Acute ozone exposure decreases terpene emissions from Canary Island pines

Biogenic volatile organic compounds (BVOCs) play an important role in ecological and atmospheric processes, including production of secondary air pollutants in urban areas. BVOC emission rates and composition are highly context-dependent and can change dramatically under conditions that elicit plant stress. This is particularly concerning given proposed expansion of urban forests where plants could regularly be exposed to spikes of at-mospheric pollution stress, such as tropospheric ozone. However, few studies have investigated the effects of ozone exposure on plants commonly found in urban forests. This study characterized the effect of acute ozone exposure on BVOC emission rates in Canary Island pines (Pinus canariensis), which are often used in urban landscaping in Southern California. Pine saplings were exposed to four different ozone doses (control, 200 ppb, 300 ppb, 400 ppb) for 2 h. BVOC emission measurements were collected both pre-treatment and 24 h after exposure. Emission rates of total monoterpenes and several individual monoterpene and sesquiterpene com-pounds decreased when treated with 200 ppb of ozone. Total sesquiterpene emissions decreased significantly only after exposure to 300 ppb ozone, an effect that was largely driven by reduced emissions of the dominant sesquiterpene, alpha-farnesene. These findings indicate that landscaping with the pines used in this study would not exacerbate urban air quality degradation due to acute ozone stress. Future studies should investigate the effect of other major stressors and combinations of stressors for this and other common urban trees.

Automated summary

Biogenic volatile organic compounds (BVOCs) play a crucial role in ecological and atmospheric processes, but their emission rates and composition can change under plant stress. This study investigated the effects of acute ozone exposure on BVOC emissions in Canary Island pines, commonly used in urban landscaping. The results showed that ozone exposure did not exacerbate urban air quality degradation in these pines.