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. [ABSTRACT FROM AUTHOR]