Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Shoot production and in vitro performance of Juglans nigra L and Quercus rubra L. was studied where 0, 3, 10, 30, or 100mM benzyladenine (BA) in a 20% white exterior latex paint diluted with deionized water were applied separately to 40 cm branch segments to determine the most effective concentration of benzyladenine on bud break and shoot growth. Softwood shoot production was maximized in the harvest months of March and April for J. nigra. Softwood shoot production was maximized in the harvest months of April and August for Q. rubra. Both shoot number and shoot length of softwood shoots decreased linearly with increasing BA concentrations applied to the branch segments of both species. Shoot production also decreased for both species during the dormant season September-December. The softwood shoots were surface disinfested and established on either 0 or 5µM Long Preece medium. When all BA treated softwood shoots were compared to the controls, the BA in the medium caused a significant increase in the number of shoots produced by explants obtained from the branch segments painted with BA. Painting with BA also increased shoot production in vitro, only if BA was also in the medium. Nodal explants cultured on 5µM LP medium taken from softwood shoots forced from branch segments painted with 3mM BA produced more shoots than any other BA concentration applied to branch segments except nodal explants on 5µM LP medium taken from softwood shoots forced from branch segments painted with 30mM BA.

Survival, growth and dieback, endogenous auxin and total non-structural carbohydrate (TNC) relations of underplanted northern red oak (Quercus rubra L.) seedlings were investigated. Greenhouse-grown red oak seedlings were subjected to 0, 63, or 92% shade and soil water potential was permitted to reach -0.3 or -2.0 MPa before rewatering. In a field study, underplanted northern red oaks were exposed to three levels of canopy removal (0, 70, or 90% residual canopy). White oak (Q. alba L.) and eastern white pine (Pinus strobus L.) were included in the field experiment for comparative purposes. In the greenhouse, dieback was observed under full sunlight and 92% shade but not in intermediate shading. In the field, dieback was greatest following complete canopy removal; but dieback was usually followed by rapid sprout growth and, as a result, average seasonal height increases generally were unaffected by light availability. Seasonal height increases were small (1-4 cm) and survival usually exceeded 90% in both the field and greenhouse. Field-grown white oaks displayed similar growth and dieback as red oaks. White pines grew 3 cm and 10 cm under 0 and 90% residual canopy, respectively. Final TNC leves from red oaks grown in drier soils and full sunlight were greater than seedlings grown under full shade and higher soil moistures (27 and 17% of total dry weight, respectively). Under full sunlight, as occur with complete canopy removal, dieback was probably related to internal moisture/temperature stress. Dieback under 92% shade was likely induced by carbohydrate depletion and weak, succulent growth resulting from the chronically low light levels. Thus, oak dieback appears to be a survival mechanism in which an advantageous root/shoot ratio is maintained and nutrients can be conserved. High or low TNC was not strongly related to dieback or sprout growth in this study. However, decreased TNC concentrations associated with increased shade indicated that long-term low light intensities may adversely affect growth and survival of red oak. Quantification of endogenous auxin in oak stems with gas chromatography was impossible due to low IAA levels (less than 0.8 uM) and small amounts of available tissue. Large amounts of IAA were found to be lost to sublimation when IAA was subjected to vacuum. / Ph. D.

Approximately five percent of the volume of red oak lumber which is harvested for use in the furniture and flooring industries in the United States is unusable due to surface checking. This thesis investigated the possibility of reducing surface checking by controlling the lumber boundary conditions. Boundary control was accomplished by applying a coating directly to the lumber surfaces.· The investigation included development of a computerized simulation to model drying behavior, testing a number of coatings to determine moisture loss resistance and evaluation of a coating using full-sized lumber tests. The results indicate a coating can be a viable method of reducing surface checking under severe drying conditions. / M.S.

No description available.

In the southern Appalachians, unforested openings known as balds persist on or near mountain peaks. These high elevation openings support a variety of unusual biota and are considered globally rare as a result of their biodiversity. Balds have historically been subject to both natural and human disturbances. Such historical and more recent disturbances have had a profound impact on vegetation dynamics in these systems. With the use of dendrochronology and GIS, this research project was aimed at 1) reconstructing the temporal and spatial patterns of tree encroachment into Craggy Gardens, a grass/heath bald, and determining the causal factors, and 2) investigating tree-growth responses of Quercus rubra L. to climatic factors at Craggy Gardens and Big Bald, North Carolina (high elevation forest-grass ecotones). Results indicate that historical grazing and land management have been responsible for vegetation changes at Craggy Gardens, in particular the advancement of Quercus rubra L. into the grass bald. Dendrochronological analyses showed that incremental growth of Quercus rubra L. growing in and adjacent to the balds was controlled by spring temperatures and drought conditions over most of the past century, until around 1970, when tree began responding primarily to growing year summer temperatures over the last four decades. This study concluded that land-uses overprinted on climatic conditions have governed local-scale vegetation structure over the past 150 years and without continuing management, trees may continue to advance into Craggy Gardens. Changing human disturbances along with observed climate changes in recent decades provides will most assuredly set the stage for future vegetation changes in southern Appalachians balds. / Master of Science

Anaerobic bacterial infection increases the proclivity of red oak lumber to develop surface, internal and end checks, and develop or aggravate ring failure during drying. It also extends the drying time. Bacterial infection is hard to identify before drying without the use of costly, time- consuming tests. Thus, there is a need for an inexpensive, rapid and accurate method for the identification that can be used at a mill. This research project investigated the possibility to use stress wave timing for the identification of bacterial infection, by studying the relationship of the level of bacterial infection and impact-induced stress wave travel time across the grain of green 4/4 red oak lumber from Southcentral Virginia. Bacterial infection increased stress wave travel time, but a considerable overiap existed between infected and uninfected boards. Tests on tensile strength perpendicular to grain, which is critical for lumber to check during drying showed a decrease in strength due to the bacterial infection. A parallel kiln- drying experiment, following a standard drying schedule (T4D2), showed more drying defects in the infected lumber than in the uninfected lumber. Defects were also more frequent in lumber with a long stress wave travel time than in lumber with a short stress wave travel time. / Master of Science

This research project investigated the upgrading of edging and trimming operations for red oak lumber through computer-aided optimization. The main objective was to evaluate how lumber value recovered by actual hardwood operations compare with the maximum value obtainable through the optimization of edging and trimming. An optimization procedure was developed involving the use of an iterative computer program for finding optimum edging and trimming solutions. The hardwood lumber grading program developed by Klinkhachorn et.al. [1988] was incorporated into the procedure. Comparison of results with actual values indicated that only 63% to 80%, approximately, of the maximum theoretical value was obtained in the sawmills studied. Edging and trimming optimizing systems equipped with scanners that provide only wane information have been successfully applied in softwood lumber manufacturing. The second part of this study investigated the lumber value recovery that can be expected if a similar system were applied to hardwood edging and trimming, i.e., if optimization were based only on wane input. Based on the output of a computer optimization program that maximizes volume yield subject to wane limitations, it was found that for red oak boards, an average value of approximately 80% of the optimum can be recovered through the application of this procedure. / Master of Science

The primary objective of this study was to assess the economic feasibility and profitability of the direct processing system for converting No.3 grade red oak logs into rough dimension parts. In the first part of this study, the cutting yields of green dimension parts and dollar value recovery from No.3 grade red oak logs by the direct processing system were estimated. A combination method of actual log sawing and simulated cutting was used to obtain the dimension yields. Two sawing patterns (live-sawing and five-part-sawing) and two cutting sequences (rip-first and crosscut-first) were tested for their effects on dimension yields, cutting lengths, and dollar value recovery. It was found that live-sawing resulted in significantly higher dimension yield than five-part-sawing. If followed by rip-first, live-sawing also resulted in higher dollar value recovery than five-part-sawing. Rip-first and crosscut-first has no significant differences in dimension yield, however, rip-first can recover more dollar value than crosscut-first if longer cuttings have higher value. The results of this study indicated that the combination of live-sawing and rip-first has the highest dimension yield and dollar value recovery if longer cuttings have higher value. In the second part of this study, the mill designs of the direct processing system for the various sawing patterns and cutting sequences were developed. The computer simulation/animation models for these designs were built using SIMAN IV/CINEMA. These models were used to predict the dynamic performances and production rates of the various mill designs. Based on simulation results, the direct processing system with one headrig saw can process from 17.8 to 20.5 MBF No.3 grade red oak logs and turn out 11 to 14.3 MBF Clear-two-face, 4/4 random width green dimension parts per shift. In the third part of this study, a financial analysis using discounted cash flow methods was conducted over a ten year planning horizon to determine the economic feasibility of the direct processing system that processes No.3 grade red oak logs directly into rough dimension parts. Under the assumptions of this study, measured by both Net Present Value (NPV) and Internal Rate of Return (IRR), all of the six designs evaluated are economically acceptable. With the highest NPV of $4,193,700 and the highest IRR of 29.6 percent, the design that uses live-sawing and rip-first with manual chop saws was found to be the most economically attractive selection. The profitability of the direct processing system, measured in ROS (Return on Sales), was estimated and compared with the reported profitability for the hardwood dimension and flooring industry. The results indicated that the direct processing system are more profitable than the conventional processing system for making dimension parts. The sensitivities of NPV and ROS to the changes in dimension part price, log price, labor cost, overhead cost, capital investment, weighting factor for part lengths, green cutting yield and drying and remanufacturing loss were analyzed. Dimension part price, green cutting yield and drying and remanufacturing loss were found to be the most important factors that affect the economic feasibility and profitability of the direct processing system. / Ph. D.

Le chêne rouge d’Amérique (Quercus rubra L.) est un arbre originaire d’Amérique du Nord et introduit en Europe à partir de la fin du XVIIème siècle pour l’ornementation et le commerce du bois. Le but de cette thèse est de comprendre les mécanismes écologiques et évolutifs qui contribuent à la dynamique et au succès de l’introduction de Q. rubra en Europe. Nous avons montré que cette espèce naturalisée et plantée dans certains pays européens parvient aisément à se développer de façon naturelle dans les forêts de feuillus et de conifères. La dispersion de ses glands est notamment rendue possible par des animaux fouisseurs-disperseurs, tels que les écureuils et les mulots, qui cependant préfèrent les glands du chêne natif Q. robur. Lors de l’introduction d’une espèce dans un nouvel environnement, des processus évolutifs sont susceptibles de se produire et d’engendrer des modifications phénotypiques et génétiques au sein des populations introduites. Une analyse comparative de la structure et de la diversité génétique des populations natives et introduites de Q. rubra a démontré que seulement deux des trois groupes génétiques de l’aire américaine sont actuellement présents en Europe. Aucun goulot d’étranglement fort n’a été détecté lors de l’introduction des populations en Europe laissant supposer que des introductions multiples ont pu maintenir la diversité génétique dans les populations introduites. Une analyse comparative des traits phénotypiques a permis de montrer que les populations introduites de Q. rubra présentent une croissance supérieure par rapport aux populations natives. Une différenciation génétique au sein des populations introduites est en cours pour le trait de débourrement foliaire suggérant une possible évolution adaptative rapide depuis l’introduction. / Northern Red Oak (Quercus rubra L.) is a tree native to North America and introduced in Europe at the end of the 17th century as an ornamental and forestry species. The aim of this dissertation is to understand the ecological and evolutionary mechanisms contributing to its dynamics and success in Europe. We demonstrated that this species naturalized and planted insome European countries can easily naturally grow in deciduous and conifer forests. Acorn dispersal away from mother-trees was made possible by scatter-hoarding animals such as squirrels and mice that take away acorns, although the animals still preferred acorns of the native oak Q. robur. During species introduction in a new environment, evolutionary processes can occurand lead to phenotypic and genetic changes. A comparative analysis of the genetic structure and diversity of Q. rubra populations from the native and introduced ranges demonstrated that onlytwo of the three genetic clusters encountered in North America are currently present in Europe.No strong bottleneck event was detected during the introduction of Q. rubra populations in Europe suggesting that multiple introductions could have maintained genetic diversity in introduced populations. A comparative analysis of phenotypic traits showed that introduced populations of Q.rubra present a higher growth compared to that of native populations. A genetic differentiation within European populations is on going regarding phenology of leaf budburst suggesting apossible rapid adaptive evolution since introduction.