Coniferous forests release large quantities of volatile organic compounds, which stimulate the formation of new particles in the atmosphere. According to field-based measurements, the mix of chemicals released varies between trees, even in a relatively homogeneous stand.
Jaana Bäck of the University of Helsinki and colleagues sampled tree branches and air from a Scots Pine forest in Finland to determine the diversity of the volatile organic compounds emitted. The chemical composition of the compounds released varied significantly between individual trees. A cluster analysis revealed three main emissions groupings, which the researchers term chemotypes, dominated by different compounds. Levels of the compound carene dominated differences between the chemotypes. Stand history and forest thinning seemed to influence the cocktail of compounds released.
Measurements of volatiles emitted from single trees — often used to parameterize atmospheric chemistry models — may be misleading, the team argues.