Vegetation and environmental dynamics in the central part of the Kola Peninsula during the past 13.3 ka as reflected by ancient plant DNA on sediments from Lake Imandra

Abstract

The first high-resolution reconstruction of the vegetation and environmental changes during the last ca 13 300 cal a BP in the central part of the Kola Peninsula (NW Russia) was reconstructed based on sedimentary ancient DNA (sedaDNA) metabarcoding on sediment core Co1410 from Lake Imandra. In total, 204 taxa known from modern flora are identified. The resulting sequences were assigned to vascular plants (87%), bryophytes (12%), and algae (1%). About half (111 taxa, 49%) are identified at the species level. They belong to 150 genera and 86 families. So far, this is the most diverse and taxonomically detailed palaeoflora described for the Late Pleistocene–Holocene of the Kola Peninsula and North-European Russia. SedaDNA studies suggest that the vegetation cover in the region developed from (1) plant colonisation of the study area after the glacier retreated during the Allerød warming at ca 13 300–13 000 a BP to (2) Younger Dryas cold period with re-entering of the glaciers in the catchment of the Grater (Bolshaya) Imandra and establishing of the steppe–tundra communities. (3) Warming and increasing in vegetation diversity during the Early Holocene, with the formation of the birch forests by the end of this time zone. (4) Mid-Holocene temperature maximum is correlated with the highest regional plant diversity and a pronounced role of the thermophilic taxa, that is, Lonicera species, Prunus padus, Populus tremula, Sorbus sp./Cotoneaster sp. The highest so far revealed regional diversity of the higher spore plants (10) and aquatic plants (23) is evidenced. Mixed deciduous and coniferous forests were established in the research area during this period, and a drop in plant diversity occurred afterwards. (5) During the Late Holocene, modern communities are formed with a slight increase in biodiversity because of increasing input from cultural plants and weeds. Human impact is clearly diagnosed after 250 a BP, indicated by the presence of Ribes sp., Hypericum sp., and Mentha arvensis as well as eutrophic weeds, that is, Trifolium sp. and Urtica dioica. In addition, this study revealed the past dynamics of some plants rare for the Murmansk region, namely Pteridium aquilinum, with its maximum of occurrence at ca 11 000–8000 cal a BP and a strong decrease thereafter, and Nuphar sp./Nymphaea sp. occurring regularly since ca 7700 cal a BP and eliminating from the record after ca 3500 cal a BP.