High methane emissions from restored Norway spruce swamps in southern Finland over one growing season

Forestry-drained peatlands in the boreal region are currently undergoing restoration in order to bring these ecosystems closer to their natural (undrained) state. Drainage affects the methane (CH4) dynamics of a peatland, often changing sites from CH4 sources to sinks. Successful restoration of a peatland would include restoration of not only the surface vegetation and hydrology, but also the microbial populations and thus CH4 dynamics. As a pilot study, CH4 emissions were measured on two pristine, two drained and three restored boreal spruce swamps in southern Finland for one growing season. Restoration was successful in the sense that the water table level in the restored sites was significantly higher than in the drained sites, but it was also slightly higher than in the pristine sites. The restored sites were surprisingly large sources of CH4 (mean emissions of 52.84 mg CH4 m-2 d-1), contrasting with both the pristine (1.51 mg CH4 m-2 d-1) and the drained sites (2.09 mg CH4 m-2 d-1). More research is needed to assess whether the high CH4 emissions observed in this study are representative of restored spruce mires in general.