4000 Years of Changing Wetness in a Permafrost Polygon Peatland (Kytalyk, NE Siberia): A Comparative High-Resolution Multi-Proxy Study

Ice-wedge polygon mires feature a micro-relief of dry ridges, shallow wet depressions, deeper wet troughs and transitional sites, resulting in a local mosaic of vegetation. The correct recognition of these landscape elements in palaeoecological studies of peat sections requires insight about the suitability of proxies and their potential for palaeoecological reconstruction in order to reconstruct vegetation and wetness patterns as well as dynamics. This paper analyses a 105.5cm long peat section with a base dating to about 4000calyr BP from an ice-wedge polygon mire near Kytalyk (NE Siberia). Pollen, macrofossils, testate amoebae, geochemistry and sediment properties were analysed in order to compare the suitability of these proxies to reconstruct past surface wetness. The proxies show similar wetness trends. Pollen and geochemistry data did not always permit wetness reconstruction, the former because many pollen types do not allow the identification of taxa at a low taxonomic resolution, the latter because later taphonomic processes modify chemical variables in deeper peat layers. Macrofossils provided the most detailed wetness reconstruction, because they could be identified to genera or species, for which the moisture requirements are accurately known from their present-day distribution in ice-wedge polygons. All proxies, except geochemistry, show an obvious change from wet to dry conditions at around 20cm depth. However, as the proxies sometimes show contradictory results, a multi-proxy approach is preferable over a single proxy interpretation as it allows the reconstruction of environmental development in a broader palaeoecological context. Copyright (c) 2016 John Wiley & Sons, Ltd.