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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 Key words: silviculture, stand density management, plantation, thinning, Pinus resinosa, long-term silviculture experiment. Cette etude porte sur un dispositif experimental d'espacement initial de pin rouge (Pinus resinosa Aiton) plante en Ontario, au Canada, il y a 60 ans. Le dispositif etait compose des combinaisons de six espacements initiaux (de 1,2 a 3,0 m) et de la presence ou de l'absence d'un regime d'eclaircie commerciale (EC) et visait a evaluer l'impact des traitements sur le diametre moyen quadratique (DMQ) et la production en volume du peuplement. Le regime d'EC, qui a debute a 30 ans, visait a obtenir une surface terriere (G) residuelle de 38 [m.sup.2] * [ha.sup.-1] apres chacune des quatre interventions. En l'absence d'eclaircie, le DMQ augmentait avec l'espacement initial alors que les productions en volume brut et net ont atteint des valeurs maximales pour des espacements entre 2,1 et 2,4 m. Quand le regime d'eclaircie etait applique, nous avons observe des tendances similaires d'augmentation du DMQ avec l'espacement, meme si la taille des arbres etait plus grande et que les differences entre les espacements etaient plus faibles. Une grande partie des differences du DMQ entre les placettes eclaircies et non eclaircies etait expliquee par l'augmentation immediate de la taille moyenne des arbres causee par la recolte des arbres selectionnes. La G residuelle commune a toutes les eclaircies a mene a des volumes sur pied similaires, peu importe l'espacement initial. La production brute cumulee etait similaire entre les espacements plus petits que 2,1 m dans le cas des peuplements eclaircis et non eclaircis, et etait plus faible pour les espacements plus grands dans le cas des placettes eclaircies. Une plus grande production en volume net dans les peuplements eclaircis dont les espacements etaient les plus petits indique que la mortalite a ete recoltee. Des productions en volume brut et net plus faibles dans le cas des espacements plus grands indiquent que l'eclaircie a provoque une sous-utilisation de l'espace de croissance. [Traduit par la Redaction] Mots-cles : sylviculture, gestion de la densite des peuplements, plantation, eclaircie, Pinus resinosa, experience sylvicole de longue duree., Introduction Planted forests are estimated to provide about one-third of the world's industrial stemwood production (Jurgensen et al. 2014). This proportion has globally increased over the past two and half [...]

Ref: Can. J. For. Res. 51(2): 181-189 (2021) https://doi.org/10.1139/cjfr-2020-0246. The authors noticed that some numbers in the main text were not updated after conducting new analyses requested during the review [...]

Knowledge of the long-term effects of silviculture treatments is crucial to forest management. The long-term effects of thinning, a common and widely used silviculture treatment, is little documented for upland black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) stands. We revisited a partial cutting experiment installed in 1961 in a 65-year-old unmanaged upland black spruce stand. The aim was to document the long-term effects of thinning on tree and stand growth and to complete previously published results of the first 15 years of response to thinning by determining its influence in terms of merchantable volume. Free thinning was applied following three intensities: 0%, 25%, and 50% of total basal area removal. The retrospective analysis of growth rings showed that the response over the first 15 years was less significant when determined in net merchantable volume instead of net total volume. Heavily thinned plots, nonetheless, showed a net stand merchantable volume increment 33% greater than that of the unthinned plots. In the longer term, a spruce budworm (Choristoneura fumiferana Clemens) outbreak affected the site; nevertheless, the heavily thinned plots maintained a superior tree growth rate and did not show senescence mortality like the other plots, allowing stand volume to catch up to that of the unthinned plots after 33 years. Results suggested that thinning upland black spruce stands may be useful in mitigating reductions in volume production associated with growing stands to longer rotations as called for by certain ecosystem-based management approaches. Resume: La connaissance des effets a long terme des traitements sylvicoles est importante pour l'amenagement forestier. Les effets a long terme de l'eclaircie, un traitement sylvicole communement applique, sont peu documentes pour les peuplements d'epicea noir (Picea mariana (Mill.) Britton, Sterns & Poggenb.) bien draines. Nous avons revisite une experience de coupe partielle effectuee en 1961 dans un peuplement d'epicea noir bien draine, age de 65 ans et non amenage. Les objectifs etaient de documenter les effets a long terme de l'eclaircie sur la croissance des arbres et du peuplement et de completer les resultats publies precedemment sur la reaction a l'eclaircie au cours des 15 premieres annees en determinant son influence en termes de volume marchand. Une eclaircie neutre a ete appliquee selon trois intensites: l'enlevement de 0%, 25% et 50% de la surface terriere totale. L'analyse retrospective des cernes de croissance indique que la reaction etait moins significative en termes de volume marchand net qu'en termes de volume total net au cours des 15 premieres annees. Neanmoins, les placettes fortement eclaircies etaient associees a un accroissement net en volume marchand 33% plus grand que celui des placettes non eclaircies. Par la suite, une epidemie de tordeuse des bourgeons de l'epinette (Choristoneura fumiferana Clemens) a affecte le peuplement. Toutefois, les arbres des placettes fortement eclaircies ont maintenu un taux de croissance plus eleve et n'ont pas subi de mortalite par senescence comme dans les autres placettes, ce qui a permis au peuplement d'atteindre le meme volume que celui des placettes non eclaircies apres 33 ans. Les resultats indiquent qu'une eclaircie appliquee dans un peuplement d'epicea noir bien draine peut etre utile pour attenuer les reductions de production en volume associees a l'allongement de la rotation des peuplements, tel que le preconisent certaines approches d'amenagement ecosystemique. [Traduit par la Redaction], Introduction Partial cutting methods, such as commercial thinning or shelterwood, are often considered in forest management strategies either for intensive wood production (Pelletier and Pitt 2008) or for close-to-nature ecosystem [...]

Regeneration of northern white-cedar (Thuja occidentalis L.) is often deficient after harvesting in mixedwood stands growing on mesic sites even where browsing pressure is low. We compared the effectiveness of silviculture treatments on early regeneration of white-cedar after single-tree selection cutting (25% of basal area removed), shelterwood seed cut (50% of basal area removed), and group selection cutting (gaps of 625 m2) in three yellow birch (Betula alleghaniensis Britt.) - softwood uneven-aged stands in Quebec, Canada. Three years after harvesting, the combination of factors that maximized abundance of white-cedar seedlings was single-tree selection cutting with artificial seeding on exposed mineral seedbeds (68.8% of plots with the presence of white-cedar). Early growth of planted white-cedar seedlings (40 cm tall) and biomass production were proportional to light availability, i.e., best under group selection cutting (mean height increment = 14.8 cm/year, mean root collar diameter increment = 3.0 mm/year). Browsing pressure has regional impacts depending on herbivore occupancy of the area. Our study was conducted near the northern limit of white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)), and deer were locally absent, while snowshoe hare (Lepus americanus Erxleben, 1777) did not have a consistent effect on seedling abundance and early survival, limiting height growth only during the first year following planting. Resume: La regeneration du thuya occidental (Thuja occidentalis L.) est souvent deficiente sur les stations mesiques exploite es ou il se retrouve en melange avec d'autres especes, meme si la pression de broutement est faible. Trois betulaies jaunes (Betula alleghaniensis Britt.) resineuses inequiennes ont donc ete selectionnees dans la partie nord de l'aire de distribution du cerf de Virginie (Odocoileus virginianus (Zimmerman, 1780)) (Quebec, Canada), afin d'etudier l'efficacite d'une coupe de jardinage par pied d'arbre (25% de la surface terriere recoltee), d'une coupe de jardinage par trouees (trouees de 625 m2) et d'une coupe progressive d'ensemencement (50% de la surface terriere recoltee) pour la regeneration du thuya. Trois ans apres la recolte, la meilleure combinaison de conditions pour la regeneration du thuya est la coupe de jardinage par pied d'arbre avec un ensemencement artificiel sur un sol mineral expose (68,8% des parcelles ont au moins un semis de thuya). Quant a la croissance et la production de biomasse des semis plantes de thuya mesurant 40 cm initialement, elles sont proportionnelles a la disponibilite de la lumiere, c.-a-d. la meilleure apres la coupe de jardinage par trouees (accroissement moyen en hauteur = 14,8 cm/an, accroissement moyen en diametre au collet = 3,0 mm/an). Le broutement a un impact variable selon les regions, dependamment de la densite des populations d'herbivores. Le cerf etait absent du territoire d'etude, tandis que le lievre d'Amerique (Lepus americanus Erxleben, 1777) n'a pas eu un effet syste-matique sur l'etablissement et la survie des semis. Il a seulement limite la croissance en hauteur des plants durant la premie re annee suivant la plantation., Introduction Northern white-cedar (Thuja occidentalis L.) occurs across a wide variety of habitats (Scott and Murphy 1987). It can reproduce on organic soils, but its development is best on mesic [...]

We present the 6 year effects of different cutting patterns (patch-selection cutting with 20, 30, and 40 m diameter gaps, 1 ha patch clear-cut, and uncut control) and spot scarification, on seedbed coverage and regeneration dynamics in yellow birch (Betula alleghaniensis Britton)--conifer stands in eastern Quebec, Canada. After 3 years, yellow birch had established better in cutting patterns with gaps than in the patch clear-cut and in the control, while its density was 7 times higher in scarified than in nonscarified subplots. After 6 years, scarified openings and the borders of openings had 3-5 times more seedlings >30 cm in height than nonscarified openings and the understory between the gaps. The loss of advance growth in openings was the main result for conifer species, although recruitment of new balsam fir (Abies balsamea (L.) Mill.) seedlings was accelerated by scarification. Despite the abundance of red spruce (Picea rubens Sarg.) seed-trees on the site, our treatment combinations failed to promote its natural regeneration. Varying gap size did not change the total density of competing vegetation but modified the composition of this shrub layer. Our 6 year results suggest that maintaining conifer species, and the mixed composition of the stands, is uncertain over the long term. Resume: Nous presentons les effets apres six ans de differents patrons de coupe (jardinage avec trouees de 20, 30 et 40 m de diametre, coupe en parquet de 1 ha, et temoin non coupe) et du scarifiage en placeaux, sur le recouvrement des lits de germination et la dynamique de regeneration dans des peuplements de bouleau jaune (Betula alleghaniensis Britton) et coniferes de l'est du Quebec, au Canada. Apres trois ans, le bouleau jaune setait mieux etabli dans les patrons de coupe avec trouees que dans le parquet et le temoin, alors que sa densite etait sept fois plus elevee dans les sous parcelles scarifie es que dans les sous parcelles non scarifiees. Apres six ans, les ouvertures scarifiees et les lisieres des ouvertures contenaient trois a cinq fois plus de semis >30 cm de hauteur que les ouvertures non scarifiees et le sous-bois entre les trouees. La perte de regeneration preetablie dans les ouvertures a ete le principal resultat pour les coniferes, bien que le scarifiage ait accelere l'etablissement de nouveaux semis de sapin baumier (Abies balsamea (L.) Mill.). Meme si des semenciers d'epinette rouge (Picea rubens Sarg.) etaient abondants sur le site, notre combinaison de traitements n'a pas favorisesa re-generation naturelle. La variation de la grandeur des trouees n'a pas change la densite totale des especes de competition, mais elle a modifie la composition de cette strate arbustive. Nos resultats apres six ans suggerent que le maintien des coniferes et de la composition mixte des peuplements est incertain a long terme., Introduction In transition between the broad-leaved and the coniferous (boreal) forest of Quebec, Canada (Saucier et al. 2009), the balsam fir (Abies balsamea (L.) Mill.)--yellow birch (Betula alleghaniensis Britton) domain [...]

Abstract: This paper examined the impact of commercial thinning on selected wood properties of jack pine (Pinus banksiana Lamb.). Wood properties evaluated include wood density (ring density, earlywood ring density, [...]

This study compares the financial return of converting old-growth boreal stands into even-aged stands to that of two approaches of selection cutting in Quebec (Canada). In this region, old-growth stands are usually harvested by completely removing the canopy while protecting the abundant advance regeneration, an approach known as careful logging around advance growth (CLAAG). These approaches were compared using a time frame of over 200 years. Consideration is given to the majority of the operating costs leading to end products. The financial analysis integrates Monte Carlo simulations, making it possible to consider the uncertainty associated with variables. The net present values (NPVs) are then associated with a distribution of probabilities. The results show that the probabilities of obtaining positive NPVs are high for all treatments, suggesting that selection cutting approaches can be appropriate alternatives to CLAAG for some stands. Depending on the criteria used, the CLAAG cut or one of the selection cuts show the best performances. In fact, the results of the financial study show that in the future, selection cutting approaches will be more profitable than CLAAG but still less than present CLAAG operations. This occurs because, according to the current yield curves and rotation ages, future stands managed with CLAAG will have smaller and less valuable trees than in the primary forest and in stands managed with the selection system. [ABSTRACT FROM AUTHOR]