Individual study: Enhancement of Sphagnum moss colonization during bog restoration by formation of floating peat rafts, Haaksbergerveen, Mariapeel and Amsterdams Veld, the Netherlands
Smolders A.J.P., Tomassen H.B.M., Lamers L.P.M., Lomans B.P. & Roelofs J.G.M. (2002) Peat bog restoration by floating raft formation: the effects of groundwater and peat quality. Journal of Applied Ecology, 39, 391-401
In the Netherlands over 250,000 ha of land were once covered in raised bogs. Now only small relics remain and efforts are being made to restore some. As a restoration technique, areas are flooded and growth of Sphagnum mosses often occurs in shallow waters. In deeper water however, regeneration appears to depend on whether residual peat becomes buoyant and forms floating rafts providing shallow water/saturated conditions which allow successful Sphagnum colonization. This study investigated peat bog restoration by floating raft formation and the effects of groundwater and peat quality.
In March 1998, peat was collected from three cut-over bog remnants at Haaksbergerveen (52º07’50”N, 6º46’20”E), Mariapeel (51º24’90”N, 5º54’90”E) and Amsterdams Veld (52º41'N, 6º55'50”E). Twelve strongly humified peat
sections (depth 30 cm, diameter 50 cm) taken from each.
The peat sections were transported to a glasshouse where experiments to assess effects of different peat quality and water chemistry on peat buoyancy, and growth of Sphagnum cuspidatum and nutrient availability, were undertaken.
Some sections were cut to 10 cm depth x 35 cm diameter and placed in an experimental set-up to record methane production. To reveal the effects of pH and sulphate levels on potential methane production, incubation experiments were carried out in the laboratory. Chemical analysis of dried peat and S.cuspidatum samples was also undertaken.
Groundwater and peat quality affected peat buoyancy and S.cuspidatum growth. When water containing bicarbonate (1 mmol l(-1) HCO3-, pH 6.0) was applied, peat pH increased from about pH 3.5 to 4.5. As a result, two of the peat types became more buoyant as the concentration and production of methane increased, induced by the increased pH.
When groundwater contained both HCO3- (1 mmol l(-1)) and sulphate (1 mmol l(-1)), pH increased to around pH 5 due to alkalinity generated by the SO42- reduction process. Methane production, however, decreased because of interference from the SO42-, as confirmed in incubation experiments. Phosphate concentrations, greatly increased in the HCO3-/SO42- addition treatment due to the interaction between sulphide and iron phosphate precipitates.
In one of the peat types, treatments did not influence methane production and buoyancy, probably because of its low decomposability; lignin and soluble phenolic content, and C:N, C:P and C:K ratios, were all notably higher than in the other two peat types.
These results suggest that when bog remnants are inundated with water, the prospects for bog successful regeneration are largely determined by peat quality and water chemistry. Peat mats with low concentration of lignin and phenolics, and low C:N ratios are most likely to become buoyant in water with a higher pH, thus providing suitable environments for Sphagnum to recolonize. When peat quality is inadequate, shallow inundation may be a restoration option.
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