Transient interaction effects of temperature and light intensity on isoprene and monoterpene emissions from Schima superba and Phoebe bournei.

Biogenic volatile organic compound (BVOC) (such as isoprene (ISO) and monoterpenes (MTs)) emissions from plants play a great role in the atmospheric chemistry. Now frequency of dramatic changes of weather such as transient temperature changing increases, most current studies focus on the effects of simulating climate change (long-term) on BVOC emissions. While studies of transient effects on that are less reported. This study aimed to identify the ISO and MT emissions and the related physiological processes in the short-term scale at different temperature (T) and light intensity (PAR), in seeding stage of Schima superba and Phoebe bournei belonging to typical subtropical tree species. The results showed that the ISO and MT emissions were significantly affected by T and PAR, either independently or interactively. With the increase of T and PAR, the ISO and MT emissions increased, with the maximum rates of ISO and MTs of 39.39 and 1042.35 pmol m s for S. superba under 40 °C × 500 μmol m s condition, while the maximum rates reached 18.73 and 6737.41 pmol m s at 30 °C × 1500 μmol m s for P. bournei. The increase of ISO and MT emissions with T and PAR increasing that was related to the promotion of Pn and g in plants. Regarding MT components, the proportion of α-pinene decreased with T and PAR increasing, with the lowest ratios of 4.91 % and 21.16 % for S. superba and P. bournei under 40 °C × 1500 μmol m s condition. However, the proportion of β-pinene significantly increased, with the highest ratios of 67.42 % and 57.93 % for S. superba and P. bournei under 30 °C × 1500 μmol m s condition, which is attributed to differences in light tolerance between the two plants. Our study provides basis for evaluating the transient changes of environmental factors on BVOC emissions and optimizing regional BVOC emission models.