Thesis (Ph. D.)--University of Waikato, 2007. / Title from PDF title page (viewed on May 6, 2007). Includes bibliographical references.

Memoria para optar al Título Profesional de Ingeniero Forestal / Se midió mensualmente el índice de área foliar en plantaciones de Pinus radiata D. Don en la región del Bío Bío en las cuatro principales zonas de crecimiento para esta especie (IV, V, VI y VII) durante 24 meses entre Octubre de 2010 y Octubre de 2012. Los predios donde se ubicaron los ensayos fueron San Pedro de la Paz (predio Lomas Coloradas), Nacimiento (predio Nacimiento), Santa Bárbara (predio Santa Bárbara) y Cabrero (predio Tapihue). Para cada sitio se consideraron tres clases de edad ([0-7), [7-14) y [14+)). En cada uno de los 12 puntos de Zona-Edad, se procedió a instalar un conglomerado de 3 parcelas permanentes de 1.000 m2, totalizando 36 parcelas, entre los meses de Agosto y Septiembre de 2010. Estos predios y rodales se ubican a menos de 10 km de las estaciones meteorológicas de Escuadrón (Lomas Coloradas), Pichún (Nacimiento), Santa Bárbara (Santa Bárbara) y Trilahue (Tapihue) que mantiene Forestal Mininco S.A. La edad se correlacionó positivamente con el índice de área foliar (L) como era de esperar. Además se aprecia que el L crece fuertemente desde la clase de edad [0-7) a la [7-14), comparado con el crecimiento entre la clase de edad [7-14) a [14+). Lo anterior implica que el mayor crecimiento en área foliar se genera antes de los 14 años. Además a lo largo de los 24 meses se observa que el L aumenta fuertemente en la clase de edad [0-7), en menor cuantía en la clase de edad [7-14), y muestra un crecimiento prácticamente imperceptible en la clase [14+) años.

Memoria para optar al Título Profesional de Ingeniero Forestal / Se realizaron inventarios forestales mensuales y mediciones fisiológicas trimestrales en plantaciones de Pinus radiata D. Don en la Región del Bío Bío en las cuatro principales zonas de crecimiento para esta especie (IV, V, VI y VII) durante 24 meses entre Agosto de 2010 y Agosto de 2012. Los predios donde se ubicaron los ensayos fueron Lomas Coloradas en la Comuna de San Pedro de la Paz, Nacimiento en la Comuna de Nacimiento, Santa Bárbara en la Comuna de Santa Bárbara y Tapihue en la Comuna de Cabrero. Para cada sitio se consideraron tres clases de edad (0-7, 7-14 y 14+ años). En cada uno de las 12 instancias de Zona-Edad, se procedió a instalar un conglomerado de 3 parcelas permanentes de 1.000 m2, totalizando 36 parcelas. Estos predios y rodales se ubicaron a menos de 10 km de las estaciones meteorológicas de Escuadrón (Lomas Coloradas), Pichún (Nacimiento), Santa Bárbara (Santa Bárbara) y Trilahue (Tapihue), pertenecientes a Forestal Mininco S.A.

The New Zealand forest industry produces a diverse range of log grades and sorts to meet domestic and export market demands and to maximise returns to the forest grower. An implication for the supply chain is the number of log grades and sorts a harvesting operation is expected to produce from one species, radiata pine (Pinus radiata). The number of log grades and sorts can impact on landing size and layout requirements, value recovery, log-making complexity, machine utilisation and quality control requirements. A study was conducted to investigate if the number of log sorts affects mechanised log processing productivity and value recovery. This would determine if any gross value gains derived from producing a higher number of sorts are offset by losses in log processing productivity. Two landing-based mechanised log processors at cable yarder harvesting operations were studied using different cutting scenarios producing five, nine, twelve and fifteen log sorts. The study collected data from over 26 hours of mechanised processing which included the processing of 578 stems at an average piece size of approximately 1.6 m³. Machine utilisation results showed processors spending 84% of total time on productive tasks and that 49% of total time was spent on the primary productive tasks of log processing. Quadratic regressions were used to model log processing productivity trends which showed piece size and cutting scenario as significant predictor variables (p-value <0.01). There was a significant difference between cutting scenario with five log sorts and the cutting scenarios with twelve and fifteen log sorts (p-values <0.05), as well as a significant difference between the nine and fifteen log sort cutting scenarios (p-value <0.01). There was not enough evidence to suggest productivity was different between cutting scenarios producing five and nine log sorts. Based on this analysis, it was likely that the null hypothesis that the number of log sorts does not affect log processing productivity should be rejected. At a piece size of 2 m³, the productivity model estimated processing productivity was 10% higher producing nine log sorts compared to producing fifteen log sorts. A linear regression model showed a strong relationship between gross value recovery, piece size and cutting scenario (p-value <0.01). Gross value recovery increased as the number of log sorts increased. A significant model suggested it is likely null hypothesis 2, that the number of log sorts does not affect gross value recovery, should be rejected. There were only some differences in variances between cutting scenarios which were statistically significant. Both the average results and regression estimates showed the five log sort cutting scenario recovering 94% of the value of the cutting scenario with fifteen log sorts. Incremental gains in value recovery as the number of log sorts increased were marginal, which appeared to be due to log prices for many major log grades trading in a close range in relation to historic price trends. Regression trends for productivity and gross value recovery indicated that the most optimal cutting scenario, in terms of processing value outturn per productive machine hour, was the cutting scenario producing nine log sorts. This suggests that declines in processor productivity offset gains in gross value recovery when producing twelve and fifteen log sorts. Market sensitivity analysis suggested that differentials in log prices impact on the number of log sorts which optimise the value outturn per productive machine hour from log processing.

A comparison of above ground forest metrics with below ground soil CO₂ respiration was carried out in an attempt to reveal if any correlations exist. Above ground measurements of 2720 clonally propagated trees were taken assessing the silvicultural treatments of stocking, herbicide and fertiliser. These were compared to 480 below ground soil CO₂ respiration measurements. Using measurements of mean height, mean dbh and basal area the data was analysed and returned significant results for mean dbh and the interactions of herbicide and clones, and stocking and herbicide. Mean height returned a significant result for the interaction of stocking and herbicide. Below ground measurements showed an interaction between ripping and stocking; however these results were not ratified by the above ground results. Overall the results were encouraging and should aid in future experiments that seek to understand what effect above ground treatments have on below ground CO₂ activity.

Pinus radiata is by far the dominant species grown in New Zealand plantations as a renewable source of wood. Several wood quality issues have been identified in the material produced, including the high incidence of compression wood, which is undesirable for end users. At present our understanding of the complex array of developmental processes involved in wood formation (which has a direct bearing on wood quality) is limited. Hence, the forest industry is interested in attaining a better understanding of the processes involved. Towards this goal, and for reasons of biological curiosity, the experiments described in this thesis were carried out to investigate several aspects of xylem cell development. In an in arbor study, changes in the orientation of cortical microtubules and cellulose microfibrils were observed in developing tracheids. Results obtained provide evidence that cortical microtubules act to guide cellulose synthase complexes during secondary wall formation in tracheids. The mechanisms involved in controlling cell wall deposition in wood cells are poorly understood, and are difficult to study, especially in arbor. A major part of this thesis involved the development of an in vitro method for culturing radiata pine wood in which hormone levels, nutrients, sugars and other factors, could be controlled without confounding influences from other parts of the tree. The method developed was used in subsequent parts of this thesis to study compression wood development, and the influence of the hormone gibberellin on cellulose microfibril organisation in the cell wall. Results from the in vitro compression wood experiments suggested that: 1. when a tree is growing at a lean, the developing cell wall was able to perceive compressive forces generated by the weight of the rest of the tree, rather than perceive the lean per se. 2. ethylene, rather than auxin, was involved in the induction of compression wood. Culture of stem explants with gibberellin resulted in wider cells, with steeper cortical microtubules, and correspondingly steeper cellulose microfibrils in the S2 layer of developing wood cells. This observation provides further evidence that the orientation of microtubules guides the orientation of cellulose microfibrils. Overall, the work described in this thesis furthers our knowledge in the field of xylem cell development. The stem culture protocol developed will undoubtedly provide a valuable tool for future studies to be carried out.

New Zealand grown Pinus radiata is limited in its application for structural purposes by its stiffness deficiencies. This dissertation aims to estimate potential improvements in stem value through selection for improved stiffness. A new method to model and value volumes of structural wood grades within a stem was used to calculate these value improvements. Data for each stem from a stand in Kaingaroa Forest bred for improved wood quality was used to perform this analysis. This data was from a stand bred for improved wood quality and included information on the stiffness, density and width of each growth ring for each stem. The data was in the form of cores. Height and volume data was not recorded and therefore needed to be modelled. The volumes of MSG8, MSG11 and MSG13 wood were estimated by modelling the stem volume at the age when wood is produced that is stiff enough to qualify for each grade. The majority of stems had merchantable volumes between 1-2.5m3 with the largest stems containing 3.6m3. Average stiffness ranged between 5.2GPa and 11.3GPa with the stand average being 8.4GPa. There was no relationship between average stiffness and merchantable volume. Stem values were found to range between $60-$131/m3 with the stand average being $91/m3. The 10 most valuable stems had a total stem value ($318) twice that of the stand average ($157). The most valuable stem ($411) showed a 160% increase in stem value from the average. The increases in value/m3 were caused by large increases in the proportion of MSG11 and MSG13 wood held within the merchantable volume. These potential gains in stem value could help tree breeders assign an accurate economic weighting to stiffness improvements. Forest managers wanting to justify using a more expensive, improved stiffness seedlot may also find these results valuable.

The increasing frequency and severity of windthrow events affecting the forestry industry in New Zealand have raised important management issues surrounding the rate of colonisation of fallen trees by sapstain fungi and the time available for salvage harvesting before sapstain degradation limits potential economic returns. These fungi are known to be spread by a multitude of factors including wind, rain splash, harvesting processes and insect vectoring. Apart from the ecological interest in these interactions between fungi, plants and insects, sapstain fungi are also economically important because their hyphae discolour the sapwood and reduce the overall quality of the timber. The amount of time available to salvage harvest damaged trees is unknown, especially on seasonal and regional scales. Manipulative experiments were established in Pinus radiata forests to examine this seasonal and regional variation in sapstain attack following windthrow, and to investigate the importance of bark beetles as vectors of sapstain fungi. A range of methods were implemented to assess the role of bark beetles as vectors and to ascertain which sapstain fungi are associated with them. Experimental billet logs were caged to exclude beetles and subsequently analyse fungal attack in comparison with identical logs left exposed to beetles. In addition, individual beetles were sampled directly to determine whether they carried spores of particular fungal species and to assess the degree of association in vector-fungal dynamics. Finally, a novel application of DNA melt peak analysis was developed to investigate variation among the fungal communities associated with beetles potentially involved in vectoring sapstain spores. The moisture content of fallen trees was found to be the main factor regulating sapstain development, and when moisture content drops below 100% (on dry weight basis) sapstain fungi grew rapidly. The speed at which this level drops depends on the season, with much faster drying occurring in the warmer months of spring and summer. As a result, trees that fell in the previous winter or autumn did not develop significant sapstain levels until temperatures rose in the following summer, suggesting that storm-damaged trees that fall in winter can be left safely until just before the next summer before they are no longer suitable for salvage harvest. In New Zealand, the bark beetle species acting as vectors of sapstain fungi are not behaviourally adapted to colonisation of logs that are not in contact with the ground. Following windthrow events in pine forests, trees generally lie with their stems suspended above the level of the ground by their branches. As a result, under these circumstances, beetle colonisation of windthrown timber was low, and bark beetles were not a significant vector of stain. The caged and un-caged experimental log billets, however, were in contact with the ground, resulting in colonisation of the un-caged logs. In this case, bark beetles did play an important role in contributing to sapstain intensity, and the stain distribution within the logs mirrored that of the stain distribution. However, this effect may be due to the provision of access points for wind- or water-borne spores of the non-insect vectored stain fungus Diplodia pinea, or to the spread of hyphae through the tunnelling and feeding activities of beetles within the tree, rather than by bark beetles acting as vectors of spores. Bark beetles were confirmed as sapstain vectors with the isolation of seven different ophiostomatoid stain fungi from them, five of which were also found in wood. Finally, the development of a laboratory based, rapid species identification method was developed to identify fungal DNA. Melt peak analysis allowed the species-specific DNA melt temperatures to be compared with the melt temperatures of known species to be able to rapidly, and cheaply, identify an unknown species. Bark beetles are vectors of sapstain fungi in P. radiata forests, however the bark beetle species naturalised in New Zealand prefer to colonise wood when it is in contact with the ground. Following windthrow, trees are generally not attacked by beetles as they are held from the ground by their branches, leaving them to be stained predominantly be wind and rain dispersed stain fungus D. pinea. Stain did not occur until the moisture content of fallen trees dropped below 100%, which only happens in the warm months of summer and spring. In New Zealand, there are interactions between trees and bark beetles, and bark beetles with fungal pathogens from all around the globe resulting in a unique novel assemblage of species together for the first time. Understanding the dynamics of these species in their novel environment is crucial to effectively responding to potential pest threats.

Wood stiffness or modulus of elasticity (MOE) is one of the most important wood properties for solid timber applications, and as such, the efficacy of wood use, especially for structural timber is strongly related to MOE. MOE in Pinus radiata is highly variable and poorly understood. In this study, the effect of initial stand spacing and breed on outerwood MOE and the vertical distribution of MOE of Pinus radiata was assessed. Understanding positive or negative influences of growth caused by initial stand spacing and genetic material on MOE is appealing because it could enable us to better comprehend how forest growers could adapt silvicultural operations to the demands of wood processing. Physical characteristics of different breeds and propagation methods of Pinus radiata were assessed at a variety of initial stand spacings. Stem diameter, crown height, stem slenderness and branch size were all heavily influenced by stand spacing. Breed had a marginally significant influence on diameter and stem slenderness. Internode length was not affected by stand spacing, but showed sizeable differences, especially between the long internode 870 breed and the remaining growth and form (GF) breeds. Outerwood MOE was significantly (P<0.0001) influenced by stand spacing and breed, but not their interaction (P>0.05). MOE scaled positively with stand spacing. MOE increased by 39% from 5.4 GPa at 209 stems ha-1 to 7.5 GPa at 2551 stems ha-1. The majority of this increase (33%) occurred between 209 and 835 stems ha-1. Physiologically aged cuttings of greater maturation status exhibited greater MOE, with the three-year-old cuttings being stiffer than the one-year-old cuttings, seedlings from the 870, 268 and 850 series, by 15, 17, 22 and 27%, respectively. Stem slenderness exhibited the strongest significant (P<0.0001) relationship with MOE (r2=0.49), followed by green crown height (r2=0.46) and diameter (r2=0.44). Stem slenderness and green crown height had a direct influence on MOE that explained 53% of the variance in MOE. MOE was also significantly (P<0.0001) influenced by spacing and breed when using the resonance technique to assess whole stem MOE. The vertical distribution of MOE showed that the lowest portion of the stem (bolt 1) was approximately 30% less stiff than bolts 2 and 3. After the greatest MOE value had been obtained at bolt 3, MOE gently declined to the top of the measured stem. Variation of MOE within trees was significant (58%) at the high stockings of 1457 and 2551 stems ha-1, but somewhat lower (36%) at the lower stockings. The 870 breed was approximately 8% and 16% stiffer than the 268 and 850 breeding series respectively, across all stockings, with the three-year-old cuttings being 7% stiffer than the one-year-old cuttings. At stockings of 481 stems ha-1 and less, the proportional height at which MOE was greatest within a tree was between 25% and 50% of stem height. At stockings above 481 stems ha-1 the proportional height at which maximum MOE was obtained was between 15% and 40% of stem height. Bolt slenderness was found to be the most significant factor impacting on MOE of the bolt. Regression of critical buckling height against diameter at ground level yielded a scaling exponent of 0.55, which was lower than the scaling exponent of 0.67 predicted with constant density-specific stiffness. There was a tendency for some bolts with lower mean diameter to display significantly higher safety margins than bolts with higher mean diameter, suggesting that the largest bolts, which occur at the base of tree, are the point of most likely critical failure.

Pinus radiata is by far the dominant species grown in New Zealand plantations as a renewable source of wood. Several wood quality issues have been identified in the material produced, including the high incidence of compression wood, which is undesirable for end users. At present our understanding of the complex array of developmental processes involved in wood formation (which has a direct bearing on wood quality) is limited. Hence, the forest industry is interested in attaining a better understanding of the processes involved. Towards this goal, and for reasons of biological curiosity, the experiments described in this thesis were carried out to investigate several aspects of xylem cell development. In an in arbor study, changes in the orientation of cortical microtubules and cellulose microfibrils were observed in developing tracheids. Results obtained provide evidence that cortical microtubules act to guide cellulose synthase complexes during secondary wall formation in tracheids. The mechanisms involved in controlling cell wall deposition in wood cells are poorly understood, and are difficult to study, especially in arbor. A major part of this thesis involved the development of an in vitro method for culturing radiata pine wood in which hormone levels, nutrients, sugars and other factors, could be controlled without confounding influences from other parts of the tree. The method developed was used in subsequent parts of this thesis to study compression wood development, and the influence of the hormone gibberellin on cellulose microfibril organisation in the cell wall. Results from the in vitro compression wood experiments suggested that: 1. when a tree is growing at a lean, the developing cell wall was able to perceive compressive forces generated by the weight of the rest of the tree, rather than perceive the lean per se. 2. ethylene, rather than auxin, was involved in the induction of compression wood. Culture of stem explants with gibberellin resulted in wider cells, with steeper cortical microtubules, and correspondingly steeper cellulose microfibrils in the S2 layer of developing wood cells. This observation provides further evidence that the orientation of microtubules guides the orientation of cellulose microfibrils. Overall, the work described in this thesis furthers our knowledge in the field of xylem cell development. The stem culture protocol developed will undoubtedly provide a valuable tool for future studies to be carried out.