School of Ecosystem and Forest Sciences - Theses
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ItemControl of thinning operations for maximum production( 1998)Thinning of plantations is a recognised practice for concentrating growth onto selected trees while providing an intermediate return from the thinnings. A great deal of work has been done on methods for estimating optimum time and weight of thinning for the particular stand. However, the selection of individual trees to be thinned in the forest has relaxed in recent years to make thinning more flexible, reduce costs and to better facilitate mechanised harvesting. Some plantations are now being thinned by the harvesting machine operator selecting the trees to be thinned while harvesting. A series of field trials were undertaken in Pinus radiata plantation at Rennick, Victoria, to compare conventional tree marked thinning with operator selected thinning (OST) where the harvesting machine operator selected trees while harvesting. The results indicate good control of tree selection by the operators: thinning to the same density and diameter distribution as the tree marked treatment while removing all required defect trees. Operator tree selection did not affect harvesting productivity, however, it improved log processing time in a second thinning by an experienced tree selecting operator, it also improved falling and work cycle time (approach tree, fall and process) in first thinning on a high site quality. Thinning trials at an operational level, about 6 ha, tested operator selection thinning to two different sets of guidelines: a diameter limit; and spacing requirements for residual trees. These OST thinning operations were no worse than the conventional tree marked thinning and resulted in less residual tree damage and more trees harvested per hour in second thinning. A simple economic analysis, based on data from the field trials, showed each operator selection thinning to be similar to the conventional tree marked thinning for revenue from thinnings and PNV of the rotation taken through to final harvest by a computer model. Of the trials, first thinning on high site quality by a relatively inexperienced operator selecting trees was the least favourable for stand production.
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ItemThe water and nitrogen dynamics of a lucerne-based farming system in the Victorian Wimmera( 1998)The water and nitrogen (N) dynamics of a lucerne-based farming system (grazed lucerne-annual medic-ryegrass pastures grown in rotation with crops) was compared to continuous cropping (cereal, pulse and oilseed crops) in the Victorian Wimmera. The growth dynamics and CO2-exchange behaviour of lucerne in the pasture phase was also investigated. Soil profiles under lucerne-based pastures remained consistently drier during the year as compared to annual cropping. The amount of plant-available soil water (0.0 to 2.0 m) after 3 to 4 years of pasture was on average 48 mm less than after annual crops (wheat, field pea), most of which (81%) was extracted at depth (1.0 to 2.0 m). In the field, crop yields (canola, wheat) after lucerne were not reduced because water use by these crops was predominantly in the top 1.0 m of the soil profile. A wheat simulation study predicted that a small median yield loss of 0.4 t ha-1 (15%) could be expected for the first wheat crop grown after lucerne, although this yield penalty varied from 0 to 0.87 t ha-1 depending upon seasonal rainfall. The risk of a large yield penalty (>0.8 t ha-1) was low (5 years in 100). From simulation studies, the time taken to fully recharge the soil profile after lucerne to levels equivalent to that under continuous cropping was estimated to occur within 4 to 5 years. The contributions of N2 fixation by the legumes (lucerne, annual medic, field pea) to the N economy of the farming systems in this study depended upon the amount of dry matter production. N2 fixation by field pea (121-175 kg N ha-1 yr-1) was greater than pasture legumes (40-95 kg N ha-1 yr-1), although a large amount of N was removed in grain at harvest (115-151 kg N ha-1 yr-1). N2 fixation by lucerne (19-90 kg N ha-1 yr-1) was consistently greater than annual medic (2-56 kg N ha-1 because the effects of seasonal rainfall patterns on dry matter production were more pronounced for annual medic. Winter-cleaning of ryegrass in the pasture before cropping resulted in both a high legume content (85%) and generally increased N2 fixation (up to 55 kg N ha-1 yr-1 ). Despite some benefits in N fertility, large responses to N fertiliser were still observed in crops following pastures; in grain yield (increases of 0.33-0.55 t ha-1 for canola, 1.0 t ha-1 for wheat), protein (0.7-2.3% for canola, 1.3% for wheat) and oil yield in canola (124-205 kg ha-1). The growth pattern of lucerne was similar to that of annual species (annual medic, ryegrass) contained in the pasture, with the majority (70%) of growth occurring between July and November. The small amount of lucerne growth from summer to early autumn (December to March) was due to the small supply of water (rainfall and stored in soil) during this period. A more detailed study of two lucerne pastures during summer revealed that the plant was under considerable water stress; leaf:stem ratios increased (from 0.9-1.6 to 2.6-3.2), leaf folding and paraheliotropic movement decreased the amount of leaf area exposed to incoming radiation in the middle of the day (by 14-29%), and it was estimated that the some 75-83% of assimilated carbon was partitioned below-ground to roots and crowns.
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ItemPhysiological aspects of root growth of Eucalyptus pauciflora, subsp. pauciflora and Eucalyptus nitens( 1997)This thesis examined i) morphological and physiological effects of low soil temperatures on root growth of subalpine Eucalyptus pauciflora Sieber ex Sprengel subsp. pauciflora and montane Eucalyptus nitens (Deane & Maiden) Maiden, ii) determined the variability, and in particular the day/night variability, in root elongation, and iii) explored the physiological basis for such variability. A series of experiments were undertaken with seedlings of E. pauciflora and E. nitens grown at soil temperatures of 3, 7, and 13C, and where seedlings were transferred from one temperature to another. E. nitens grew faster than E. pauciflora at 7 and 13C, but E. pauciflora grew faster than E. nitens at 3C. E. pauciflora always produced greater total and white root length than E. nitens. E. nitens roots browned faster in response to lowering soil temperatures than E. pauciflora. The osmotic potential of the roots decreased with soil temperature, but more so in E. pauciflora than E. nitens. Proline was a prominent osmoregulant in roots of E. pauciflora and arginine in E. nitens roots. It is suggested that E. pauciflora is better adapted than E. nitens to root growth at low soil temperatures because it can keep roots white longer and can maintain lower root osmotic potentials. Root growth of E. pauciflora was examined for 31 months (December 1992 - June 1995) in a mature stand at an elevation of 1545 m on Mt Stirling, Victoria, Australia. Greater night than day root elongation was recorded from eight in situ rhizotrons during the summer and early autumn of 1993. Shoot growth was also monitored during part of this study (April 1994 - June 1995). It was found that root growth commenced in the spring at soil temperatures 5 1.5C, under 550 mm of snow, at least one month before the onset of shoot growth and continued at least two months longer that shoot growth during the autumn. A period of root dormancy for at least one month a year occurred in roots of E. pauciflora. The seasonal variability in root numbers of E. pauciflora appeared to be related mainly to soil temperature and to a lesser extent to soil water content. Moreover, there appeared to be some internal periodicity in root growth which was independent of the external environment on Mt Stirling. Greater night than day root elongation was recorded in seedlings of both eucalypts in a glasshouse. Root elongation rates were greatest in E. nitens, and root elongation of both eucalypt seedlings were greater than that of the mature E. pauciflora on Mt Stirling. The zones of day and night elongation were determined in root marking experiments. Histological studies of the zone of elongation showed that cell division occurred mainly during the day and cell elongation mainly at night. Night root elongation rates were increased by increasing day-time air temperatures, light-period, and light intensity; and by decreasing water stress during the night. The turgor pressure of the root tips was greater during the night than the day. It is suggested that the amount of root growth during the night is determined directly by turgor pressure during the night and indirectly by processes during the day (light duration and intensity, and temperature during the light period) which determine the extent of cell division during the day. A greater rate of cell division during the day will be translated into a greater rate of root elongation, especially in the night.
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ItemStain development in Victorian hardwoods( 1996)Fungal stain in value added hardwood has resulted in the loss of millions of dollars in downgraded timber over the past few years in Victoria (Vinden 1994). The causes of fungal stain in Victorian hardwoods, particularly Eucalyptus regnans and Eucalyptus delegatensis, were determined at J.L. Gould Sawmill in Alexandra, Victoria. Systematic sampling of the logs in the log pile under sprinklers revealed a complex ecological niche of fungi, many of which are capable of causing stain. Further studies on logs with incipient decay identified Penicillium glabra as the fungus potentially responsible for the yellow stain and Ophiostoma sp. as the fungus potentially responsible for the black stain. A mill audit pinpointed areas in the processing procedure in need of improvement. Log storage times must be radically reduced and storage facilities must be improved to provide an environment that does not encourage fungal growth. A study concentrating on the moisture content of logs in the log pile also revealed the need for an improved water sprinkling system. Proposals to counter the stain problem include improving control measures, implementation prophylactic treatment after log sawing, and further research into biological control in the log pile.
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ItemA marketing approach to recreation management in national parks( 1995)Recreation managers have always attempted to ensure that resources are used effectively in planning and delivering outdoor recreation opportunities. However the lack of a sound theoretical understanding of management's' role and function in the provision of these opportunities limits the ability of managers to meaningfully evaluate the effectiveness of their actions. Many authors believe that the challenge facing recreation research is the development of a model to provide this much needed theoretical base (Allen 1988, Watkins 1990). Using data derived from a visitor survey conducted at Wilsons Promontory National Park, this study examines the potential of defining and evaluating the role of outdoor recreation management from a market-oriented perspective. The concept of voluntary exchange underpins this perspective. Fundamentally, approaching recreation management from this perspective suggests that effectively providing opportunities for outdoor recreation is not necessarily contingent on fully understanding participants recreation experience outcomes. Rather, what is important, is understanding the nature of the exchange between management and participants and how well management performs in this exchange. The visitor survey principally contained two research instruments, importance-performance analysis (Martilla and James 1977), and recreation experience preference scales (Driver 1977, Driver 1983). This not only enabled the nature of the exchange between management and participants to be investigated, but also provided a means to compare a market oriented approach to outdoor recreation management with the more traditional approaches based on the recreation demand hierarchy. The results identified 13 general dimensions to the recreation opportunity provided at Wilsons Promontory National Park. Three visitor segments were identified in the Park visitor population. Analysis of the components of the recreation opportunity important in producing satisfaction for each of these segments suggests that the role of visitor management at the Park is to deliver recreation opportunities which primarily differentiate along a facility based comfort/asceticism continuum. The study also shows that visitor perceptions of management's performance in the voluntary exchange process can be used to help management ensure resources are used effectively in the delivery of recreation opportunities. The study concludes that a market-oriented approach to visitor management in national parks and outdoor recreation areas has considerable potential. However, further research is required to refine the methodology and techniques explored in this study.
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ItemPotential impact of a farm forestry industry on the Goulburn regional economy( 1996)Transactions for a hypothetical farm forestry industry in the Goulburn region were constructed from the output of the FARMTREE model. Eleven different regimes were simulated, including hardwood and softwood, woodlots, timberbelts and wide-spaced agroforestry. This output included estimates of annual cash flows of costs and revenues per hectare. These were transformed to regional aggregated cash flows projected forward over one hundred years. A regional input-output table without farm forestry was constructed using the national input-output table and GRIT and adjusted for future growth. For certain years or 'snapshots' the farm forestry industry transactions were inserted into the future projected input-output table for the Goulburn regional economy. The new balanced input-output table summarizes the inter-sectoral flows and describes the regional structure with the new farm forestry industry inserted. Three snapshots were taken representing different stages of the development of the farm forestry industry: i 2004, the establishment phase: when the cost of plantation formation is greater than the predicted returns from wood sales. ii 2019, the transition phase: when the returns from wood sales have begun to swell whilst new sites are still being planted. iii the steady state phase: when harvesting is equal to replanting, no new sites are being planted, a full range of plantations exist at different stages of formulation and returns from wood sales have trebled since the previous transition year. Two methods were used to analyse the input-output tables constructed and the associated impacts. The first method was the analysis of the difference between the input-output table with farm forestry inserted compared to the input-output table without farm forestry inserted. This method allowed the estimation of the effects of farm forestry industry and the value-added processing of farm forestry products on the other sectors in the regional economy and hence the economy as a whole. The second was with conventional multiplier analysis used to estimate the changes in a given year resulting from an increase in demand for the farm forestry industry, wood manufacturing and other sectors. In the year 2034, the introduction and integration of a farm forestry industry in the Goulburn regional economy potentially generates, using multiplier analysis: $53 million worth of output; $13 million worth of income; and provides for up to 234 jobs. The farm forestry industry, using the difference method of analysis, produced a change in the economy of: $1,268 million in total output, a change of 6 per cent; $302 million in total income, a change of 5 per cent; and 5,750 jobs, a change of 4 per cent. The industry that experiences the single largest increase was the wood manufacturing industry through its value adding of the product purchased from the farm forestry industry.
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