Does Parental Environment Prime Offspring bVOC Responses to Heat and Drought in Scots Pine?

Biogenic volatile organic compounds (bVOCs) constitute a highly complex and diverse group of chemicals emitted into the atmosphere by the Earth’s biosphere. Through atmospheric oxidation, they alter the mixing ratios of trace gases such as methane, carbon monoxide, and tropospheric ozone. Moreover, oxidation products contribute to aerosol formation, which plays a crucial role in Earth’s radiative balance and air‑quality regulation.

Projected rises in global temperatures over the coming decades are expected to produce warmer and drier conditions in Alpine regions, resulting in combined heat‑ and drought‑stress for forest ecosystems. Understanding how trees respond to these co-occurring abiotic changes is essential for assessing impacts on atmospheric chemistry and secondary organic aerosol (SOA) properties.

We conducted controlled laboratory experiments spanning the peak growing season (July to October) to examine the effects of elevated temperature (heat, +4°C above average), reduced water availability (drought, 50% decrease in volumetric soil water content), and their combination on conifer seedlings grown from seeds collected in the Pfynwald Long‑Term Irrigation Experiment (established in 2003). By using offspring from Scots pine mother trees that experienced contrasting water regimes (naturally dry versus artificially irrigated), we assessed both immediate stress responses and potential maternal‑priming effects on bVOC emissions. Specifically, we investigated (i) bVOC precursors in conifer needles (secondary metabolites) and (ii) bVOC emissions in the gas phase.

To achieve this, we (i) developed an analytical method for extracting and chromatographically separating terpenes and terpenoids from conifer needles, and (ii) designed and built a novel plant chamber for bVOC gas‑phase measurements - online with a PTR‑ToF‑MS and offline with thermodesorption‑GC‑MS.

We present results illustrating terpenes and terpenoid in conifer needles and in the gas-phase from seedlings under different maternal water availability and compare baseline conditions to heat and drought stress. We hypothesize that parental environmental history influences offspring stress responses, and that incorporating these mechanisms into Earth‑system models will improve predictions of bVOC emissions and their feedbacks on atmospheric chemistry under future climate scenarios.