Intermediate time scale response of atmospheric CO2 following prescribed fire in a longleaf pine forest. Issue 10 (29th October 2016) - Viner, B.
Abstract: Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multiyear periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high‐frequency measurements of CO2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements of the CO2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO2 concentration and CO2 flux during the fire and increases in atmospheric CO2 concentration and reduced CO2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO2 measurements and NEE were found to return to their preburn states within 60–90 days following the burn when no statistical significance was found between preburn and postburn NEE. This study examines the micrometeorological conditions during a low‐intensity prescribed burn and its short‐term effects on local CO2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO2 concentration and fluxes. Key Points: The impacts of prescribed fire on local carbon cycle are not limited to the period of fire but may extend several weeks beyond the fire Micrometeorological impacts were limited to 1‐2 days or less, but the impacts to the CO2, particularly to the flux of CO2, lasted longer Large initial changes in the net ecosystem exchange between the preburn and postburn periods were no longer observed 60‐90 days following