Nelson Thiffault

Natural Resources Canada | NRCan · Canadian Forest Service

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 ecosyste...

Developing land use strategies to optimize carbon sinks and improve carbon footprints involves proposing efficient nature-based solutions that industries and businesses can implement while considering financial and legislative constraints. The pulp and paper industry is associated with significant greenhouse gas (GHG) emissions, primarily due to th...

There is increasing concern across Canada regarding the use of chemical herbicides in forestry. In Quebec, the use of herbicides for forest management on public lands has been discontinued since 2001, and there is mounting pressure to eliminate or greatly reduce their use in Ontario. To this end, we present a digital compendium of studies that asse...

Mechanical site preparation (MSP) is used prior to planting to control competing vegetation and enhance soil conditions, particularly in areas prone to paludification. Tree planting density can be adapted to the management context and objectives, as it influences yield and wood quality. However, the combined effects of MSP and planting density on u...

Biomass from surplus forest growth that is not harvested for wood supply of conventional industries can be an important source of feedstock for bioenergy. Its procurement can be integrated with little effort into current harvest operations. However, the increasing harvesting intensity to meet greater demand for biomass procurement can impact forest...

Forest plantations play an increasingly important role in meeting global demand for wood. They usually have higher yield than naturally regenerated forests. Thus, plantations can support economically viable wood production, enable forest conservation elsewere, help mitigate climate change by contributing to carbon sequestration and increase forest...

Atteindre des objectifs de production de bois tout en garantissant la durabilité de l’aménagement forestier est un défi constant de la foresterie. Une étude récente a cherché à étudier les effets de différentes intensités de récolte dans des peuplements de pins sur la perturbation du sol et la régénération forestière dans le cadre du système de cou...

Mixed plantations are garnering increased attention due to their potential to provide a broader array of benefits compared to monocultures. Although numerous studies have indicated promising complementarity between black spruce (Picea mariana) and tamarack (Larix laricina), few have delved into individual tree growth interactions to thoroughly asse...

Foresters are constantly navigating the challenge of meeting timber production goals while ensuring the sustainability of forest management. Using a recent study, we have sought to investigate the effects of different harvesting intensities on soil disturbance and tree regeneration within the uniform shelterwood system, providing insights that coul...

Browsing can be an environmental stress to forest ecosystems, where the composition and structure of plant communities depend on the balance between ungulate browsing and the ability of plants to tolerate and accli-mate to this stressor. Tree planting is a management tool for restoring forest whose integrity has been compromised by the intensity an...

Information about post-disturbance regeneration success and successional dynamics is critical to predict forest ecosystem resistance and resilience to disturbances and climate change. Our objective was to identify and classify post-disturbance empirical research conducted by the Canadian Forest Service (CFS) of Natural Resources Canada and their co...

Le mélèze laricin, ou Larix laricina de son nom latin, est le seul représentant indigène de son genre au Canada. Sa capacité à croître dans une large gamme d’environnements fait en sorte qu’on le trouve bien réparti sur le territoire. Espèce pionnière intolérante à l’ombre, elle résiste bien, à contrario, aux inondations. Aujourd’hui, on s’intéress...

Little is known about the growth interactions of black spruce (Picea mariana) and tamarack (Larix laricina), two important commercial tree species of the Canadian boreal forest. We investigated growth relations between black spruce and tamarack in mature mixed stands. We sampled tree-rings of 223 black spruce and 103 tamaracks to analyze their basa...

Drought-induced cavitation in plants is caused by low soil water availability and/or high atmospheric water demand, resulting in the disruption of water columns in plant conduits. This phenomenon leads to the obstruction of sap flow when the conduit elements become embolized due to a strong negative xylem water potential. The vulnerability curve (V...

The future climate of northern temperate forests is projected to be drier and warmer by the end of this century. As a result, more drought-induced forest dieback events are anticipated in northeastern North America, and assessing the vulnerability of dominant tree species to drought is critical for understanding the future composition of these fore...

Introduction Reforestation of degraded lands in the boreal forest is challenging and depends on the direction and strength of the plant-soil feedback (PSF). Methods Using a gradient in tree productivity (null, low and high) from a long-term, spatially replicated reforestation experiment of borrow pits in the boreal forest, we investigated the inte...

Total soil CO2 efflux (F CO2) is the second most important carbon flux after photosynthesis in boreal forests. However, accurate modelling of F CO2 remains challenging because of its high variability, both temporally and spatially. Using an Abies balsamea-dominated boreal landscape in Quebec (eastern Canada) as a case study, we modelled seasonal, i...

We present an ecological framework for classifying sites to support vegetation management decisions in the boreal and northern temperate forests of northeastern Ontario and northwestern Quebec. This first approximation draws on several regional ecological classifications to provide an initial framework and background information for the Herbicide A...

Nous présentons un cadre écologique pour la classification des sites afin de soutenir les décisions de gestion de la végétation dans les forêts boréales et tempérées septentrionales du nord-est de l’Ontario et du nord-ouest du Québec. Cette première approximation s’appuie sur plusieurs classifications écologiques régionales pour offrir un cadre ini...

Les populations surabondantes de grands herbivores constituent à la fois une ressource faunique et une menace pour l’intégrité des écosystèmes qu’ils occupent. Les cervidés en forte densité peuvent surexploiter les forêts et compromettre leur régénération. L’île d’Anticosti représente un laboratoire naturel à ciel ouvert pour tester les méthodes d’...

As Earth's climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimila...

Ericaceous shrubs often interfere with the growth of black spruce seedlings on regenerating forest sites in Eastern Canada. Mechanical site preparation such as scarification may improve this situation, but it is uncertain whether this is solely due to a reduction in direct competition from the shrubs, or also from a sustained improvement in nutriti...

The shelterwood system is considered appropriate to regenerate Pinus strobus. However, there is a need to quantify the amount of harvesting damage that can be expected relative to the amount of overstory removed during removal harvests and the amount of regeneration that exists prior to harvest. We thus evaluated regeneration response to harvest in...

A reliable assessment of forest carbon sequestration depends on our understanding of wood ecophysiology. Within a forest, trees exhibit different timings and rates of growth during wood formation. However, their relationships with wood anatomical traits remain partially unresolved. This study evaluated the intra-annual individual variability in gro...

Clear-cutting has been the dominant harvesting method used in boreal forest silviculture. Reducing the potential negative effects of intensive forestry activities on ecosystems, e.g., the simplification and homogenization of stand structure, requires diversifying silvicultural practices to promote forest resilience in the face of climate change. Pr...

Successful stand regeneration is one of the keystone elements of sustainable forest management. It ensures that ecosystems submitted to stand-replacing disturbances return to a forested state so that they can maintain the provision of wood fiber, biodiversity, carbon sequestration, and other ecosystem services. This chapter describes how plantation...

Afin d’atteindre les cibles climatiques, le gouvernement du Québec prévoit une augmentation de la production de bioénergie forestière pour favoriser la transition énergétique. Cependant, l’utilisation de la biomasse forestière à des fins énergétiques présente des défis sociaux, économiques et environnementaux particuliers. Au cours d’un atelier de...

Ecosystem-based forest management associated with partial harvesting (PH) is intended to balance ecological and economic values of sustainable forest management. The potential for delayed growth response and elevated mortality of advance regeneration following PH remains a critical concern, and may present a barrier to more widespread implementatio...

Les écosystèmes de la planète sont soumis à un rythme de changements qu’ils n’ont jamais connu auparavant. L’augmentation rapide des températures moyennes causée par l’utilisation de combustibles fossiles qui relâchent des gaz à effet de serre dans l’atmosphère, ou la prolifération de plantes ou d’insectes exotiques envahissants qui résulte de l’au...

This document is available at: https://cfs.nrcan.gc.ca/publications?id=40869. This fibre fact provides an overview of costs and revenues from biomass supply for bioenergy production using cut-to-length method.

Ce document est disponible à : https://cfs.nrcan.gc.ca/publications?id=40869. Ce fait sur la fibre aborde les coûts et les revenus liés à l'approvisionnement en biomasse forestière en utilisant un procédé de récolte pour bois tronçonnés.

En 2020, le Québec a adopté une stratégie nationale de production de bois (SNPB) afin d’augmenter la quantité et la qualité de la matière ligneuse produite. Au cours d’une table ronde tenue à l’automne 2021, des experts de la foresterie et de domaines connexes se sont prononcés sur cette nouvelle stratégie et sur les défis de mise en oeuvre qu’elle...

In 2020, Quebec adopted a strategy to increase the quantity and quality of timber it produces. During a roundtable discussion held in the fall of 2021, experts in forestry and in related fields expressed their views on the new strategy and its implementation challenges. The main purpose of this article is to present the key observations from the ro...

Safeguarding Earth’s tree diversity is a conservation priority due to the importance of trees for biodiversity and ecosystem functions and services such as carbon sequestration. Here, we improve the foundation for effective conservation of global tree diversity by analyzing a recently developed database of tree species covering 46,752 species. We q...

This data article describes datasets of plant community composition, dendrometric measurements, quantity and quality of snags of humid boreal stands (Quebec, Canada) from an experiment comparing silviculture scenarios of increasing intensity: (i) careful logging around advance growth (CLAAG); (ii) CLAAG followed by pre-commercial thinning; (iii) pl...

Intraspecific trait variability (ITV) provides the material for species' adaptation to environmental changes. To advance our understanding of how ITV can contribute to species' adaptation to a wide range of environmental conditions, we studied five widespread understorey forest species exposed to both continental‐scale climate gradients, and local...

Compensatory growth (CG) appears common in biology and is defined as accelerated growth after experiencing a period of unfavorable conditions. It usually leads to an increase in biomass that may eventually equal or even surpass that of sites not experiencing disturbance. In forestry, with sufficient time the stand volume lost in a disturbance such...

Cet article provient du magazine d’information sur le milieu forestier et ses ressources, le Progrès Forestier, qui est publié par l’Association forestière du sud du Québec quatre fois par année partout au Québec. Pour plus d’information sur ce magazine spécialisé en foresterie ou pour vous abonner à celui-ci, consultez le www.afsq.org/magazine-pro...

Cet article provient du magazine d’information sur le milieu forestier et ses ressources, le Progrès Forestier, qui est publié par l’Association forestière du sud du Québec quatre fois par année partout au Québec. Pour plus d’information sur ce magazine spécialisé en foresterie ou pour vous abonner à celui-ci, consultez le www.afsq.org/magazine-pro...

Integrating forest biomass procurement in wood procurement for conventional products is a potential means of reducing bioenergy system supply costs. We studied forest harvest operations to procure biomass in the form of trees and tree sections, along with sawtimber and pulpwood. We evaluated the cost-effectiveness of the supply chain with a particu...

Changing climates are altering the structural and functional components of forest ecosystems at an unprecedented rate. Simultaneously, we are seeing a diversification of public expectations on the broader sustainable use of forest resources beyond timber production. As a result, the science and art of silviculture needs to adapt to these changing r...

Successive disturbances such as fire can affect post-disturbance regeneration density, with documented adverse effects on subsequent stand productivity. We conducted a simulation study to assess the potential of reactive (reforestation) and proactive (variable retention harvesting) post-fire regeneration failure mitigation strategies in a 1.37 Mha...

We reviewed recent literature to identify the positive and negative effects of thinning on both stand-and tree-level resistance and resilience to four stressors that are expected to increase in frequency and/or severity due to global change: (1) drought, (2) fire, (3) insects and pathogens, and (4) wind. There is strong evidence that thinning, part...

This document is available at: https://cfs.nrcan.gc.ca/publications?id=40607. This fibre fact provides an overview of how salvage logging can provide an opportuntiy for the forest industry to supply Canada's bioeconomy with wood fibre as well as regenerate a forest.

Ce document est disponible à l'adresse : https://scf.rncan.gc.ca/publications?id=40608&lang=fr_CA. Cette fiche d'information donne un aperçu de la manière dont la récolte forestière de récupération peut permettre à l'industrie forestière d'approvisionner la bioéconomie du Canada en fibre de bois et de régénérer les forêts.

Cet article provient du magazine d’information sur le milieu forestier et ses ressources, le Progrès Forestier, qui est publié par l’Association forestière du sud du Québec quatre fois par année partout au Québec. Pour plus d’information sur ce magazine spécialisé en foresterie ou pour vous abonner à celui-ci, consultez le www.afsq.org/magazine-pro...

Ce rapport est une adaptation d’un mémoire déposé en mai 2021 au Comité permanent des changements climatiques et de l’intendance de l’environnement, un comité multipartite de l’Assemblée législative du Nouveau-Brunswick. Il avait été rédigé en réponse à une invitation à soumettre un mémoire relativement à la question de l’utilisation dans la provin...

This report is adapted from a brief that was delivered in May, 2021 to the Standing Committee on Climate Change and Environmental Stewardship, an all-party committee of the New Brunswick Legislature. It was drafted in response to an invitation for proposals on the use of pesticides and herbicides, including glyphosate, in the province. It is freely...

Density, height, and diameter at breast height of trembling aspen (Populus tremuloides Michx.) sucker regeneration were assessed over a 26-year period in openings created by harvesting in a 40-year-old aspen stand in northeastern Ontario (Canada). The opening types were 9- and 18-m diameter circles, 9- and 18- 150-m east-west strips, and a 100- 150...

This Special Issue of Forests focuses on the role of silviculture to enhance forest productivity, value, and health in the context of global change. It comprises nine papers describing studies conducted in the temperate deciduous and coniferous forests from the United States, Canada, and Sweden. This collection contains studies investigating variou...

Ce document est disponible à l'adresse : https://cfs.nrcan.gc.ca/publications?id=40463 Cette fiche d'information résume une étude sur les implications l'éclaircie précommerciale dans des peuplements de sapin baumier. Bien que les effets de l'éclaircie précommerciale sur la croissance et la qualité des peuplements soient bien connus, une étude réali...

The document is available at https://cfs.nrcan.gc.ca/publications?id=40464 This fact sheet provides an overview of a study on the management implications of pre-commercial thinning in balsam fir. While the effects of pre-commercial thinning on stand growth and quality are well known, a New Brunswick study sheds light on the outstanding question of...

Density, height, and diameter at breast height of trembling aspen (Populus tremuloides Michx.) sucker regeneration were assessed over a 26-year period in openings created by harvesting in a 40-year-old aspen stand in northeastern Ontario (Canada). The opening types were 9- and 18-m diameter circles, 9- and 18- _ 150-m east-west strips, and a 100- _...

The ability of plantations to provide ecosystem services relies on interdependent actions, notably the control of competing vegetation to provide planted seedlings with adequate resource levels. While short-term results from silviculture trials can inform about resource acquisition and use by planted seedlings during the establishment phase, longer...

Forests play a critical role in addressing some of the biggest world challenges such as mitigating climate change, conserving biodiversity, and providing a variety of ecosystems services, including nutrient cycling, air and water purification, carbon sequestration and storage, and wildlife habitats. Forests also have social and spiritual benefits a...

Le document est disponible à https://scf.rncan.gc.ca/publications?id=40410&lang=fr_CA Le défi pour les forestiers consiste à trouver le bon espacement des arbres afin d’optimiser l’utilisation des ressources du site pour la productivité et la santé du peuplement. Un dispositif expérimental dans des plantations de pins rouges de 60 ans montre que l’...

The document is available at https://cfs.nrcan.gc.ca/publications?id=40411&lang=en_CA The challenge for foresters in managing Red Pine lies in finding the right tree spacing to optimize the use of site resources for stand productivity and health. An experiment in 60 year-old Red Pine plantations shows that thinning allowed for the harvest of fib...

Biomass procured from forests affected by natural disturbances as a bioenergy source is increasingly considered in the context of climate change mitigation. By comparing clearcuts with and without biomass procurement, we aimed to determine the effects of biomass extraction performed alongside lumber harvesting on regeneration density, number of pla...

La demande mondiale pour les produits du bois est en croissance. D'ici 2050, il est estimé que les plantations, dont la productivité peut être supérieure à celle des forêts naturelles, pourraient fournir jusqu'à 75 % de la matière ligneuse. Un scénario de plantation (comprenant une coupe totale, une préparation mécanique du sol et la plantation d'u...

Natural forest regeneration after natural or anthropogenic disturbance is difficult to predict given its high variability. The process is poorly documented for commercial northern hardwood species in the Acadian forest of eastern Canada. Our objective was to identify the silvicultural, environmental, and ecological factors that best explain the var...

Understory vegetation plays an important role in maintaining biodiversity, soil nutrient cycling and carbon stocks, yet the ability of understory functional traits to predict forest productivity after harvesting disturbance is unknown. Our objective was to investigate the utility of individual traits (the community-weighted trait mean) and combined...

Les plantations, en raison de leur productivité élevée, contribuent à répondre aux besoins en matière ligneuse de la société. Toutefois, pour atteindre une productivité élevée, les plantations doivent habituellement être entretenues. Cet entretien est utile, notamment pour maitriser la végétation concurrente qui s’établit naturellement. Puisque l’u...

We assessed 27 indicators of plant diversity, stand yield and individual crop tree responses 25 years post-treatment to determine long-term trade-offs among conifer release treatments in boreal and sub-boreal forests. This research addresses the lack of longer-term data needed by forest managers to implement more integrated vegetation management pr...

Climate change is threatening our ability to manage forest ecosystems sustainably. Despite strong consensus on the need for a broad portfolio of options to face this challenge, diversified management options have yet to be widely implemented. Inspired by functional zoning, a concept aimed at optimizing biodiversity conservation and wood production...

As part of the Carrefour Forêts 2019 Conference, the forest research branch of Quebec's Ministère des Forêts, de la Faune et des Parcs and the Canadian Wood Fibre Centre of Natural Resources Canada organized jointly the symposium "Adaptive silviculture to climate change: from concepts to reality". The symposium brought together a hundred actors fro...

Dans le cadre du Carrefour Forêts 2019, le colloque Sylviculture d'adaptation aux changements climatiques : des concepts à la réalité, organisé conjointement par la Direction de la recherche forestière du ministère des Forêts, de la Faune et des Parcs du Québec et le Centre canadien sur la fibre de bois de Ressources naturelles Canada, a rassemblé...

We report on a 60-year-old Pinus resinosa spacing trial experiment located in Ontario (Canada) that included the combinations between six initial spacings (from 1.2–3.0 m) and the presence/absence of a commercial thinning (CT) regime, and their impacts on quadratic mean diameter (QMD) and stand volume yield. The CT regime, initiated at age 30, targ...

The demand for wood products continues to increase globally. Productivity of forest plantations can be greater than that of naturally regenerated forests. Plantation forestry could thus be employed to meet up to 75% of global wood supply by 2050. The resilience of natural forests could jeopardize plantation productivity. If the plantation scenario...

Reforestation in the boreal forest is challenging; trees must survive to large daily temperature variations and to the cold environment. Even if local tree species are adapted to withstand these harsh environmental conditions, spruce plantation failure after artificial regeneration occurs frequently, with important impacts on sustainable forest man...

The main objective for even-aged plantation (EAP) management of producing sawlog material has driven practices towards low initial planting densities and lower post thinning densities. For semi-shade tolerant species, the resulting stand density potentially leaves enough growing space for the introduction of a second cohort of trees in the understo...

Both historical and contemporary environmental conditions determine present biodiversity patterns, but their relative importance is not well understood. One way to disentangle their relative effects is to assess how different dimensions of beta-diversity relate to past climatic changes, i.e., taxonomic, phylogenetic and functional compositional dis...

The increase in soil organic matter mineralization rate in boreal forests that may result from global warming is a major concern as it could release large amounts of C to the atmosphere. On the other hand, this may also release N to the soil and stimulate tree growth, which could partly offset the C losses from the soil. The long-term interaction b...

Forest vegetation management can improve planted seedling survival and growth and is thus widely used in plantation silviculture. In some jurisdictions, mechanical release using brushsaws has replaced the traditional use of chemical herbicides for forest vegetation management purposes. However, its associated costs and the increasing difficulty of...

Nous avons mené une étude sur quatre sites forestiers récemment récoltés dans l’Est du Québec. Notre objectif était de comparer l’effet de la préparation mécanique de terrain par lame en V et par monticules (en plus d’un témoin) sur la croissance du peuplier hybride et sur la concentration en azote inorganique du sol, quatre saisons de croissance a...