Factors affecting monoterpene emission from Chamaecyparis obtusa

抄録

Monoterpenes are major compounds emitted by plants and contribute to the formation of photochemical oxidants and secondary organic aerosols in the troposphere. We measured monoterpene emissions from Chamaecyparis obtusa, a major coniferous tree species in Japan, in both the field and the laboratory. Short-term monoterpene emission from C. obtusa was typically dependent on temperature but barely dependent on light intensity. We calculated the basal emission rate E_s assuming β = 0.09 in the G93 model. Three individual trees showed similar, but large seasonal variations in E_s; e.g., 0.21–5.42 μg g_DW^–1h^–1 for a tree showing the highest emission rate. The emission rate was much higher in winter and autumn. Although E_s values averaged over 4 seasons indicated that C. obtusa is an intermediate emitter among coniferous trees, our results suggest that the large seasonal variation in E_s should be considered in estimating annual monoterpene emission from this species. Furthermore, we found a significant effect of branch-to-branch touching by vibration on monoterpene emission from this species, suggesting that wind effect should be considered in the future for more precise emission estimation.