Holocene development of the Rogovaya River peat plateau, European Russian Arctic

In this study, the Holocene development of a peat plateau area in the east-European Russian Arctic is reconstructed based on detailed macrofossil, physico-chemical and radiocarbon analyses from two peat sequences. Basal dates from these two, c. 2m long, pear profiles are c. 9420 BP and c. 9250 BP. From another six peat sequences gross-stratigraphic descriptions and additional radiocarbon dates are available. Basal dates from two short (<1 m) pear profiles indicate further peatland expansion at c. 3635 BP and c. 1285 BP. The oldest macrofossils of tree birch are dated to c. 9500 BP and those of conifers, presumably spruce, to c. 8000 BP. Tree stands became rare in the study area after c. 2800 BP, but occasionally occur until present. Peatlands formed through terrestrialization of ponds or paludification of forested uplands. Between 9000 and 3100 BP the peatlands were wet rich fens. Beginning from c. 3100 BP there are marked changes in their surface hydrology, connected with climatic cooling and permafrost aggradation. Sphagnum species started to play a dominant role. Permafrost aggradation at the six pear plateau sites is tentatively dated to c. 3100 BP, c. 2200 BP and <600 BP. Nowadays the area is mostly dry peat plateau with interspersed thermokarst lakes. Generally, peat accumulation rates are lower in the upper layers, which consist mostly of Sphagnum peat, than in the lower layers of sedge/brown moss peat. This is most probably due to ceased accumulation or even erosion in the currently widespread dry lichen stage in the peat plateau. Very high accumulation rates are recorded from moist sites with incipient permafrost. This study supports previous multiproxy climate reconstructions in the area according to which temperatures were at least 2-3 degreesC higher during the mid-Holocene compared to present.