Ice-age steppe vegetation in east Beringia

Tiny plant fossils indicate how this frozen region once sustained huge herds of mammals.

Abstract

The landmass known as Beringia is an extensive region that existed during the Pleistocene epoch and included the land bridge between present-day Siberia and Alaska, now submerged beneath the Bering Strait. It must have been covered with vegetation even during the coldest part of the most recent ice age (some 24,000 years ago) because it supported large populations of woolly mammoth, horses, bison and other mammals during a time of extensive Northern Hemisphere glaciation, although the nature of this vegetation has not been determined^1,2,3. Here we report the discovery of macrofossils of prairie sage (Artemisia frigida), bunch-grasses and forbs that are representative of ice-age steppe vegetation associated with Pleistocene mammals in eastern Beringia. This vegetation was unlike that found in modern Arctic tundra, which can sustain relatively few mammals, but was instead a productive ecosystem of dry grassland that resembled extant subarctic steppe communities^4,5.