Monitoring soil respiration using an automatic operating chamber in a Gwangneung temperate deciduous forest

This study was conducted to quantify soil CO2 efflux using the continuous measurement method and to examine the applicabilityof an automatic continuous measurement system in a Korean deciduous broad-leaved forest. Soil respirationrate (Rs) was assessed through continuous measurements during the 2004-2005 full growing seasons using an automaticopening/closing chamber system in sections of a Gwangneung temperate deciduous forest, Korea. The study site was anold-growth natural mixed deciduous forest approximately 80 years old. For each full growth season, the annual Rs, whichhad a gap that was filled with data using an exponential function derived from soil temperature (Ts) at 5-cm depth, andRs values collected in each season were 2,738.1 g CO2 m-2 y-1 in 2004 and 3,355.1 g CO2 m-2 y-1 in 2005. However, the diurnalvariation in Rs showed stronger correlations with Ts (r = 0.91, P < 0.001 in 2004, r = 0.87, P < 0.001 in 2005) and air temperature(Ta) (r = 0.84, P < 0.001 in 2004, r = 0.79, P < 0.001 in 2005) than with deep Ts during the spring season. However,the temperature functions derived from the Ts at various depths of 0, -2, -5, -10, and -20 cm revealed that the correlationcoefficient decreased with increasing soil depth in the spring season, whereas it increased in the summer. Rs showed aweak correlation with precipitation (r = 0.25, P < 0.01) and soil water content (r = 0.28, P < 0.05). Additionally, the diurnalchange in Rs revealed a higher correlation with Ta than that of Ts. The Q10 values from spring to winter were calculatedfrom each season’s dataset and were 3.2, 1.5, 7.4, and 2.7 in 2004 and 6.0, 3.1, 3.0, and 2.6 in 2005; thus, showing high fluctuationwithin each season. The applicability of an automatic continuous system was demonstrated for collecting a highresolution soil CO2 efflux dataset under various environmental conditions.