Early vegetation control for the regeneration of a single-cohort, intimate mixture of white spruce and aspen on upland boreal sites-10th year update

In Canada's boreal forest region, mixedwood stands dominated by trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca [Moench] Voss) are prominent and provide important timber and non-timber values. A paucity of silvicultural tools for regenerating mixedwood conditions prompted the establishment of an experiment in 2002, replicated in west-central Alberta and northeastern Ontario, to test a strategy for regenerating a single-cohort, intimate mixture of aspen and white spruce. After ten growing seasons, spruce planted at 5-m spacing, each free of woody and early (first two years) herbaceous competition within a 2-m radius, had equivalent or better survival, height growth and health status than spruce growing competition-free for the duration of the experiment (alpha = 0.05). Select aspen situated in the vicinity of these spruce were at least as large as aspen crop trees situated in undisturbed plots. The year-10 results of this long-term experiment suggest the hypothesized mixedwood regeneration strategy may offer a practical means of establishing mixedwoods capable of producing an early fibre rotation of aspen (similar to age 30) and long term (> 60-years) sawlog crop of spruce.