux. The corrected soil CO₂ flux (0.40 micro-mol m^-2 s^-1), if the wind pumping effect being eliminated, would be 48% larger than the apparent CO₂ flux. A total amount of 61.9 g C m^-2 soil carbon emission in the snow season was estimated.