HOLOCENE VEGETATION HISTORY AT THE BOREAL-FOREST - SHRUB-TUNDRA TRANSITION IN NORTH-WESTERN QUEBEC

1. Pollen analysis of sediment cores from the four zones that comprise the forest-tundra transition in northern Quebec provide a history of the vegetation that can be compared with extensive macrofossil data from the region. Basal radiocarbon dates indicate that the entire region was deglaciated around 6000 BP. 2. Pollen diagrams from three sites in the boreal forest and the forest-tundra are broadly similar and show a brief period, following deglaciation, with important non-arboreal pollen values. This was followed by a period dominated by Alnus crispa, which ended synchronously at all sites around 4000 BP. From then on Picea pollen dominated the pollen spectra. 3. During the past 3000 years there has been a progressive deforestation at the two sites in the forest tundra, but not at the site in the boreal forest. 4. A pollen diagram from a fourth site in the present-day shrub tundra shows few changes, and suggests that the forest was never further north than it is today.