Exploring the role of post-fire erosion as a carbon sink mechanism

Wildfires release approximately 2.1 Pg C to the atmosphere each year. The impact of wildfires on the carbon cycle, however, extends well beyond direct emissions, involving complex interactions among various source and sink processes. One such process, the enhanced post-fire soil organic carbon (SOC) erosion, remains unquantified as a potential C sink mechanism. Post-fire SOC erosion functions as a C sink when the subsequent burial and stabilization of eroded C offsite, coupled with the recovery of net primary production and SOC content onsite, outweigh the C losses to the atmosphere during post-fire transport of SOC. In this work, we synthesize published data on post-fire SOC erosion and evaluate its overall potential to act as C sink. In addition, we estimate its magnitude at continental scale following the 2017 wildfire season in Europe, showing that SOC erosion can indeed play a quantitatively significant role in the overall C balance of wildfires.