Canadian Forest Service Publications
Early vegetation control for the regeneration of a single-cohort, intimate mixture of white spruce and aspen on upland boreal sites – 10th year update. 2015. Pitt, D.G.; Comeau, P.G.; Parker, W.C.; Hoepting, M.K.; MacIsaac, D.; McPherson, S.; Mihajlovich, M. The Forestry Chronicle 91(3):238-251.
Issued by: Great Lakes Forestry Centre
Catalog ID: 36228
Availability: PDF (request by e-mail)
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 (α = 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 (~ age 30) and long term (> 60- years) sawlog crop of spruce.
Plain Language Summary
There are few recommended silvicultural methods for the regeneration of mixed stands on upland sites of the boreal forest. Starting in 2002, we studied the growth of trembling aspen and planted white spruce following clearcut harvest on an Alberta and an Ontario site. We compared the growth of aspen and planted white spruce each on their own, to mixes of the two species following a range of vegetation management (competition reduction) intensities. We found that survival, height growth and health of spruce trees planted at 5-m spacing, each free of woody and herbaceous competition within a 2-m radius for the first two years, matched or exceeded the 10th-year measures of spruce growing competition-free for the duration of the experiment. Aspen trees growing in proximity to these spruce tree were at least as large as aspen crop trees situated in undisturbed plots. These results suggest that this mixedwood regeneration strategy may be a practical way to produce aspen for fibre within 30 years, followed by sawlog quality spruce within 60 years.