Biogenic volatile organic compounds (BVOCs) emitted by plants play an important role in the atmospheric chemistry of the troposphere. We conducted f ield measurements of monoterpene emissions from leaves of Chamaecyparis obtusa, which is one of the major tree species in Japan. Diurnal and seasonal variations of monoterpene emissions from C. obtusa were measured at the Kiryu Experimental Watershed (KEW) at 34°58′ N, 135°59′ E in Shiga Prefecture, central Japan. In August and October 2006 and in January and April 2007, the monoterpene emission rate (E), together with the leaf temperature, was measured using branch enclosure methods for a branch of two trees. The obtained data sets revealed that E highly correlated with leaf temperature throughout the seasons. The basal emission rate (ES) under the standard conditions of 30°C, calculated using a widely used emission algorithm, ranged from 0.088 and 4.126 μg g-1 h-1. The estimated E values were consistent with the measured E values within a root-mean-square (RMS) error of 0.005-0.525 μg g-1 h-1, suggesting that the emission model can be used to determine the monoterpene emission responses of C. obtusa to temperature. However, the ES values were significantly different between the trees and also different between seasons, indicating that a representative ES value must be obtained from more data sets using more branches and trees.
