Climate change is expected to increase the frequency and severity of droughts in alpine regions, significantly affecting plant physiological processes and ecosystem functioning. Drought can alter the production and emission of Biogenic Volatile Organic Compounds (BVOCs), which impact atmospheric chemistry by contributing to the formation of tropospheric ozone, secondary organic aerosol (SOA), and cloud condensation nuclei, thereby influencing air quality and climate feedback mechanisms.

We present data from a study examining BVOC emissions from two alpine conifer species, i.e., Pinus sylvestris and Juniperus communis, which often occur in parallel in forest ecosystems. Both species were exposed to different drought scenarios (control, mild, intermediate, severe) for four weeks using the VOC-SCREEN facility at the Helmholtz Center Munich, Germany. Besides carbon assimilation and transpiration, the plant’s BVOC exchange was continuously monitored using PTR-ToF-MS. To facilitate compound identification, samples for GC-MS analysis were taken twice a week.    Overall, P. sylvestris showed much larger BVOC exchange rates than J. communis. BVOC emissions of both species were dominated by monoterpenes, which showed little response to drought. Sesquiterpenes, however, showed clear species-specific responses to drought: P. sylvestris showed a decline in sesquiterpene emissions under severe drought towards the end of the experiment, while J. communis displayed stable emissions over the four weeks that increased with the severity of the applied drought. In the GC-MS analysis, key BVOC species were identified that showed pronounced differences between the different drought levels. These patterns as well as the data we gained about carbon uptake suggest contrasting drought tolerance strategies of P. sylvestris and J. communis.