Intermediate time scale response of atmospheric CO₂ following prescribed fire in a longleaf pine forest

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.