The importance of groundwater-derived carbon dioxide in the restoration of small Sphagnum bogs

Essential for successful bog restoration is the reestablishment of Sphagnum mosses. High carbon dioxide availability has been shown to be of great importance for the growth of Sphagnum mosses. In well-developed Sphagnum bogs large amounts of carbon dioxide are produced by (an)aerobic decomposition of the peat layer. In cut-over Sphagnum bogs this carbon source is often greatly reduced. In this study the importance of groundwater-derived carbon dioxide is demonstrated in aquatic environments, where Sphagnum species have started to form floating mats after former cutover activities by farmers. We discuss the results of measures taken to restore one of the largest wet heathland reserves in western Europe. After rewetting, some bogs developed markedly well, whereas others did not. The developmental success of 10 small bogs was quantified by analysing aerial photographs and sampling of surface and groundwater. The analysis of the ground- and surface water samples revealed that in the well-developed bogs there were significantly higher TIC/CO2 concentrations than in poorly developed bogs. It is concluded that in the early stages of bog formation the growth of Sphagnum is better in bog systems that are fed by an inflow of carbonrich groundwater from outside the bog. The present findings suggest that high carbon dioxide availability is a prerequisite for the successful reestablishment of Sphagnum mosses in peat-bog restoration projects and that carbon-rich groundwater can substitute for the carbon dioxide from decomposing peat.