Holocene vegetation dynamics of the Yamal Peninsula based on palaeobotanical data from relict peat bog deposits

Abstract

We have performed a comprehensive paleoecological study of the peat bog deposits from six localities of the Seyakha, Yuribey and Khadytayakha rivers in the subarctic tundra zone on the Yamal Peninsula. Radiocarbon dating, as well as pollen and plant macrofossil analyses were used to track the chronological changes of the plant communities on the peninsula along the North-South transect in the Late Glacial and Postglacial periods. It was found that open woodland with tree birch and spruce existed in the Yuribey river valley during the Bölling-Allerød interstadial (between 14.7 and 12.7 cal. ka BP). Shrub tundra with Betula nana was widespread in this area during the Younger Dryas, between 12.6 and 11.7 cal. ka BP, under climatic conditions similar to modern ones. The spread of arboreal species (Betula sect. Betula, Picea obovata, Larix sibirica) and associated boreal herbaceous plants began later (between 10.2 and 9.7 cal. ka BP) as climatic conditions improved. The most favorable conditions for tree birch and larch existed in the Seyakha river valley between 10.2 and 8.7 cal. ka BP, whereas the best conditions for the same species and spruce in the Yuribey river valley were observed between 10.2 and 4.4 cal. ka BP. It was much warmer than it is today, and open woodland or even closed forests were widespread. Forest degradation and spread of open landscapes with tundra communities occurred in the Seyakha river valley after 8.7–8.5 cal. ka BP and in the Yuribey river valley after 4.7–4.3 cal. ka BP. Climatic conditions became similar to modern ones. Today, arboreal species grow in the Khadytayakha river valley, forming extrazonal forest communities in the subarctic tundra zones.