The Effects of Hydrological Management on Methane Emissions from Southeastern Shrub Bogs of the USA

Peatlands are responsible for the majority of methane (CH4) emission from wetlands globally. Hydrological changes induced by climatic and anthropogenic disturbance may substantially alter CH4 emission in peatlands. Here we measured CH4 emission monthly for 1.5 years in natural, drained and restored shrub bogs in North Carolina, USA. Methane emissions from all sites were consistently low (< 0.05 mg CH4 m− 2 h− 1). We occasionally detected markedly higher CH4 emissions (> 1 mg CH4 m− 2 h− 1) at sites where the water level remained close to the ground surface for 2–3 months, suggesting that surface litter mostly, not deep peat, contributes to CH4 emission. We verified this inference by incubating 2-cm sections of peat sliced from intact soil cores for 6 months. Only the saturated surface litter emitted CH4, which indicated a 5-cm threshold of ground water level for CH4 emission in our shrub bogs. During a wet year, water levels in the wet sites (natural and restored) remained at least 5 cm below soil surface for about 90 % of the days. We thus demonstrate the CH4 emission is negligible from these shrub bogs. This study also indicates that restoration through a non-inundated rewetting would not stimulate CH4 emission in drained/degraded low-latitude shrub bogs, such as pocosins.