The Effects of Shoreline Transgression on Woody Plants, Upper St. Lawrence Estuary, Quebec

Abstract

The effects of high water levels on forest margins were studied along the shores of the upper St. Lawrence estuary in Quebec. In recent decades lower limits of trees displaced landward along with a transgressive migration of beaches. Accompanying disturbance events by ice and waves caused many instances of damage to trees and shrubs. Anomalous growth forms, such as ice scars on stems, proliferating sprouts, irregular tree-ring patterns and severe decrease of population recruitment, were observed in the shoreline disturbance zone. Distribution of ice-scars, broken stems and branches, dead plants, seedlings and saplings at various distances from the river indicated the degree of ecological stability of the different shore zones. Combinations of these field parameters are used to define a descriptive index disturbance of the different parts of the shore.