ABSTRACT: La vegetation et le climate postglaciaires du centre et de l'est de la Gaspesie, au Quebec [Postglacial vegetation and climate of the central and eastern Gaspesie, Quebec].

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Abstract

Pollen and macrofossil analyses were used to reconstruct the postglacial vegetation history in the central (Lac du Triangle) and the eastern (Petit Lac Bouchard) part of Gaspesie. A sparse dwarf birch tundra existed as early as 11,200 BP. Afforestation occurred around 10,700 BP involving black spruce sometimes accompanied or not by aspen. Growth of black spruce populations slowed down or was even reversed around 10,000 BP, and green alder and aspen experienced increased abundance during a period of elevated fire incidence. It took 1000 years for closed forests to be installed in central Gaspesie but in the eastern region, the process lasted 2000 years. Such a delayed afforestation could be due to a cold maritime climate. During the forest phase, regional thermophilous taxa like white pine and yellow birch occupied the eastern area whereas central Gaspesie was dominated by boreal tree species: balsam fir, black spruce, and, to a lesser extent, white birch, Jack pine presently absent from Gaspesie, was present around Lac du Triangle between afforestation to about 3500 BP. In response to a cooler and wetter climate during the last 3500 years, black spruce and balsam fir became more abundant, while white birch decreased in the two regions, more so around the eastern site. A first paleohydrological reconstruction is proposed, based on lake level changes.

Bibliography of Canadian Geomorphology