| The boreal mixedwood forests of western Canada are largely composed of mixtures of trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) and are of critical ecological and economic importance. Natural regeneration of white spruce after forest harvesting may provide the means to re-create natural mixedwood stands while minimizing effort and cost. I quantified the amount of natural spruce regeneration found 8--15 years after harvest in aspen-dominated cutblocks which had received no silvicultural treatments to encourage spruce growth and explored the effects of mast years, season of harvest, and other spatial and non-spatial variables upon levels of natural regeneration. Significant amounts of natural spruce regeneration were found in aspen-dominated cutblocks, with an average stocking rate of nearly 7 %. Stocking levels were much higher in mast years, especially in summer-harvested cutblocks. The proximity and density of seed sources also played a major role in determining stocking levels, as did several climatic and competition-related factors. |
