School of Agriculture, Food and Ecosystem Sciences - Theses

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    Adoption of agronomic technologies by farmers
    Konstantinidis, Jim ( 1999)
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    Quality, management and value to landholders of remnant vegetation in the box-ironbark region of Victoria
    Dettmann, P. D ( 1999)
    Since European settlement of Australia, forest cover has been reduced from 10 to 5 % of the continent, woodland cover from 23 to 15 %, and in Victoria, forests and woodlands have been reduced from 75 to 33 % of the state's area. The Box-Ironbark ecosystem is a major vegetation type, stretching from Wodonga to Stawell, and was the centre of activity in the Victorian gold rush of the 1850s. Mining and agriculture have led to the clearance of 75 % of the original 1 Mha of the Box-Ironbark in northern Victoria. Of the 250,000 ha remaining, 15 % is located on private land, and 85 % on public land. The private land remnants are often smaller, isolated, and affected by surrounding land use. A recent Department of Natural Resources and Environment report identified that some of the best examples of some habitat types can be found on private land. This research seeks to attain an understanding of the values and concerns of landholders with respect to their remnant vegetation, and to understand the quantity and quality of remnants on private land, so as to better manage remnants in the future. A mail survey was sent to 552 landholders, receiving a 70 % response rate. The survey requested information regarding habitat quantity and quality, values and concerns about remnant vegetation, landholders contact with agencies, and demographics. In order to assess remnant quality, nine components of habitat quality which landholders could easily identify and grade for abundance were chosen to give an integrated numerical rating of habitat quality. The mail survey found that some 65 % of landholders managed Box-Ironbark remnants, and these approximated 4 % of the total private land. Results indicate that 50 % of the Box- Ironbark remnants had been impacted by grazing or other disturbance, 10 % of this severely, with approximately 20-50 % of Box-Ironbark remnants of moderate to high quality. The size of the remnant had the largest impact on habitat quality, with larger remnants generally being of higher quality. With regard to landholder values and concerns, results demonstrate that landholders hold mainly utilitarian values for their remnant vegetation, such as erosion control and water table protection. However, habitat and wildlife values were also held, especially among landholders with smaller properties and those with a higher level of education. One third of landholders believe remnant vegetation lifts production on their properties. Weeds, pests, and fire were the main concerns of landholders regarding Box-Ironbark remnants. Three quarters of landholders would not consider clearing any of their remnant vegetation, and 92 % would not consider clearing all or a large part of their remnant. Landholders on larger properties clearly value funding for on-ground works more than demonstrations and provision of technical advice, and this was also demonstrated in that they value the Land Protection Incentive Scheme and Landcare as the most useful programs. Those on smaller properties value the provision of technical advise more, and Land For Wildlife is the most highly regarded program. Other programs were relatively unknown to landholders. Findings demonstrate that landholders can be divided into two general groups according to property size. Those with larger properties would benefit from incentives as the remnant vegetation may be an economic hindrance. Education on the benefits that remnant vegetation can provide the property would also be worthwhile. Landholders with smaller properties are less concerned with productivity, and utilise the remnant for recreation and lifestyle. This group would benefit more from a program of education on best management of remnant vegetation.
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    Control of thinning operations for maximum production
    Yeo, Byron John ( 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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