LAUSR

Abstract Measurements of emissions of biogenic volatile organic compounds (BVOCs), solar global radiation, photosynthetically active radiation and meteorological parameters were carried out in a subtropical Pinus plantation, China during 2013–2016. The results were used to further develop and evaluate an empirical model of BVOC emissions (EMBE). Simulated BVOC emissions are in good agreement with observations with relative biases of 32.8% and 2.6%, and normalized mean square error values of 0.092 and 0.001, for isoprene and monoterpene fluxes, respectively. Validation of the BVOC empirical model for half-hourly, hourly and mean hourly emission variations show that most BVOC emission patterns are reproduced. The validation of EMBE using gradient (GRA) measurements shows relative bias of 45.7% for isoprene and 76.9% for monoterpenes. Sensitivity tests show that BVOC emissions were more sensitive to changes in PAR than to changes in water vapor content or to the scattering factor. Using the EMBE model, average hourly and annual emissions were 0.59 and 2333.1 mg m−2 for isoprene and 0.79 and 2625.9 mg m−2 for monoterpenes during 2013–2016. Decreasing trends of isoprene and monoterpene emissions were observed in 2013–2016. EMBE estimated BVOC emissions were compared with estimates using the MEGAN model and measured fluxes. MEGAN estimated annual emissions by 2.5 times higher for isoprene, and a factor of 2 lower for monoterpenes than those estimated using EMBE over 2013–2016. Finally, a generalized EMBE model covering different conditions for three typical forests in China was presented and evaluated for better understanding BVOC emissions.