Late-entry commercial thinning effects on Pinus banksiana: growth, yield, and stand dynamics in Québec, Canada

Abstract

We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine (Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area (BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm (25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume (GMV) tree -1 by 46% compared to the control. The 27% BA removal had twice as much GMV ha -1 compared to the 47% BA removal after 15 years. Moreover, cumulative GMV ha -1 was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce (Picea mariana (Mill.) B.S.P.), white birch (Betula papyrifera Marsh.), and trembling aspen (Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.

Partial Retention of Legacy Trees Protect Mycorrhizal Inoculum Potential, Biodiversity, and Soil Resources While Promoting Natural Regeneration of Interior Douglas-Fir

“…Total ingress of natural regeneration increased with tree retention in the range of harvesting treatments, in keeping with our first hypothesis. This agrees with many studies showing increased recruitment and regeneration density with retention harvesting (Coates, 2002;Newsome et al, 2010;Gottesman and Keeton, 2017) or thinning (Kuehne and Puettmann, 2008;Roberts and Harrington, 2008;Shatford et al, 2009;Dodson et al, 2012;Olson et al, 2014;Gauthier and Tremblay, 2019; Williams and Powers, 2019). The regeneration response we observed with partial overstory retention was associated with changing resource levels, providing better growing conditions for leave trees and natural regeneration.…”

“…Ingress and height growth of western redcedar was by far greater in the 60% retention treatment, where the small openings provided the best balance of shade and substrate. Multiple studies have shown that ingress density of shade tolerant species increases with any amount of thinning (Olson et al, 2014;James, 2016;Puettmann et al, 2016), but with shifts toward later successional species at higher retention densities (Nabel et al, 2013;Crotteau et al, 2018;Gauthier and Tremblay, 2019).…”

Simulating the Effects of Intensifying Silviculture on Desired Species Yields across a Broad Environmental Gradient

“…While intensive and elite treatments often ended with similar, or slightly lower, standing volumes than those of the extensive and basic treatments, the total volume (i.e., final standing volume plus removed volume) was often much higher for the former. This finding is comparable to results of previous studies on the effects of commercial thinning in other Canadian forests, including for jack pine [78], spruce [79], and temperate pine stands [80]. Our results combined with those from previous investigations suggest that commercial thinning may reflect an opportunity to improve overall yields while producing high-quality lumber at rotation age and preserving desired species composition.…”

Exploring the Impact of Thinning Operations on Forest Ecosystems in Tropical and Temperate Regions Worldwide: A Comprehensive Review

“…The effect of thinning from below on stand volume growth is strongly site dependent, but heavy thinning usually leads to a reduction in volume and density. Unlike some commercial thinning in mature and older forest stands, pre-commercial thinning failed to initiate an understory cohort of shade-tolerant conifer species (Bose et al, 2018; Gauthier and Tremblay, 2019). From the effect of early and heavy thinning, a strong positive increment in quadratic mean diameter has been noted.…”