An Assessment of Carbon Cycling in Restored Wetland Easements on Ranchland in South Florida, USA

The Wetland Reserve Easement (WRE/WRP) programs, administered by the United States Department of Agriculture, restore freshwater wetlands in agricultural areas to reestablish critical ecosystem functions. While these wetlands provide valuable services such as wildlife habitat and carbon sequestration, the potential loss of carbon through greenhouse gas emissions—specifically carbon dioxide (CO₂) and methane (CH₄)—has not been thoroughly evaluated. This study examined carbon cycling across ten seasonal wetland sites located on the Archbold Reserve and Buck Island Ranch, an operating cattle ranch in south-central Florida, both managed by the Archbold Biological Station. Sites had one of three treatment types: grazed-restored, ungrazed-restored, and grazed-unrestored (control). Over the course of the study, CO₂ and CH₄ fluxes were measured every two to three months using a LI-7810 LI-COR CO₂/CH₄/H₂O trace gas analyzer. Groundwater and surface water levels were monitored, and soil and plant samples were analyzed for total carbon, nitrogen, and phosphorus to assess nutrient storage. Results indicate that hydrology, water residence time, and grazing are key determinants of carbon storage and greenhouse gas emissions. Well-drained ephemeral wetlands primarily lost carbon through CO₂ emissions, while more poorly drained wetlands supported CH₄ production due to lower oxygen concentrations. Grazing was found to further increase soil methane emissions. Although wetlands remain effective carbon sinks overall, restoration and management strategies that consider hydrologic regime and inundation duration could enhance carbon capture and minimize seasonal greenhouse gas losses.