Abstract. Drought events are expected to become more frequent with
climate change. To predict the effect of plant emissions on air quality and
potential feedback effects on climate, the study of biogenic volatile
organic compound emissions under stress is of great importance. Trees can
often be subject to a combination of abiotic stresses, for example due to
drought or ozone. Even though there is a large body of knowledge on
individual stress factors, the effects of combined stressors are not much
explored. This study aimed to investigate changes of biogenic volatile
organic compound emissions and physiological parameters in Quercus robur L. during moderate
to severe drought in combination with ozone stress. Results show that
isoprene emissions decreased while monoterpene and sesquiterpene emissions
increased during the progression of drought. We exposed plants with daily
ozone concentrations of 100 ppb for 1 h for 7 d, which resulted
in faster stomatal closure (e.g., a mean value of −31.3 % at an average stem
water potential of −1 MPa), partially mitigating drought stress effects.
Evidence of this was found in enhanced green leaf volatiles in trees without
ozone fumigation, indicating cellular damage. In addition we observed an
enhancement in (C8H8O3)H+ emissions likely corresponding
to methyl-salicylate in trees with ozone treatment. Individual plant stress
factors are not necessarily additive, and atmospheric models should implement
stress feedback loops to study regional-scale effects.
Combined effects of ozone and drought stress on the emission of biogenic volatile organic compounds from <i>Quercus robur</i> L.
