Hydrologic restoration decreases greenhouse gas emissions from shrub bog peatlands in southeastern US

Peatlands play a disproportionate role in the global carbon cycle. However, many peatlands have been ditched to lower the water table and converted into agriculture, which contributes to anthropogenic greenhouse gas emissions. Hydrologic restoration of drained peatlands could offset greenhouse gas emissions from these actions, but field examples that consider various greenhouse gases are still rare. Here, we examined emissions of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) from soils in drained shrub bogs in North Carolina, USA, before and after hydrologic restoration. We used static chamber methods and a before-and-after, control-impact (BACI) experimental design. We found that hydrologic manipulation (akin to restoration) increased water table levels by 65%, even with the impact of two hurricanes before and one after hydrologic manipulation. Increased water table levels led to a 58% decrease in CO₂ fluxes, and an increase in CH₄ (251%) and N₂O fluxes (85%). Water table depth and soil temperature explained 43% of variation in CO₂, while water table depth explained 25% and 18% of variation in CH₄ and N₂O fluxes, respectively. Despite the increases in CH₄ and N₂O, the higher magnitude of fluxes and large decline in CO₂ lead to an overall lowering of greenhouse gas emissions after hydrologic restoration. Our results suggest that raising the water table in this shrub bog peatland decreased overall greenhouse gas emissions, illustrating that hydrologic restoration of peatlands can be a valuable climate mitigation practice.