Restoration of retired agricultural land to wetland mitigates greenhouse gas emissions

Retired farmland restoration is increasingly seen as a valuable opportunity to improve ecosystem functions in sensitive regions. For example, with expected mass retirement of cranberry farms in New England, there is increasing interest in restoring retired cranberry farms back to wetlands. To understand how restoration of retired cranberry farms to wetland ecosystems influences climate‐related ecosystem functions, we assessed methane and carbon dioxide emissions from different post‐farming management options, including an actively farmed cranberry bog, young and old retired cranberry bogs, young and old restored cranberry bogs, and a natural reference bog. In addition to methane and carbon dioxide, we measured key soil properties influential in greenhouse gas flux, including soil organic matter, moisture, pH, redox potential, and bulk density. Greenhouse gas flux differed significantly by site type, with the restored systems functioning similarly to the natural reference wetland while retired sites had fluxes similar to the actively farmed site. The older restored site had significantly lower emissions of both methane and carbon dioxide than the newly restored site, indicating that over a larger time scale, restored systems may transition from net carbon dioxide sources to sinks. Overall, the results of this study suggest that in addition to the many other ecological benefits, the restoration of wetlands may also play a role in climate change mitigation through their ability to store carbon.