The aim of this research is to reconstruct the post-wisconsinian vegetational history of south-central Quebec. The effort has been placed on three fronts: 1° the pollen morphology of the Quebec flora, 2° the methodology of the interpretation of the pollen diagram in the Quebec context and 3° the accumulation of pollen diagrams. The effort on pollen morphology allowed the improvement of the identifications in pollen analysis. A total of 199 taxa have been recognized, 111 at the species level. A pollen reference collection of more than 800 species has been made. The region chosen for the palaeophytogeographical studies comprises the central portion of southern Quebec, south of lake Saint-Jean down to the USA border, east of Montreal and west of Tadoussac. It is broadly limited by latitudes 45 and 49 degrees North, and longitudes 70 and 74 degrees West. It covers approximately 160 000 square kilometers, about 450 km south to north and 350 km from east to west. This area has been chosen because of the great amplitude of physiographic, geological, climatic and vegetational features. A total of 21 pollen diagrams has been established from lake or bog sediments in the area. Besides this, a small scale study of the relations between the pollen spectra and the present vegetation has been conducted. It showed the possibility of reconstructing past vegetation at the climax domain level, which greatly improved the interpretation of the pollen diagram in terms of vegetation, in Quebec. Reconstruction of past vegetation is then expressed in a system, the unit of which serves to describe the present vegetation cover. The results of this study and several methodological considerations have been the keys for the interpretation of the pollen diagrams.
