Stable carbon isotopic composition of peat columns, subsoil and vegetation on natural and forestry-drained boreal peatlands

ABSTRACT

We studied natural and forestry-drained peatlands to examine the effect of over 34 years lowered water table on the δ¹³C values of vegetation, bulk peat and subsoil. In the seven studied sites, δ¹³C in the basal peat layer was 1.1 and 1.2 ‰ lower than that of the middle-layer and surface layer, respectively. Furthermore, there was a positive correlation between the δ¹³C values of the basal and surface peat layers, possibly due to carbon (C) recycling within the peat column. In the same mire complex, natural fen peat δ¹³C values were lower than those of the nearby bog, possibly due to the dominance of vascular plants on fen and the generally larger share of recycled C in the fens than in the bogs. Furthermore, natural and 51 years previously drained fen and bog, on the opposite sides of a ditch on the same mire complex, showed no significant differences in δ¹³C values. Plant δ¹³C values were lower, while δ¹³C values of subsoil were higher in the drained than in the natural site of the fen.

KEYWORDS:

• Biogeochemistry
• bog
• carbon-13
• carbon cycle
• carbon dioxide
• diagenesis
• fen
• drainage
• isotope ecology
• Sphagnum
• Suess effect

Acknowledgements

We thank Lammi Biological Station, University of Helsinki, for the facilities available and all personnel assisting with the measurements. We thank Jukka Turunen for peat profile data source and C. Treat for making the map. Referees are thanked for their patience and constructive advice. James Blande checked the English text.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Academy of Finland grants 136455 and 140964 to HN and 286642 to AJR; Biotieteiden ja ympäristön tutkimuksen toimikunta.