LATE QUATERNARY LACUSTRINE POLLEN RECORDS FROM SOUTHWESTERN BERINGIA

Sediment cores from three lakes in the Upper Kolyma region, northeast Russia, provide the first well-dated continuous record of late Quaternary vegetation change from far southwestern Beringia. The oldest pollen zone, tentatively assigned to the Karginsk (mid-Wisconsinan) Interstade, indicates an Artemisia shrub tundra with Pinus pumila, Betula, and Alnus at mid- to low elevations. With the onset of the Sartan (late Wisconsinan) Stade, Pinus disappeared, probably indicating severely cold, dry winters and cool summers. As conditions deteriorated further, an Artemisia -Gramineae tundra developed. Selaginella rupestris and minor herb taxa indicate the presence of poor soils and disturbed ground. This herb tundra was replaced by a short-lived (< 1000 yr) Betula-Alnus shrub tundra followed by the rapid establishment of a Larix dahurica forest with a Betula exilis-ericales-lichen understory. Populus suaveolens and Chosenia may have formed limited hardwood gallery forests at this time. Modern vegetation associations probably developed during the early Holocene with the arrival of Pinus pumila ca. 9000 yr B.P. This shrub became important in the forest understory and, with B. exilis, formed a belt of shrub tundra beyond altitudinal treeline. Comparison of the Upper Kolyma and Alaskan pollen records indicates that important differences in vegetation types and timing of vegetation change occurred across Beringia during the late Quaternary. © 1993 University of Washington.