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

Pitt, Doug; Comeau, Philip G.; Parker, William C.; Hoepting, Michael K.; MacIsaac, Daniel MacIsaacD.; McPherson, Scott; Mihajlovich, Milo

doi:10.5558/tfc2015-045

Cited by 13 publications

(8 citation statements)

References 37 publications

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“…To compensate for this effect, analysis was completed using only the dominant subset of aspen in each plot (200 stems ha −1 top DBH aspen). Similar studies in this region have used 256 aspen ha −1 [30] or 100 aspen ha −1 [13][14][15] for analysis of aspen growth response to silvicultural treatments.…”

Section: Aspen Growth Response To Thinning Treatmentsmentioning

confidence: 99%

Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Bjelanovic

Comeau

Meredith³

et al. 2021

Forests

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A few studies in young mixedwood stands demonstrate that precommercial thinning of aspen at early ages can improve the growth of spruce and increase stand resilience to drought. However, information on tree and stand responses to thinning in older mixedwood stands is lacking. To address this need, a study was initiated in 2008 in Alberta, Canada in 14 boreal mixedwood stands (seven each at ages 17 and 22). This study investigated growth responses following thinning of aspen to five densities (0, 1000, 2500, 5000 stems ha−1 and unthinned (control)). Measurements were collected in the year of establishment, and three and eight years later. Mortality of aspen in the unthinned plots was greater than in the thinned plots which were not significantly different amongst each other. Eight years following treatment, aspen diameter was positively influenced by thinning, while there was no effect on aspen height. The density of aspen had no significant effect on the survival of planted spruce. Spruce height and diameter growth increased with both aspen thinning intensity and time since treatment. Differentiation among treatments in spruce diameter growth was evident three years from treatment, while differentiation in height was not significant until eight years following treatment. Yield projections using two growth models (Mixedwood Growth Model (MGM) and Growth and Yield Projection System (GYPSY)) were initialized using data from the year eight re-measurements. Results indicate that heavy precommercial aspen thinning (to ~1000 aspen crop trees ha−1) can result in an increase in conifer merchantable volume without reducing aspen volume at the time of harvest. However, light to moderate thinning (to ~2500 aspen stems ha−1 or higher), is unlikely to result in gains in either deciduous or conifer merchantable harvest volume over those of unthinned stands.

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Section: Aspen Growth Response To Thinning Treatmentsmentioning

confidence: 99%

Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Bjelanovic

Comeau

Meredith³

et al. 2021

Forests

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“…Treatment plot values were calculated for mortality (%), and weevil incidence (%). Height growth increment at age 10 was calculated by fitting a second-order polynomial to the time-series height values for each treatment plot and then evaluating the first derivative of the resulting function at age 10 [38].…”

Section: Planted Pine Response To Treatmentsmentioning

confidence: 99%

Optimum Vegetation Conditions for Successful Establishment of Planted Eastern White Pine (Pinus strobus L.)

Pitt

Hoepting

Parker

et al. 2016

Forests

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The 10th-growing season performance of planted eastern white pine (Pinus strobus L.) seedlings was evaluated in response to herbaceous and woody vegetation control treatments within a clearcut and two variants of the uniform shelterwood regeneration system (single vs. multiple future removal cuts). Herbaceous vegetation control involved the suppression of grasses, forbs, ferns and low shrubs for the first 2 or 4 growing seasons after planting. Deciduous woody vegetation control treatments, conducted in combination with the herbaceous treatments within a response-surface design, involved the permanent removal of all tall shrubs and deciduous trees at the time of planting, at the end of the 2nd or 5th growing seasons, or not at all. In general, the average size of planted pine was related positively to the duration of herbaceous vegetation control and negatively to delays in woody control. White pine weevil (Pissodes strobi Peck) altered these trends, reducing the height of pine on plots with little or no overtopping deciduous woody vegetation or mature tree cover. Where natural pine regeneration occurred on these plots, growth was similar but subordinate to the planted pine. Data from the three sites indicate that at least 60% of planted pine may be expected to reach an age-10 height target of 2.5 m when overtopping cover (residual overstory + regenerating deciduous) is managed at approximately 65% ± 10%, and total herbaceous cover is suppressed to levels not exceeding 50% in the first five years. On productive sites, this combination may be difficult to achieve in a clearcut, and requires fairly rigorous vegetation management in shelterwood regeneration systems. Currently, synthetic herbicides offer the only affordable and effective means of achieving such vegetation control.

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“…Yields from mixedwood stands may be higher than from single-species stands because of the physical, phenological, and successional differences in growth strategies that exist between aspen and white spruce (Man and Lieffers 1999;MacPherson et al 2001;Kabzems et al 2016;Kweon and Comeau 2019). Overstory aspen reduces damage of young spruce by growing season frost (Groot 1999;Pritchard and Comeau 2004;Filipescu and Comeau 2011) or winter injury (Pitt et al 2010(Pitt et al , 2015, and also reduces the vigor of understory competitors such as bluejoint reedgrass (Calamagrostis canadensis (Michx.) Beauv.)…”

Section: Introductionmentioning

confidence: 99%

“…In addition, preharvest treatments (using aerial application of herbicides, stem injection with herbicides, or girdling) can lead to reductions in post-harvest vigor of aspen and facilitate development of intimate mixtures (Bancroft 1989;Man et al 2011). Pitt et al (2010Pitt et al ( , 2015 proposed a strategy that involves planting spruce at 5-m spacing (400 stems per ha) together with naturally regenerating aspen and applying spot treatments to control competition immediately proximal to white spruce followed by precommercial thinning of the aspen. This approach could create intimate mixtures and promote the benefits of mixtures (nutrient cycling, mitigation of climatic extremes, biodiversity conservation), while reducing the area involved in vegetation management treatment and amount of herbicide used.…”

Section: Introductionmentioning

confidence: 99%

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Using spot treatments to regenerate an intimate mixture of trembling aspen and white spruce in Alberta: Results at age 15

Comeau

Hoepting

Mihajlovich³

2023

The Forestry Chronicle

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Mixedwood stands, dominated by trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss), are an important fibre source in Canada’s boreal forest and provide a range of ecological services. We present results from a study established in 2002 to test a strategy for growing intimate, single cohort mixtures of these two species involving controlling woody and herbaceous vegetation within 2-m radius spots centered on the spruce planted at 5-m spacing. After 15 growing seasons spruce survival was high (74–90%) in the radial treatments with spruce DBH and height being intermediate between untreated spruce growing under a dense aspen canopy and spruce growing without aspen in the broadcast complete control treatment. Repeated browsing by snowshoe hare, associated with reduced height of spruce, lead to severe reductions in spruce survival and size in the untreated stand, which had an average of 24 500 stems/hectare of aspen at age 15. While spot treatment alone did not significantly affect aspen height or diameter at age 15, thinning of the aspen matrix at age 10 in spot treated stands resulted in increases in diameter growth of both aspen and spruce. Results indicate that radial spot herbicide treatments can effectively improve early survival and growth of white spruce through control of aspen, shrubs, herbs, and grasses and that adding precommercial thinning leads to additional increases in growth of both trembling aspen and white spruce.

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

Cited by 13 publications

References 37 publications

Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Optimum Vegetation Conditions for Successful Establishment of Planted Eastern White Pine (Pinus strobus L.)

Using spot treatments to regenerate an intimate mixture of trembling aspen and white spruce in Alberta: Results at age 15

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

Cited by 13 publications

References 37 publications

Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Optimum Vegetation Conditions for Successful Establishment of Planted Eastern White Pine (Pinus strobus L.)

Using spot treatments to regenerate an intimate mixture of trembling aspen and white spruce in Alberta: Results at age 15

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