Volatile organic compound emissions from Siberian larch

We determined hourly emissions of isoprene, monoterpenes and sesquiterpenes from Siberian larch, one of the major tree species in Siberian forests. Summer volatile organic compounds (VOCs) emission from Siberian larch consisted mainly of monoterpenes (about 90%). The monoterpene emission spectrum remained constant during the measurement period, almost half was sabinene and other major monoterpenes were Delta(3)-carene, beta- and alpha-pinene. During spring and summer, about 10% of the VOCs were sesquiterpenes, mainly a-farnesene. The sesquiterpene emissions declined to 3% in the fall isoprene, 2-methyl-3-buten-2-ol (MBO) and 1,8-cineole contributed to less than 3% of the VOC emission during the whole period. The diurnal variation of the emissions could be explained using a temperature-dependent parameterization. Emission potentials normalized to 30 degrees C were 5.2-21 mu g g(dw)(-1)h(-1) (using beta-value of 0.09 degrees C-1) for monoterpenes and 0.4-1.8 mu g g(dw)(-1)h(-1) (using beta-value of 0.143 degrees C-1, mean of determined values) for sesquiterpenes. Normalized monoterpene emission potentials were highest in late summer and elevated again in late fall. Sesquiterpene emission potentials were also highest in late summer, but decreased towards fall. (c) 2007 Elsevier Ltd. All rights reserved.