PARENT SESSION
Poster Session #63: Late Breaking and Newsworthy Papers.
Friday, August 9. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Effects of sea level rise on CO₂ and CH₄ fluxes in a forested wetland soil.

Ji, Baoming^*,1, Engelhaupt, Erika², Gulledge, Jay³, ¹ Tulane University, New Orleans, LA² University of Louisville, Louisville, KY³ University of Louisville, Louisville, KY

ABSTRACT- Forested wetlands have unique carbon dynamics and are important sources of the dominant greenhouse gases CO₂ and CH₄. Hydrology is the most important control on CO₂ and CH₄ flux rates in wetland soils. Southeast Louisiana is currently experiencing rapid relative sea level rise due to subsidence, resulting in increased seasonal hydroperiod and flooding area in coastal bottomland forests. From October 2000, we have measured flux rates of CO₂ and CH₄ bi-weekly in a forested wetland with three sites across an elevation gradient of 1.5 m, a space-for-time substitution equivalent to about 100 years of relative sea level. The purpose of this study was to investigate the controls on flux rates and predict the effect of future sea-level rise on the net change in radiative forcing of greenhouse gases emitted from the soil. CO₂ effluxes were mainly controlled by the interaction of soil moisture and temperature, but the influence of soil moisture became more important toward the wet end of the gradient, which is frequently inundated. For CH₄ fluxes, soil moisture was the controlling factor, while soil temperature had little influence. We predict that as sea level rises, CH₄ emission will increase, and CO₂ effluxes from soils will decrease, resulting in the accumulation of soil organic matter. Despite decreased CO₂ emissions, 100-year sea level rise would have a net positive feedback on the greenhouse effect because of increased CH₄ emissions.

KEY WORDS: CO2 and CH4 fluxes, hydrology fluctuation, sea level rise, forested wetland soil