Arctic periglacial landscape and habitat dynamics during the late Quaternary

The history of Arctic periglacial landscapes northern Yakutian lowlands is closely connected to the aggradation and degradation of permafrost trough the Quaternary climate cycles and resulted in repeated strong changes of past habitats. Braided river systems characterized by migrating channels on wide alluvial flood plain areas are assumed as major environment for the Early Weichselian (Zyryan) stadial period. During the Middle Weichselian (Karginsky) interstadial, the fluvial landscapes were transformed into flat, swampy accumulation plains, where polygonal patterned ground with numerous small ponds therein characterised the micro-relief. The polygonal landscape remained under drier environment during the Late Weichselian (Sartansky) stadial. Records of this paleolandscape are preserved in ice-rich deposits of the Yedoma Suite. Similar environments occurred already during the Late Saalian (Tazovky) glacial period. With the climate amelioration from the Late Glacial to the Early Holocene, permafrost degradation was initiated and led to the formation of abundant thermokarst depressions and other thermo-erosional geomorphic features. The dramatic landscape changes were connected with a transformation of local and regional hydrological regimes. Similar processes are already recorded from the Eemian (Kazansevky) interglacial. Although the thermal permafrost degradation continued till modern times, the periglacial landscape is again characterised by permafrost aggradation the filling up of thermokarst lakes, the formation of new polygon systems on the bottom of depressions and the growth of Pingos. Each stage is characterised by a specific association of habitats which are reflected by fossil bioindicators such as pollen, plant macrofossils, testate amoebae, ostracods, chironomids, beetles, and mammal bones.