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Abstract:
Here we investigate the vegetation history and peat accumulation at the eastern boarder of the West Siberian plain, near the river Yenisey, south of permafrost. In this region peat started to accumulate 15 000 yr ago as gyttia of shallow lakes in ancient river valleys. This peat is older than previously reported mainly due to separating particulate organic carbon (POC) from dissolved organic carbon (DOC), which was 1900 to 6500 yr younger than POC. The probability to finding peat layers older than 12 000 yr is about 2 %. Peat accumulated as fen-peat at a constant rate of 0.2 mm yr−1 and 0.01 kg C m2 yr−1. The accumulation was higher in ancient river valley environments. Since 2000 yr these bogs changed into Sphagnum mires which accumulate up to about 0.1 kg C m2 yr−1 until present.
The long-lasting fen stage, which makes the Yenisey bogs distinct from the West Siberian bogs is discussed as a consequence of the local hydrology. The high accumulation rate of peat in un-frozen mires is taken as an indication that thawing of permafrost peat may change northern peatlands also into long-lasting carbon sinks.
