Ecosystem-specific forest management requires comprehension of tree species productivity in managed settings, and how this productivity varies with the ecological determinants of site quality, i.e., the environmental factors that directly affect the growth of plants: light, heat, soil moisture, soil nutrients, and soil aeration. A good understanding of this variation is necessary for making species- and site-specific silvicultural decisions to maximize productivity. Productivity of a given species is usually measured by site index (tree height at 50 years at breast height age). Quantitative relationships between site index and these measures of site quality provide predictive models for estimating site index. Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in the coastal forests of British Columbia. In relation to climate, its range in southwestern British Columbia extends from sea level to almost timberline, and from the hypermaritime region on western Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. In relation to soils, its range extends from slightly dry to wet sites and from very poor to very rich sites. In view of this relatively wide climatic amplitude, a large variability in productivity can be expected. It is particularly important to consider the growth performance of Pacific silver fir when decisions are made regarding whether or not to cut stands on high-elevation sites. In the study summarized here, relationships between Pacific silver fir site index and selected ecological measures of site quality were examined, and site index models using these measures as predictors were developed.

This study examines the influence of climate on tree-ring properties of several major tree species: Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and lodgepole pine (Pinus contorta var. latifolia Dougl. ex Loud.). Our three objectives were to determine how (1) tree-ring properties change along an elevation gradient, (2) short-term climatic influences are correlated with tree-ring properties, and (3) long-term climatic influence on tree-ring properties.

The Mountain Hemlock (MH) zone includes all subalpine forests along British Columbia’s coast. It occurs at elevations where most precipitation falls as snow and the growing season is less than 4 months long. The zone includes the continuous forest of the forested subzones and the tree islands of the parkland subzones (Figure 1). Old-growth stands are populated by mountain hemlock, Pacific silver fir, and Alaska yellow-cedar, and are among the least-disturbed ecosystems in the world. Canopy trees grow slowly and are commonly older than 600 years, while some Alaska yellow-cedars may be up to 2000 years old. Understanding regeneration patterns in the MH zone has become increasingly important as logging continues towards higher elevations of the zone where snowpacks are deeper.

Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in coastal forests of B.C. Its range extends from sea-level to almost timberline, and from the hypermaritime region on the west coast of Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. With this relatively wide climatic amplitude, a large variability in the height growth pattern of Pacific silver fir can be expected, since climate is considered to be the most influential determinant of the trajectory of height over age of forest trees. This variability, however, is not reflected in the height growth curves and site index tables used to estimate Pacific silver fir site index, since the curves and tables were developed from low-elevation stands on Vancouver Island. Consequently, when these curves and tables are applied to high-elevation or submaritime stands, we get biased estimates of site index. Accurate estimates of site index are necessary for accurate yield predictions. Furthermore, they are essential for making rational decisions about whether to cut the forest in situations where potential tree growth is marginal, such as in high-elevation forests.

Le changement climatique (CC) actuel, très rapide, va imposer aux espèces de faire évoluer leurs traits d’histoire de vie ou leur aire de répartition. En raison de leur long cycle reproductif, les arbres pourraient ne pas avoir la capacité à s’adapter suffisamment vite et leur aptitude à la migration devrait être déterminante. Les vitesses de colonisation des essences forestières lors de l'holocène ont fortement été revues à la baisse aux cours de la dernière décennie (quelques centaines contre quelques centaines de m/an). Dans ce contexte et en s'appuyant sur le sapin pectiné (Abies alba Mill.) en tant qu'espèce modèle nous avons étudié les principaux facteurs conditionnant l'aptitude à la migration. A partir de placettes de régénérations situées sur la face nord du Mont Ventoux, nous avons estimé la dispersion et le recrutement du sapin, en intégrant les sources de graines et les principales caractéristiques environnementales. La dispersion a également été estimée à partir de données génétiques. Dans les deux cas, les distances de dispersion sont de l’ordre du décamètre. La diversité génétique et l'évolution démographique ont été étudiées au sein de la régénération de sapins afin de tester l'hypothèse de purge de consanguinité. L'espèce présente en effet un régime de reproduction mixte, et la part d'autofécondation, à laquelle s'ajoute la reproduction entre individus consanguins, est à l’origine de l'excès d’homozygotie observé généralement dans la régénération, excès diminuant avec l’âge sous l’action d'une probable purge des individus les plus homozygotes. Les semis étudiés ne présentent pas un fort excès d’homozygotie, néanmoins, les individus les plus homozygotes meurent préférentiellement. Enfin, un modèle de dynamique forestière intégrant les processus, qui contrôlent la migration, a été implémenté afin d'évaluer la compatibilité entre la migration des espèces à long cycle de vie et le CC. Les premiers résultats de nos simulations indiquent que le sapin n’est pas capable de migrer aussi vite que s’opère le réchauffement. / Current climate change (CC), really fast, will impose species to change their history life traits or their distribution range. Trees may not be able to adapt because of their long reproductive cycles hence their potentialities of migration is decisive. Past tree migration rates, during Holocene, were revised in downward these rates (several decameters against several hundred m/year). In this context, and focusing on silver fir (Abies alba Mill.) as “model species”, we studied main factors decisive for migration potentialities. Using regeneration plots, installed on Mont Ventoux north face, silver fir dispersal and seedling recruitment have been studied, including seed sources and main environmental characteristics. Dispersal was also estimated using genetic data. For both cases, dispersal distances are of the order of decameters. This species shows a mixed mating system, and auto-fertilization rate, plus reproduction between half-sibs, induces homozygosity excess, generally observed in regeneration, this excess decreases probably under the purge of inbred individuals. Our results show that seedlings do not have show homozygosity excess, however inbred seedlings die preferentially. Lastly, we constructed a model of forest dynamics that includes processes that determine migration, in order to evaluate the concordance between long life cycle species and CC. Our results show that silver fir does not migrate as fast as climate warming velocity.

1 Abstract Forests are the native Central European vegetation, which have dominated in the landscape for the last c. 10,000 years. Stands with an oak and hornbeam dominance occupied lower elevations before human colonization, beech and silver fir-beech forests middle elevations and spruce stands at higher elevations. Only a few remnants of forests, which can be regarded as primeval or with a minimal impact of forest management, have survived in densely populated Central Europe. Examples of the most preserved primeval forests are Rothwald (Austria), Białowieża (Poland, Belorussia), Stužica/Stuzhytsia (Slovakia, Ukraine) and Boubín (Czech Republic). Although these sites are small and isolated, they are local diversity centers for many organisms, mainly for fungi, lichens and bryophytes, refugia for numerous endangered species and some of them have their last localities there. Epiphytic and epixylic lichens are an ideal model group for studies about forests because they sensitively indicate management, continuity, heterogeneity and age of a woodland. Therefore they could help us to answer many important questions about the conservation of natural forests. This thesis comprises several different points of view on lichens in Central European forests and its aim is to join these heterogeneous fields into one...

Les sous-produits qui proviennent de l’industrie du bois, particulièrement les nœuds, contiennent différents types de molécules qui peuvent être valorisées comme source de composants bioactifs pouvant répondre à des besoins thérapeutiques. C’est sur cette idée que le projet "Le Bois Santé" a été conçu. Grâce à la collaboration de plusieurs partenaires, le présent travail vise dans un premier temps à développer des procédés d’extraction "verts" (solide-liquide et supercritique) pour obtenir un extrait riche en lignanes à partir d’un mélange de nœuds d’épicéa commun et de sapin pectiné. Les effets des conditions opératoires sur le rendement d’extraction de chaque composé cible et sur l’activité anti-oxydante des extraits ont été déterminés. Afin d’étudier le procédé complet, le projet vise à étudier l’impact des procédés de concentration et de séchage de l’extrait à partir de l’évaporation sous vide et de la lyophilisation. De plus, la séparation et la purification des composés ont été développées et optimisées par simulation grâce à la technique de chromatographie frontale / By-products from wood industry, particularly knots, contain different types of molecules that can be valued as a source of bioactive components meeting therapeutic needs. It is on this idea that the project "Le Bois Santé" was designed. Through the collaboration of several partnerships, the present work aims initially to develop a "green" extraction processes (solid-liquid and supercritical) to obtain an extract rich in lignans from a mixture of norway spruce and silver fir knots. The effects of operating conditions on the extraction yield of each target compound and the antioxidant activity of the extracts were determined. To understand the entire process, the project aims to investigate the impact of concentration and drying processes using vacuum evaporation and lyophilisation. Moreover, the separation and purification of the compounds have been developed and optimized using frontal chromatography technique