Vegetation Response to the Climate Change in Polar Chukotka from 2.510-2.554 Ma BP

The response of vegetation to climate change in Polar Chukotka between 2.510 and 2.554 Ma was determined by a palynological study of sediment cores from Lake Elgygytgyn recovered during the international expedition "El'gygytgyn Drilling Project". Six pollen zones were defined for this interval, which spans marine isotope stages (MIS) 101 and 100. Pollen zones 1 and 2 (MIS 101) as well as zones 3 and 4 (MIS 100) indicate the presence of Larix and Larix-Betula forests during interglaciations. The plant communities reflected in the spectra of zone 3 represent the warmest climates during the early Gelasian Age. During MIS 100, the period of maximum climate cooling is marked by the regional presence of shrub and herb dominated tundra (pollen zone 5). During the interstade (MIS 100, zone 6), the vegetation was dominated by Larix forest tundra. Pollen zones 3 and 4, which have spectra more indicative of interglacial rather than glacial plant communities, are more consistent with climate of MIS 101 and not MIS 100, as suggested by the core's age model. The incorrect age assignment of the boundary between these stages indicates that the Lake El'gygytgyn age model needs revision.