Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

• Published in: Quaternary Research
• Main Author: Ager, Thomas A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2003
• Subjects: Bering Land Bridge; Bering Sea; Betula nana; Dwarf birch; Tundra; Alaska; Beringia
• Online Access: http://dx.doi.org/10.1016/s0033-5894(03)00068-1; http://api.elsevier.com/content/article/PII:S0033589403000681?httpAccept=text/xml; http://api.elsevier.com/content/article/PII:S0033589403000681?httpAccept=text/plain; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400012230

Abstract Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ≥30,000 14 C yr B.P. During the late middle Wisconsin interstadial (≥30,000–26,000 14 C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows ( Salix ) and minor dwarf birch ( Betula nana ) and Ericales. During the late Wisconsin glacial interval (26,000–15,000 14 C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ≥30,000 to 15,000 14 C yr B.P. Between 15,000 and 13,000 14 C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca.11,000–9500 14 C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs ( Alnus crispa ) colonized the St. Michael Island area ca. 8000 14 C yr B.P. Boreal forests dominated by spruce ( Picea ) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island.