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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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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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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ItemEvaluating community involvement in revegetation( 1994)As community awareness of the effects of land degradation has increased, groups of volunteers have formed to return native vegetation to the Australian landscape. Community involvement in revegetation expands the economic, social and environmental impacts of such projects. The research reported in this thesis aims to develop an evaluative framework for assessing such impacts for community-based revegetation projects in central Victoria. From this general aim, a specific set of research objectives were developed. They were: 1) To gain an understanding of land degradation and describe the development of community involvement in revegetation from an historical perspective. 2) To define 'revegetation', 'community', and 'government support' as key terms of reference; and hence projects eligible for the study. 3) To briefly review literature describing the terms social impact, economic impact and environmental impact. 4) To review literature investigating techniques for evaluating these impacts, with specific reference to revegetation projects and projects involving volunteers. 5) To identify the types of groups and structures involved in community-based revegetation in metropolitan Melbourne and rural central Victoria. 6) To categorise and describe the broad impacts of these revegetation projects. 7) To select three groups for investigation on a case study basis. 8) Develop a set of criteria appropriate for the evaluation of community-based revegetation. 9) To evaluate the case study groups using these criteria and discuss the strengths and weaknesses of the framework. 10) Based on the research findings make general recommendations regarding the community-based revegetation movement. The review of the literature revealed decreases in agricultural productivity and moves by land managers to counter these losses with conservation measures. Revegetation was one such measure that had the greatest net social benefit when it was part of potentially sustainable land use system. Further investigation of the literature failed to reveal techniques specifically developed to evaluate the range of impacts associated with community-based revegetation projects in Australia. Baseline data were collected at 44 rural and 35 urban revegetation sites by personal interview. Multiple regression analysis was used to identify the factors which influenced plant survival. The major objective for revegetation of urban sites was improvement of amenity and scenic values. Planning of the revegetation projects generally was primitive and once established, some 70 per cent of sites relied on government. organisations for maintenance. Volunteers had contributed more hours than government officers to establish approximately 347,100 plants. The major factors influencing plant survival were season, planning, use of indigenous plants, plant protection and vandalism. The major objectives for rural revegetation were amelioration of salinity and erosion and creation of windbreaks. Planning of revegetation projects also was primitive. Rural group members had established almost 233,700 plants at group planting sites and 1,163,200 plants by individual plantings. Respondents believed lack of moisture, vermin, weed competition, insect and waterlogging had contributed to plant loss. The groups were categorised on the basis of their organisational structures. Three groups were selected for case study analysis, using Bennett and Nelson's (1975) evaluative model for community development as a framework. Performance indicators were drawn from the preliminary survey and recent evaluations of ParkCare and LandCare. Castle Creek Catchment LandCare group members were farmers who had joined the group because they were interested in better land management. Many respondents preferred to plant individually on their own farms, with availability of time as their major constraint. The group had planted approximately 25,000 trees and shrubs with 70 per cent survival rate. The combined value of volunteer and government labour, government grants and the cost of materials gave a estimate of $353,900 spent on revegetation. The ratio of Castle Creek Catchment LandCare group inputs to government inputs was 2:1. The cost per tree was calculated to be $20, the major component of which was labour costs. The second group, Sunbury LandCare group, was located on the urban fringe. As most members were hobby farmers there was division between those interested in public land and those whose priority was to revegetate their own properties. The group had established approximately 29,400 plants with 71 per cent plant survival. The value of contributions to revegetation was $236,000, with a ratio of 3:1 for volunteer inputs to government inputs. The cost per tree was estimated to be $11. At Greenlink Box Hill, an urban group, all members understood and agreed with group objectives. The group leaders were experts in the field of indigenous revegetation, so the standard of revegetation was high. The ratio of volunteer inputs to government inputs was 9:1. The group had established in the vicinity of 60,000 trees, shrubs, grasses, herbs and forbs. The cost per plant was $10. From the case studies, it was concluded that group success required a clear set of objectives which reflected member interests. Government support through grants and staff support was significant for all three groups. Officers working with the groups required technical and liaison skills. The standard of revegetation projects was linked to the constraints upon individuals and within the groups. Time, money and knowledge all influenced the level of planning, site preparation and maintenance. It appeared that the aims of shelter creation and improvement of landscape aesthetics were achievable through community-based revegetation. However, lack of monitoring of land degradation processes made it impossible to speculate upon the extent to which more complex processes such as erosion were affected. The underlying distinction between rural and urban revegetation was that most rural projects were on private land, whereas urban revegetation took place on public land. Lack of planning and explicit arrangements for follow-up maintenance, management and protection raise questions about the extent to which project objectives will be achieved in the long term. It is suggested that some of these shortcomings could be alleviated through a change in funding arrangements.
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ItemSoil physical and chemical properties under Casuarina cunninghamiana Miq. (river sheoak) shade trees in northern Victoria( 1994)Casuarina cunninghamiana Miq. (river sheoak) is an Australian native tree with a natural distribution throughout eastern Australia. It is one of the three Australian casuarinas being widely grown in many countries as an exotic multipurpose tree. This thesis reports on a study of soil physical and chemical properties under C. cunninghamiana shade trees in northern Victoria. The study aimed to assess whether the presence of the trees had any effect on soil properties (bulk density, organic matter and chemical properties) by comparing soil under the canopy with soil under the adjacent open pasture. The study was conducted at the Department of Agriculture Rutherglen research station which has a mean annual rainfall of 590 mm and moderately to strongly acid Rutherglen loam soil. The study involves two main treatments: under the tree canopy and under open pasture. The treatments were replicated in each quarter of the sample plot containing nine sample trees. Soil samples were collected only once for soil bulk density, organic matter and chemical properties. The results showed that the presence of C. cunninghamiana shade trees did not improve soil bulk density, organic matter content and chemical properties of the surface soil (0-15 cm depth) under the canopy. Soil bulk density and organic matter content under the canopy were not significantly different (1.12 g cm-3 and 4.44% respectively) compared with open pasture (1.19 g cm-3 and 4.07% respectively). Soil pH and total nitrogen were significantly less (pH 4.20 and 0.08% respectively) under the canopy compared with under the open pasture (pH 4.48 and 0.01% respectively). Available phosphorus and exchangeable potassium levels under the canopy (2.09 ?g/g and 4.22 cmol kg-1 respectively) were not significantly different compared with open pasture (0.773 .Lglg and 4.88 cmol kg- I respectively). The lack of improvement in soil bulk density and nutrients under the canopy is probably due to the inherent acidity of the soil. This may make conditions unsuitable for litter breakdown and nitrogen fixation. Low rainfall and seasonal flooding of the study site may also be influencing these soil properties. The results demonstrate that the potential of C. cunninghamiana to improve soil properties may be variable depending on the site conditions.
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ItemAn evaluation of fuel-reduction burning in the dry sclerophyll Wombat State Forest( 1994)Each year, between one and three per cent of the total forested area in Victoria is fuel-reduced as a part of the Department of Conservation and Natural Resources' program to implement its overall fire protection policy. The dry sclerophyll Wombat State Forest has been fuel-reduced since the 1960's, - a practise considered important because of its susceptibility to fire and its highly flammable plant community. This thesis presents the results of an evaluation of fuel-reduction burning in the Wombat State Forest, commencing with a review of forest conditions, principles of fuel-reduction burning, fire behaviour and fire effects. This is followed by observations and measurements in the field to document current practices of fuel-reduction burning, to select an appropriate fire-behaviour prediction model, to identify time-intervals between successive burns and to evaluate the effects of fuel-reduction burning on forest trees. Historical data of wildfires were used to evaluate the effectiveness of fuel-reduction burning in limiting the number, area and losses from wildfires. "Multi-criteria analysis" was then applied to select priority areas for fuel-reduction burning. The fuel-reduction burning program which is conducted 'every year during autumn and spring requires detailed planning and preparation, because it can only be carried out under certain prescriptions for weather, fuel and fire behaviour. Depending on the extent and conditions of each area, either ground or aerial ignition is applied. Large areas ignited from the air often result in variations of fire behaviour and intensity that leave many un-burnt patches within the broad areas of burnt forest. In order to predict fire-behaviour, comparisons were made between the Control Burning Meter, the McArthur Fire Danger Meter and the Fire Behaviour Tables for Western Australia (the Red Book). From a study of small trial plots, it was shown that the fire behaviour model incorporated in the Control Burning Meter for messmate-gum or silvertop forest type provided quite realistic predictions of low-intensity prescribed fires compared with predictions based on the McArthur Forest Fire Danger Meter and the Fire Behaviour Tables for Western Australia. Since its inception, fuel-reduction burning in the Wombat State Forest has decreased the quantity of litter and twigs, but it has had no significant effect on the quantity of humus and coarse fuels. This reduction of flammable fuels has reduced the potential for major fires and the study showed that a fuel-reduction burning cycle of less than five years is required to restrict the build up of fine fuels to acceptable levels. With regard to the impact of fuel-reduction burning, it was shown that it causes scorches on most trees, and that there is a significant relationship between scorch-height and tree diameter for the two dominant species, messmate (Eucalyptus obliqua L'Herit) and peppermint (E. radiata Sieb. ex. DC.). However, because of their different bark types, average scorch height was higher for messmate. Due to the considerable variation in the severity of fire seasons, hence in the frequency and severity of fire, no significant differences were detected in the number of wildfires and the extent of areas burnt, before and after the application of fuel-reduction burning in the Wombat State Forest. However, analysis of the historical fire data led to the conclusion that fuel-reduction burning has achieved its objective of limiting the severity of wildfires. Most of the wildfires occurred on areas that either had never been fuel-reduced or that had been fuel-reduced for more than five years. The costs of fuel-reduction burning have been relatively modest in comparison with the potential losses. Therefore, when properly planned and implemented, fuel-reduction burning is a valuable management tool for protecting forests and wider community values. This study has also provided a general idea on the applicability of "multi-criteria analysis" for identifying priority areas for fuel-reduction burning in the Wombat State Forest, with priority areas being selected on the basis of level of fire hazard (fuel, weather and topographical conditions) and values of particular sites (significant values, timber quality, distance from the nearest township and extent of the area). The result was a ranking of areas according to their priorities for burning.