School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemEffects of adding nutrients on soil chemistry and tree growth in native Eucalyptus forests of south-eastern Australia( 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.
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ItemPerceptions of ecoforestry in selected project sites in Papua New Guinea( 2005)Land and forest resources in Papua New Guinea are held under customary ownership by clans. But clans have participated little in decision-making processes in any major forest resource development projects, although these have often had major effects on their areas and lives. The decisions about industrial logging have been made mainly by the government and multinational logging companies - though royalties have been paid to clans for extraction of the timber. Past logging operations have provided some infra-structural benefits but have also led to many environmental and socio-economic problems that affect the livelihoods of rural people. In an attempt to halt the further spread of large-scale logging, and under pressure from the World Bank, the European Union Commission to PNG and the Government of Papua New Guinea entered into a bilateral agreement to initiate the Papua New Guinea Ecoforestry Program in 1995. This was to be implemented through the involvement of clans as the forest resource owners. This study explores the experiences and views of clan members in two ecoforestry projects in West New Britain Province. The aims of the study were to describe the ecoforestry program in general and the two project study sites, and then to explore clan members' perceptions of the ecoforestry approach being promoted, based on their experience. The study was conducted with a view to identifying ways of improving the effectiveness of ecoforestry development projects in Papua New Guinea. Two ecoforestry project sites were chosen as case studies. The main data collection techniques were in-depth interviews with clan members participating in the ecoforestry projects, and observations of activities. The qualitative data collected were analysed using elements of a 'grounded theory' approach, which involved transcription of interviews from PNG Pidgin/English to word processed files in English, then examining and coding the transcripts for main themes. From these themes theory was developed about the way clan people viewed ecoforestry, and the prospects for the future of the approach. Data from secondary sources were used in description of the sites, and in the analysis and interpretation of data from interviews. The findings revealed strong views among some respondents about their gains in mechanical and management skills through the ecoforestry projects, and also on problems of transparency in financial management of projects, the hard work involved in ecoforestry, and difficulties faced by their female members left at home alone. Other difficulties mentioned were those of maintaining equipment and of sourcing spares for machines and securing reliable markets. Despite the many negative views expressed on ecoforestry, there was quite wide acceptance that the approach had major potential advantages in terms of self-determination for clans, learning skills, employment and income, village infrastructure and environmental care of the forest - when compared to industrial logging. In the final chapter a Force Field Analysis is used as a framework to discuss the implications of the main finding - for future efforts in ecoforestry in PNG. In general, the clan members were reluctant to give definite views on the future prospects of ecoforestry after withdrawal of the supporting aid agency. In answer to questions on this topic they tended to express views on the need for certain types of support in the future, and other ways for overcoming the difficulties of the past. There was a general desire to be given the opportunity to continue with the ecoforestry approach, in the hope that there would be improvement in community participation, skills and hence in benefits to their clans and communities.
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ItemPrivate forest farming in China( 2002)Since the early 1980s, China has adopted a series of policies to promote the development of private forest farming. The early moves to increase private participation in forestry were based on the introduction of the Household Responsibility System in the agriculture sector in the late 1970s. Since then, private forest farming has been developing throughout the country and become a main form of forest management in some collective forest regions, variously through sole proprietorships, leaseholder arrangements, partnership arrangements, joint management of state forests and foreign investment. With the shift of timber supply source from natural forests to plantations and the increasing demand for timber generated by the rapid development of the economy, a great potential exists for private forest farming to be further developed. It is therefore important to develop a policy framework that can encourage private participation in plantation development. This study reviewed the evolution of and future prospects for forestry property rights and the other factors likely to influence private forest farming. It identified a number of policy changes needed to ensure that private forest farming continues to expand. The continuing role of central and other levels of government in overcoming impediments is noted, as well as the special role governments must continue to play in relation to the development of protective plantations.
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ItemIssues for enhancing farmer participation in farm forestry research in Australia( 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.
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