Biogenic volatile organic compound (BVOC) flux dynamics during the subarctic autumn are largely unexplored and have been considered insignificant due to the relatively low biological activity expected during autumn. Here, we exposed subarctic heath ecosystems to predicted future autumn climate scenarios (ambient, warming, and colder, dark conditions), changes in light availability, and flooding, to mimic the more extreme rainfall or snowmelt events expected in the future. We used climate chambers to measure the net ecosystem fluxes and bidirectional exchange of BVOCs from intact heath mesocosms using a dynamic enclosure technique coupled to a proton-transfer-reaction time-of-flight mass spectrometer (PTR–ToF–MS). We focused on six BVOCs (methanol, acetic acid, acetaldehyde, acetone, isoprene, and monoterpenes) that were among the most dominant and that were previously identified in arctic tundra ecosystems. Warming increased ecosystem respiration and resulted in either net BVOC release or increased uptake compared to the ambient scenario. None of the targeted BVOCs showed net release in the cold and dark scenario. Acetic acid exhibited significantly lower net uptake in the cold and dark scenario than in the ambient scenario, which suggests reduced microbial activity. Flooding was characterized by net uptake of the targeted BVOCs and overruled any temperature effects conferred by the climate scenarios. Monoterpenes were mainly taken up by the mesocosms and their fluxes were not affected by the climate scenarios or flooding. This study shows that although autumn BVOC fluxes on a subarctic heath are generally low, changes in future climate may strongly modify them.
|Journal||Journal of Geophysical Research: Biogeosciences|
|Publication status||Published - 2022 Jun|
Bibliographical noteFunding Information:
The authors thank Mathias Madsen for constructing the freezer climate chambers, Gosha Sylvester, Thea Jedig Steenberg, and Marie Louise Kristensen for help with soil analysis, Annika Kristofferson for meteorological data, and Søren Kristensen for graphical help. Abisko Scientific Research Station provided accommodation during field work. The study was financially supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 771012) and the Danish Council for Independent Research | Natural Sciences (DFF‐4181‐00141). Activities within CENPERM (CENPERM DNRF100) were supported by The Danish National Research Foundation. RS acknowledges grants RYC2020‐029216‐I and CEX2018‐000794‐S funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future.”
© 2022. The Authors.
Subject classification (UKÄ)
- Climate Research
- Physical Geography
- ecosystem-atmosphere interactions
- global change
- volatile organic compound