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Climate change interacts with ecological processes leading to changes in tree and forest growth rate, biome shifts and species composition, all of which are influenced by disturbances. This study explores future overarching climate trends of eight of Canada's ecozones containing managed forests. For the 2071 to 2100 period, climate projections indicate a warming trend of up to an additional 5.5 °C and an overall increase in annual precipitation. Future trends suggest marked contrast between coastal and interior forests and polarization between western and eastern forests. Warmer temperatures, accumulating degree-days above 5 °C and frost-free days suggest longer and drier growing seasons and greater risk of drought particularly in moisture-limited areas such as montane cordillera, taiga shield and boreal shield ecozones. Warmer temperatures and rising precipitation combined with less snow suggest shorter and wetter future winters. This indicates greater risk of rain-on-snow and freeze-thaw events, flooding and landslides particularly in coastal ecozones. We discuss how these projections are likely to result in shifts in dominant species and abundance, which when coupled with the cumulative effects of future disturbances, is likely to alter future forest dynamics and impact harvestable wood volumes for Canada's forestry industry. [ABSTRACT FROM AUTHOR]

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Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to several earlier studies, the prevalence of Heterobasidion in peat soils is generally lower compared to mineral soils. However, in some Norway spruce (Picea abies (L.) Karst.) stands on drained peat soils in Latvia, serious damage caused by Heterobasidion root rot has been observed. To determine the spread of Heterobasidion spp. on peat soil, we analyzed the structure of Heterobasidion genets in 20 study plots established in disease centres in 11 spruce-dominated peatland forest stands. A total of 381 standing spruce trees and 244 spruce stumps were examined for Heterobasidion infection. The fungus was isolated from 181 spruce trees (47.5%) and 43 stumps (17.6%). In total, 101 different Heterobasidion genotypes (genets) were identified (on average five genotypes per study plot). The average number of trees infected by a single Heterobasidion genotype was 2.2. Most of the genets (68.3%) had infected only one tree or stump while the rest of the genets (31.7%) had infected several trees and stumps. To the best of our knowledge, this is the first study to investigate the spread of Heterobasidion genotypes in peatland forest stands. To reduce losses caused by Heterobasidion root rot in spruce forests on drained peat soils, it is important to prevent primary spore infections as well as to avoid planting pure spruce stands with high density. Key words: Heterobasidion spp., genets, Picea abies, drained peat soil, spore infection, mycelium spread. Selon de nombreuses etudes anterieures, la prevalence de l'Heterobasidion dans les sols tourbeux est generalement plus faible comparativement aux sols mineraux. Toutefois, on a constate des dommages importants causes par le pourridie d'heterobasidion dans certains peuplements forestiers d'epinettes de Norvege (Picea abies (L.) Karst.) sur des sols tourbeux draines en Lettonie. Afin de determiner la propagation d'especes d'Heterobasidion sur des sols tourbeux, nous avons analyse la structure des genets d'Heterobasidion dans 20 placettes d'echantillonnage etablies dans 11 centres de lutte contre la maladie de peuplements de tourbieres forestieres dominees par les epinettes. Un total de 381 epinettes sur pied et de 244 souches d'epinettes ont ete examinees pour y detecter une infection d'Heterobasidion. Le champignon a ete isole sur 181 epinettes (47,5%) et 43 souches (17,6%). Au total, 101 genotypes (genets) differents d'Heterobasidion ont ete identifies (cinq genotypes en moyenne par placette d'echantillonnage). Le nombre moyen d'arbres infectes par un seul genotype d'Heterobasidion etait de 2,2. La plupart des genets (68,3%) avaient infecte un seul arbre ou une seule souche alors que le reste des genets (31,7%) avaient infecte de nombreux arbres et de nombreuses souches. A notre connaissance, ceci est la premiere etude qui vise a examiner la propagation des genotypes d'Heterobasidion dans des peuplements de tourbieres forestieres. Afin de reduire les pertes causees par le pourridie d'heterobasidion dans des forets d'epinettes sur des sols tourbeux draines, il est important de prevenir les infections primaires de spores de meme que d'eviter de planter des peuplements purement constitues d'epinettes avec une forte densite. [Traduit par la Redaction] Mots-cles : especes d'Heterobasidion, genets, Picea abies, sol tourbeux draine, infection des spores, propagation de mycelium., Introduction The economic losses caused by Heterobasidion root rot in Europe are estimated to be 790 million [euro] per year (Woodward et al. 1998). Damage caused by the fungus can [...]

Mechanized treatment for root diseases such as Coniferiporia sulphurascens (Pilat) L. W. Zhou & Y. C. Dai (syn. Phellinus sulphurascens Pilat) and Armillaria ostoyae (Romagn.) Herink (syn. Armillaria solidipes Peck) is often avoided due to cost or the perception that removal of stumps creates detrimental soil disturbance or degradation that hinders site productivity. Our study tested five diseased stands that were treated by extracting stumps following harvesting and replanted with susceptible Douglasfir. Soil disturbance surveys were conducted in treated and untreated plots, and individual planted spots were assessed and categorized for soil disturbance using existing and proposed new categories specific to disturbance caused by the stump removal. Tree measurements were taken at intervals over the first 10 years of stand development, and foliage was sampled for nutrient analysis. The percentage of total and counted disturbance was 20%-46% and 8%-11% greater, respectively, in treated versus untreated plots; however, mean tree growth in height and diameter was not statistically different between treatments and was more positive for treated plots at all sites but one. Tree nutrition and survival to age 10 was not negatively affected by stump removal. Total site productivity represented by basal area and tree volume differed widely between sites but was not significantly different between treatments. Key words: Douglas-fir, inoculum reduction, root disease, soil disturbance, stump removal. On evite souvent d'utiliser le traitement mecanise pour les maladies de racines telles que Coniferiporia sulphurascens (Pilat) L. W. Zhou & Y. C. Dai (syn. Phellinus sulphurascens Pilat) et Armillaria ostoyae (Romagn.) Herink (syn. Armillaria solidipes Peck) a cause de la perception que le dessouchage engendre la degradation ou une perturbation du sol prejudiciable qui nuit a la productivite de la station. Notre etude a teste cinq peuplements malades traites en enlevant les souches a la suite de la recolte et en replantant avec du douglas de Menzies sensible. Les perturbations du sol ont ete inventoriees dans des parcelles traitees et temoins non traitees, et chaque microsite de plantation a ete evalue et categorise en fonction de la perturbation du sol a l'aide de categories existantes et de nouvelles categories proposees specifiquement pour les perturbations causees par le dessouchage. Les mesures dendrometriques ont ete prises a differents intervalles au cours des 10 premieres annees du developpement du peuplement et le feuillage a ete echantillonne pour analyser les nutriments. Le pourcentage de toutes les perturbations et celui des perturbations repondant a certains criteres etaient respectivement 20-46 % et 8-11 % plus eleves dans les parcelles traitees comparativement aux parcelles temoins; cependant, la croissance moyenne des arbres en hauteur et en diametre n'etait pas significativement differente selon le traitement mais davantage positive dans les parcelles traitees dans toutes les stations a l'exception d'une seule. Le dessouchage n'a pas eu d'impact negatif sur la survie et la nutrition des arbres jusqu'a l'age de 10 ans. La productivite totale de la station, representee par la surface terriere et le volume des arbres, etait tres differente d'une station a l'autre mais elle n'etait pas significativement differente selon le traitement. [Traduit par la Redaction] Mots-cles: douglas de Menzies, reduction de l'inoculum, maladie de racines, perturbation du sol, dessouchage., Introduction Root diseases are a major consideration in the management of many commercial conifer species in western North America. Such diseases are difficult to detect due to the lack of [...]

The seed coats of several conifers contain terpene-filled resin vesicles, which may be involved in the protection of the dormant embryo and the seed storage tissue against herbivores or pathogens. We analyzed the terpenoid composition of seeds from four Abies species (Abies amabilis Douglas ex J. Forbes, Abies balsamea (L.) Mill., Abies grandis (Douglas ex D. Don) Lindl., and Abies lasiocarpa (Hook.) Nutt.), two Thuja species (Thuja plicata Donn ex D. Don and Thuja occidentalis L.), and three Tsuga species (Tsuga canadensis (L.) Carriere, Tsuga mertensiana (Bong.) Carriere, and Tsuga heterophylla (Raf.) Sarg.) and examined histological features of resin vesicles in seeds from one species from each genus. Resin vesicle morphology was generally similar among the species analyzed. The composition of the seed terpenes varied largely between species. The described seed terpene profiles of the nine species will serve as a foundation for future studies into the function of seed terpenes and resin vesicles in the seed coat. Key words: monoterpene, diterpene, oleoresin, conifer, seed coat. L'enveloppe des graines de plusieurs coniferes contient des vesicules resiniferes pleines de terpenes qui pourraient jouer un role dans la protection de l'embryon dormant et des tissus de reserve de la graine contre les herbivores et les pathogenes. Nous avons analyse la composition en terpenes des graines de quatre especes d'Abies (Abies amabilis Douglas ex J. Forbes, Abies balsamea (L.) Mill., Abies grandis (Douglas ex D. Don) Lindl. et Abies lasiocarpa (Hook.) Nutt.), deux especes de Thuya (Thuja plicata Donn ex D. Don et Thuja occidentalis L.) et trois especes de Tsuga (Tsuga canadensis (L.) Carriere, Tsuga mertensiana (Bong.) Carriere et Tsuga heterophylla (Raf.) Sarg.) et nous avons etudie les caracteristiques histologiques des vesicules resiniferes dans les graines d'une espece de chaque genre. La morphologie des vesicules resiniferes est generalement semblable chez les especes etudiees. La composition en terpenes des graines varie beaucoup d'une espece a l'autre. Les profils des terpenes qui ont ete decrits dans les graines des neuf especes serviront de base pour les etudes futures portant sur la fonction des terpenes presents dans les graines et celle des vesicules resiniferes dans l'enveloppe des graines. [Traduit par la Redaction] Mots-cles : monoterpene, diterpene, oleoresine, conifere, enveloppe de la graine., Introduction Conifer oleoresin is a physical and chemical defense against herbivores and pathogens (Franceschi et al. 2005; Keeling and Bohlmann 2006a; Zulak and Bohlmann 2010). The oleoresin is a complex [...]

Forests are sensitive to the effects of climate change and play a significant role in carbon cycles. This duality has important implications for forest management in terms of requirements for enhanced and integrated adaptation and mitigation interventions. Two ideal conceptual level changes could provide the means for implementation. First, the incorporation of climate change considerations into definitions of sustainable forest management (SFM) would provide mandates for enhanced approaches. Second, the mainstreaming of enhanced SFM would facilitate implementation. There are, however, factors that may impede implementation. Identifying and evaluating these factors informs our understanding of requirements for adaptation and mitigation mainstreaming. This study reviews, organizes, and interprets the literature for the purposes of identifying and evaluating potential impediments. Harmonization barriers pertain to differences between adaptation and mitigation in preexisting frames and beliefs. Enabling barriers are psychological and institutional in nature. Implementation barriers include capacity deficits (e.g., funding limits, science and knowledge deficits regarding benefits, trade-offs, and synergies between adaptation and mitigation) and governance issues. Barriers are interrelated, dynamic, and subjective. Addressing barriers requires a holistic approach that recognizes the complex and dynamic nature of forest management policy change processes. Key words: climate change, sustainable forest management, adaptation and mitigation integration, mainstreaming barriers. Les forets sont sensibles aux effets des changements climatiques et elles jouent un role important dans les cycles du carbone. Cette dualite a d'importantes repercussions sur l'amenagement forestier en termes d'exigences pour l'integration de mesures d'attenuation et d'adaptation ameliorees et integrees. Idealement, deux changements de niveau conceptuel pourraient offrir les moyens d'implantation. Premierement, l'incorporation d'elements relies aux changements climatiques dans la definition de l'amenagement forestier durable (AFD) fournirait des mandats pour developper de meilleures approches. Deuxiemement, l'integration d'un AFD ameliore faciliterait son implantation. Il y a cependant des facteurs qui peuvent entraver son implantation. L'identification et l'evaluation de ces facteurs nous permet de mieux comprendre les exigences pour integrer l'adaptation ou l'attenuation. Cette etude passe en revue, organise et interprete la litterature dans le but d'identifier les obstacles potentiels. Les obstacles a l'harmonisation ont trait aux differences entre adaptation et attenuation dans les croyances et schemas preexistants. La mise en place d'obstacles est par nature psychologique et institutionnelle. Les obstacles a l'implantation incluent les deficits de capacites, (p. ex., les limites de financement, le manque de connaissances et de donnees scientifiques concernant les benefices, les compromis et les synergies entre adaptation et attenuation) ainsi que des questions de gouvernance. Les obstacles sont etroitement relies, dynamiques et subjectifs. S'attaquer aux obstacles requiert une approche holistique qui reconnait la nature complexe et dynamique des processus de modification des politiques forestieres. [Traduit par la Redaction] Mots-cles: changement climatique, amenagement forestier durable, integration des mesures d'adaptation et d'attenuation, integration des obstacles., Introduction The purpose of this review is to identify barriers to comprehensive and integrated climate change adaptation and mitigation in Canadian forest management. In its strategy document A vision for [...]

Planting white spruce (Picea glauca (Moench) Voss) under established aspen (Populus tremuloides Michx.) stands has substantial potential for regenerating mixedwood ecosystems in the western Canadian boreal forest. The presence of an aspen overstory serves to ameliorate frost and winter injury problems and suppresses understory vegetation that may compete with white spruce. Under future climatic regimes with more frequent and severe drought episodes, underplanting may be a cost-effective strategy for lowering the risk of mortality in mixedwood regeneration. We examine the growth of white spruce during the first 18 years after being planted beneath a 39-year-old stand of trembling aspen. Treatments included thinning from over 6000 stemsx[ha.sup.-1] to 3000, 2000, and 1000 stemsx[ha.sup.-1] and fertilization. Initial stimulation of understory vegetation by fertilization had no measureable effect on spruce heights or diameters at year 18. Aspen thinning treatments did not have a significant effect on spruce height growth rates after spruce crowns had emerged above the understory shrub layer due to rapid aspen basal area increases after thinning. Small, but significant, increases for spruce height and diameter were present in the 1000 and 2000 stemsx[ha.sup.-1] aspen thinnings. A much wider range of aspen stand conditions may be suitable for planting spruce to create mixedwood ecosystems than has been previously considered. Key words: white spruce, aspen, boreal mixedwood, underplanting, thinning. La plantation d'epinette blanche (Picea glauca (Moench) Voss) sous un couvert de peuplier faux-tremble (Populus tremuloides Michx.) a un potentiel interessant pour regenerer les ecosystemes mixtes de la foret boreale de l'Ouest canadien. La presence d'un couvert dominant de peuplier est utile pour attenuer les problemes de gel et de blessures hivernales et pour reprimer la vegetation de sous-etage qui peut concurrencer l'epinette blanche. Sous les futurs regimes climatiques caracterises par des episodes de secheresse plus frequents et plus severes, la plantation sous couvert peut constituer une strategie rentable pour diminuer les risques de mortalite de la regeneration dans les peuplements mixtes. Nous etudions la croissance de plants d'epinette blanche au cours des 18 premieres annees apres leur plantation sous un peuplement de peuplier faux-tremble age de 39 ans. Les traitements incluent des eclaircies faisant passer la densite du peuplement de 6000 tigesx[ha.sup.-1] a 3000, 2000 et 1000 tigesx[ha.sup.-1], ainsi que la fertilisation. La stimulation initiale de la vegetation de sous-etage par la fertilisation n'a pas eu d'effet mesurable sur la hauteur ou le diametre de l'epinette blanche apres 18 ans. Les traitements d'eclaircie du peuplier n'ont pas eu d'effet significatif sur le taux de croissance en hauteur de l'epinette apres que leur cime ait depasse la strate arbustive du sous-etage parce que la surface terriere du peuplier a augmente rapidement apres les eclaircies. Une augmentation faible, mais significative, de la hauteur et du diametre des epinettes a ete observee dans les eclaircies du peuplier qui ont laisse 1000 et 2000 tigesx[ha.sup.-1]. Une gamme de conditions de peupleraie beaucoup plus large que ce qui a ete precedemment envisage pourrait convenir a la plantation d'epinette dans le but de creer des ecosystemes mixtes. [Traduit par la Redaction] Mots-cles : epinette blanche, peuplier faux-tremble, peuplements boreaux mixtes, plantation sous couvert, eclaircie., Introduction The underplanting of mature (40- to 60-year-old) trembling aspen (Populus tremuloides Michx.) stands with white spruce (Picea glauca (Moench) Voss) has been recommended as a feasible mixedwood management silviculture [...]

After affecting millions of hectares of pine forests in western Canada, the mountain pine beetle (MPB; Dendroctonous ponderosae Hopkins) is spreading out of its native range and into Canada's boreal forest. Impacts of outbreaks can be environmental, economic, and social, and an ecosystem services (ES) viewpoint provides a useful perspective for an integrated approach to assessing these impacts and may help to identify how possible management strategies could minimize these impacts. In this regards, a comprehensive overview of the ecosystem functions and socioeconomic factors that have been impacted by the current outbreaks in western Canada was carried out to facilitate a more general ES assessment. In addition to timber production, current MPB outbreaks have negative effects on provisioning services (water supply and food production) and aesthetic cultural services, while effects on regulating services (carbon and forest fire) are still in debate. Among the supporting services, nutrient cycling and aquatic habitat showed short- and long-term negative effects, while terrestrial habitat showed a mostly positive response. The overall impact on ES may be more severe if salvage logging is practiced as a post-MPB forest management strategy. The outcomes of this study may help to identify areas of greatest socioecological vulnerability to MPB and identify knowledge gaps and avenues for research to advance the ES framework for MPB outbreak management. Key words: ecosystem function, lodgepole pine, provisioning services, regulating services, salvage logging. Apres avoir devaste des millions d'hectares de foret de pin dans l'ouest du Canada, le dendroctone du pin ponderosa (DPP) se repand a l'exterieur de son aire de repartition indigene dans la foret boreale canadienne. Les impacts des epidemies peuvent etre environnementaux, economiques et sociaux et l'angle des ecoservices (ES) offre une perspective utile pour une approche integree de revaluation de ces impacts et peut aussi bien aider a identifier comment des strategies potentielles d'amenagement pourraient minimiser ces impacts. A cet egard, une synthese complete des fonctions de l'ecosysteme et des facteurs socio-economiques qui ont subi l'impact des epidemies en cours dans l'ouest du Canada a ete effectuee pour faciliter une evaluation plus generale des ES. En plus de la production de matiere ligneuse, les epidemies actuelles du DPP ont des effets negatifs sur les services d'approvisionnement (alimentation en eau et production de nourriture) et les services esthetiques et culturels, tandis que les effets sur les services de regulation (carbone et feux de foret) sont encore controverses. Parmi les services de support, le recyclage des nutriments et l'habitat aquatique ont subi des effets negatifs a court et long terme tandis que l'habitat terrestre a surtout reagi positivement. L'impact global sur les ES pourrait etre plus severe si la coupe de recuperation est utilisee comme strategie d'amenagement forestier apres le passage du DPP. Les resultats de cette etude peuvent aider a identifier les zones de plus grande vulnerabilite socio-ecologique au DPP ainsi qu'a identifier les lacunes dans les connaissances et les avenues de recherche visant a ameliorer le cadre des ES pour la gestion des epidemies du DPP. [Traduit par la Redaction] Mots-cles: fonction de l'ecosysteme, pin ponderosa, services d'approvisionnement, services de regulation, coupe de recuperation., 1. Introduction Outbreaks of mountain pine beetle (MPB; Dendroctonous ponderosae Hopkins) are natural phenomena that play a critical role in the development of western North American pine forests (Safranyik and [...]

Some regenerating stands of the boreal forest exhibit low juvenile growth after major disturbances, which compromises sustainable forest management objectives. In black spruce--feather moss stands of eastern Canada subject to paludification, careful logging methods could decrease stand productivity with time by preventing a beneficial reduction in organic soil thickness. The aim of this project was to confirm decreases in juvenile growth between stands originating from careful logging and the former stands originating from old fires on the same sites. Stem analyses showed that stands originating from CPRS had significantly better juvenile height growth than the former stands but significantly lower growth than stands originating from recent fire in the study region. If organic matter thickness apparently played a role in the growth differences observed between fire and harvesting, it was not the only factor determining stand productivity. According to our results, cohort status, climatic regime, and quality of the residual organic matter are other factors that seem to drive productivity. Our results show that postharvest management approaches (e.g., site preparation) should be used to increase yields after harvest for the sites to express their full growth potential. Key words: black spruce (Picea mariana), paludification, height growth, careful logging, fires. En foret boreale, certains peuplements regeneres par des perturbations majeures montrent une faible croissance juvenile. Cela compromet les objectifs de gestion durable de la ressource forestiere. Dans les peuplements de la pessiere noire a mousses de l'est du Canada sujets a la paludification, les methodes de coupes limitant les impacts sur les sols et la regeneration pre-etablie (CPRS, CLAAG) pourraient diminuer la productivite des peuplements dans le temps, en evitant une reduction benefique de l'epaisseur de la matiere organique. Ce projet avait pour objectif de verifier s'il existe une diminution de croissance juvenile entre des peuplements issus de coupes a faibles impacts et la generation precedente de peuplements issus de feux anciens, sur les memes sites. Des analyses de tiges ont montre que les peuplements issus de CPRS avaient une croissance juvenile en hauteur significativement superieure aux precedents peuplements, mais significativement inferieure a celle mesuree dans des peuplements post-feux recents dans la zone d'etude. Si l'epaisseur de matiere organique semblait jouer un role dans les differences de croissance observees entre feu et coupe, ce n'etait pas le seul facteur determinant la productivite du peuplement. Selon nos resultats, la cohorte, le regime climatique et la qualite de la matiere organique residuelle sont d'autres facteurs qui semblent conditionner la productivite. Nos resultats montrent que des interventions de preparation des sites apres coupe devraient etre utilisees pour permettre aux sites d'exprimer leur plein potentiel de croissance. Mots-cles: epinette noire (Picea mariana), paludification, croissance en hauteur, coupes a faibles impacts (CPRS, CLAAG), feux., Introduction In Canada, black spruce (Picea mariana (Mill.) BSP) is a major commercial species that supports the forest products industry (Viereck and Johnston 1990; Burton et al. 2010). In boreal [...]

Forest ecosystems in eastern Canada are particularly sensitive to climate change and may shift from carbon sinks to carbon sources in the coming decades. Understanding how forest biomass responded to past climate change is thus of crucial interest, but past biomass reconstruction still represents a challenge. Here we used transfer functions based on modern pollen assemblages and remotely sensed biomass estimation to reconstruct and quantify, for the last 14 000 years, tree biomass dynamics for the six main tree genera of the boreal and mixedwood forests (Abies, Acer, Betula, Picea, Pinus, Populus). We compared the mean genera and total biomass with climatic (summer temperatures and annual precipitation), physical (C[O.sub.2], insolation, ice area), and disturbance (burned biomass) variables to identify the potential drivers influencing the long-term trends in tree biomass. For most genera, tree biomass was related to summer temperature, insolation, and C[O.sub.2] levels; Picea was the exception and its biomass also correlated with annual precipitation. At the onset of the Holocene and during the Holocene Thermal Maximum (ca. 10 000-6000 BP), tree biomass tracked the melting of the Laurentide Ice Sheet with high values (>50 tonnes x [ha.sup.-1] and a total of 12 Pg). These values, in the range of modern forest ecosystems biomass, indicate that trees were probably able to survive in a periglacial environment and to colonize the region without any discernible lag by tracking the ice retreat. High biomass at the beginning of the Holocene was likely favoured by higher than present insolation, C[O.sub.2] levels higher than during the Last Glacial Maximum, and temperature and precipitation close to present-day levels. Past tree biomass reconstruction thus brings novel insights about the drivers of postglacial tree biomass and the overall biogeography of the region since the deglaciation. Key words: tree biomass, pollen, Last Glacial Maximum, Holocene, modern analogue technique, climate. Les ecosystemes forestiers de l'est du Canada sont particulierement sensibles aux changements climatiques et pourraient passer de puits a source de carbone dans les decennies a venir. Il est par consequent crucial de comprendre de quelle facon la biomasse forestiere a reagi aux changements climatiques passes. Cependant, la reconstitution de la biomasse passee represente encore actuellement un defi. Dans cette etude, nous avons utilise des fonctions de transfert developpees a partir d'assemblages modernes de pollen et d'estimations de la biomasse arboree aerienne issues de la teledetection afin de reconstituer et quantifier, pour les 14 000 dernieres annees, la dynamique de la biomasse des six principaux genres d'arbres (Abies, Acer, Betula, Picea, Pinus, Populus) des forets mixtes et boreales. Nous avons ainsi compare la biomasse moyenne de chaque genre et la biomasse totale des six genres a des variables climatiques (temperatures estivales et precipitation annuelle), physiques (C[O.sub.2], insolation, etendue de glace) et en lien avec les perturbations (biomasse brulee) afin d'identifier les facteurs potentiels qui influencent l'accumulation de biomasse a long terme. La biomasse des arbres etait, chez la plupart des genres, reliee a la temperature estivale, au degre d'insolation et au niveau de C[O.sub.2]; le genre Picea faisant exception, sa biomasse etant egalement correlee aux precipitations annuelles. Au debut de l'Holocene et durant le maximum thermique holocene (il y a environ 6000-10 000 ans), la biomasse des arbres a suivi la fonte de l'inlandsis laurentidien avec des valeurs elevees (>50 t x [ha.sup.-1] et un total de 12 Pg). Ces valeurs, qui correspondent a celles de la biomasse des ecosystemes forestiers modernes, indiquent que les arbres etaient probablement capables de survivre dans un environnement periglaciaire et de coloniser la region sans aucun decalage en suivant le retrait de la glace. Les valeurs elevees de la biomasse forestiere au debut de l'Holocene ont vraisemblablement ete favorisees par une insolation plus prononcee qu'actuellement, des niveaux de C[O.sub.2] plus eleves que durant le Dernier Maximum Glaciaire ainsi que des temperatures et des precipitations proches de l'actuel. La reconstruction de la biomasse passee des arbres apporte par consequent de nouvelles informations concernant les facteurs qui ont influence la construction de la biomasse forestiere durant la periode postglaciaire et sur la biogeographie generale de la region depuis la deglaciation. Mots-cles: biomasse des arbres, pollen, Dernier Maximum Glaciaire, Holocene, technique des analogues modernes, climat., 1. Introduction In eastern Canada, forests are particularly sensitive to climate change, and numerous factors may contribute to reversing their carbon sink capacity into a source such as, for example, [...]

Climate development models predict alterations that will critically influence plant metabolism in southern and central Europe. Although the molecular players involved in the response to climatic stress factors have been well described in crops, little information is available for forest tree species. Consequently, the identification of molecular biomarkers suitable for evaluating the actual impact of different environmental stress conditions on forest plants would be of great importance for monitoring purposes and forest management. In this study, we evaluated a biochemical methodology for the assessment of temperature stress in European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) seedlings by analyzing a set of metabolites and enzymes involved in free radical scavenging and cell wall synthesis. The results indicate that the combined analysis of the specific activities and isoform profile of peroxidases, superoxide dismutases, and glutathione peroxidases coupled with the amount variation of phenolic compounds enabled the discrimination between stressed and control seedlings. This approach represents a promising platform for the assessment of temperature stress in forest trees and could also enhance selection and breeding practices, allowing for plants more tolerant and (or) resistant to abiotic stress. Key words: abiotic stress, enzyme activity, forestry, peroxidase, temperature stress. Les modeles devolution du climat prevoient des changements qui auront une influence determinante sur le metabolisme des plantes dans le sud et le centre de l'Europe. Bien que les acteurs moleculaires impliques dans la reaction aux facteurs de stress climatiques aient ete decrits pour les cultures, il y a peu d'information disponible dans le cas des arbres. Par consequent, l'identification de biomarqueurs moleculaires adequats pour evaluer l'impact reel de differentes conditions environnementales causant un stress aux plantes forestieres serait d'une grande importance a des fins de suivi et d'amenagement forestier. Dans cette etude, nous avons evalue une methodologie biochimique pour l'estimation du stress du a la temperature chez des semis de hetre commun (Fagus sylvatica L.) et de pin sylvestre (Pinus sylvestris L.) en analysant un ensemble de metabolites et d'enzymes impliques dans le piegeage des radicaux libres et la synthese de la paroi cellulaire. Les resultats indiquent que l'analyse combinee de l'activite specifique et du profil isoforme des peroxydases, des superoxyde dismutases et des glutathion peroxydases, couplee a la variation de laquantite de composes phenoliques, permet de distinguer les semis stresses des semis temoins. Cette approche constitue une plateforme prometteuse pour evaluer le stress du a la temperature chez les arbres forestiers et pourrait aussi ameliorer les croisements et la selection visant a obtenir des plants tolerants ou resistants aux stress abiotiques. [Traduit par la Redaction] Mots-cles: stress abiotique, activite enzymatique, foresterie, peroxydase, stress du a la temperature., 1. Introduction Recent studies of global climate change suggest that there will be more intense, more frequent, and longer lasting heat in upcoming climate. For example, coupled models of climate [...]

We report estimates of the amount, distribution, and uncertainty of aboveground biomass (AGB) of the different ecoregions and forest land cover classes within the North American boreal forest, analyze the factors driving the error estimates, and compare our estimates with other reported values. A three-phase sampling strategy was used (i) to tie ground plot AGB to airborne profiling lidar metrics and (ii) to link the airborne estimates of AGB to ICESat-GLAS lidar measurements such that (iii) GLAS could be used as a regional sampling tool. We estimated the AGB of the North American boreal forest at 21.8 Pg, with relative error of 1.9% based on 256 GLAS orbits (229 086 pulses). The distribution of AGB was 46.6% for western Canada, 43.7% for eastern Canada, and 9.7% for Alaska. With a single exception, relative errors were under 4% for the three regions and for the major cover types and under 10% at the ecoregion level. The uncertainties of the estimates were calculated using a variance estimator that accounted for only sampling error, i.e., the variability among GLAS orbital estimates, and airborne to spaceborne regression error, i.e., the uncertainty of the model coefficients. Work is ongoing to develop robust statistical techniques for integrating other sources of error such as ground to air regression error and allometric error. Small ecoregions with limited east-west extents tended to have fewer GLAS orbits and a greater percent sampling error. AGB densities derived from GLAS agreed closely with the estimates derived from both forest inventories ( Key words: aboveground biomass, lidar, North American boreal forest, ICESat-GLAS, Landsat, MODIS, forest inventory, kNN. Nous presentons les estimations de quantite, distribution et incertitude de la biomasse aerienne de differentes regions ecologiques et de differentes classes de couverts forestiers en Amerique du Nord, analysons les facteurs controlant les erreurs d'estimation, et comparons nos resultats avec ceux de la litterature. Un dispositif d'echantillonnage en trois etapes a ete utilise (i) pour associer la biomasse mesuree dans des placettes d'inventaire aux profils de lidar aeroporte et (ii) pour relier les estimations lidar aeroporte de biomasse aux mesures d'ICESat-GLAS, de sorte que (iii) GLAS puisse etre utilise comme outil d'echantillonnage regional. A partir de 156 orbites GLAS (229 086 impulsions), nous avons estime la biomasse aerienne de la foret boreale d'Amerique du Nord a 21.8 Pg avec une erreur relative de 1.9 %. La distribution de la biomasse aerienne etait de 46.6 % pour l'ouest du Canada, 43.7 % pour l'est du Canada, et 9.7 % pour l'Alaska. Avec une seule exception, les erreurs relatives etaient inferieures a 4 % pour les trois regions et pour les principaux types de couvert, et inferieures a 10%a l'echelle des regions ecologiques. L'incertitude des estimations a ete calculee via un estimateur de variance qui a seulement pris en compte l'erreur d'echantillonnage, c'est-a-dire la variabilite entre les estimations orbitales de GLAS, et l'erreur de la regression de l'estimation aeroportee sur les mesures satellitaires, c'est-a-dire l'incertitude des coefficients du modele. Les travaux se poursuivent pour developper des techniques statistiques robustes pour integrer d'autres sources d'erreur telles que l'erreur de regression de l'estimation au sol sur l'estimation aeroportee et des erreurs allometriques. De petites regions ecologiques ayant une etendue est-ouest limitee ont generalement observe moins d'orbites GLAS et donc un pourcentage d'erreur d'echantillonnage plus eleve. Les densites de biomasse aerienne obtenues par GLAS correspondaient etroitement aux estimations derivees des inventaires forestiers ( Mots-cles : biomasse aerienne, lidar, foret boreale nord-americaine, ICESat-GLAS, Landsat, MODIS, inventaire forestier, kNN., Introduction Extending east to west across the entire continent, the North American boreal forest encompasses ~3.7 million [km.sup.2] of which ~58% is classified as forest and other wooded land (Brandt [...]

As fire is a major disturbance in boreal forests, it is now recognized that it has to be taken into account in forest management planning. Moreover, as the time of exposure to fire is related to stand productivity, combining information on productivity and fire should help in assessing the potential to sustainably manage forests. We present a method to assess potential vulnerability to the risk of fire and illustrate it in the boreal coniferous forest of Quebec. This method takes into account some sources of uncertainty related to the estimation of productivity and fire risk. Spatialization of stand productivity from growth and yield curves allowed us to compute the area comprised of productive stands of each district with or without considering fire risk. Results showed that productive area is generally decreasing with decreasing degree-days, increasing elevation, or in relation to surficial geology. Furthermore, districts with moderate to good productivity were found to be vulnerable to fire when burn rates were greater than 0.333% x [year.sup.-1]. Our innovative approach allowed us to assess the vulnerability of the districts to fire and could be helpful in many regions in the context of a projected increase in future area burned under climate change. Key words: fire, productivity, sustainable forest management, black spruce--moss forests, black spruce--lichen forests, mathematical bioeconomics. Le feu est considere comme etant une perturbation majeure en foret boreale. Il importe donc d'en tenir compte dans le processus de planification de l'amenagement forestier. De plus, comme le temps d'exposition des peuplements au feu est relie a leur productivite, le fait de combiner des donnees sur la productivite a celle du risque lie au feu devrait nous aider a evaluer le potentiel d'un territoire pour y pratiquer un amenagement forestier durable. Dans cet article, nous presentons une methode qui permet d'evaluer la vulnerabilite potentielle d'une region au risque relie aux feux de foret et nous l'illustrons en l'appliquant a la foret boreale coniferienne du Quebec. Cette methode prend en compte quelques elements d'incertitude lies a la productivite et a l'activite des feux. Nous avons spatialise la productivite des peuplements pour l'ensemble du territoire a l'etude, a partir des tables de rendement, de maniere a estimer, pour chaque secteur, la superficie occupee par des forets productives, en considerant ou non le risque relie au feu. Les resultats indiquent que la superficie des peuplements productifs decroit generalement avec une diminution du nombre de degres-jours et une augmentation de l'altitude ou selon les depots de surface. De plus, meme les secteurs ayant une productivite de moyenne a bonne sont juges comme etant vulnerables au feu lorsque leur taux de brulage excedent 0,333 % x [annee.sup.-1]. Notre approche innovatrice a permis d'evaluer le degre de vulnerabilite des differents secteurs par rapport au feu. Elle pourra aussi etre utile dans plusieurs regions ou, en raison des changements climatiques, nous pouvons prevoir un accroissement des superficies annuelles brulees. Mots-cles: feu, productivite, amenagement forestier durable, pessiere a mousse, pessiere a lichen, bioeconomie mathematique., Introduction In the softwood boreal forest, wildfires play a key role in shaping the forest landscape (Payette 1992; Johnson 1992; Bergeron et al. 2001, 2004; Price et al. 2013) by [...]

Boreal forests in northern Alberta have a growing anthropogenic footprint due to a rapidly growing oil sands mining industry. Although land reclamation is a necessary aspect of responsible industrial development, these activities nearly always affect higher order landscape components such as the broader landform, and its hydrology and biogeochemistry. Recent anthropogenic impacts are then believed to result in new environmental conditions and obstacles under which the boreal forest is developing, potentially leading to irreversibly different environments that could be characterized as novel ecosystems. Reflecting an emerging trend across the field of restoration ecology, these novel ecosystems are not necessarily undesirable. Instead, they are an unavoidable consequence of pervading anthropogenic effects on natural ecosystems. It is our view that successful reclamation outcomes can still be derived so long as policy and regulatory requirements are afforded the necessary scope and economic flexibility to account for the development of hybrid and novel ecosystems among highly disturbed mine sites. Hence, this analysis seeks to situate current and anticipated challenges affecting the reclamation of boreal forest following oil sands mining by describing (i) how regulatory criteria shape reclamation practices and targeted end goals and (ii) how these approaches embody latest trends and priorities in the area of restoration ecology. Key words: land reclamation, equivalent land capability, boreal forest, oil sands, novel ecosystems. Les forets boreales du nord de l'Alberta subissent une empreinte anthropique croissante due a l'expansion rapide de l'industrie des sables bitumineux. Alors que la rehabilitation des sites est un aspect essentiel d'un developpement industriel responsable, ces activites affectent presque toujours des composantes majeures du paysage telles que son relief, son hydrologie et sa biogeochimie. On suppose que les impacts anthropiques recents creent des conditions environnementales et des obstacles nouveaux pour le developpement de la foret boreale, ce qui pourrait mener a des environnements irreversiblement differents qui pourraient etre qualifies d'ecosystemes nouveaux. Refletant une tendance emergente en ecologie de la restauration, ces nouveaux ecosystemes ne sont pas necessairement indesirables. Ils sont plutot une consequence inevitable des effets anthropiques invasifs sur les ecosystemes naturels. Nous sommes d'avis que la rehabilitation des sites peut encore donner de bons resultats dans la mesure oU on accepte que les exigences politiques et reglementaires aient l'ampleur et la flexibilite economique necessaires pour prendre en compte le developpement d'ecosystemes hybrides et nouveaux dans des sites miniers hautement perturbes. Ainsi, cette analyse vise a identifier les defis actuels et anticipes de la rehabilitation de la foret boreale a la suite de l'exploitation des sables bitumineux en decrivant (i) la maniere dont les criteres reglementaires influencent les pratiques et les objectifs finaux de la rehabilitation et (ii) comment ces approches refletent les dernieres tendances et priorites en matiere d'ecologie de la restauration. [Traduit par la Redaction] Mots-cles : rehabilitation des sites, capacite equivalente des sites, foret boreale, sables bitumineux, ecosystemes nouveaux., 1. Introduction Canada's oil sands--a bitumen reserve equivalent to ~1.6 trillion barrels of oil within the Peace River, Cold Lake, and Athabasca River regions of northern Alberta (Fig. 1)--are a [...]

Empirical knowledge of long-term ecosystem response to single and compound disturbances is essential for predicting disturbance effects and identifying management practices to maintain productive capacity of managed and restored landscapes. We report on soil, foliar nutrition, and regeneration growth response to wildfire, clearcut harvesting, and postfire salvage logging, as well as undisturbed control stands within the first year following disturbance and 10-11 years after disturbance in trembling aspen--white spruce mixedwood forests near Lesser Slave Lake, north-central Alberta, Canada. The compound disturbance of salvage logging resulted in greater long-term impacts on forest floor properties than either wildfire or harvesting alone. Changes in forest floor properties such as carbon and nitrogen pools and cation exchange capacity under salvage logging have persisted for 10 years and exhibit a different recovery trajectory than fire or harvesting. Forest floor properties under harvesting, including depth, carbon content, pH, extractable ammonium, and extractable sulphur, were not different from the control condition 10 years after harvest. Effects on soil and foliar nutrition were not reflected in productivity (height and diameter) of regenerating vegetation. Our results show differences between short- and long-term responses to disturbance, among single natural and anthropogenic disturbances, and among single and compound disturbances. Key words: compound disturbance, salvage logging, soil carbon, soil nutrients, Boreal Plains Ecozone, boreal mixedwood forest. La connaissance empirique de la reponse des ecosystemes a des perturbations simples ou combinees est essentielle pour predire les effets et identifier les pratiques d'amenagement pour maintenir la capacite productive des paysages amenages et restaures. Nous rapportons les effets du feu, de la coupe totale et de la coupe de recuperation apres feu, ainsi que leur comparaison avec des sites non perturbes, sur les sols, la nutrition foliaire et la croissance de la regeneration, un an et 10-11 ans apres perturbation dans des forets mixtes de peuplier faux-tremble et d'epinette blanche pres de Lesser Slave Lake (centre-nord de l'Alberta, Canada). Par rapport au feu ou a la coupe, la coupe de recuperation apres feu, qu'on peut qualifier de perturbation combinee, a cause des impacts plus importants a long terme sur les horizons organiques de surface. Les changements dans les proprietes des horizons organiques, tels que les reservoirs de carbone et d'azote et la capacite d'echange cationique, ont persiste apres 10 ans, et montrent une trajectoire dans le temps differente de celles observees apres feu ou coupe. Dix ans apres perturbation, les proprietes des horizons organiques incluant l'epaisseur, le contenu en carbone, le pH et les concentrations en ammonium et soufre extractibles n'etaient pas differentes dans les sites coupes par rapport aux sites non perturbes. Les effets sur la nutrition des sols et des arbres ne se sont pas traduits par une plus grande productivite (hauteur et diametre) de la regeneration a ce stade precoce de la revolution du peuplement. Nos resultats montrent des differences entre la reponse a court et a long terme des ecosystemes suite a une perturbation, entre les perturbations d'origine naturelle et anthropique, et entre les perturbations simples et combinees dans les forets boreales mixtes de l'Ouest. Mots-cles: perturbation combinee, coupe de recuperation, carbone du sol, elements nutritifs du sol, Ecozone de la Plaine Boreale, foret boreale mixte., Introduction The western boreal mixedwood forest is experiencing an increasing anthropogenic footprint and an evolving suite of land-use pressures. It remains an important region of forest management for the sustainable [...]

Disturbances such as fire and harvesting shape forest dynamics and must be accounted for when modelling forest properties. However, acquiring timely disturbance information for all of Canada's large forest area has always been challenging. Therefore, we developed an approach to detect annual forest change resulting from fire, harvesting, or flooding using Moderate Resolution Imaging Spectroradiometer (MODIS) imagery at 250 m spatial resolution across Canada and to estimate the within-pixel fractional change (FC). When this approach was applied to the period from 2000 to 2011, the accuracy of detection of burnt, harvested, or flooded areas against our validation dataset was 82%, 80%, and 85%, respectively. With FC, 77% of the area burnt and 82% of the area harvested within the validation dataset were correctly identified. The methodology was optimized to reduce the commission error but tended to omit smaller disturbances as a result. For example, the omitted area for harvest blocks greater than 80 ha was less than 14% but increased to between 38% and 50% for harvest blocks of 20 to 30 ha. Detection of burnt and harvested areas in some regions was hindered by persistent haze or cloud cover or by insect outbreaks. All resulting data layers are available as supplementary material. Key words: boreal forest, National Burned Area Composite, remote sensing, regression tree, decision tree, change detection. Les perturbations telles que le feu et la coupe faconnent la dynamique forestiere et doivent etre prises en compte lorsqu'on modelise les proprietes de la foret. Cependant, l'acquisition rapide de l'information au sujet des perturbations pour l'ensemble des vastes superficies de foret du Canada a toujours presente un defi. Nous avons par consequent developpe une approche pour detecter les changements annuels de la foret dus au feu, a la coupe ou aux inondations en utilisant l'imagerie MODIS avec une resolution spatiale de 250 m partout au Canada et pour estimer le changement fractionnel (FC) a l'echelle du pixel. Lorsque appliquee a la periode allant de 2000 a 2011, la precision de la detection des superficies brulees, coupees ou inondees sur la base de notre jeu de donnees de validation atteignait respectivement 82,80 et 85%. Avec le FC, 77% des superficies brulees et 82% des superficies coupees ont ete correctement identifiees dans le jeu de donnees de validation. La methodologie a ete optimisee pour reduire les erreurs dues a la detection de faux changements avec le resultat cependant qu'elle a tendance a ne pas detecter les plus petites perturbations. Par exemple, les superficies non detectees pour les aires de coupe plus grandes que 80 ha etaient inferieures a 14%, mais atteignaient entre 38 et 50% pour les aires de coupe de 20 a 30 ha. La detection des superficies brulees et coupees etait difficile dans certaines regions du a la brume ou au couvert nuageux persistant, ou par les epidemies d'insecte. Toutes les couches de donnees resultantes sont disponibles dans la section Materiel supplementaire. [Traduit par la Redaction] Mots-cles: foret boreale, Composite nationale des superficies brulees, teledetection, arbre de regression, arbre de decision, detection de changement., Introduction The managed forests of Canada cover approximately 229 Mha (Environment Canada 2012). Much of this area is in the boreal forest, which is characterized by slow growth and significant [...]

There is considerable interest in understanding the repercussions of compaction and organic matter removal on soil quality and forest productivity. However, long-term field trials examining the effects of machinery and forest biomass removal on soil quality and stand regeneration are scarce. We present 20-31 years of tree growth results from four unique stump removal field trials. Each site had both treatments with varying amounts of organic matter removal (from tree stem harvesting to removal of tree stumps to loss of roots) and treatments with different levels of compaction due to site preparation machinery. Tree heights among the different treatments at midrotation were the same or taller than those with minimal organic matter removal and compaction. However, when stand development was evaluated using the quantity of tree volume for the given number of trees planted, treatment effects were clearly evident; tree volumes were significantly lower in compacted treatments, whereas organic matter removal did not appear to effect stand production. Although the sites were not directly comparable, when combined, the field trials provide insights to the possible implications of forest biomass harvesting on stand regeneration and overall forest soil quality. Key words: forest soil quality, compaction, organic matter removal, stumping, root rot. La comprehension des repercussions de la compaction et du prelevement de la matiere organique sur la qualite des sols et la productivite de la foret suscite un interet considerable. Cependant, il y a peu d'experiences a long terme sur le terrain qui portent sur les effets de la machinerie et du prelevement de la biomasse sur la qualite du sol et la regeneration des peuplements. Nous presentons des resultats de croissance des arbres provenant de quatre essais experimentaux particuliers 20 a 31 ans apres un dessouchage. Des traitements consistant a enlever differentes quantites de matiere organique (integrant successivement la recolte du tronc des arbres, le dessouchage et l'elimination des racines) ont ete appliques dans chacun des sites qui avaient aussi subis differents degres de compaction du sol par la machinerie utilisee pour la preparation du site. A mi-rotation la hauteur des arbres etait semblable dans les differents traitements ou plus grande que dans le traitement ou il y avait eu le minimum de prelevement de matiere organique et de compaction du sol. Cependant, lorsque le developpement du peuplement etait evalue en utilisant le volume des arbres pour un nombre donne d'arbres plantes, l'effet des traitements etait nettement visible : le volume des arbres etait significativement plus faible dans les traitements ou le sol avait ete compacte tandis que le prelevement de la matiere organique ne semblait pas avoir d'effet sur la production du peuplement. Bien que les sites ne soient pas directement comparables, lorsqu'ils sont combines les essais experimentaux donnent un apercu des consequences potentielles de la recolte de la biomasse forestiere sur la regeneration des peuplements et la qualite generale des sols forestiers. [Traduit par la Redaction] Mots-cles: qualite des sols forestiers, compaction, prelevement de la matiere organique, dessouchage, carie de racines., 1. Introduction Mechanization of the forest industry in North America increased through the 1940s, and this prompted a growing concern on the impacts of harvesting techniques on forest soil quality. [...]

In British Columbia, Canada, a recent epidemic of mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) caused widespread forest mortality. This epidemic was due in part to the changing climate, and damage from pests and diseases is expected to increase in the future. Therefore, we used a historical retrospective approach as a proxy to evaluate management options on reducing the forest health damage that may occur under a future changing climate. We assessed two landscape-scale strategies, intended to increase tree species diversity, for the response in ecosystem resilience and compared the results with the business-as-usual strategy. The assessment was based on simulation modelling of the Merritt Timber Supply Area for 1980-2060. We applied a strategy to increase the harvest of the most dominant tree species, plant more diverse species, and increase natural regeneration. This strategy resulted in greater ecological resilience (higher diversity and growing stocks), higher harvest rates, and higher, more consistent net revenue over time than the business-as-usual strategy or the strategy that only employed a diversity of planting. A sensitivity analysis indicated a high level of robustness in the results. Our study showed that it may not be necessary to compromise economic viability to reduce forest health risks and consequently improve socio-ecological resilience. Key words: resilience, adaptation, climate change, forest management, temperate forests, mountain pine beetle, landscape ecology, economic analysis, timber supply. En Colombie-Britannique, au Canada, une epidemie recente du dendroctone du pin ponderosa (Dendroctonus ponderosae Hopkins, 1902) a cause de la mortalite tres repandue dans les forets. Cette epidemie etait due en partie au changement climatique et les dommages causes par les insectes et les maladies devraient augmenter dans l'avenir. Par consequent nous avons eu recours a une retrospective historique comme substitut pour evaluer les options d'amenagement susceptibles de reduire les dommages a la foret qui pourraient survenir eventuellement a cause du changement climatique. Nous avons evalue deux strategies a l'echelle du paysage visant a augmenter la diversite des especes d'arbre pour augmenter la resilience de l'ecosysteme et nous les avons comparees a la strategie courante. devaluation a ete realisee a l'aide d'un modele de simulation de <> de 1980 a 2060. Nous avons applique une strategie consistant a accroitre la recolte des especes d'arbre les plus dominantes, a planter une plus grande diversite d'especes et a favoriser la regeneration naturelle. Avec le temps cette strategie a engendre une plus grande resilience ecologique (plus grande diversite et plus de matiere ligneuse sur pied), des taux de recolte plus eleves et un revenu net plus important et plus regulier que la strategie courante ou qu'une strategie se limitant a diversifier les plantations. Une analyse de sensibilite indiquait que les resultats avaient un haut degre de robustesse. Notre etude a montre qu'il est possible de reduire les risques pour la sante de la foret et consequemment ameliorer la resilience socio-ecologique sans necessairement compromettre la viabilite economique. [Traduit par la Redaction] Mots-cles: resilience, adaptation, changement climatique, amenagement forestier, forets temperees, dendroctone du pin ponderosa, ecologie du paysage, analyse economique, approvisionnement en bois., 1. Introduction Forest health surveys show that pests, drought, and disease are common events in forests. A changing climate is expected to contribute to increased losses of timber through a [...]

The International Boreal Forest Research Association (IBFRA) was founded in 1991 to foster pan-boreal research and facilitate communication of research results relating to this immense forest biome. The 16th IBFRA [...]