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Conceptual models of wood formation suggest that trees with large crowns produce low quality wood, but few studies have explicitly examined the relationship between crown size and wood quality. In this study, I examine how crown size influences the strength and stiffness of wood, as measured by Modulus of Elasticity (MOE) and Modulus of Rupture (MOR), using 42- and 72-old year plantation white spruce (Picea glauca) from Ontario, Canada. Mechanical properties were determined from 10x10x140 mm mini-clear samples (n=657), selected from a radial gradient at three heights within the stems. Non-linear mixed-effects models showed that strength and stiffness significantly decreased with crown size, and that MOE and MOR were best predicted by cambial age and crown ratio. The results suggest that the models could be used in conjunction with remotely sensed data to identify high quality timber prior to harvest.

Conceptual models of wood formation suggest that trees with large crowns produce low quality wood, but few studies have explicitly examined the relationship between crown size and wood quality. In this study, I examine how crown size influences the strength and stiffness of wood, as measured by Modulus of Elasticity (MOE) and Modulus of Rupture (MOR), using 42- and 72-old year plantation white spruce (Picea glauca) from Ontario, Canada. Mechanical properties were determined from 10x10x140 mm mini-clear samples (n=657), selected from a radial gradient at three heights within the stems. Non-linear mixed-effects models showed that strength and stiffness significantly decreased with crown size, and that MOE and MOR were best predicted by cambial age and crown ratio. The results suggest that the models could be used in conjunction with remotely sensed data to identify high quality timber prior to harvest.

The heritability of microfibril angle (MFA) in loblolly pine, Pinus taeda L., and its genetic relationships with height, diameter, volume and specific gravity were examined in two progeny tests with known pedigrees. Significant general combining ability (GCA), specific combining ability (SCA), and SCA x block effects indicated that there are both additive and non-additive genetic influences on MFA. Individual-tree narrow-sense heritability estimates were variable, ranging from 0.17 for earlywood (ring) 4 MFA to 0.51 for earlywood (ring) 20 MFA. Genetic correlations between MFA, specific gravity and the growth traits were non-significant due to large estimated standard errors. Multiple-trait selection and breeding in a mainline and elite population tree improvement program were simulated using Excel and Simetar (Richardson 2001). The effects of four selection indices were examined in the mainline population and the effects of seven selection indices and four breeding strategies were examined in the elite population. In the mainline population, selection for increased growth caused decreased wood quality over time. However, it was possible to maintain the overall population mean MFA and mean specific gravity at levels present in the base population by implementing restricted selection indices. Likewise, selection for improved wood quality in the elite population resulted in decreased growth unless restricted selection indices or pulp indices derived from those of Lowe et al. (1999) were used. Correlated phenotypic responses to selection on indices using economic weights and heritabilities were dependent on breeding strategy. When a circular mating system (with parents randomly assigned to controlled-crosses) was used, the index trait with a higher economic weight was more influential in determining correlated responses in non-index traits than the index trait with a lower economic weight. However, when positive assortative mating was used, the index trait with a greater variance was more influential in determining correlated responses in non-index traits than the index trait with a lower variance regardless of economic weight.

This thesis is a study of the kiln drying of radiata pine with a primary focus on the change in wood colour that occurs during this process. The energy efficiency of the drying process has also been examined using computer modelling. The aim of this work was to develop guidelines for commercial wood dryers who wish to produce high quality appearance grade timber in a competitive commercial environment. The colour change in radiata pine wood during kiln drying is mainly caused by sap compounds accumulating at the wood surface and reacting to form coloured compounds. The initial research involved drying experiments designed to determine the relationship between this colour change and the kiln schedule and also measure the accumulation of colour forming compounds. The kinetics of the colour change reaction were also measured using two methods, one in-vitro and the other using small samples of wood. From these experiments a colour change equation was developed that predicts the rate of colour formation based on the drying conditions and this was incorporated into a kiln stack model along with an energy efficiency model. The combined model was used to simulate the drying process to find schedules optimised for energy use and wood quality. The model was also used to simulate the energy efficiency of different humidity control configurations for wood drying kilns. A kiln micro-sensor system was also developed for use in kiln diagnostics and control with the particular aim of identifying areas in wood drying kilns with adverse drying conditions. The recommendation to kiln operators wishing to reduce colour change is to not exceed 70? and to use lower relative humidity schedules with a wet bulb depression of 15-20?. Operating at lower humidity can increase the energy used by the kiln so it is also recommended that kiln designers incorporate heat recovery into the humidity control mechanisms of the kiln.

Orientador: Elias Taylor Durgante Severo / Coorientador: Fred Willians Calonego / Banca: Cláudio Angeli Sansígolo / Banca: João Vicente de Figueiredo Latorraca / Resumo: A madeira de Hevea brasiliensis é considerada uma fonte importante de renda após o ciclo produtivo do látex. Porém, as tensões de crescimento e a madeira de reação apresentam-se como entrave para a indústria de transformação e de processamento de madeira. Assim, o objetivo desta pesquisa foi avaliar os níveis de tensões de crescimento e verificar a influência da temperatura de vaporização de toras na qualidade do desdobro da madeira de Hevea brasiliensis. Para tanto foram utilizados pé franco da árvore Hevea brasiliensis com 53 anos de idade nas quais foram verificados os níveis de tensões de crescimento. Posteriormente, a vaporização ocorreu à 54,4±4,1ºC, 74,5±3,9ºC e 91,8±3,0ºC, com umidade relativa de 100%, por 36 horas. Durante todo o tratamento as toras tiveram a sua temperatura monitorada através do uso de termopares. Em seguida as toras foram desdobradas pelo sistema de corte tangencial e medições dos defeitos decorrentes das tensões de crescimento foram realizadas, com o intuito de avaliar o efeito do tratamento de vaporização. Foi ainda realizada uma análise anatômica macroscópica e microscópica com o intuito de comprovar a existência da madeira de reação e verificar o comportamento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The wood of Hevea brasiliensis is considered an important source of income after the production cycle of the latex. However, the growth stress and wood reaction are presented as an obstacle to the processing industry and wood processing. Thus, the objective of this research was to evaluate the levels of growth stresses and the influence of logs steaming in the quality of the sawing wood of Hevea brasiliensis. Therefore, we used ungrafted tree Hevea brasiliensis with 53-year-old were checked in which the levels of growth stresses. Later, the vaporization occurred at 54,4±4,1ºC, 74,5±3,9ºC e 91,8±3,0ºC, with relative humidity of 100%, for 36 hours. Throughout the treatment the logs have its temperature monitored by thermocouples. Then the logs were sawing by the system tangential and measurements of defects resulting from growth stresses were realized in order to assess the treatment effect of vaporization. Was also realized macroscopic and microscopic anatomical analysis in order to prove the existence of reaction wood and verify the behavior of this. The results show that: the species presents a longitudinal residual strain average of 0,099 mm and there isn't significant difference of strain between the trees, however, the four cardinal positions around the stem assessed, due to wind action, the values differed significantly; vaporization promoted the relief 4 of growth stresses and the temperature of steam... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:30:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-31Bitstream added on 2014-06-13T18:40:22Z : No. of bitstreams: 1 pelozzi_mma_me_botfca.pdf: 1675035 bytes, checksum: 8156804b674ddb057e91341a41780010 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A madeira de Hevea brasiliensis é considerada uma fonte importante de renda após o ciclo produtivo do látex. Porém, as tensões de crescimento e a madeira de reação apresentam-se como entrave para a indústria de transformação e de processamento de madeira. Assim, o objetivo desta pesquisa foi avaliar os níveis de tensões de crescimento e verificar a influência da temperatura de vaporização de toras na qualidade do desdobro da madeira de Hevea brasiliensis. Para tanto foram utilizados pé franco da árvore Hevea brasiliensis com 53 anos de idade nas quais foram verificados os níveis de tensões de crescimento. Posteriormente, a vaporização ocorreu à 54,4±4,1ºC, 74,5±3,9ºC e 91,8±3,0ºC, com umidade relativa de 100%, por 36 horas. Durante todo o tratamento as toras tiveram a sua temperatura monitorada através do uso de termopares. Em seguida as toras foram desdobradas pelo sistema de corte tangencial e medições dos defeitos decorrentes das tensões de crescimento foram realizadas, com o intuito de avaliar o efeito do tratamento de vaporização. Foi ainda realizada uma análise anatômica macroscópica e microscópica com o intuito de comprovar a existência da madeira de reação e verificar o comportamento... / The wood of Hevea brasiliensis is considered an important source of income after the production cycle of the latex. However, the growth stress and wood reaction are presented as an obstacle to the processing industry and wood processing. Thus, the objective of this research was to evaluate the levels of growth stresses and the influence of logs steaming in the quality of the sawing wood of Hevea brasiliensis. Therefore, we used ungrafted tree Hevea brasiliensis with 53-year-old were checked in which the levels of growth stresses. Later, the vaporization occurred at 54,4±4,1ºC, 74,5±3,9ºC e 91,8±3,0ºC, with relative humidity of 100%, for 36 hours. Throughout the treatment the logs have its temperature monitored by thermocouples. Then the logs were sawing by the system tangential and measurements of defects resulting from growth stresses were realized in order to assess the treatment effect of vaporization. Was also realized macroscopic and microscopic anatomical analysis in order to prove the existence of reaction wood and verify the behavior of this. The results show that: the species presents a longitudinal residual strain average of 0,099 mm and there isn’t significant difference of strain between the trees, however, the four cardinal positions around the stem assessed, due to wind action, the values differed significantly; vaporization promoted the relief 4 of growth stresses and the temperature of steam... (Complete abstract click electronic access below)

The quality of whole-tree wood chips has been the focus of much attention during the past few years because of the increased use of lower grade wood über in pulp production. The need to up-grade the quality has resulted in the use of some form of screening system to separate acceptable wood chips from unwanted material at most pulp mills. In order to upgrade the chip quality, a study was conducted to determine the effect of selected parameters of a separation system with an inclined, vibrating screen on screening efficiency. The parameters studied included screen aperture size and frequency of oscillation. Two screen sizes (3/8 and 1/4 inch apertures) and four different frequencies (1.25, 1.50, 1.75, and 2.00 Hertz) were considered. All other shaker unit parameters were held constant. Statistical analysis revealed that the lowest frequency resulted in the highest screening efficiencies for both the pin chips and fines categories. Screening efficiencies were higher with 3/8 inch screen as opposed to 1/4 inch screen, for all frequencies considered, but at 1.25 Hertz, the screening efficiency of fines was only 6 percent better with 3/8 inch screen. This analysis revealed that the lowest acceleration vectors produced the best screening efficiencies. Velocity and acceleration vectors were directly related to frequency of oscillation since all other parameters were held constant for this study. A Programmer’s Hierarchical Interactive Graphics System (PHIGS) program was developed to graphically simulate the screen motion and to analyze the maximum velocity and acceleration vectors of the upper swing arm (input link). By interactively changing the shaker unit parameters, the screen motion was animated and viewed, with the calculated vectors used in the statistical analysis. / Master of Science

Thesis (PhD(For))--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Pinus patula is the most intensively planted conifer in the tropics and sub‐tropics. In South Africa Pinus patula plantations are the main saw‐log resource for structural lumber production. Improved intensive silvicultural practices and tree breeding have resulted in marked increases in the rate of growth. To reap the financial benefits of the faster growth, plantation managers are more and more inclined to reduce rotation ages, which inevitably results in the production of higher proportions of juvenile wood at final harvest, and lumber which often does not meet the minimum requirements for stiffness for structural lumber. Knowledge of the variation and the accurate prediction of the mechanical properties of the timber of standing trees can have various benefits for growers and processors of trees. It can be used for tree allocation to different processing facilities, for processing production planning, and to assist tree breeders to screen and select for superior breeding material. The objectives of this study were (1), to examine the within‐ and between‐tree variation in wood properties of young South African grown Pinus patula trees known to have important impacts on the suitability of sawn lumber for structural purposes and (2), to develop empirical prediction models for the flexural lumber properties from standing Pinus patula, based on variables that could be assessed non‐destructively from standing trees. Sample material was obtained from 170 trees (16‐20 years old) established in 17 compartments along the Mpumalanga escarpment of South Africa. A large number of variables which could be obtained non‐destructively from the trees while they were still standing, were measured. The trees were subsequently felled and two logs, 2.1 m in length, were extracted from each tree at two height positions. The 340 logs were processed into 1402 pieces of lumber for further measurements and destructive testing. Results showed that the mean modulus of elasticity measured on edge (MOEedge) was far below the limits set for structural grade softwood timber in South Africa. All the desirable properties for structural lumber improved with distance from the pith with the exception of the 5th percentile value for modulus of rupture (MOR), which was higher at the pith than for the boards processed adjacent to the pith. Boards processed from the lower part of the stem were superior in most of the important properties compared to those higher up in the stem. Separate multiple regression models for predicting the average dynamic MOE (MOEdyn) of individual boards, trees and compartments were developed. The models managed to explain 68%, 60% and 95% of the variation in MOEdyn respectively. The models developed for MOR explained 40% and 42% of variability at board and tree level respectively. At compartment level, 80% of the variation in the 5th percentile MOR value could be explained by the model. Sensitivity analyses showed that site index at base age of 10 years, acoustic time‐of‐flight, wood density and ring width were the most influential variables in the MOE models. The models indicated that tree slenderness during early growth seems to play a major role in determining the dynamic MOE and MOR of lumber. This is in agreement with Euler’s buckling theory and the bending stress theory. Microfibril angle (MFA) and density were measured on radial strips taken from a sub‐sample of trees with the Silviscan 3 technology. The mean microfibril angle per year ring in Pinus patula varied between 7o and 29o. In general MFA decreased with distance from the pith and height above ground level. A multiple regression model including microfibril angle, density and ring width explained 71% of the variation in the dynamic MOE of boards. Sensitivity analysis on the model showed that microfibril angle and density had roughly equal influences on predicting the MOEdyn of Pinus patula boards. / AFRIKAANSE OPSOMMING: Pinus patula is die mees aangeplante naaldhoutspesie in die tropiese en sub‐tropiese areas van die wêreld. Dit is die grootste bron van saagblokke vir die produksie van strukturele hout in SA. Intensiewe boskultuurpraktyke en boomteling het gelei tot ‘n merkbare verhoging in die groeitempo van die spesie. Plantasiebestuurders is gevolglik geneig om rotasie‐ouderdomme te verlaag, wat lei tot ‘n groter persentasie jeughout wat nie aan die minimum styfheidvereistes van strukturele hout voldoen nie. Kennis van die variasie en die akkurate voorspelling van die meganiese eienskappe van staande bome kan voordele inhou vir beide die verbouers en verwerkers van bome. Dit kan byvoorbeeld van hulp wees met die toewysing van bome aan verwerkingsfasiliteite, vir produksiebeplanning, en vir ondersteuning met die keuse van teelmateriaal vir boomtelers. Die doelwitte van hierdie studie was (1), om die binne– en tussenboomvariasie in die houteienskappe, wat ‘n bepalende invloed het op die geskiktheid van jong Suid Afrikaanse Pinus patula bome vir strukturele hout produksie, te ondersoek en (2), om empiriese modelle vir die voorspelling van die buigeienskappe van planke te ontwikkel, gebaseer op veranderlikes wat niedestruktief op staande Pinus patula bome ge‐evalueer is. Monsters vir die studie is verkry vanaf 170 bome (16‐20 jaar oud), geplant in 17 vakke op die Mpumalanga platorand van Suid Afrika. ‘n Groot aantal veranderlikes is nie‐destruktief gemeet op die staande bome waarna die bome gevel is en twee saagblokke, 2.1m in lengte, is op twee hoogte posisies uit elke boom verwyder. Die 340 blokke is verwerk tot 1402 planke vir verdere metings en destruktiewe toetse. Resultate het getoon dat die gemiddelde modulus van elastisiteit gemeet op die dwarskant (MOEedge) aansienlik laer was as wat vereis word vir strukturelegraad hout in Suid Afrika. Al die gewenste eienskappe het toegeneem met afstand vanaf die murg behalwe die 5de persentiel breekmodulus (MOR), wat hoër was vir murgplanke as vir aangrensende planke. Planke afkomstig van die laer dele van die stam het oor die algemeen beter eienskappe gehad as planke afkomstig van die hoër dele. Veelvuldige regressiemodelle kon 68%, 60% en 95% van die variasie in die gemiddelde dinamiese MOE (MOEdyn) op die vlak van onderskeidelik individuele planke, bome en vakke verklaar. Die modelle vir MOR kon 40% en 42% van die variasie op onderskeidelik plank‐ en boomvlak verklaar. Die model vir 5de persentiel MOR van vakke kon 80% van die variasie verklaar. ‘n Sensitiwiteitsanalise het aangetoon dat groeiplekindeks op ouderdom 10, akoestiese vlugtyd, digtheid en jaarringwydte die belangrikste veranderlikes was wat MOEdyn beïnvloed het. Die modelle het aangetoon dat die slankheid van bome tydens vroeë groei vermoedelik ‘n belangrike invloed op die MOEdyn en MOR van planke het. Dit is in ooreenstemming met Euler se knikteorie en die buigsterkteteorie. Die mikrofibrilhoek en digtheid van ‘n steekproef van die bome is gemeet met die Silviscan 3 apparaat. Die gemiddelde mikrofibrilhoek per jaarring het tussen 7 o en 29o varieer. Hierdie variasie was hoofsaaklik afhanklik van boomhoogte en aantal jaarringe vanaf die murg. ‘n Veelvuldige regressiemodel wat mikrofibrilhoek, digtheid en jaarringwydte insluit, kon 71% van die variasie in MOEdyn verklaar. ‘n Sensitiwiteitsanalise op die model het aangetoon dat mikrofibrilhoek en digtheid ongeveer ewe belangrik was wat betref hulle invloed op die voorspelde MOEdyn van Pinus patula planke.

Orientador: Rinaldo Cesar de Paula / Coorientador: Nadia Figueiredo de Paula / banca: Miguel Luiz Menezes Freitas / Banca: Gustavo Vitti Môro / Resumo: O Eucalyptus tereticornis Smith tem boa adaptabilidade a diferentes regiões e resistência à seca, apresentando crescimento rápido e grande potencial de aplicação da madeira para diferentes usos. Neste sentido, o presente trabalho visou avaliar a divergência genética entre progênies de polinização aberta de E. tereticornis com base em caracteres de crescimento e tecnológicos da madeira. O experimento foi implantado no município de Luiz Antonio (SP), com 30 progênies de E. tereticornis, pertencentes a duas procedências, no delineamento experimental em blocos casualizados, parcelas de uma planta e 100 repetições, no espaçamento de 4 x 4 m. Com 31 anos de idade foram avaliados, em todo o ensaio, o diâmetro à altura do peito (DAP, cm), a altura total (m), sobrevivência (%) e forma do fuste. Foram abatidas três árvores representativas de cada progênie para determinações do volume e retirados discos em diferentes posições do fuste para a determinação da densidade básica (DBM), biomassa, teores de celulose (CEL), lignina (LIG), extrativos (EXT) e holocelulose (HOLO) na madeira. Os dados foram analisados pelo método REML/BLUP, obtendo-se estimativas de componente de variância e de parâmetros genéticos. Visando transformar o teste em um Pomar de Sementes por Mudas, foi simulada a seleção de 150 plantas (5%) para todos os caracteres, obtendo-se estimativas de ganhos genéticos e de tamanho efetivo (Ne). Adicionalmente, para o DAP outras duas estratégias de seleção foram simuladas: a sele... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Eucalyptus tereticornis Smith has good adaptability to different regions and drought tolerance, showing fast growth and great potential of application of the wood for multiple purposes. In this sense, the present work aimed to evaluate the genetic divergence among progenies of open pollination of E. tereticornis based on growth and wood technological characters. The experiment was carried out in Luiz Antonio (SP), with 30 progenies of E. tereticornis, belonging to two provenances, in the randomized blocks design, single tree plot and 100 replicates, at 4 x 4 m spacing. At 31 years old, the diameter at breast height (DAP, cm), total height (m), survival (%) and stem shape. Three representative trees of each progeny were harvested for determination of volume and discs were sampled at different positions of the stem for determination of wood basic density (DBM), biomass and wood contents of cellulose (CEL), lignin (LIG), extractive (EXT) and holocellulose (HOLO). The data were analyzed by the REML/BLUP method, obtaining estimates of variance component and genetic parameters. Aiming to transform the test into a Seed Orchard by Seedling, the selection of 150 plants (5%) for all traits was simulated, obtaining estimates of genetic gains and effective size (Ne). Additionally, for the DAP, two other selection strategies were simulated: the combined selection among and within progenies and the restricted selection in the number of individuals per family (n≤20). Nine characters, evalua... (Complete abstract click electronic access below) / Mestre