Dynamics of monoterpene emissions in Pinus sylvestris during early spring

The seasonal dynamics of biogenic volatile organic compound (BVOC) emissions, which can be related to the formation and growth of secondary organic aerosols, represent an important but at the present poorly understood linkage between vegetation activity and climate. Although a close relationship between photosynthesis and terpenoid emissions has been proposed, high monoterpene emission rates for Scots pine shoots (Pinus sylvestris) are frequently recorded during spring, in times when photosynthetic activity is strongly inhibited due to inherent seasonal restrictions. We suggest that terpenoid emissions are related to either photosynthesis or photorespiration for precursors for terpenoid biosynthesis. We developed two dynamic models describing temporal fluctuations in Scots pine monoterpene emissions, calculating the emissions by using CO2 exchange and ambient climate data. The models accurately predicted the measured monoterpene flux, and especially in March–April, during the time when photosynthesis was negligible and ambient temperatures were between –5 and +15 °C, a good agreement was found with measured emissions and the model involving photorespiration.