We measured CO2 flux from coarse woody debris (CWD) of Pinus densiflora and Quercus serrata using automated chamber systems. To investigate temperature dependence of the respiration rate, we also monitored temperatures at four depths near and within the CWD. The respiration rate of two CWD samples showed clear diurnal variations, with maximum values measured in the afternoon (1400-1500 h). The CWD temperatures also showed clear diurnal variations, although the time when the peak value was observed and the variation range of the temperature varied with measurement depth, resulting in different relationships between respiration rate and temperature at different depths. Q10 values calculated from the relationships varied about twice in magnitude depending on measurement depth, meaning that we must choose the appropriate depth to correctly evaluate temperature dependence. We assumed that the depth at which the r2 value was the highest was suitable to evaluate the temperature- dependent function correctly. From this analysis, we obtained the best-fit depth of temperature for an accurate evaluation of CWD respiration sensitivity to temperature.
