School of Ecosystem and Forest Sciences - Theses

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 15
  • Item
    Thumbnail Image
    Making the connection between history, agricultural diversity and place: the story of Victorian apples
    Christensen, Johanna Annelie ( 2016)
    Apple growing practices are embedded in a productivist mentality aiming for ever higher efficiency and productivity. And while the climate change impacts are to a large extent known, there is little attention given to the coupling of the social and the ecological effects. I use apple growing as a case study to explore the relationship between place, biodiversity and rural change in Victoria. My research is based on historical research; including an analysis of the Museum Victoria’s collection of wax apple models, and in-depth interviews with orchardists. By drawing on environmental history, social-ecological systems thinking and Bourdieu's theory of practice, I highlight the importance of a systems perspective and inform it by emphasis on the critical role of underlying power structures and individual dispositions, or the habitus, of the growers. These dispositions have been shaped and internalised by the growers’ histories and their physical surroundings. Orchardists have been able to respond to intensifying production requirements by utilizing technologies and scientific nous to keep up with the continuous aim for efficiency. Growers are caught up in a self-reinforcing cycle of satisfying the demand for perfect apples by adopting expensive techno-scientific approaches to enable ever more intensive production. The symbolic violence and amplified biophysical pressure orchardists experience has driven many to despair; resulting in a significant decline in small scale apple growing businesses over the last decade. I offer some suggestions for government policy and support measures and argue that any services or support programs need to be tailored to the appropriate level and need of each orchard business and the individuals who are involved. My analysis shows that those growers, who engage more closely with their biophysical place as well as their history and identity as apple growers in that place are (re-)creating another version of what it means to be an apple grower. In some cases this is resulting in resistance to the vortex of agricultural productivism that has been the basis of their existence for many generations.
  • Item
    Thumbnail Image
    Effects of adding nutrients on soil chemistry and tree growth in native Eucalyptus forests of south-eastern Australia
    Severino, Dean Christopher ( 2007)
    The decreasing area available for timber extraction in south-eastern Australia, due largely to social pressure to reserve greater areas of forest, has led to the consideration of fertiliser-application to increase wood output from the remaining available forest. Potentially deleterious effects of fertilising on water quality must be assessed before implementation on a wide scale. This is in accordance with relevant forest management policies. This study examined the effects of applying fertilisers containing nitrogen and phosphorus, on soil and soil-water chemistry in two pole-sized stands of mixed Eucalyptus spp in the Wombat Forest, in the Midlands Forest Management Area, Victoria, Australia. The findings are synthesised and discussed in relation to management of regenerating mixed-eucalypt forests in south-eastern Australia. Fertiliser treatments were none (R); 400 kg N ha-1 as ammonium-sulphate (N); or 400 kg ha-1 plus 202 kg P ha-1 as triple superphosphate coated with 10% sulphur (NP). It was calculated that incidental additions of S were 1371 kg ha -1 (N treatments), and 1696 kg ha-1 (NP treatments). It was expected that P would be principally adsorbed on soil surfaces; N immobilised in the soil organic pool and that metallic cations would enter the soil solution to varying degrees. Fertiliser-addition increased both plot-basal-area (BA) growth and the rate of stand self-thinning. In 3.8 years, BA in reference (R) plots at two sites increased by 7.3% and 23.4%. Where N alone was added, BA increased by 14.2% and 27.1%, while in NP plots BA increased by 17.1% and 42.7% respectively. Mortality was 9% in untreated plots compared to 14% in NP plots. Estimated increases in biomass growth equated to additional above-ground nutrient accumulation of 0.4 to 1.5 kg ha-1 of P, and 5.5 to 20.8 kg ha-1 of N. This represented only 0.2 to 0.7% of added P, and 1.4 to 5.2% of added N. Soil solution was extracted from 10 and 50 cm with porous-ceramic-cup tension-lysimeters (-0.6 kPa). Concentrations of P and N were low both before and after adding fertiliser. Across all treatments the maximum median PO43- concentration in soil-water at 50 cm was 0.12 ppm (mean 0.28 ppm). Typically PO43- concentrations were not higher than 0.03 ppm. The 400 kg ha-1 of added N was rapidly immobilised in the soil organic pool. The greatest mean NH4' concentration from a single sampling occasion was 1.1 ppm. The mean NO3 concentration at 50 cm was never higher than 0.26 ppm. After adding N in fertiliser the proportion of NO3- relative to NH4* in soil-water increased and was correlated with decreasing soil-water pH. Less than 1% of added P and N was recovered from soil solution at 50 cm. The largest pool of added P recovered was PO43- adsorbed to soil between 0 and 20 cm, due to the soil adsorption capacity being well in excess of the applied 202 kg P ha-1. Phosphate desorption using sequential extractions with a mild acid extractant (0.3M NH4F, 0.1M HCI) recovered between 25% and 116% of added P. Differences were attributed to both the amount of P added and the effect of time since treatment at different sites. Soil disturbance during sampler installation was found to be more likely to raise soil-water P concentrations at 50 cm than would adding up to 202 kg P ha-1. Among the ions in solution. SO42- and CI' were the dominant anions while Cat+ dominated the cation chemistry. In untreated forest 5042- in soil-water ranged from 7.7 to 16.0 ppm at 10 cm and 7.9 to 12.2 ppm at 50 cm. In fertilised plots up to 100.5 ppm SO42 was measured in soil-water at 50 cm depth. In the N treatment at 50 cm, SO42- in soil-water accounted for 9.4 % of applied S. compared to 14.0 % in NP. In untreated forest, soil-water Cl- and SO42- accounted for over 98% of the total soil-water anions, in roughly equal proportions at 10 cm, and CI- slightly higher at 50 cm. Following fertiliser-application soil-water pH at 10 cm fell from 6.3 in R to as low as 4.81 (N) and 4.45 (NP). At 50 cm pH never dropped below 6 and there were no visible departures from reference concentrations. Relative activities of K+ and Mg2+ in solution increased with decreasing pH, indicating increased leaching potential. Sulphate in soil-water increased total anion charge further in NP than in N. Total charge (cmolc L-1) for cations followed anions. A slight deficit in anion charge was likely due to the unquantified contribution of organic anions. These results confirm that despite the quantity of fertilisers added in this trial being double likely operational quantities, the forest and associated soils had the capacity to retain these nutrients through a variety of processes. The study validates the environmental sustainability of proposed intensive management practices including fertiliser-application in this forest type. It also emphasises the importance of understanding fundamental forest nutrient cycling processes when aiming to carry out intensive forest management practices in an environmentally sensitive manner.
  • Item
  • Item
    Thumbnail Image
    Photosynthetic responses to light, nitrogen, phosphorus and pruning of Eucalyptus in south-eastern Australia
    Turnbull, Tarryn Louise ( 2005)
    Eucalypts frequently grow faster after additions of fertiliser, but more slowly in the shade or following `green pruning'. The coupling of rates of growth to environmental factors is at least partly due to acclimation of photosynthetic processes. Photosynthesis rarely proceeds at maximum rates in natural environments as photosynthetic processes and the supply of basic requirements of photosynthesis (CO2, H20, light, phosphorus and nitrogen) vary at both short (minutes to hours) and longer (days to months) time scales. Currently we lack mechanistic explanations for how these variables, alone and in combination underpin changed growth rates in Eucalyptus. This study examined growth and photosynthetic characteristics in glasshouse-grown seedlings and field-grown trees of Eucalyptus species that are commonly planted for forestry and revegetation purposes in central Victoria. Acclimation to light (among seedlings and within canopies), nutrient availability (phosphorus and nitrogen) and increased sink-strength for photosynthates were the primary foci of the study. In each instance I examined distribution of leaf nutrients within a canopy and allocation of N to Rubisco and chlorophyll to assess the degree to which nutrients limit photosynthesis in Eucalyptus. A novel technique was introduced to quantify the allocation of inorganic phosphorus within cells (cytoplasm versus vacuole), followed by an assessment of inorganic phosphorus allocation in response to a long-term reduction in phosphorus supply. In all circumstances, rates of growth were responsive to environmental conditions. Growth responses were underpinned by altered patterns of biomass partitioning and changed leaf morphology more than by rates of photosynthesis per se. There was little difference in adaptive strategies implemented by seedlings and trees: both were oriented towards the accumulation of nutrients rather than increasing rates of photosynthesis. Photosynthesis was reduced by shading (among different plants and within the canopy of a tree) and reduced phosphorus supply whereas N had little effect on photosynthesis. Analysis of pools of inorganic P revealed that adequate supplies were maintained for photosynthetic processes regardless of P supply, therefore reduced photosynthesis follows, rather than leads, a more general leaf-level response to reduced P. Similarly, changed partitioning of nitrogen between Rubisco and chlorophyll was unnecessary as leaf nitrogen concentrations were consistently maintained at well above published minimum levels. Hence, photosynthesis was not up-regulated following increased nitrogen or phosphorus supply; instead excess nutrients were accumulated and used to support increased biomass. One exception was after defoliation, when up-regulation of photosynthesis was observed, presumably to ensure the demand for photosynthates could be met by a reduced leaf area. Sensitivity analyses consistently revealed variation in photosynthetic rates owed more to altered biochemical activity (e.g. Jmax and Vcmax) rather than stomatal conductance regardless of growth condition (glasshouse versus field). Hence, whilst Eucalyptus has considerable photosynthetic potential, faster rates of carbon fixation are only exhibited in the short-term. In part, this is due to the multiplicity of factors involved in `optimisation' of photosynthesis and their individual and collective responses to environmental conditions. In the long term however, increased canopy photosynthetic capacity follows only an increased photosynthetic area.
  • Item
    Thumbnail Image
    An investigation of environmental conditions experienced during the life of high value wood components and products
    Hopewell, Gary P ( 2004)
    The purpose of this project was to collate data on Australian wood products' exports as well as the environmental conditions that these products are exposed to during manufacture, transportation and service. These data are essential for understanding the potential for wood components to `move' in response to periods of drier or more humid conditions than those at the time of manufacture. The knowledge generated will contribute to a subsequent project, whereby a user-friendly tool will be developed to enable for the design and production of appropriate components, joints, adhesives, coatings, and packaging systems that will ensure superior performance of Australian wood products throughout a wide range of climatic conditions. Wood, a hygroscopic material, will undergo changing moisture contents, fluctuating with changes in atmospheric conditions. As a consequence of these changes in moisture content, wood will swell or shrink. For high-value products, these changes can be detrimental to the utility of the product, for example panels can warp, drawers and doors can jam, and glued components can delaminate. Despite the common occurrence of product degrade or failure due to exposure to changing atmospheric conditions, very little effort has been undertaken to quantify the range of expected conditions for Australian exports. Australian forest industries have a long history of export trade in a wide range of products, from woodchips and sandalwood, through to high-value manufactured commodities such as outdoor furniture and assorted flooring products. Current export markets for high-value wood products were found to be predominantly northern hemisphere countries, including United States of America, China (including Hong Kong), Korea, Japan, Europe (including the United Kingdom) and the Middle East. Other regions importing Australian high-value wood products were south-east Asia (Philippines, Indonesia, Thailand and Malaysia), New Zealand and South Africa. A survey was undertaken to determine the range of value-added products currently exported, and it was found that high volumes of flooring, decking, outdoor furniture and kiln-dried boards for furniture and pre-finished flooring products account for the majority of our value-added export effort. There are currently only minor volumes of assembled indoor furniture suites exported from Australia. Wood fibre panels such as plywood, particleboard and medium density fibreboard were outside the scope of this project due to the in-built stability of these products and only solid wood products were considered. Data generated from the survey included the range of timber species used in the manufacture of export products, sawn orientation and typical section sizes used in components. Results from this work showed that the major timbers are: the ash-type eucalypts from south-eastern Australia; jarrah from Western Australia; spotted gum, hoop pine, white cypress, imported kwila, blackbutt, brush box and Sydney blue gum from New South Wales and Queensland. Environmental conditions, especially the combined effect of temperature and relative humidity in microclimates as determined during this research project, can fluctuate extensively during transport from one location to the next. Equilibrium moisture contents (EMC) as low as 5% and as high as 20% were experienced during the shipping of wood products. In addition, the conditions at the place of manufacture (often 10 to 12% EMC) may be vastly different to the environment where the wood products are ultimately placed in service. The in-service conditions for many of our export destinations are between 6 to 9% EMC. This range of conditions, from manufacturing through transportation and in-service, can potentially create problems, due to wood components swelling and/or shrinking corresponding with periods of higher and/or lower temperatures and humidities. Packaging systems incorporating plastic and cardboard were shown to offer some protection against humidity changes. For the Australian wood-manufacturing sector to achieve and maintain a reputation for superior high-performance products in overseas markets, designers and manufacturers will require a clear understanding of the potential effects of changing environmental conditions on their products. When the range of conditions anticipated throughout the service life of an item is combined with data for timber stability, a manufacturer can allow for movement in the design of the item. An understanding of effective packaging systems is also necessary to ensure maintenance of timber moisture content during transportation. The research highlighted the inherent risks of exporting high-value wood products to distant markets and the need for development of a user-friendly tool, which would allow manufacturers to determine appropriate design parameters such as species, dimensions, jointing systems, adhesives, coatings and packaging for export products.
  • Item
    Thumbnail Image
    Bioenergy in a biofuture : a place for policy
    Morton, Jamie C ( 2003)
    With a focus on issues and opportunities for the forest industry and in the context of policy development, this study aims to examine the future of bioenergy in Australia US policy and developments are also considered given current alignment with US policy (eg Kyoto). Bioenergy is energy derived from non-fossil organic matter and includes a diverse range of processes and products. This thesis begins with a strategic look at world trends, fossil fuel supplies, the electricity industry and competition from other renewable energy sources, and moves to a detailed look at biomass feedstocks and bioenergy technologies. It concludes with energy policy developments both in Australia and the US, along with environmental, community support and green power marketing issues relevant to the development of bioenergy in Australia. Concerns over greenhouse gases and sustainable development are driving a world-wide trend towards renewables, with concerns over air pollution and energy security also playing a role. Energy use contributes to 80 % of total green house gas emissions in Australia A commitment to the Kyoto Protocol by the Australian government would assist policy development in support of renewable energies. Bioenergy offers a greenhouse friendly alternative, with some of the practical advantages of fossil fuels. Use of renewable sources of energy in Australia presently represents 6% of total energy consumption, of which bioenergy makes up over 75% (though in renewable electricity generation, hydro-electricity is by far the dominant source). The price of fossil fuels affects the competitiveness of bioenergy, making the future supply of crude oil relevant. Like most countries Australia is a net importer of crude, with imports to double by 2015. Biofuels (particularly ethanol) and biochemicals are being strongly promoted in the US and interest is growing in Australia. Biomass derived chemicals could substitute for crude oil in the manufacture of plastics, lubricants, composites and paints. Bioenergy must compete with a range of renewable technologies in addition to fossil fuels. Bioenergy compares well against other renewables though it has the disadvantage that it is neither well recognised or understood, and the community is not convinced that bioenergy is renewable. However bioenergy has the following advantages: it is the only alternative for production of liquid fuels, it is suitable for base load electricity; and it is the most flexible renewable energy source with a wide range of energy products. Feedstock cost is the main factor affecting the economic viability of bioenergy applications, often more important than differences in technology/application Waste biomass provides the cheapest source. Bioenergy plantations are struggling to compete with other sources on cost. The most common operational problem for bioenergy plants is the handling and transportation of feedstock within the mill (conveyor systems). Flexibility is an important design criterion for these systems, which must be robust and well designed. Policies such as PURPA and production tax credits have made significant contributions to expansion of renewables in the US Of developments in policy in Australia, the most important is the Renewable Energy (Electricity) Act 2000 The Australian federal government has also introduced a Biofuels initiative -however details of implementation await completion of a Biofuels Feasibility Study State governments across Australia have a diverse range of initiatives and funding programs as well. Prime environmental issues with bioenergy relate to resource use and air pollution. Resource use concerns relate primarily to intensification of forest harvesting. NSW is in the process of banning the use of any timber from native forests for biomass generation (except sawmill wastes). 'Green power' schemes reflect the pulse of community attitudes to renewable energy options. To succeed bloenergy must be more than greenhouse friendly, it must be demonstrably renewable with a net environmental benefit. Bioenergy can meet these needs, but community support is critical. In developing bioenergy proposals: Make sure proposals are well thought out and sensitively sited Consult communities early in development, with openess and honesty and a strong ongoing commitment to follow it through. Credibility and trust are crucial. Market the benefits of bioenergy accurately and thoughtfully and try to add broader environmental appeal - to improve prospects for success and to add marketable appeal for electricity retailers or Greenpower eligibility. Bioenergy is most viable when certain conditions are met These are: a) Access to 'cheap' feedstocks. b) Ready access to the market for the energy product(s) free of major costs/obstacles. c) Unsubsidised fossil fuel or electricity prices. d) Access to Renewable Energy Premiums. e) Community Support. Not all of these conditions must be met for bioenergy to be viable, but at least items b, e and either a, c or d are typically required. These conditions exist in Australia. The prime bioenergy options for the forest industry include: Co-firing - blending of wood wastes and chips in coal fired power stations; Utilisation of off-season generating capacity in sugar refineries using forest residues. Co-generation in wood processing facilities for power and process heat. Production of pellet fuels from mill wastes for direct combustion in homes for heat Production of ethanol using both forest and agricultural residues in an enzymatic hydrolysis process when commercially viable (earliest 2004-2007).
  • Item
    Thumbnail Image
    Issues for enhancing farmer participation in farm forestry research in Australia
    Crewe, Peta Marijan ( 2002)
    For many years, the scientific and professional community have determined the priorities for agriculture research with little input from farmers. Farm forestry may be a new industry but it already faces the dilemma that other agricultural enterprises have experienced, where farmer research needs are not being met, adoption of new technologies is slow, and as a result further development is inhibited. For other agricultural industries these issues have lead to the adoption of collaborative or participatory approaches of securing farmer input into the priorities for research, from defining the research needs to carrying out the work and disseminating the information. Through a series of focus group discussions, farm foresters who have been involved in the Australian Master TreeGrowers Program and members of the farm forestry research community were asked to provide their attitudes and opinions towards farmer participation in farm forestry research. The objective was that these comments and perceptions might provide insight into the potential and constraints facing farmer participation and highlight opportunities for establishing a more participatory approach to farm forestry research. A qualitative methodology and analysis of results highlighted many issues that impact on farmer and scientists attitudes towards participatory research. It also highlighted that farmers and scientists see a role for farmer participation in defining research needs, but that involvement in other stages of the research would depend on a number of factors. In terms of encouraging a participatory approach to farm forestry research, the scientists believe in the use of `leader' farmers, whereas the farmers supported the use of grower groups and coordinators to facilitate the process. The outcomes also highlighted the need to develop methods for getting farm forestry information to farmers, that research organisations need to become unified in their approach to farm forestry research, and that the scientific community needs a culture change to accept participatory research as a legitimate means of investigation.
  • Item
  • Item
  • Item