Development of floating rafts after the rewetting of cut-over bogs: the importance of peat quality

The usual method of restoring cut-over bogs is to rewet the peat surface, but this often leads to the remaining peat layers being deeply inundated. For Sphagnum-dominated vegetation to develop at deeply inundated locations, it is important for floating rafts of buoyant residual peat to develop. In this study, the chemical and physical characteristics of buoyant and inundated peat collected from rewetted cut-over bog were compared. In general, buoyant peat was poorly humified; high methane (CH₄) production rates (2 µmol g ^–1 DW day ^–1) were important to ensure buoyancy. Although the peat water CH₄ concentrations increased with depth, the CH₄ production rates were higher in the uppermost peat layers. High CH₄ production rates were related positively with P concentrations and negatively with lignin concentrations. The pH to bulk density ratio (0.05) also appeared to be a good indicator of CH₄ production rates, providing an easy and cheap way to measure the variable for restoration practitioners. Our results indicated that analysing certain simple characteristics of the residual peat can greatly improve the success of the rewetting measures taken in cut-over bogs. If the analysis reveals that the residual peat is unsuitable for floating raft formation, deep inundation is inappropriate unless suitable peat from other locations can be introduced.