A pollen study has been undertaken in a palsa bog of the forest-tundra zone, %Richmond Guif, Nouveau-Québec. The pollen analysis of a palsa mound shows a palynological sequence from a fen vegetation initiated 4900 years BP (radiocarbon dating) ago and remplaced by a bog vegetation 3550 years BP ago. This evolution is correlated with a cooling trend of the climate. Because of the specific nature of the sampled site, the pollen diagram illustrates a local plant succession. Relationships between recent pollen spectra and present vegetation are made in order to give a better interpretation of the pollen diagram.