Poliakova, Anastasia; Lenz, Matthias; Melles, Martin; Fedorov, Grigory B; Alsos, Inger Greve: Data on the chronology of the sediment core Co1410 (Lake Imandra, NW Russia, Murmansk Region): 14C dates and tie points, sedaDNA weighted PCR repeats, sedaDNA total reads, and biogeochemical data [dataset bundled publication]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.942504 (dataset in review)

First high-resolution reconstruction of the vegetation and environment changes in the western part of Kola Peninsula (NW Russia, Murmansk Region, the eastern part of Fennoscandia) during the last 13.3 cal. kyr BP was reconstructed based on sedaDNA metabarcoding analysis on the sediment material from the core Co1410 retrieved from the Lake Imandra. In total, 204 taxa are identified. The resulting sequences were assigned to vascular plants (87%), bryophytes (12%), and algae (1%). About a half (111 taxa, 49%) are identified to the level of species that belong to 150 genera and 86 families. So far, this is the most diverse palaeofloras known from Late Pleistocene-Holocene for the Kola Peninsula and NW Russia. Five palaeoecological zones are described with two subzones in the first zone: Co-1a (Bølling-Allerød interstadial), Co-1b (Younger Dryas), Co-2 (Early Holocene), Co-3 (Mid Holocene), Co-4 (Late Holocene), Co-5 (Late Holocene: modern samples dated the latest back to ca 380 cal. yr BP that revealed a clear anthropogenic influence on the plant communities). A statistically significant increase in the number of taxa is traced from Bølling-Allerød (50 taxa, arctic-alpine plants mainly) to Younger Dryas (82 arctic-alpine and arctic-boreal plants), Early Holocene (109 taxa, arctic-boreal plants with some amount of arctic-alpine taxa) to Mid Holocene (with 141 boreal with a few boreal-nemoral plants in the geographical spectrum) and Late Holocene (with 177, predominantly boreal taxa). Since 380 cal. yr BP, a decrease in plant diversity is noticed (162 boreal taxa with some arctic-boreal and arctic-alpine plants). Sediment ancient DNA studies suggest that vegetation cover in the region from (1) initial colonization after the glacial retreated and during Bølling-Allerød warming to (2) Younger Dryas cold period with re-entering of the glaciers and establishing steppe-tundra communities. (3) Warming and increasing in vegetation diversity during the Early Holocene with establishing of the shrub tundra. (4) Mid-Holocene climatic maximum with the highest regional plant diversity, woody vegetation and a drop in diversity afterwards, (5) Late Holocene stage of modern, antropogenically influenced communities. Human impact is clearly diagnosed after 250 cal yrs BP and is indicated by the presence of Ribes sp., Hypericum sp., and Mentha arvensis as well as synantropic taxa, i.e. Trifolium sp. and Urtica dioica.