School of Ecosystem and Forest Sciences - Theses

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Now showing 1 - 10 of 11
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    Impregnation of wood with stains
    Kwiatkowski, Aleksander ( 2007)
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    A study of the creep performance of microwave-modified radiata pine in different external environments
    Dang, Lam Dien ( 2007)
    A new innovative timber treatment developed at the CRC Wood Innovations, which involves high intensity microwave application and resins impregnation, is intended to provide products for a range of applications including structural engineering members. This study has been undertaken to obtain experimental data and provide better understanding of the creep performance and long-term behaviour of the new products. In the experiment, fifteen samples, five untreated, five treated with MUF resin and five treated with Isocyanate resin were loaded in four-point bending at 30 percent of the matched samples' failing stress, in a protected external environment in Brisbane, Australia for a period of nine months to date. The treated samples were found to produce lower relative creep deformations than the untreated sample. The samples treated with MUF resin showed better creep resistance than the samples treated with Isocyanate resin. Data from the first 90 days were used to obtain parameters for the two chosen models: the power law model and the 5- parameter model. While both models provided good fitting for the data, the 5-element model was found to possess better extrapolation capacity beyond the regression period. An increase in the period of regression data from 90 days to 150 days significantly lowered the errors in both of the models.
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    Towards association studies in Pinus radiata D.Don - populations and wood property candidate-genes
    Tibbits, Josquin Frederick George ( 2006)
    In Australia and New Zealand Pinus radiata D. Don wood quality is receiving increasing interest from tree breeders. This is partly due to declining resource wood quality associated with more advanced generation breeds leading to increased rejection and product downgrading in processing. While log segregation and wood grading at mill-door yields immediate benefits to processors the underlying cause is not addressed. The only long-term solution is to include wood quality in breeding programs. Wood quality traits are costly and difficult to measure. Marker-assisted selection offers a potential solution and quantitative trait loci (QTL) mapping studies have been undertaken with the aim of facilitating this. It is becoming increasingly clear that in widely outcrossing species with long generation times and very large genomes these approaches will not work. The identification of the underlying genetic sites, or tightly linked marker sites, would rectify this and in model species linkage-map based cloning has been used extensively. This approach is also not practical in species such as P. radiata. Association testing combined with a candidate-gene approach is therefore widely believed to be one of the only methods remaining. This approach uses a priori information to select and then test the phenotypic effects of variants within candidate-gene loci. Implementation of these studies relies heavily on the results of other investigations, especially those that generate DNA sequence information. Also required is detailed knowledge of the genetic population structure, the patterns of nucleotide diversity and the patterns of linkage disequilibrium. On a more practical level suitable populations need to be identified while the current methods for the collection and handling of samples for molecular investigations are limiting. The selection of candidate genes is also a non-trivial process. For candidate-gene association studies to be successful in P. radiata all these factors need to be addressed. This formed the main aim of this thesis. A multi-pronged approach was used. Firstly, at the population level, the genetic resources available for association studies were identified and the underlying genetic population structure of these resources and the patterns of nucleotide diversity and linkage disequilibrium were investigated. Secondly, improved methods for the collection and isolation of genomic DNA were developed and thirdly, a small set of wood quality candidate-genes were selected and further characterised with the aim of identifying those with the most promise of harbouring causative variation for inclusion in future association studies. This was achieved by literature based review, linkage mapping onto wood property QTL maps and neutrality testing. Results include support for previous population genetic studies showing P. radiata to have a complex genetic structure compared to most pine species. This study also indicated significant levels of migration between the three mainland populations. Within the candidate-genes two, cinnamyl alcohol dehydrogenase and sucrose synthase, showed interesting patterns of population differentiation and/or nucleotide diversity while the results for one other gene, korrigan, did not agree with previous investigations.
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    Chemical treatment of wood and its effect on wood/water interactions
    Hann, Jeffrey Albert ( 1999)
    Wood-water interactions including the effect of grain orientation, sample size and water potential in Pinus radiata D.Don were investigated. The influence of various chemical treatments on the wood-water interaction was also evaluated. The uptake of moisture by wood soaking in water was determined using the water soak method developed by Rowell and Banks (1985). Treatments with surfactants such as ammoniacal copper-didecyldimethylammonium chloride (DDAC-ACQ) and linoleate salts increased the initial uptake rates of the wafers, whilst treatment with copper chrome arsenic (CCA), linseed oil (LO) and a combined CCA/LO treatment reduced uptakes of moisture. The length of time used to assess the water repellent effectiveness (WRE) was found to be crucial to the test, with most of the reduction in WRE occurring in the first 15 minutes of soaking. Exposure of wax treated wafers to weathering indicated an initial gradual reduction in efficacy, which decreased more rapidly as the length of exposure time increased Tests on the effectiveness of different wood coatings subjected to high humidity illustrated the importance of a film with low permeability and some elasticity. Wood blocks coated with resorcinol-formaldehyde resin initially inhibited moisture ingress, but failed after prolonged exposure. An extra coat increased the time required before failure. Coating the wood wafer with a silicone resin slightly reduced the uptake of water into the wafer. However, this resin was more permeable than the resorcinol-formaldehyde resin and was not as efficacious. The effect of various oil treatments on the uptake of water vapour indicated that the distribution of the oil is critical to inhibiting vapour uptake. No significant difference was found between the moisture uptake of hardwood and softwood stakes. Treatment with trimethylborate (TMB), DDAC-ACQ and CCA had no significant effect on the extent of vapour taken up by the wood. An experiment designed to investigate the importance of sample size when assessing wood performance was carried out using matched samples of treated and untreated quartersawn and flatsawn Pines radiata D.Don. It was found that samples treated with DDAC-ACQ and exposed outdoors experienced a greater flux in moisture content compared to controls. CCA reduced the extent of moisture uptake, with the incorporation of oil further enhancing the short term weathering performance. Quartersawn wood exhibited a smaller moisture flux than the flatsawn timber.However, the performance of CCA/Oil treated quartersawn wood was only marginally better than the quartersawn controls. Laboratory trials gave an identical treatment ranking as the exterior trial; however the use of the smaller sample size was identified as being inappropriate for the assessment of check formation in the timber. A sample size effect was demonstrated when assessing the efficacy of treatments by the water soak method. A treatment gradient could be demonstrated when whole stakes were impregnated with CCA and linseed oil by a two-stage process. The test indicated that the significance of improvements in the water repellency of treated wafers diminishes when larger sized samples are investigated. The effect of soil water availability on wood moisture content was determined for untreated hardwood and softwood sticks. At low soil moisture contents, hardwood sticks were found to be significantly more saturated than their softwood counterparts. At higher soil water contents (100% water holding capacity (WHC)) the performance of the two species of wood became less significant. Chemical treatment was found to have a significant effect on reducing wood moisture levels when free water was available in the soil. Linseed oil was responsible for a significant reduction in moisture uptake, by blocking the pathways for water uptake as well as by decreasing the void volume available in the wood for water to occupy. Incorporation of a drying agent did not improve the quality of the film formed by the linseed oil as no significant change in water repellent performance was identified. The uptake and movement of water through a horticultural post was simulated using a procedure described by Baines and Levy (1979). The wick action of heartwood and sapwood stakes of Pinus radiata D.Don was investigated with distinct moisture distribution and behaviours found. Heartwood, being less permeable, showed a reduction in the volume of vapour that moved through the wood, as well as a much lower stake moisture content compared to the sapwood. This difference was most pronounced above the air/water interface and helps to explain the difference in decay resistance exhibited by the two wood types. End sealing the stakes with silicone resin was found to have no significant effect on the wick action of the stake. Lumen filling treatments with wax, oil and alkyd resins were found to significantly alter the wick action of the stakes. Treatment with low concentrations of surface active compounds such as DDAC-ACQ and linoleate soaps were found to increase the rate of water uptake. At higher concentrations the presence of the surfactant increased the hydrophobicity of the wood and reduced moisture uptake. Biological testing using a fungal cellar determined that treatment of the wood with CCA/LO, CCA, DDAC-ACQ/LO, LO and DDAC-ACQ significantly improved the resistance of the wood to decay. The incorporation of linseed oil did not cause a significant improvement to the decay resistance of the stakes over the trial period
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    Nutritional physiology of eucalyptus grandis and pinus radiata irrigated with municipal effluent
    O'Brien, Nicholas David ( 1998)
    The aim of this study is to compare the processes of accumulation and use of N, P, K, Mg and Ca between two and four years of age in plantations of Eucalyptus grandis and Pinus radiata irrigated at several rates with municipal effluent, and with bore water. A series of five harvests over two years was used to estimate above-ground biomass and nutrient content. Growth rate was greater in E. grandis than in P. radiata. Total biomass at 34 months ranged from 34 to 45 t ha-1 in E. grandis and from 21 to 26 t ha-1 in P. radiata, with a trend towards higher rates of growth with increased irrigation rate. Foliage mass and leaf area index (LM) were initially greater in E. grandis than P. radiata. However, the rate of increment in foliage mass and LAI in E. grandis decreased after canopy closure (at about 20 months). At 34 months foliage mass averaged 5.9 t ha-1 in E. grandis and 7.4 t ha-1 in P. radiata. Nutrient accumulation was primarily a function of growth rate, in particular the rate of canopy development. Rate of nutrient accumulation in E. grandis was greatest prior to canopy closure, decreasing thereafter, and in P. radiata it was greatest in the last year. As a result, mean annual increment of nutrient accumulation was maximum in E. grandis at 28 months, and in P. radiata at the end of the study. Implications for management of effluent-irrigated plantations are discussed. The mass of each nutrient accumulated varied greatly and decreased in the order Ca
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    An analysis of radiata pine-pasture agroforestry systems
    Kellas, J. D ( 1993)
    Agroforestry, the integration of forestry and agricultural production, requires an understanding of the interactions between trees, agriculture and the environment. This thesis presents an analysis of the effects of a variety of Radiata Pine-pasture agroforestry treatments on soil water, tree growth and form and pasture production together with a series of economic analyses using the FARMTREE model to simulate the various agroforestry regimes established at Carngham in western Victoria. The Carngham study site consists of a replicated randomized block design of five Radiata Pinepasture treatments. The treatments were: open pasture (no trees), 100 trees/ha (8 m x 12 m), 277 trees/ha-wide-spaced (4 m x 9 m), 277 trees/ha-5 row (5 rows, 4 x 3 m, with 10 row gap) and 1650 trees/ha (no pasture). Results, 11 years after tree establishment, show that soil water content under the various treatments has a cyclical pattern of recharge and discharge with an annual amplitude of approximately 100 mm. Within the 100 trees/ha and 277 trees/ha-5 row and 277 trees/ha-wide-spaced treatments, the soil water content was generally significantly less than under open pasture in the upper 170 cm of the upper profile. Within the 1650 trees/ha treatment, the trees utilize water to a depth of at least 270 cm. Tree form was influenced by tree density. Tree diameter decreased but height increased with tree density with the trees of largest volume produced in the 277 trees/ha-wide-spaced treatment. Variable-lift pruning was routinely applied on an annual basis from tree age 6 years, to minimize the internal knotty-core and to maximise the volume of knot-free timber produced. Pruning was virtually completed (to 6 m) after five or six annual treatments, and significant relationships between DOS (diameter over stubs) and various tree parameters were identified as predictors for determining the volume of the knotty-core. Agricultural production was assessed as net pasture production using rising-plate methodology during the major growth seasons. Trees in single rows, as in the 100 trees/ha and 277 trees/ha-wide-spaced treatments, had only a limited effect on net pasture production compared to the zone within 4.5 m from the trees in the 277 trees/ha-5 row treatment where pasture production was significantly less than in open pasture, or in the zone from 4.5 to 18 m from the tree line where there was a possible shelter benefit. Although pasture production was similar between treatments, animal production decreased with increasing tree density. Economic analyses using the FARMTREE model and progressive data from the Carngham trial showed that simulations of the agroforestry regimes at Carngham were more profitable than grazing alone using real discount rates up to 7%. The 277 trees/ha-wide-spaced regime returned the greatest net present values over the range of discount rates used. The optimum rotation length, assuming a 5% real discount rate, was 26 years. Based on the 277 trees/ha-5 row treatment, shelter benefits for agricultural production could be obtained with a distance between belts of 150 to 200 m and by leaving at least 10% of the trees unpruned. The Carngham trial represents one case study of Radiata Pine-pasture agroforestry for south west Victoria. On this basis, the data presented provides information on patterns and trends likely to be encountered in applying agroforestry to other locations in Victoria. The adoption of agroforestry requires ongoing research trials and demonstrations and the Carngham trial has been well planned and maintained and should be seen as a valuable asset for the advancement of agroforestry in Victoria.
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    Growth of Pinus radiata (D.Don) stands in relation to intra- and inter-specific competition
    Bi, Huiquan ( 1989)
    This study investigated the growth of even-aged Pinus radiata stands in relation to intra-specific and inter-specific competition. The first part of the thesis used a data set of 30 year experiments together with a glasshouse experiment. A maximum stand biomass-density line was estimated for the P. radiata stands undergoing self-thinning. This line constrained the stand biomass-density trajectories of the individual stands. Growing along the trajectories, most stands increased the skewness of tree size distribution and the size hierarchy of the population. This was closely related to competitive status-dependent growth and death of trees in the stands. Height/diameter ratio decreased with competitive status. The relationship between them did not change significantly during stand growth. The experiment with P. radiata seedlings implied that competition for light was relatively important in affecting the growth, allocation and allometry of P. radiata during intra-specific competition. The second part of the thesis studied a 10 year old P. radiata plantation invaded by Eucalyptus obliqua. The study was done in conjunction with a replacement experiment with P. radiata and Eucalyptus regnans seedlings. The experiment revealed that P. radiata was more aggressive towards Eucalyptus regnans at the seedling stage. In P. radiata stands invaded by E. obliqua, the size and stem form of P. radiata was closely related to the polygon area defined by its by' E. obliqua neighbours. As the density of E. obliqua increased, its rooting density also increased. This related closely to the decrease in (1) rooting density, (2) aboveground tree size, (3) total projected leaf area, (4) total stem volume and to the increase in the skewness of size distribution and the size hierarchy of the P. radiata populations. The results suggested that competition for water and nutrients was relatively important for P. radiata in competition with E. obliqua in these stands.
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    Growth and yield models for South Australian radiata pine plantations: incorporating fertilising and thinning
    O'Hehir, James Francis ( 2001)
    This thesis describes the development of models to predict the volume growth response of South Australian radiata pine plantations to the interaction of the silvicultural tools of thinning and fertiliser used in combination. Some years ago this issue was identified as the component of the ForestrySA yield regulation system most in need of addressing and as a result a large thinning and fertiliser experiment was established. This was designed to determine whether a thinning and fertiliser interaction existed and to enable this interaction to be modelled. At the time it was established it was believed to be the only experiment of its kind in the world and this still appears to be the case. The thinning and fertiliser interaction models described in this thesis were designed to integrate with the models already implemented in the ForestrySA yield regulation system so that more precise predictions of future log availability can be provided, and improved management decisions can be made. Three sets of component sub models are described which operate at a stand level to: • predict the total volume growth of the main crop between the time of fertilising and the next thinning, approximately seven years hence; • predict the total volume growth of the portion of the stand which will be thinned (known as the thinnings elect) at the next thinning, between the time of fertilising and the next thinning; • predict the annual volume growth response of the stand between the time of fertilising and the next thinning. Further research is described to identify the data sets that are likely to be required for future analysis and revision of the South Australian growth and yield models. Adopting the future research recommendations will ensure that the consideration of the financial and economic benefit of alternative silvicultural prescriptions is broadened to include a more diverse range of sites and include log and wood quality considerations.