Understorey plant regeneration after wildfire in the boreal borest of Northwestern Ontario / by Alexander J.A. Zeller.

Abstract

The ecological patterns and processes of the boreal forest of northwestern Ontario are dominated by large-scale disturbances such as wildfire. These disturbances have the potential to control or affect the composition of the regenerating understorey vascular plant communities. This thesis examines vegetation regeneration in 'Picea mariana' (black spruce) dominant forests following a wildfire in the boreal forest of northwestern Ontario. The influence of burn intensity and pre-fire spruce composition on understorey species regeneration was examined, and modeled environmental gradients were created using a Geographic Information System (GIS) and remotely sensed imagery. Understorey species composition was sampled using randomly distributed total composition plot clusters within different spruce/burn intensity classes. The influence of bum intensity and pre-fire spruce composition on the regenerating vascular plant community was examined using a two-way analysis of variance (two-way ANOVA), blocked multiple response permutation procedure (MRPP), discriminant function analysis (DFA), and indicator species analysis. The species composition of these regenerating plots was also examined using twenty-four common indices that were modeled with a GIS and Landsat TM satellite imagery. Canonical Correspondence Analysis (CCA) was used to determine the importance of each environmental gradient. Both burn intensity and pre-fire spruce composition classes showed significant differences in post-fire species composition. The combined classes of burn intensity and pre-fire spruce composition better explained the variance in understorey composition. The results also indicate that modeled environmental gradients derived from remote sensing and GIS have the potential to become effective tools to predict regenerating species composition after a major fire disturbance.