Terpenoid emissions from fully grown East Siberian Larix cajanderi trees.

While emissions of many volatile compounds, such as terpenoids, have been studied quite intensively in North American and Scandinavian boreal forests, the vast Siberian boreal forests have remained largely unexplored by experimental emission studies. In this study the shoot scale terpenoid emission rates from mature Larix cajanderi trees growing in their natural habitat in Eastern Siberia were measured. Dynamic flow-through enclosure technique was applied for adsorbent sampling (Tenax-TA and Carbopack-B used as adsorbents), and the samples were analysed offline with a gas chromatograph. The emissions were dominated by monoterpenes, which constituted between 61 and 92% of the total emission. About half of the monoterpene emissions comprised of Δ³-carene; α- and β-pinene had significant emissions as well. Linalool emissions were also substantial, especially in June. Sesquiterpenes accounted for less than 3% and isoprene less than 1% of the total emissions. Based on the measured emission rates, the relative atmospheric concentration of each compound was estimated. Monoterpenes were the species with the highest relative concentration, while linalool and sesquiterpenes had a notably smaller contribution to the estimated atmospheric concentration than to the emission rates. Temperature dependent pool algorithm with a constant β (0.09° C0^-1 for monoterpenes and 0.143° C^-1 for sesquiterpenes) was used to normalize the measured emission data. For monoterpenes the emission potential varied between 0.5-18.5 µg gdw^-1 h^-1 and for sesquiterpenes between 0.02 and 0.4 µg g_dw^-1 h^-1. [ABSTRACT FROM AUTHOR]