Biogenic volatile organic compound (BVOC) response to heat stress and implications for emission models

Plants emit a diverse range of biogenic volatile organic compounds (BVOCs) into the atmosphere and these emissions are the dominant source of atmospheric VOCs. Many BVOCs have high chemical reactivities and contribute to ozone and secondary organic aerosol (SOA) production, which can influence climate and radiative forcing on a regional to global scale. Therefore, accurate estimations of BVOC emissions are needed to advance predictions of current and future climate scenarios. The magnitude of BVOC emissions is modulated by environmental conditions, principally light and temperature, and by external stresses (e.g., heat, drought, ozone). Current emission models perform well in characterizing the emission behavior of constitutive terpenoids at unstressed temperatures (less than approximately 35°C) but could sometimes underestimate the emission response from heat-stressed plants. In my dissertation, I investigated the effects of short-term (15–20 minutes) and longer-term (1–24 hours) heat stress on the BVOC emissions from different plant species via leaf-, branch-, and plant-scale enclosure measurements. My results indicate that plants with specialized terpenoid storage structures (i.e., glandular trichomes, resin ducts/glands, or secretory cavities) have a greater potential of emitting stress-induced terpenes at elevated temperatures (greater than approximately 37–40°C), which are not accounted for in current emission models. With climate warming and the increasing frequency and severity of heat waves, strong heat-induced BVOC emissions from plants with specialized terpenoid storage structures could potentially represent a large and unanticipated source of hydrocarbon emissions that could have important implications for regional and global atmospheric chemistry