Fire severity in relation to canopy composition within burned boreal mixedwood stands

Three boreal mixedwood stands burned by the 1999 Black River fire in southeastern Manitoba were sampled to determine if within-stand variation in fire severity was related to local variation in species composition. On each stand, three fire severity classes (scorched, lightly burned, and severely burned) were identified based on the impact of fire on the forest floor. Pre-fire basal areas and densities of coniferous and deciduous species associated with each fire severity class were determined. The severely burned class had significantly higher coniferous basal area (38.2 m(2)/ha) and significantly lower deciduous basal area (7.0 m(2)/ha) than the scorched and lightly burned classes. No significant differences in species composition were found between the scorched and lightly burned classes. Among 20 plots sampled on the severely burned class, 16 plots had coniferous basal area greater than or equal to30 m(2)/ha but no plot had deciduous basal area greater than or equal to20 m(2)/ha. Plots sampled on the severely burned class were either classified as softwood stands (16 plots) or softwood-dominated mixedwood stands (4 plots) according to percentage coniferous basal area. (C) 2002 Elsevier Science B.V. All rights reserved.