Sphagnum moss moisture retention following the re-vegetation of degraded peatlands

Northern peatlands store approximately one-third of the World's soil carbon through the long-term accumulation of carbon as peat. However, when peatlands are exploited for Sphagnum moss and horticultural peat, they become degraded and large, persistent sources of atmospheric carbon dioxide. Recent advances in peatland restoration techniques have succeeded in the re-vegetation of Sphagnum moss on previously cutover surfaces. The long-term success of peatland restoration depends on the development of a sufficiently thick new peat layer that has ecohydrological and hydrophysical properties similar to natural peatlands. We determined these properties for an upper (0-4 cm) and lower (8-12 cm) peat layer in a recently restored peatland, a naturally re-vegetated cutover peatland, and a natural peatland in eastern Quebec. The properties of the new peat layer differed significantly between the sites, especially for the lower layer samples. Lower samples for the natural and naturally re-vegetated sites had a bulk density of 43 +/- 5 and 41 +/- 11 kg m(-3), respectively, almost twice as high as the value for lower samples from the restored site (24 +/- 4 kg m(-3)). Sphagnum rubellum capitula density (rho(c)) was significantly higher (p < 0.05) for the restored peatland (28 726 # m(-2)) compared to the natural site (26 050 # m(-2)). Residual moisture content at a soil water pressure of -200 tub (theta(r)) was significantly lower (p < 0.05) for the restored site in comparison to the natural and naturally re-vegetated sites for the lower samples. This suggests that S. rubellum in a natural peatland is able to hold onto more moisture under increasing soil tension than the same species growing in a restored site likely due to its higher bulk density and relatively more decomposed state. We suggest that it is possible that S. rubellum growing in the harsher cutover peatland environment has possibly allocated more carbohydrates to vertical growth and as a consequence has a lower bulk density and poorer water retention. Copyright (C) 2010 John Wiley & Sons, Ltd.