Étude de la végétation des zones riveraines de l'archipel des Cent-îles du fleuve Saint-Laurent, Québec

Abstract

The riparian vegetation of about 30 islands located upstream of lake Saint-Pierre has been analysed. Eleven natural vegetation units were identified, described and defined along with five units of human origin and six agricultural types. The aquatic habitat is characterized by a Vallisneria americana plant community-type. In the semiaquatic floodland habitats, four community-types were present: a Sagittaria latifolia, a Sparganium eurycarpum, a Phalaris arundinacea, and a Scirpus pedicellatus type. The wetlands were characterized by an Acer saccharinum – Ulmus americana – Fraxinus pennsylvanica forest. Both vegetational analysis and fluctuations of the superficial water table pointed to the existence of four variants in this last type of riparian forest. Those are respectively a Matteuccia struthiopteris, a Laportea canadensis, an Onoclea sensibilis, and a Rorippa amphibia variant. Granulometric and pedologie analyses of typical soil samples are also presented and discussed.