Decomposition of Coarse Woody Debris (CWD) is an important source of CO2 in the forest ecosystem. To understand the mechanism and estimate the amount of CO2 emission from CWD is one of critical issues clarifying the carbon cycle in forests. To date, many researches have been done with mass Loss approaches. However we have little research regarding CO2 emission directly. So, we directly measured CO2 emission from CWD in a tropical lowland dipterocarp forest with the closed dynamic chamber system in order to estimate the amount of CO2 emission.

Study site is the Pasoh Forest Reserve in Peninsula Malaysia.In February 2010, six trees were logged off and cut to approximately 30-cm length pieces. After measuring the 'alive' respiration rate, these stems were set on the forest floor. In August 2011, we measured CO2 emission from these samples with the closed dynamic chamber system using the LI-840 (LI-COR).

The emission based on dried weight of samples is 0.244 nmol g-1 s-1 on median, 0.411 on avg (SD: 0.547 n=79). On the other hand, the emission from 'alive' logs is 0.0572 nmol g-1 s-1 on median, 0.0927 on avg (SD: 0.112 n=119) We adopt simple exponential model, ln(Mt/M0)=-kt(Olson 1963), and got k=0.217 on median, 0.242 on average(SD:0.156 n=79).