La tomographie par rayons X permet un accès direct aux caractéristiques internes des billons scannés par l'intermédiaire des variations de densité et de teneur en eau. L'objectif de ce travail est de démontrer la faisabilité de la détection automatique de caractéristiques dans des billons à des fins d'analyses scientifiques. Nous disposons pour cela d'une base d'images tomographiques de 24 épicéas communs (Picea abies (L.) Karst.) obtenues avec un scanner médical. Les arbres sont représentatifs de différents statuts sociaux et proviennent de quatre peuplements du nord-est de la France, eux-mêmes sont représentatifs de plusieurs classes d'âge, de densité et de fertilité. Les procédures de détection développées sont les suivantes : - détection de la moelle dans les billons, y compris en présence de nœuds et/ou d'excentricité des cernes. La précision de la localisation est inférieure au millimètre ; - détection de la limite aubier/duramen dans les billons, y compris en présence des nœuds (principale source de difficulté). L'erreur sur le diamètre du duramen est de 1.8mm soit une erreur relative de 1.3%. ; - détection de la localisation des verticilles et une comparaison à une méthode optique ; - détection des nœuds individualisés. Cette procédure permet de compter les nœuds dans un billon et de les localiser (hauteur dans le billon et azimut); cependant, la validation de la méthode et l'extraction du diamètre et de l'inclinaison des branches reste à effectuer. Une application de ce travail a été l'analyse de la variabilité de la quantité d'aubier dans le tronc: en intra-arbre, la largeur d'aubier était constante sous la base du houppier; en inter-arbre, une forte corrélation avec la quantité de branches vivantes a notamment été mise en évidence. De nombreuses analyses sont envisageables à partir des résultats de notre travail, parmi lesquelles: l'étude architecturale des arbres avec le suivi de la moelle dans les billons et l'occurrence des prises de relais sur l'axe principal, l'analyse des variations radiales de la forme du duramen, l'analyse de la distribution des nœuds dans les billons.

<p>Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, ¹³C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ¹³C, and above and below ground abiotic conditions. In both forests, variation in δ¹³C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ¹³C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ¹³C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ¹³C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ¹³C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.</p>

Mechanical pulping for producing pulps from softwood suitable for printing grade papers, like news, is a highly energy-intensive process consuming around 2000 kWh/t in electrical energy. Due to increasing energy costs and environmental issues there is a high demand for decreasing this energy consumption. The mechanical treatment of wet wood pieces in a refiner, in the mechanical pulp plant, is a complex mechanical loading. This is a process occurring between rotating discs at high speed and temperatures of 140 °C - 160 °C, where by means of shear and compression forces the fibres are separated and then made flexible, fibrillated and collapsed for good bonding ability. In this process also fines are created giving the optical properties of the paper. In mechanical pulping only a fraction of the applied energy is used for the structural changes of the wood material. Thus fundamental studies of the loading modes of wood under refining conditions and in particular under combined shear and compression loading are desired to gain more information regarding the possibility of affecting the mechanical pulping in an energy efficient way. The possibilities to study the behaviour of wood under a combined shear and compression load were in this thesis investigated using two methods: the Iosipescu shear test and the Arcan shear test. In both apparatus different combinations of shear and compression load were achieved by different rotations of the shear test device itself. Measurements with the Iosipescu device on a medium density fibreboard showed good agreement between experimental results and numerical simulations. Finite element analysis on wood showed, however, that with the use of a homogeneous material in the model the level of strain reached would be ten times smaller than experimentally measured. This fact is probably due to the honeycomb structure of the wood cells that allows for different local deformations that could not be represented by a continuous material model. Thus to study the deformations on the fibre level of wood an experimental equipment that uses smaller samples was needed. With a modified Arcan shear device such deformations under combined shear and compression load and in pure compression were possible showing different deformation patterns. During pure compression the cell walls bend in a characteristic “S” shape, independently of the shape of the fibre cells and their cell wall thickness. Under combined shear and compression, however, mainly the corners of the fibre cells deform giving a “brick” shape to the cells. In a second deformation performed in compression, the fibre cells follow the same deformation pattern as given by the first deformation type whether in compression or in combined shear and compression. The interpretation is that permanent defects in the cells themselves are introduced already in the first load cycle of the wood samples. The energy used under the different loading conditions showed that the first deformation required the largest amount of energy, for all loading conditions. The deformation in compression required larger amounts of energy than the deformation in combined loads. For subsequent deformations less energy was needed for compression if a combined load had preceded it. Due to the fact that less energy is needed to start to deform wood in combined load than under compression load, the application of a combined load as a first cycle may thus be a way to permanently deform fibres using less energy. To investigate the critical parameters determining the permanent deformation of cells, a finite element model of a network of twelve cells was developed. Special care was given to the material properties to study how the variation of the fibril angle in the different layers affects the deformation pattern of the wood fibres under the different loading conditions. The model shows that whether modelled as homogeneous linear isotropic material or as an orthotropic material defined for every layer of the cells wall, no difference in the deformation of the network of the fibres was achieved. It is probable that the deformation type is more determined by the geometry of the fibres themselves than by their material properties / QC 20101005

The effect of steady shear stress on somatic embryos were investigated in a flow chamber and evaluated at different time intervals using microscopy technique. The development of meristematic cell clusters, i.e. the immature embryos, into a polarized somatic embryo, and the effect on the localization of the suspensor cells that form during development of the immature embryos, were studied as a function of shear stresses. With the distribution and growth rate of the meristematic and suspensor cells, the effect of stress on the embryo development was established. Furthermore, the effect of shear stress on the cells at molecular level, the reaction of integrin-like proteins, the production of reactive oxygen species and the pore size of the cell walls involved in the shear stress responses, were investigated with molecular techniques. In general, shear stress inhibits meristematic cells growth. Meristematic cells grow fastest at shear rate of 86 s-1 among all the tested shear stress conditions. By combining the results of meristematic cells growth and suspensor cells formation, it suggests that there is a critical shear rate between 86 and 140 s-1, at which no suspensor cells form. The unidirectional flow with different shear stresses helps the polarized growth and the unidirectional alignment of suspensor cells. Reactive oxygen species and integrin-like protein are detected in the stressed cells as cellular responses to shear stresses. By monitoring the pore size and uptake time of cells to macromolecules with solute-exclusive experiments, it suggests that the stressed cells expedite the response to plasmolyzing components that are used to induce maturation treatment thus affect the response to maturation stimuli.

<p>The interactions between plants and insects are mediated by volatile molecules. Plants respond to stress by biosynthesis of chemical substances which can deter invading insects or pathogens. Some of these substances are volatile and are emitted to the surroundings and may attract or repel insects. Information about the susceptibility of individual plants to infestation, their volatile emissions and chemical defence is of interest, for example in selecting plants for tree breeding programs.</p><p>This research was focused on finding volatile chemical markers of resistance in Norway spruce plants that do influence insects associated to conifers. Collection of headspace volatiles by SPME followed by separation and identification with GC-MS is effective in investigating biological systems with a minimum of disturbance. This method has here been used to investigate Norway spruce plants of different ages and stress conditions as well as trapping semiochemicals like nepetalactone emitted by the spruce shoot aphids. It was even possible to analyse the emission of single needles <i>in vivo</i> and obtain a chemical pattern of the site of the stress reaction. Seedlings of different ages showed differences in chemical composition of emitted volatiles, with the pine weevil repellent (<i>S</i>)-(-)-limonene as one of the main compounds. Wounded phloem of conventional plants emitted high amounts of monoterpenes while the phloem of mini plants emitted (3Z)-hexenal and (3Z)-hexen-1-ol.</p><p>Norway spruce plants did respond to different stress elicitors with similar response, regardless of their genetic origin. The emissions from stressed Norway spruce plants mainly consist of (<i>E</i>)-β-farnesene, (<i>E,E</i>)-α-farnesene, (<i>E</i>)-α-bisabolene, (<i>R</i>)-(-)-linalool and methyl salicylate. Emissions from live spruce shoot aphids were detected during autumn periods, and a method to separate and identify the four diastereomers of nepetalactone by GC-MS and characteristic m/z-fragments was accomplished.</p>

Thesis (M.S.)-Oregon State University, 1975. / Typescript (photocopy). Includes bibliographical references (leaves 120-127). Also available via the Internet.

Final Report / Contract on 43-8371-4-628 / For: USDA, Forest Service, Southwestern Region / Regional outbreaks of western spruce budworms (Choristoneura occidentalis Freeman) have recurred at least three times in northern New Mexico since the early 1920's when the U. S. Forest Service first began systematic forest-pest surveys and documentation (Lessard 1975, U. S. Forest Service documents). The current outbreak was first noticed in a small area on the Taos Indian Reservation in 1974, and since then the defoliated areas have increased in New Mexico and Arizona to more than 370,000 acres of Federal, Indian, State and private lands (Linnane 1984). Losses in timber values can generally be ascribed to radial growth loss, height growth loss, topkilling, reduced regeneration, and mortality (Carlson et al. 1983, Fellin et al. 1983). A damage assessment project was initiated in 1978 and was aimed at obtaining measurements of some of these losses in budworm infested stands on the Carson National Forest, New Mexico (Holland and Lessard 1979). A large data base has subsequently been developed, including yearly measurements on topkilling, mortality, defoliation, and insect population changes (Stein 1980, 1981, Stein and McDonnell 1982, Rogers 1984). A growth assessment study was undertaken in 1982 to determine the feasibility of using dendrochronological methods to identify the timing of past outbreaks and to quantify radial growth losses associated with budworm defoliation (Swetnam 1984). Results of this work showed that three major outbreaks during the twentieth century were clearly visible in the tree-ring samples obtained from currently infested trees. The radial growth of host trees was corrected for age, climate and other non-budworm environmental effects, and then growth losses were computed as a percentage of expected growth (Swetnam 1984). Additional collections were obtained in 1984 in order to expand the scope of the radial growth study. The objectives included 1) assessment of a larger number of tree -ring samples, 2) comparison of radial growth losses between the two primary host species - Douglas-fir (Pseudotsuga menziesii) and white fir (Abies concolor), 3) comparison of radial growth losses between age classes, and 4) analysis of the relationship between yearly measurements of defoliation, insect populations and radial growth. This report summarizes the findings of the above analyses. Increment core samples from the 1982 collections are included here, therefore this report supersedes the earlier report (Swetnam 1984). Information is also presented on observations derived from the dated tree-ring series on the timing of occurrence of known and inferred spruce budworm outbreaks for the past 284 years (1700- 1983). This is the longest record of spruce budworm occurrence yet developed for western North America.

When making decisions on which areas to harvest in a sustained yield, even-flow manner in mountainous areas such those in coastal British Columbia, it is important to know how timber productivity changes with elevation. This information allows foresters to decide at what elevation to start increasing the rotation age and to decide at what elevation sustainable harvesting becomes infeasible due to low productivity. Since Pacific silver fir (Abies amabilis Dougl. ex Forbes) has an elevation range that extends from sea level nearly to the tree line (0 m to approximately 1,650 m; from the Coastal Western Hemlock zone, through the Mountain Hemlock zone; to the lower limits of the Alpine Tundra zone), productivity-elevation relationships are especially important. To acquire quantitative measures of productivity decrease with increasing elevation a regression equation relating site index (the height of the dominant trees at a base age of breast height age of 50 years) to elevation in southern coastal BC was developed. In turn, we used this regression as an input into the height driven yield model named the Variable Density Yield Prediction model (VDYP). The use of the VDYP model allows the site index values to be translated into actual productivity measures (e.g., volume per hectare, mean annual increment at culmination age).

Magistro darbe tiriama kai kurių medelyno ekologizavimo priemonių įtaka paprastosios eglės (Picea abies (L.) H. Karst.) sodmenų augimui, vystimuisi, išlikimui, išeigai, dirvožemiui. Darbo objektas – vienerių metų paprastosios eglės sėjinukai ir 2+1 sodinukai bei sideralinis pūdymas. Darbo tikslas – ekologizuoti miško medelyną, pakeičiant mineralines trąšas organinėmis. Darbo metodai – literatūros loginė analizė, apskaitos aikštelių metodas; matematinės statistikos metodai. Darbo rezultatai. Paprastosios eglės sodmenų (pirmamečių sėjinukų ir 2+1 sodinukų) biometrinių požymių matavimai rodo, kad tręšimas kompostu, pagamintu iš mėšlo ir durpės, naudojant 50 ir 100 t ha-1 komposto normas yra netikslingas, nes sodmenims neužtikrinamas pakankamas mitybos lygis. Eglės sodmenis tikslinga tręšti 150 t ha-1 ir didesne komposto norma. Ši tręšimo norma sąlygoja panašius, kaip ir tręšiant mineralinėmis trąšomis, daugelio sodmenų antžeminės ir požeminės dalies biometrinius matavimus (augalų aukštį, šaknies kaklelio skersmenį, šoninių pumpurų skaičių, spyglių ilgį, pagrindinės šaknies ilgį, pirmos eilės šoninių šaknų skaičių). Dažniausiai biometriniai eglių sodmenų parametrai yra mažesni, nei mineralinėmis trąšomis tręštų sodmenų, tačiau skirtumai nėra esminiai. Eglės sodinukų, tręštų 150 t ha-1 komposto norma metinis aukščio prieaugis buvo 10 proc. patikimai mažesnis, nei tręštų mineralinėmis trąšomis sodinukų. Geriausiai eglės sėjinukai ir sodinukai augo dirvožemį patręšus 150 t ha-1... [toliau žr. visą tekstą] / The master thesis examined some of the nurseries’ ecology tools impact on simple spruce (Picea abies (L.) H. Karst.) planting stock cultivation, growth, survival, stocks yield, soil. Object of the work – first year seedlings and first year sapling of simple spruce and sideralic lea. The aim of work – to assess ecological organic fertilizer (green manure and compost) usage impact on simple spruce planting stock growth. Methods of the work – logical analysis of the literature, method of accounting sites, methods of mathematical statistics. The results of the work. Simple spruce planting stocks’ (first year seedlings and first year sapling) biometric features measurements demonstrate that fertilization with compost, made from dung and peat, with 50 and 100 t ha-1 compost rate is pointless, as sufficient nutritional level is not ensured for spruce planting stocks. Spruce planting stocks are appropriate to fertilize with 150 t ha-1 and a higher compost rate. This results in similar fertilization rate, as the fertilization with mineral fertilizers, the biometric measurements of many saplings in surface and underground part (plant height, root neck diameter, lateral bud number, spine length, main root length, the number of lateral root in first order). Frequently the biometric parameters of spruce planting stocks are lower than fertilized with mineral fertilizers, but the differences are not essential. The annual growth of spruce saplings, fertilized with 150 t ha-1 compost rate was... [to full text]

Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.