Separating direct and indirect effects of rising temperatures on biogenic volatile emissions in the Arctic

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Rinnan, Riikka, Iversen, Lars L., Tang, Jing, Vedel-Petersen, Ida, Schollert, Michelle, Schurgers, Guy
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Academy of Sciences 2020
• Subjects: Ecology; Climate Research; Arctic; Tundra
• Online Access: https://lup.lub.lu.se/record/6188428d-bd25-4ecc-8c19-86680d9daea2; https://doi.org/10.1073/pnas.2008901117

Plants release to the atmosphere reactive gases, so-called volatile organic compounds (VOCs). The release of VOCs from vegetation is temperature-dependent and controlled by vegetation composition because different plant species release a distinct blend of VOCs. We used modelling approaches on ecosystem VOC release data collected across the Arctic, which is experiencing both rapid warming and vegetation changes. We show that warming strongly stimulates release of plant-derived VOCs and that vegetation changes also increase VOC release, albeit less than temperature directly, and with large geographic differences in the Pan-Arctic area. The increasing VOC flux from the Arctic tundra to the atmosphere may have implications via climate feedbacks, for example, through particle and cloud formation in these regions with low anthropogenic influence.Volatile organic compounds (VOCs) are released from biogenic sources in a temperature-dependent manner. Consequently, Arctic ecosystems are expected to greatly increase their VOC emissions with ongoing climate warming, which is proceeding at twice the rate of global temperature rise. Here, we show that ongoing warming has strong, increasing effects on Arctic VOC emissions. Using a combination of statistical modeling on data from several warming experiments in the Arctic tundra and dynamic ecosystem modeling, we separate the impacts of temperature and soil moisture into direct effects and indirect effects through vegetation composition and biomass alterations. The indirect effects of warming on VOC emissions were significant but smaller than the direct effects, during the 14-y model simulation period. Furthermore, vegetation changes also cause shifts in the chemical speciation of emissions. Both direct and indirect effects result in large geographic differences in VOC emission responses in the warming Arctic, depending on the local vegetation cover and the climate dynamics. Our results outline complex links between local climate, vegetation, and ecosystem–atmosphere ...