Comparative carbon dioxide efflux rates from respiration of coarse woody debris among three mangrove species in Thailand

Abstract

Coarse woody debris (CWD) is an important component in forest ecosystems. A knowledge of CWD respiration, in addition to its storage, is necessary to clarify the carbon dynamics in a forest ecosystem. However, data on CWD respiration in mangrove forests is still scarce. We measured the carbon dioxide (CO₂) efflux rates from the CWD respiration of three mangrove species (Avicennia alba, Rhizophora spp. and Xylocarpus granatum) using gas chromatography (GC) and soda-lime (SL) methods. The results revealed that the CO₂ efflux rates obtained by the SL method were not significantly different to those obtained by the GC method for all three species. Therefore, the CO₂ efflux rate from CWD respiration of the three mangrove species was measured by the SL method without calibration. The CO₂ efflux rate of A. alba CWD was significantly higher than the other two species, whereas the CO₂ efflux rates of Rhizophora spp. and X. granatum were not different. The differences in the CO₂ efflux among the species was likely to be due to their different wood densities and water contents, and the interaction of these terms. Although, the CO₂ efflux rate from CWD respiration showed a relatively low value in a comparison to that from soil respiration, the CO₂ efflux rates from CWD respiration should still be measured for clarifying the carbon dynamics in a mangrove ecosystem, especially those with a high CWD mass.