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Late Holocene ice-wedge polygon dynamics in northeastern Siberian coastal lowlands

Version 3 2021-12-20, 18:47
Version 2 2019-10-25, 13:45
Version 1 2018-07-10, 14:00
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posted on 2021-12-20, 18:47 authored by Lutz Schirrmeister, Anatoly Bobrov, Elena Raschke, Ulrike Herzschuh, Jens Strauss, Luidmila A. Pestryakova, Sebastian Wetterich

Ice-wedge polygons are common features of northeastern Siberian lowland periglacial tundra landscapes. To deduce the formation and alternation of ice-wedge polygons in the Kolyma Delta and in the Indigirka Lowland, we studied shallow cores, up to 1.3 m deep, from polygon center and rim locations. The formation of well-developed low-center polygons with elevated rims and wet centers is shown by the beginning of peat accumulation, increased organic matter contents, and changes in vegetation cover from Poaceae-, Alnus-, and Betula-dominated pollen spectra to dominating Cyperaceae and Botryoccocus presence, and Carex and Drepanocladus revolvens macro-fossils. Tecamoebae data support such a change from wetland to open-water conditions in polygon centers by changes from dominating eurybiontic and sphagnobiontic to hydrobiontic species assemblages. The peat accumulation indicates low-center polygon formation and started between 2380 ± 30 and 1676 ± 32 years before present (BP) in the Kolyma Delta. We recorded an opposite change from open-water to wetland conditions because of rim degradation and consecutive high-center polygon formation in the Indigirka Lowland between 2144 ± 33 and 1632 ± 32 years BP. The late Holocene records of polygon landscape development reveal changes in local hydrology and soil moisture.

Funding

The study is part of the joint Russian–German project “Polygons in Tundra Wetlands: State and Dynamics under Climate Variability in Polar Regions” (Russian Foundation for Basic Research, RFBR Grants No. 16-04-00451, 15-29-02518, 15-45-05063; Deutsche Forschungsgemeinschaft, DFG Grant No. HE 3622-16-1). Financial support came also from RFBR Project No. 11-04-01171-a “Geography and Ecology of Soil-inhabiting Testate Amoebae.” In addition, Jens Strauss was supported by the European Research Council (# 338335) and the Helmholtz Association (ERC-0013).

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