To understand the effect of forest fire on the regeneration of Cephalostachyum pergracile Munro bamboo, we compared the culm dynamics in the early regeneration stage for 3 years between a site protected from natural fires since 1995 and a site that had been burnt almost annually in a mixed deciduous forest in Thailand. Although the repeated fires distinctly decreased the number and basal area of culms per clump and the proportion of surviving culms throughout the study period, this bamboo species basically represents an adaptation to fire disturbance. A greater number of thin culms and many small branches produced by the fire-disturbed bamboos may have maximized photosynthesis with minimum allocation of photosynthate after they lose their aboveground parts. Further, the ratio of surviving clumps was higher at the unprotected site than at the protected site where self-thinning among clumps occurred. In contrast to these dynamic responses of bamboos against the fire disturbances, the number of individual clumps and their sizes remained smaller at the unprotected site than at the protected site. These results indicate that the intensity and frequency of fires primarily determine the dynamics of the bamboo population, having potential to alter the forest succession to either less or more bamboo dominating forest community. Further studies are required to elucidate the role of fire on the interaction between bamboo and tree species, specifically at the middle and matured stages of bamboo life history and along a gradient of fire regimes for better understanding assembly of the MDF community.
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.
Fast-growing tree species are being considered as an alternative source of timber to augment the supply in southern Asian countries. Eucalyptus is one of the most promising genus because its fast-growing characteristics and hybridization among species can produce superior characteristics valuable to both the pulp and timber industries. To evaluate the possibility of using it for timber, growth characteristics and wood properties were investigated for three nine-year-old Eucalyptus species (E. urophylla, E. grandis, and E. pellita) planted for pulpwood in Indonesia. E. pellita showed superior growth characteristics and wood properties compared to the other two species. No negative correlation coefficients were observed between growth characteristics and wood properties in any of the species, indicating that improvement of wood properties might not reduce the growth characteristics. The hybrids from E. pellita and E. urophylla might produce a next generation with better growth characteristics, resistance to pests and diseases, tolerance to low soil fertility, and relatively good wood properties. In addition, based on the obtained results, hybridization between E. grandis and E. urophylla or E. pellita might improve the relatively low wood properties of E. grandis.