The influences of geoclimatic site conditions, disturbance type and canopy composition on the composition of understorey vegetation of boreal mixedwoods

grantor: University of TorontoThe conversion of conifer- to hardwood-dominated boreal forests in Ontario has been attributed to the effects of the mechanization of clear-cut logging within the last several decades. Little has been known, however, about the influence of this conversion on the composition of understorey vegetation. A survey of vegetation composition and edaphic conditions was conducted in 12 logged and 12 unlogged mature boreal mixedwood stands located in northeastern Ontario. Climatic and geological data were acquired from Canadian government sources. The bivariate and multivariate techniques were used to assess the contribution of the environmental variables to the vegetation composition. Understorey vegetation exhibited sensitivity to soil moisture/drainage regime, growing season length, canopy composition and edaphic factors related to site productivity. Results suggest that the mechanism by which the disturbance type influences understorey vegetation is based on the relationship between the proportion of hardwood in the canopy and composition of the understorey vegetation.M.Sc.F