Latest Pleistocene shrub expansion and steppe-tundra persistence in easternmost Beringia

A multi-proxy analysis of the Mint Gulch site in Yukon Territory reveals that steppe-tundra vegetation persisted alongside shrub expansion during the late Pleistocene in eastern Beringia, challenging the notion of a uniform ecosystem collapse. The study integrates sedimentary ancient DNA (sedaDNA), macrofossils, pore-ice isotopes, and radiocarbon chronology to document a transitional period around 13,910 calibrated years before present (cal yr BP), where both steppe-tundra and shrub-tundra communities coexisted. Pore-ice isotope data indicate regional warming and hydroclimate shifts beginning ca. 14,000 cal yr BP, while sedaDNA records show a shift from grazing megafauna to shrub-dependent taxa. Macro-fossils from an Arctic ground squirrel midden further confirm the persistence of steppe-tundra indicators like Artemisia sp. and Potentilla sp., highlighting spatial heterogeneity in ecosystem transitions.

Cocker, S. L., Francis, E., Wanket, C., Monteath, A. J., Kuzmina, S., Tirlea, D., Jensen, B. J. L., Heintzman, P. D., Shapiro, B., & Froese, D. G. (2026). Latest Pleistocene shrub expansion and steppe-tundra persistence in easternmost Beringia. Quaternary Science Reviews, 388, 110081. https://doi.org/10.1016/j.quascirev.2026.110081