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Silvicultural thinning can lead to rapid microclimatic changes for residual trees. Despite the benefits of decreased competition, thinning may induce 'thinning shock'--temporary negative physiological responses as trees acclimate to new conditions. We examined the impact of thinning on the microclimate and physiology of residual, previously shaded red spruce (Picea rubens Sarg.) trees relative to non-thinned controls. Both daily maximum temperature and vapor pressure deficit increased post thinning, with larger increases observed on hotter and drier days. In response to these environmental changes, we found clear evidence of physiological declines. At 1.7 weeks post thinning, we found a 0.59 MPa reduction in average midday water potential relative to control trees, which lasted for an additional 1.4 weeks. Thus, the trees in the thinning treatment were at or beyond published estimates of needle turgor loss. Thinning decreased the photosynthetic efficiency of current-year needles by 3.8% after 2 weeks, and it declined by 1.3% per week for the remainder of the growing season. These results suggest that thinning shock occurs in red spruce, a shade-adapted, climate-sensitive species. Thinning shock may contribute to the lagged growth responses commonly observed post thinning, and these effects may be more extreme in novel future climates. Key words: Picea rubens, water potential, silvicultural thinning, photosynthesis, microclimate, vapor pressure deficit, Introduction In the northeastern United States (US), climate change is driving warming and increasing the likelihood of extreme weather events (Vose et al. 2016; Karmalkar and Horton 2021). Average annual [...]

Eastern white cedar (Thuja occidentalis) and red spruce (Picea rubens) contribute to the biodiversity and resilience of mixedwood forests. However, cuts that remove most or all the forest cover can cause the decline of these species. Among partial cutting options, the irregular shelterwood system (ISS) can create successful conditions for the development of advance regeneration and enrichment planting. We studied 6 years of ecophysiology of lower advance regeneration and planted seedlings of eastern white cedar and red spruce growing under a first ISS cut according to three cutting intensities: light cut (35% removal, 20 [m.sup.2]*[ha.sup.-1] residual basal area), moderate cut (42%, 18 [m.sup.2]*[ha.sup.-1]), and heavy cut (52%, 15 [m.sup.2]*[ha.sup.-1]). Light-saturated photosynthesis and height growth of planted cedar and both spruce types decreased with increasing cutting intensity, in response to an increase in competing vegetation. Therefore, to limit the negative impact of competing species on cedar and spruce regeneration, we recommend protecting tall advance regeneration (2 m+) during partial cut operations and using large-sized containerized seedlings (40-50 cm height) for enrichment planting. Results also suggest that a mechanical release could help optimize the physio-morphology and growth of both regeneration types of cedar and red spruce. Key words: continuous cover forestry, declining species, ecological silviculture, enrichment planting, natural regeneration, uneven-aged management Le thuya occidental (Thuja occidentalis) et l'epinette rouge (Picea rubens) contribuent a la biodiversite et a la resilience des forets mixtes. Cependant, les coupes qui suppriment la majeure partie ou la totalite du couvert forestier peuvent entrainer le declin de ces especes. Parmi les options de coupe partielle, le procede de regeneration par coupes progressives irregulieres (CPI) peut creer des conditions favorables au developpement de la regeneration preetablie et a la plantation d'enrichissement. Nous avons etudie pendant 6 ans l'ecophysiologie de la basse regeneration preetablie et de semis plantes de thuya occidental et d'epinette rouge poussant sous une premiere CPI selon trois intensites de coupe: coupe legere (35% de prelevement, 20 [m.sup.2]*[ha.sup.-1] de surface terriere residuelle), coupe moderee (42%, 18 [m.sup.2]*[ha.sup.-1]) et coupe forte (52%, 15 [m.sup.2]*[ha.sup.-1]). La photosynthese sous lumiere saturante et la croissance en hauteur du thuya plante et des deux types d'epinette ont diminue avec l'augmentation de l'intensite de la coupe, en reponse a une augmentation de la vegetation concurrente. Par consequent, pour limiter l'impact negatif des especes concurrentes sur la regeneration du thuya et de l'epinette, nous recommandons de proteger la regeneration preetablie de grande taille (2 m+) pendant les operations de coupe partielle et d'utiliser des semis en conteneur de grande taille (40-50 cm de hauteur) pour la plantation d'enrichissement. Les resultats suggerent egalement qu'un degagement mecanique pourrait contribuer a optimiser la physio-morphologie et la croissance des deux types de regeneration de thuya occidental et d'epinette rouge. Mots-cles : foresterie a couvert permanent, especes en declin, sylviculture ecologique, plantation d'enrichissement, regeneration naturelle, amenagement inequienne, Introduction The temperate mixedwood forest of Quebec (Canada) represents a rich, diversified, and complex ecosystem providing many economic and ecological services to society. Located in the balsam fir (Abies balsamea [...]

Black spruce (Picea mariana (Mill.) BSP) is the main tree species growing within peatlands. The difficult growing conditions within peatlands are associated with low individual wood productivity, and only tree species tolerant to high ground water level can survive. We examine the effect of water-saturated soil on the growth potential of black spruce trees and specific adaptation of the root system. Experimental mesocosms were constructed with two drainage regimes (saturated and well-drained soil conditions). We measured biomass, height, and diameter at stem base of 55 black spruce saplings and noted the location of each horizontal root. Black spruce exhibited a very shallow root system located above saturated commercial peat 19 years after the experiment was initiated. Most roots were adventitious in the water- saturated mesocosms. Overall aerial and root biomass accumulation of the black spruce trees growing under saturated soil conditions was significantly lower than that of the well-drained mesocosms. Interestingly, root-shoot ratios were similar across the two drainage regimes. Soil conditions induced adaptation of the root system in black spruce trees, and physiological stress affected the entire individual with lower biomass productivity in all components (stem, branches, root system). However, biomass distribution remained similar to that of trees growing in well-drained mesocosms. Key words: peatland, black spruce, root system, adventitious root, biomass, root-shoot ratio. L'epinette noire (Picea mariana (Mill.) BSP) est la principale espece d'arbre poussant dans les tourbieres. Les conditions de croissance difficiles dans les tourbieres sont associees a une faible productivite du bois, et seules les especes d'arbres tolerantes aux niveaux eleves de la nappe phreatique peuvent survivre. Nous examinons l'effet d'un sol sature en eau sur le potentiel de croissance des epinettes noires et l'adaptation specifique du systeme racinaire. Experimental mesocosms were constructed with two drainage regimes (saturated and well-drained soil conditions). Nous avons mesure la biomasse, la hauteur et le diametre a la base du tronc de 55 gaules d'epinette noire et note l'emplacement de chaque racine horizontale. L'epinette noire presentait un systeme racinaire tres peu profond situe au-dessus de la tourbe commerciale saturee, 19 ans apres le debut de l'experience. La plupart des racines etaient adventives dans les mesocosmes satures d'eau. L'accumulation globale de biomasse aerienne et racinaire des epinettes noires poussant dans des conditions de sol sature etait significativement plus faible que celle des mesocosmes bien draines. Il est interessant de noter que les ratios racinespousses etaient similaires pour les deux regimes de drainage. Les conditions du sol ont entraine une adaptation du systeme racinaire chez l'epinette noire, et le stress physiologique a affecte l'ensemble de la plante avec une baisse de la productivite de la biomasse dans toutes les composantes (tige, branches, systeme racinaire). Cependant, la distribution de la biomasse est restee similaire a celle des arbres poussant dans des mesocosmes bien draines. [Traduit par la Redaction] Mots-cles : tourbiere, epinette noire, systeme racinaire, racine adventive, biomasse, rapport racines-pousses., Introduction Extensive peatlands occur in Canada, accounting for more than 13% of its terrestrial surface. They are mostly located (more than 85%) northward of the 51st parallel in the boreal [...]

Our objective was to study how changes in the light spectra affect growth; the concentration of carbohydrate, chlorophyll, carotenoid, terpene, alkaloid, and phenolic compounds; and the emissions of BVOC (biogenic volatile organic compound) of Norway spruce (Picea abies (L.) Karst.) seedlings. This study was conducted during the growth of the third needle generation in plant growth chambers. The plants were exposed to two light spectra with equal photon flux densities but different proportions of blue light (400-500 nm) produced by LED (light-emitting diode) lamps: (i) control (white light +12% blue light) and (ii) increased blue light (+B) (white light + 45% blue light). The +B treatment increased the concentrations of total flavonoids and acetophenones in needles. The major changes in the phenolic profile were an accumulation of astragalin derivatives and the aglycone of picein. The +B treatment also decreased concentrations of the main alkaloid compound, epidihydropinidine, and its precursor, 2-methyl-6-propyl-1,6-piperideine; the emission rates of limonene, myrcene, and total monoterpenes; and the concentrations of a few terpenoid compounds, mainly in stems. Growth as well as the carbohydrates and pigments present in the needles were not affected. The results suggest that supplemental blue light shifts carbon allocation between secondary metabolism routes--from alkaloid and terpenoid synthesis to flavonoid and acetophenone synthesis. The changes may affect herbivory and abiotic stress tolerance of Norway spruce. Key words: blue light, Norway spruce, biogenic volatile organic compounds, phenolic compounds, alkaloids. Notre objectif consistait a etudier de quelle facon les changements dans le spectre lumineux influencent la croissance, la concentration des hydrates de carbone, de la chlorophylle, des carotenoides, des terpenes, des alcaloides et des composes phenoliques, ainsi que les emissions de composes organiques volatiles biogeniques chez des semis d'epicea commun (Picea abies (L.) Karst.). Cette etude a ete effectuee en phytotrons durant la croissance des aiguilles de troisieme generation. Les plants ont ete exposes a deux spectres lumineux avec une densite egale du flux photonique qui se distinguaient principalement par la proportion de lumiere bleue (400-500 nm) produite par des lampes a DEL (diode electroluminescente) : (i) temoin (lumiere blanche + 12 % de lumiere bleue) et (ii) plus forte proportion de lumiere bleue (+B) (lumiere blanche + 45 % de lumiere bleue). Le traitement +B a augmente la concentration totale des flavonoides et des acetophenones dans les aiguilles. L'accumulation de derives de l'astragaline et de l'aglycone de la piceine est le changement majeur observe dans le profil des composes phenoliques. Le traitement +B a aussi reduit la concentration du principal compose alcaloide, l'epidihydropinidine et son precurseur, la 2-methyl-6-propyl-1,6-piperideine, les taux d'emission du limonene, du myrcene et des monoterpenes totaux, ainsi que la concentration de quelques composes terpenoides, principalement dans la tige. La croissance, ainsi que les pigments et les hydrates de carbone presents dans les aiguilles n'ont pas ete modifies. Les resultats indiquent que le supplement de lumiere bleue modifie l'allocation du carbone vers les sentiers metaboliques secondaires, de la synthese des alcaloides et des terpenoides vers la synthese des flavonoides et des acetophenones. Ces changements pourraient avoir un impact sur la tolerance de l'epicea commun aux herbivores et aux stress abiotiques. [Traduit par la Redaction] Mots-cles : lumiere bleue, epicea commun, composes organiques volatiles biogeniques, composes phenoliques, alcaloides., Introduction Quality and quantity of light are primary factors affecting plant germination, morphogenesis, growth, reproduction, and defence. Several photoreceptors participate in perceiving different wavelengths of light, such as phototropins and [...]

Phyllosphere microbial communities have received considerable attention given their important influence on their plant hosts and on ecosystem functioning. In a context where climate change threatens the sustainability of ecosystems, it is important to understand how phyllosphere microbes will respond to changes in their environment. We used 16S rRNA gene amplicon sequencing to quantify phyllosphere bacterial communities of black spruce (Picea mariana (Mill.) B.S.P.) exposed to nitrogen canopy enrichment and soil warming in the boreal forest of Quebec, Canada. The treatments were applied from April to September 2015 and the sampling was done in September. Neither treatment influenced the overall community structure and diversity of black spruce phyllosphere bacterial communities. However, some bacterial taxa and inferred microbial functions did differ among treatments, revealing in particular a stronger response of some bacteria to soil warming rather than nitrogen enrichment. Our results suggest that soil warming could potentially induce more changes in phyllosphere bacterial taxa abundances and functions than could nitrogen addition, with potential consequences for microbial diversity and boreal forest ecosystem function under likely climate change scenarios. Our study suggests avenues for further research to integrate a more mechanistic understanding of the importance of phyllosphere microbes for black spruce and boreal forest ecosystems. Key words: phyllosphere, nitrogen, soil warming, black spruce, climate changes. Les communautes microbiennes de la phyllosphere ont suscite un interet considerable compte tenu de l'influence significative qu'elles exercent sur les plantes hotes et sur le fonctionnement de l'ecosysteme. Dans un contexte oU le changement climatique menace la durabilite des ecosystemes, il est important de comprendre de quelle facon les microbes de la phyllosphere vont reagir aux changements dans leur environnement. Nous avons utilise le sequencage du produit de l'amplification du gene codant pour l'ARNr 16S pour quantifier les communautes bacteriennes de la phyllosphere de l'epicea noir (Picea mariana (Mill.) B.S.P.) en presence d'un apport d'azote dans le couvert forestier et d'un rechauffement du sol dans la foret boreale du Quebec, au Canada. Les traitements ont ete appliques du mois d'avril au mois de septembre 2015 et l'echantillonnage a ete realise en septembre. Aucun des traitements n'a globalement influence la structure ni la diversite des communautes bacteriennes de la phyllosphere de l'epicea noir. Cependant, certains taxons bacteriens et par consequent certaines fonctions bacteriennes differaient selon le traitement, revelant en particulier que certaines bacteries reagissaient plus fortement au rechauffement du sol qu'a l'apport d'azote. Nos resultats indiquent que le rechauffement du sol pourrait induire plus de changements dans les fonctions et l'abondance des taxons bacteriens de la phyllosphere que l'apport d'azote, et possiblement avoir des consequences sur la diversite microbienne et la fonction de l'ecosysteme de la foret boreale compte tenu des scenarios probables de changement climatique. Notre etude suggere des avenues futures de recherche pour integrer une comprehension plus mecaniste de l'importance des microbes de la phyllosphere pour l'epicea noir et les ecosystemes de la foret boreale. [Traduit par la Redaction] Mots-cles : phyllosphere, azote, rechauffement du sol, epicea noir, changements climatiques., Introduction Phyllosphere microbial communities, the microorganisms living on aerial plant surfaces including leaves (Lindow and Brandl 2003), have recently received considerable attention due to the various impacts they can have [...]

Most hypotheses about controls over high-altitude forests, including treeline, the elevation for upright woody plants, or timberline, the upper elevation for aggregated forest, suggest that low temperature drives forest dynamics, either through effects on cell division and tree growth or indirectly through frost damage or nutrient availability. However, abiotic factors other than temperature, including water availability, may serve as other important controls at high elevations, particularly for seedlings. To test the hypothesis that the timing and amount of precipitation exerts a strong control over the high-elevation forest boundary on the Wasatch Plateau in central Utah, USA, we conducted a field experiment that manipulated water availability and monitored photosynthesis, growth, and survivorship in Picea engelmannii Parry ex Engelm. seedlings. Survivorship increased from the driest to the wettest conditions, whereas the timing of precipitation did not explain differences in survival. However, we found that large, infrequent rain events increased maximum photosynthetic flux density compared with small, frequent rain events. Our results highlight the potential role of growing season water availability in limiting timberline expansion below the low-temperature thermal limits of P. engelmannii. As a consequence, the infilling of trees below the treeline in this region in response to climate change is likely to be episodic and driven by multiyear periods of high water availability and frequency that overcome drought limitations. Key words: treeline, hydrology, Picea engelmannii, photosynthesis, survivorship. La plupart des hypotheses concernant les controles sur les forets de haute altitude, incluant la limite des arbres, l'altitude a laquelle on retrouve encore des plantes ligneuses dressees, ou la limite de vegetation des arbres, l'altitude superieure a laquelle il y a encore de la foret, indiquent que la basse temperature determine la dynamique forestiere, soit en ayant des effets sur la division cellulaire et la croissance des arbres, soit indirectement a cause des dommages dus au gel ou de la disponibilite des nutriments. Cependant, des facteurs abiotiques autres que la temperature, incluant la disponibilite en eau, pourraient etre d'importants facteurs alternatifs de controle a haute altitude, particulierement pour les semis. Pour tester l'hypothese que le moment et la quantite de precipitation exercent un controle significatif sur la limite de la foret a haute altitude sur le plateau des Wasatch dans le centre de l'Utah, aux Etats-Unis, nous avons realise une experience sur le terrain dans laquelle nous avons manipule la disponibilite en eau et suivi la photosynthese, la croissance et la survie des semis de l'epicea d'Engelmann (Picea engelmannii Parry ex Engelm.). La survie augmentait en passant des conditions les plus seches aux plus humides tandis que le moment des precipitations n'expliquait pas les differences dans la survie. Cependant, nous avons trouve que des episodes peu frequents de forte pluie ont augmente la densite du flux photosynthetique maximum comparativement a des episodes frequents de faible pluie. Nos resultats font ressortir le role potentiel de la disponibilite en eau durant la saison de croissance qui limiterait l'expansion de la limite de vegetation des arbres en deca des limites thermiques de temperature minimale de l'epicea d'Engelmann. En consequence, le recrutement des arbres en deca de la limite des arbres dans cette region en reponse au changement climatique sera probablement episodique et determine par des periodes de plusieurs annees de disponibilite en eau elevee et a une frequence qui surmonte les restrictions imposees par la secheresse. [Traduit par la Redaction] Mots-cles: limite des arbres, hydrologie, Picea engelmannii, photosynthese, survie., Introduction Renewed interest in upper treeline dynamics is, in part, driven by the hope that these systems will help us understand how ecosystems will respond to climate change (Harsch et [...]

Within dry inner Alpine environments, climate warming is expected to affect the development of forest ecosystems by changing species composition and inducing shifts in forest distribution. By applying dendroecological techniques we evaluated the climate sensitivity of radial growth and the establishment of Picea abies (L.) Karst. in a drought-prone mixed-coniferous forest in the Austrian Alps. Time series of annual increments were developed from >220 trees and assigned to four age classes. While radial growth of old P. abies trees (mean ages of 121 and 174 years) had highly significant responses to May--June precipitation, young trees (mean ages 28 and 53 years) were insensitive to precipitation in the current year. Because tree age was closely correlated to height and diameter ([r.sup.2] = 0.709 and 0.784, respectively), we relate our findings to the increase in tree size rather than age per se. The synchronicity found among trends in basal area increment and tree establishment suggests that canopy openings increased light and water availability, which favoured growth and establishment of moderately shade-tolerant P. abies. We conclude that, although P. abies is able to regenerate at this drought-prone site, increasing inter-tree competition for water in dense stands gradually lowers competitive strength and restricts scattered occurrence to dry--mesic sites. Resume: Dans les milieux intra-alpins secs, le rechauffement climatique devrait avoir un effet sur le developpement des ecosystemes forestiers en modifiant la composition en especes et en induisant des changements dans la distribution des forets. A l'aide de techniques dendroecologiques, nous avons evalue l'impact du climat sur la croissance radiale et l'etablissement du Picea abies (L.) Karst. dans une foret melangee de coniferes sujette a la secheresse dans les Alpes autrichiennes. Des series temporelles d'accroissements annuels ont ete construites a partir de plus de 220 arbres et assignees a quatre classes d'age. Tandis que la croissance radiale des vieilles tiges du P. abies (age moyen de 121 et 174 ans) reagissait de facon tres significative aux precipitations durant les mois de mai et juin, les precipitations de l'annee courante n'avaient aucun effet sur les jeunes tiges (age moyen de 28 et 53 ans). Etant donne que l'age des arbres etait etroitement correle a la hauteur et au diametre ([r.sup.2] = respectivement 0,709 et 0,784), nous attribuons nos resultats a l'augmentation de la taille des arbres plutot qu'a l'age en soi. La synchronicite observee entre l'evolution de l'accroissement en surface terriere et celle de l'etablissement des arbres indique que les ouvertures dans le couvert forestier ont augmente la disponibilite de la lumiere et de l'eau, ce qui a favorise la croissance et l'etablissement du P. abies, une essence moderement tolerante a l'ombre. Nous concluons que, bien que le P. abies soit capable de se regenerer dans cette station sujette a la secheresse, la competition croissante entre les arbres pour l'eau dans les peuplements denses reduit graduellement la competitivite et confine l'occurrence sporadique aux stations seches a mesiques. [Traduit par la Redaction], Introduction Climate sensitivity of tree growth and establishment will affect the development of forest ecosystems under a warmer and drier climate by changing species composition and inducing shifts in forest [...]

Jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) total stem volume increment and vertical growth distribution after thinning were quantified and related to foliage biomass, foliage density, and growth efficiency (GE) (stem to foliage biomass ratio). Significant positive stem volume increments were observed following thinning for jack pine (3 years after) and black spruce (4 years after). Both species reacted differently in terms of the distribution in specific volume increments (SVI) (annual stem volume increment to cambial surface ratio): (i) for jack pine, an increase in SVI was first observed at the base of the tree, with the increase moving upwards, showing that the taper was likely to increase following thinning and (ii) for black spruce, the vertical distribution of SVI was constant, leading to no modifications in stem taper. For jack pine, total stem volume growth was related to an increase in GE and a greater foliage biomass at midcrown, with foliage density staying constant. For black spruce, however, no changes in GE, foliage biomass, and foliage mass density were observed. Resume: L'accroissement total du volume de bois de la tige et la distribution de cette croissance le long de la tige du pin gris (Pinus banksiana Lamb.) et de l'epinette noire (Picea mariana (Mill.) B.S.P.) ont ete quantifies apres une eclaircie et relies a la biomasse foliaire, la densite foliaire et l'efficacite de croissance (EC) (rapport de la biomasse de bois de la tige sur la biomasse foliaire). Le volume de bois de la tige du pin gris et de l'epinette noire s'est accru de facon significative, respectivement 3 et 4 ans apres l'eclaircie. Des differences ont ete observees entre les especes dans l'accroissement specifique en volume (ASV) (rapport de l'accroissement annuel du volume de bois de la tige sur la surface cambiale): (i) dans le cas du pin gris, l'accroissement a commence a la base de la tige et s'est propage vers le haut indiquant que le defilement etait susceptible d'augmenter a la suite de l'eclaircie et (ii) dans le cas de l'epinette noire, l'ASV a ete plut?t constant tout au long de la tige, ce qui n'a pas beaucoup modifie son defilement. Chez le pin gris, la croissance totale de la tige etait reliee a une augmentation de l'EC et a une plus grande biomasse foliaire a mi-cime, la densite foliaire demeurant inchangee. Par ailleurs, aucun changement dans l'EC, la biomasse foliaire et la densite de la masse foliaire n'a ete observe chez l'epinette noire. [Traduit par la Redaction], Introduction Thinning forest stands can induce a sudden increase in resource availability for the residual trees (Aussenac 2000), leading to physiological and morphological modifications such as increases in stem volume [...]

In forestry, science-based seed transfer systems, the foundation of effective reforestation programs, will likely be used in some form to mitigate the negative effects of climate change. In this study, we developed fixed and focal point seed transfer systems for interior spruce (Picea glauca (Moench) Voss, Picea engelmannii Parry ex Engelm., and their hybrids) in British Columbia, Canada, and compared the effectiveness of both systems. Growth, phenology, and physiology traits were measured for 112 populations, and population means were transformed to principal components that were modeled using climate variables and multiple regression analysis. Compared with the fixed seed zone system, the focal point system had a greater area of seed use for a given risk of maladaptation. The relationship between growth and adaptive distance (i. e., adaptive similarity between test populations and populations local to test sites) was used to calculate critical seed transfer distances for focal point seed zones, which were defined according to expected forfeiture of growth. Changes in climate observed over the past 100 years and predicted in the next one third of a rotation were used to calculate appropriate assisted migration distances and develop methods for incorporating assisted migration into a focal point seed transfer system. Resume: etant le fondement de programmes efficaces de reboisement en foresterie, les systemes de transfert de semences qui reposent sur des donnees scientifiques seront probablement utilises sous une forme ou une autre afin d'attenuer les effets negatifs des changements climatiques. La presente etude avait pour but de developper des systemes de transfert des semences bases sur les points fixes et focaux pour l'epinette de l'interieur (Picea glauca (Moench) Voss, Picea engelmannii Parry ex Engelm. et leurs hybrides) en Colombie-Britannique, au Canada, et de comparer l'efficacite des deux types de systeme. Des caracteres relies a la croissance, la phenologie et la physiologie ont ete mesures chez 112 populations et les moyennes de populations ont ete transformees en composantes principales qui ont ete modelisees a l'aide des variables climatiques et de l'analyse de regression multiple. Comparativement au systeme de zones semencieres base sur les points fixes, le systeme a points focaux produisait de plus grandes zones d'utilisation des semences pour un risque donne de mesadaptation. La relation entre la croissance et la distance reliee a l'adaptation (c.-a-d. la similitude d'adaptation entre les populations d'elevage et les populations locales en reference aux sites experimentaux) a ete utilisee pour estimer les distances critiques de transfert des semences pour les zones semencieres basees sur les points focaux, telles que definies selon la baisse anticipee de croissance. Les changements climatiques observes durant les 100 dernieres annees et predits pendant le premier tiers de la revolution ont ete utilises pour estimer les distances appropriees de migration assistee et pour developper des methodes qui incorporent la selection assistee au systeme de transfert des semences base sur les points focaux., Introduction Climate change is expected to result in forests becoming increasingly maladapted in many regions as the climates they experience depart from the climates in which they evolved (Schmidtling 1994; [...]

The effects of depth, size, location, and season of artificial logging damage on increment and decay of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) trees were studied in long-term experiments in central Finland. Damage types applied were root damage, root collar damage, increment borer hole, and stem damage. In root collar and stem damages, two sizes (100 or 400 [cm.sup.2]) and depths (shallow or deep) were applied. Five to 20 years after damaging, the damages did not result in a decrease in radial, height, or volume increment. In Norway spruce, the frequency of decay in the root collar and stem damages was high. From large and deep damages, decay spread faster than from smaller and shallow ones. In Scots pine, a lower proportion of trees were decayed compared with Norway spruce. Increment coring resulted in decay in most of the trees, but the decay spread slowly. The effect of compass direction or the month of damaging was negligible. The most common decay fungus in Norway spruce was Stereum sanguinolentum (Alb. & Schwein. Fr.:) Fr. In Scots pine, only nondecay fungi were isolated. In general, logging damages decreased sawlog production through the rejection of butt logs containing decay or discoloration. Les effets de la profondeur, de la dimension et de la localisation de blessures artificielles d'exploitation, ainsi que de la saison durant laquelle les blessures ont ete causees, sur l'accroissement et la carie de l'epicea commun (Picea abies (L.) Karst.) et du pin sylvestre (Pinus sylvestris L.) ont ete [Traduit par la Redaction], Introduction In the early 1960s, the intensity of thinnings in practical forestry increased mainly because of the mechanization of terrain transport of timber. In Finland, the current silvicultural practice consists [...]