Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage

Plant macrofossils from the "Mamontovy Khayata" permafrost sequence (71 degrees 60'N, 129 degrees 25'E) on the Bykovsky Peninsula reflect climate and plant biodiversity in west Beringia during the last cold stage. 70 AMS and 20 conventional (14) C dates suggest sediment accumulation between about 60,000 and 7500 C-14 yr B.P. The plant remains prove that during the last cold-stage arctic species (Minuartia arctica, Draba spp., Kobresia myosuroides) coexisted with aquatic (Potamogeton vaginattts, Callitriche hermaphroditica), littoral (Ranunculus reptans, Rumex maritimus), meadow (Hordetan brevisubulatum, Puccinellia tentriflora) and steppe taxa (Alyssum obovatum, Silene repens, Koeleria cristata, Linum pereune). The reconstructed vegetation composition is similar to modern vegetation mosaics in central and northeast Yakutian relict steppe areas. Thus, productive meadow and steppe communities played an important role in the Siberian Arctic vegetation during the late Pleistocene and could have served as food resource for large populations of herbivores. The floristic composition reflects an extremely continental, arid climate with winters colder and summers distinctly warmer than at present. Holocene macrofossil assemblages indicate a successive paludification possibly connected with marine transgression, increased oceanic influence and atmospheric humidity. Although some steppe taxa were still present in the early Holocene, they disappeared completely before similar to similar to 2900 C-14 yr B.P. (c) 2005 University of Washington. All rights reserved.