Vegetation dynamics at Bol'shoy Lyakhovsky Island (New Siberian Archipelago) since the last interglacial

Climate models project an annual average temperature increase of about 3-5°C in the terrestrial Arctic until the year 2100, which corresponds to the reconstructed temperatures of the last interglacial (Eemian, ~130-110 kyr BP). Hence, the past vegetation composition might provide an analogue for the future. Bol’shoy Lyakhovsky is a treeless island, framed by the Laptev and East Siberian Seas. Our goal was to reconstruct the vegetation history from four permafrost sediment cores, focusing on terrestrial vegetation during warm phases since the last interglacial. We used sedimentary ancient DNA metabarcoding of thetrnLp6-loop. A total of 264 taxa were detected with 39% being assigned to species and 37% to genus level. During several potentially warmer phases tree and shrub taxa were detected. The Eemian was the most diverse phase, also in recording three different tree taxa (Picea, Larix, Populus), whereas Larix was the only tree taxon recorded afterwards. During the Bølling-Allerød interstadial complex (~14.7-12.7 kyr BP), soon after the Last Glacial Maximum (LGM), Larix had already re-colonized Bol’shoy Lyakhovsky, suggesting the persistence of larches at high latitudes throughout the LGM. Despite warmer temperatures of the Holocene, Larix was not detected. Increasing humidity combined with the disconnection of the island from the mainland due to the global sea level rise might have made persistence and/or re-colonization impossible. As the current coastline position has been suggested to differ from the one of the last interglacial, it is however uncertain to which degree the vegetation composition represents a potential future analogue for north-eastern Siberia