ELSEVIER Palaeogeography, Palaeoclimatology, Palaeoecology 136 (1997) 293-308 P tl 0 Late Wisconsin environments of the Bering Land Bridge Scott A. Elias a,,, Susan K. Short ", Hilary H. Birks b a Institute of Arctic and Alpine Research, Campus Box 450, University of Colorado, Boulder, CO 80309, USA b Botanical Institute, University of Bergen, Allkgaten 41, N-5007 Bergen, Norway Received 22 July 1996; accepted 12 February 1997 Abstract Late Wisconsin paleobotanical and fossil insect data from the central and northern sectors of the Bering Land Bridge indicate widespread mesic shrub-tundra environments even during the last glacial maximum. Vegetation before the last glacial maximum was a birch-heath-graminoid tundra with few or no steppe elements. Shrubs were not an important element of the vegetation, but were present in small numbers. During the interval 20,000-14,000 yr BP, land-bridge vegetation was dominated by birch-graminoid tundra with small ponds containing aquatic plants. Heaths were relatively unimportant. Insects from this interval were indicative of arctic climate, with drier tundra than during the late glacial. During the late-glacial interval (14,000-11,000 yr BP), land-bridge vegetation was dominated by birch-heath-graminoid tundra with small ponds choked with aquatic plants. The insect record indicates open-ground habitats dominated by mesic tundra. By 11,000 yr BP, insect data suggest that summer temperatures on the emergent Bering Shelf were warmer than present-day upland regions in western Alaska; summer temperatures on the Chukchi Shelf were warmer than the present-day North Slope of Alaska. Contrary to previous hypotheses, we found no evidence of steppe tundra on the land bridge. New accelerator mass spectrometer (AMS) 14C dates show that much of the land bridge was above sea level and thus available for human and animal migration until as late as 11,000 yr BP. © 1997 Elsevier Science B.V. Keywords: Beringia; paleoecology; palynology; insects; plant macrofossils 1. Introduction The Bering Land Bridge connected Alaska and Siberia during the last (Wisconsin) glaciation, when sea level was about 100 m lower than at present. Understanding the environments of the land bridge (the central part of Beringia) and determining the timing of the inundation of the region at the end of the Pleistocene are important issues in the fields of palaeoclimatology, palaeo- * Corresponding author. 0031-0182/97/$17.00 © 1997 ElsevierScience B.V. All rights reserved. PH S0031-0182(97) 00038-2 ceanography, archaeology, palaeoecology, and ecology (e.g., Hopkins et al., 1982; Anderson, 1988; Guthrie, 1990; Bartlein et al., 1991; Edwards and Barker, 1994). As sea level rose at the end of the last glaciation, the inundation of the land bridge re-established the circulation between the Pacific and Arctic oceans (Elias et al., 1996a). The inundation reintroduced oceanic circulation pat- terns that had been cut off for tens of thousands of years. It also brought an end to Beringia as a continuous land mass stretching from the banks of the Mackenzie River in the east to the banks of the Lena River in the west. In so doing, it