2011 Volume 45 Issue 3 Pages e15-e22
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 Es assuming β = 0.09 in the G93 model. Three individual trees showed similar, but large seasonal variations in Es; e.g., 0.21–5.42 μg gDW–1h–1 for a tree showing the highest emission rate. The emission rate was much higher in winter and autumn. Although Es 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 Es 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.
