Variability of the Carbon Isotope Composition of Peat-Forming Plants during the Biochemical Transformation

In this study, we describe the variation in δ13C value in the litter of two species of peat-forming plants: Sphagnum fuscum and Eriophorum vaginatum, during 3 years of field decomposition in oligotrophic bog ecosystems drained for the purpose of forest melioration and fire affected and at the stage of post-pyrogenic restoration. Litterbags were periodically retrieved in the autumn and the δ13C value in the residual litter was related to mass loss, litter chemistry, and hydrothermal conditions. Sph. fuscum decomposes much more slowly than E. vaginatum. Low rate of transformation for Sph. fuscum is observed in drained and post-pyrogenic sites, while for E. vaginatum minimal rate of transformation is observed in the native site. During the decomposition of Sphagnum residues, 13C enrichment occurs, and during the decomposition of E. vaginatum, we observed 12C enrichment. The changes in the isotope composition of carbon for investigation sites are insignificant for Sphagnum fuscum, but it was observed for E. vaginatum, the largest of 13C depletion is observed in the drained site (−28.3‰) and minimal in the postpyrogenic site (−27.4‰).