Modelling recruitment of Populus tremuloides, Pinus banksiana, and Picea mariana following fire in the mixedwood boreal forest

Abstract

We examined the relationship between the post-fire regeneration density of Populus tremuloides Michx., Pinus banksiana Lamb., and Picea mariana (Mill.) BSP and their pre-fire basal area density at the spatial scale of 70 m (the width of the stands studied) in four fires in central Saskatchewan and one in Quebec. For these three species with mechanisms for in situ reproduction, there were highly significant relationships between regeneration density and pre-fire basal area density (basal area per area). Given equal source basal area densities, Populus tremuloides has an advantage, relative to the other two species, in initial regeneration densities, but the advantage is not great because the asexual stems thin rapidly. The overriding conclusion is that, for these three species, there is little change in species composition following fire. Simple predictive equations performed reasonably well for Pinus banksiana and Picea mariana: FD = 806BD0.95 and FD = 593BD0.86, where FD is regenerative stem density (no./m2), and BD is basal area density (m2/m2). For asexual reproduction by Populus tremuloides, the thinning begins immediately following fire, and the regeneration model was FD = 11 600BD0.79(t + 1)-1.64, where t is years since fire.

Structure, spatial distribution and competition in mixed jack pine (Pinus banksiana) stands on clay soils of eastern Canada

“…According to Greene and Johnson [20], post-fire composition in aspen, jack pine and black spruce stands is largely dependant on composition before fire. This stability in forest composition could be caused by the effect of forest composition on fire intensity; jack pine fuels would favor more intense fires that kill most of the aspen roots and aspen fuels would lower fire intensity favoring more aspen root suckering.…”

“…Greene and Johnson [20] argued that initial high aspen densities found after cutting are likely to diminish due to rapid selfthinning among root suckers. However, that may not be enough to change the relative dominance of species.…”

A stand-level tool for predicting the natural regeneration density of black spruce and jack pine following fire and salvage

“…In the absence of salvage, therefore, we expect pure pine stands to reliably replace themselves, and mixed stands to increase their proportion of pine (cf. Greene and Johnson 1999). For black spruce however, regeneration adequacy will depend very much on post-fire seedbed quality and can be problematic even if basal area is high.…”

Spatial analysis of response of trembling aspen patches to clearcutting in black spruce-dominated stands

“…In the absence of major disturbance, these large patches will likely fragment into smaller patches with lower cover values and eventually disappear. Senescence of the aspen component would lead to a progressive increase in conifer dominance with time (Greene andJohnson 1999, Bergeron 2000). At the other extreme, small aspen patches may be more vulnerable to their immediate environment.…”