Terpenoid emissions from Quercus robur. A case study of Galicia (NW Spain)

Isoprene and monoterpenes emission fluxes emitted by Quercus robur seedlings were measured at a leaf scale in the field. Isoprene emissions were always predominant over the monoterpene ones, alpha-pinene, beta-pinene and camphene being the most abundant emitted monoterpenes. Emission fluxes were normalised at standard conditions of temperature and photosynthetically active radiation, PAR, (30 degrees C and 1000 micromol m(-2) s(-1) respectively) using temperature and light dependent algorithms. The standardised emission fluxes ranged from 43 to 73 microg g(DM)(-1) h(-1) for isoprene and from 0.04 to 2.95 microg g(DM)(-1) h(-1) for the monoterpenes. The values reported in the literature are within our experimental intervals. These standardised fluxes were used to estimate the Quercus robur emissions in Galicia (NW Spain). This region is characterised by its abundant forest extensions where Quercus robur occupies the second place in species abundance with a total of 195029 ha of Quercus robur pure stands. To estimate the region emission fluxes, both the extension and distribution of the forest areas and the regional climatic conditions over five years (2002-2006) were taken into account. The averaged annual fluxes regarding the forest extension were 0.04 t ha(-1) yr(-1) for isoprene and 0.52 kg ha(-1) yr(-1) for monoterpenes. This means averaged annual fluxes of 9730 t yr(-1) and 114 t yr(-1) for isoprene and monoterpenes, respectively. These values place Galicia as an important isoprene emitter power in Spain as a consequence of the extension of its forests more than of the climatic conditions.