Underestimated Short- and Long-Term Impact of Clear-Cutting on Volatile Organic Compounds in a Boreal Forest

Boreal forests are a major source of biogenic volatile organic compounds (BVOCs), which undergo atmospheric oxidation and contribute to the formation of secondary organic aerosol (SOA) and cloud condensation nuclei. Clear-cutting, a common forest management practice involving the uniform removal of most or all trees within a designated area, can substantially alter biosphere–atmosphere interactions. In Sweden, approximately 2% of the managed forest area is harvested annually.

Here we present results from continuous observations conducted from 2020 to the present at the Norunda ACTRIS and ICOS research station in the Swedish boreal forest, where a clear-cutting event occurred in 2022 surrounding the main measurement tower. This event provided a unique opportunity to investigate the short- and long-term impacts of forest clear-cutting on atmospheric composition.

Our results show that clear-cutting significantly altered BVOC concentrations. While enhanced emissions of terpenes were expected, we also observed unexpectedly elevated concentrations of aromatic compounds, indicating that stressed boreal forests may represent an important source of aromatics. Source apportionment analysis reveals the emergence of new VOC sources during and after cutting, highlighting a more complex response of VOC emissions to forest management than previously recognized. Post-cutting factors further suggest a persistent, long-term influence on atmospheric composition. In addition, a chemical box model is used to simulate VOC oxidation processes under different clear-cutting scenarios, providing further insight into the underlying chemical mechanisms.