We report on a 60-year-old red pine (Pinus resinosa Aiton) spacing trial experiment located in Ontario, Canada, that included the combinations between six initial spacings (from 1.2 to 3.0 m) and the ...presence or absence of a commercial thinning (CT) regime, as well as their impacts on quadratic mean diameter (QMD) and stand volume yield. The CT regime, initiated at age 30, targeted a residual basal area (BA) of 38 m.sup.2 * ha.sup.-1 after each of four entries. Without thinning, as initial spacing increased, QMD increased; gross and net volume production peaked in the 2.1-2.4 m spacings. With thinning, similar trends with spacing were evident for QMD, although piece sizes were larger and differences between spacings were lower. The immediate increase of mean tree size caused by tree selection explained most of the differences in QMD between thinned and unthinned plots. Thinning to a common target BA resulted in similar standing volume across spacings. Cumulative gross yield was similar between spacings of <2.1 m for both thinned and unthinned stands and decreased for thinned plots for wider spacings. Greater net volume production in thinned stands with the narrower spacings confirmed that mortality was captured. Lower gross and net production for wider spacings suggested that thinning resulted in underutilized growing space.
The Green River precommercial thinning (PCT) trial was established between 1959â1961 in New Brunswick (Canada) within natural balsam fir ( (L.) Mill.)-dominated stands. Three silviculture scenarios ...differing only by the increasing nominal spacings of PCT treatments (1.2 m, 1.8 m, 2.4 m) were compared to an unthinned control within randomized replicates that were clearcut harvested in 2008 and treated with herbicide in 2011. During the fourth post-harvest growing season, we assessed regeneration, competing vegetation and coarse woody debris (CWD; differentiated between large woody debris and slash) to assess the legacy effects of PCT on regeneration of next rotation stands. Our results confirmed that silviculture scenarios including PCT significantly increased conifer stocking in treated plots compared to control conditions, but only in the 1.8 m nominal spacing. Considering that treated and untreated stands were fully stocked, we conclude that PCT using the spacing gradient tested has no legacy effect on the regeneration of next rotation natural balsam fir stands. Given the known sensitivity of balsam fir to future climate conditions in this region, we suggest that future treatments should promote tree species diversity to support ecosystem resilience to climate change by favouring more warm-adapted species, such as some hardwoods.
Abies balsamea
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.
We present the implementation of the Adaptive Silviculture for Climate Change (ASCC) initiative at the Petawawa Research Forest (PRF) in Ontario, Canada. The study addresses the urgent need for ...adaptive forest management strategies in response to climate change by examining silvicultural treatments aimed at mitigating its impacts on forest ecosystems. It addresses the complex interplay between climate change projections, regional climate characteristics, and forest management practices for pine dominated forests in the Great Lakes-St. Lawrence Forest region of Canada, underscoring the importance of adaptive approaches in sustaining forest ecosystems. We outline the design and objectives of five distinct treatments—control, business-as-usual, resistance, resilience, and transition—implemented over 4 replicate blocks on a 212-ha area at the PRF. We provide detailed descriptions of each treatment’s management objectives, desired future conditions, and silvicultural strategies. We conclude by summarizing planned research efforts, including seedling survival assessments, phenological monitoring, and measuring treatment impact on fuel loads. By addressing the challenges and opportunities of climate change as part of an international research network, this research will contribute to a deeper understanding of forest ecosystem responses to climate change and inform adaptive management strategies for sustainable forest management.
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.
► We studied the effects of partial harvesting on birds in a northern hardwood forest. ► Bird communities had not fully recovered by 10–12years post-harvest. ► Populations of some early successional ...species remained elevated. ► Ovenbird numbers were reduced. ► Repeated applications of selection cutting could have cumulative effects on birds.
We previously investigated the responses of forest birds to habitat changes 1–7years post-harvest in three northern Ontario tolerant hardwood forest stands cut under the selection system. The same three cut blocks and a control area were re-sampled in 2009, 10–12years post-harvest, to compare community composition, total and species abundances and species richness. We found that the breeding bird communities of the selection cut blocks had not fully recovered 10–12years post-harvest. Veery, Chestnut-sided Warbler, Magnolia Warbler, American Redstart and Mourning Warbler numbers were elevated in all three cut blocks, and White-throated Sparrow numbers were elevated in two of the three cut blocks, 10–12years post-harvest. In contrast, Ovenbird numbers remained depressed in two cut blocks 10–12years post-harvest. Overall, species richness remained high in all three cut blocks, even though total abundance declined. The data suggest that repeated applications of selection cutting could have long-term, cumulative effects on forest bird communities.
We report on a 60-year-old red pine (Pinus resinosa Aiton) spacing trial experiment located in Ontario, Canada, that included the combinations between six initial spacings (from 1.2 to 3.0 m) and the ...presence or absence of a commercial thinning (CT) regime, as well as their impacts on quadratic mean diameter (QMD) and stand volume yield. The CT regime, initiated at age 30, targeted a residual basal area (BA) of 38 m
2
·ha
−1
after each of four entries. Without thinning, as initial spacing increased, QMD increased; gross and net volume production peaked in the 2.1–2.4 m spacings. With thinning, similar trends with spacing were evident for QMD, although piece sizes were larger and differences between spacings were lower. The immediate increase of mean tree size caused by tree selection explained most of the differences in QMD between thinned and unthinned plots. Thinning to a common target BA resulted in similar standing volume across spacings. Cumulative gross yield was similar between spacings of <2.1 m for both thinned and unthinned stands and decreased for thinned plots for wider spacings. Greater net volume production in thinned stands with the narrower spacings confirmed that mortality was captured. Lower gross and net production for wider spacings suggested that thinning resulted in underutilized growing space.
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