Effects of a prescribed fire on dissolved inorganic carbon dynamics in a nutrient-enriched Everglades wetland

Abstract

The purpose of this study was to assess the short-term response of dissolved inorganic carbon (DIC) chemistry to a prescribed fire in a nutrient-enriched area of the Everglades. Surface water samples were analyzed for water temperature, pH, total carbon (TC) and DIC concentrations in the bum area, in addition to one upstream and two downstream stations, pre- and post-fire for a period of 14 weeks. Dissolved free carbon dioxide (CO 2 ), the partial pressure of CO 2 (pCO 2 ) and CO 2 flux between surface water and the atmosphere were calculated. Although a large amount of unburned litter remained in the burned area and an immediate increase in the DIC concentration was observed post-fire, the average DIC concentration at the bum area was only slightly higher than the upstream station and lower than the two downstream stations. Similarly, CO 2 concentrations and pCO 2 at the burn area were lower than those of the three control stations. The low CO 2 and pCO 2 immediately post-fire were likely attributed to the elevated pH due to the addition of basic ash. However, the continuously low CO 2 and pCO 2 were the combined results of high pH and increased CO 2 sequestration by the growth of periphyton triggered by increased availability of light and growth space. These factors also explain why the DIC concentration at the burn area did not show a dramatic increase after the fire. Overall, our results suggest that despite decreases in pCO 2 post-bum, this wetland continues to act as a net source of CO 2 to the atmosphere.