Resource Management and Geography - Theses

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End date: 2015 × Type: PhD thesis ×

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Now showing 1 - 10 of 101
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    I just cant see myself doing it : occupational aspirations and identities : young people from family farms, Victoria
    Geldens, Paula Michelle (University of Melbourne, 2004)
    The purpose of this study has been to gain an understanding of the relationships between the identities and occupational aspirations of young people from family farms in the State of Victoria. The theoretical and philosophical approach utilised in this thesis is best characterised as viewing Gottfredson's (1981; 1996) modern developmental model of occupational aspirations and identities through a postmodern lens. A mixed method approach was employed in the investigation of the relationships between aspirations and identities. The project involved 138 participants from four sites in rural regions of the state: Orbost. Ouyen, Kyabram, and Casterton. Participating secondary college students (of years 10 � 12) each completed a questionnaire, a further subset of 37 participating in an interview. Follow-up interviews were conducted with 36 of these participants between 13 and 15 months after the initial interview. These follow-up interviews offered a unique opportunity to explore with these young people the fluidity of their identities and occupational aspirations during the intervening period. One third of these participants were no longer attending secondary school at the time of this second interview, including eight who were employed and six who were attending tertiary institutions. The findings developed, and conclusions drawn, from this project related to a range of subject areas and have been presented according to the following headings: What of young people?, Ruralities of multiple and diverse meaning, Identities within contemporary social worlds, and Occupational aspirations and post-school 'futures. This research has shown that the discourses that pervaded and constructed the social worlds of these young people were powerfully informative of the ways in which they constructed both their identities and their aspirations. These young Victorians constructed career goals with reference to their understandings of self (identities) and how these identities positioned them in relation to particular occupations and the broader social worlds in which they were positioned. This thesis provides meaningful insight into the lives of these young people at a time when making decisions about post-secondary goals were at the forefront of their lives. Further, this thesis illustrates the inadequacy of a number of singular discursive conceptualisations in accounting for the lives of these young Victorians. The implications and applications of this work are of particular relevance to audiences including but not exclusive of: rural communities, parents, careers advisors, educational policy makers, agricultural industries, employers, researchers, and policy makers in general.
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    The morphodynamics and evolution of intermittently closed and open coastal lakes and lagoons in Victoria, Australia
    McSweeney, Sarah ( 2015)
    Intermittently Closed/Open Coastal Lakes/Lagoons (ICOLLs) are a form of wave-dominated, microtidal estuary that experience periodic closure in times of low river flow and high onshore sediment transport. Prolonged closure results in an array of management issues including flooding and a decline in water quality with low pH and anoxia. ICOLLs are important sites for ecology, recreation and are highly valued for amenity although the dynamic entrance condition also makes these estuaries highly sensitive to environmental change. Despite the complexities associated with the dynamic entrance condition, the specific processes controlling entrance opening and closure are not well understood over a weekly to daily scale. This thesis takes a scaled approach firstly investigating the global distribution of ICOLLs and the boundary conditions controlling this distribution. It then aims to differentiate between the different types of ICOLLs and identifies the processes controlling their entrance morphodynamics using the coast of Victoria, Australia as a case study. ICOLLs are identified to constitute the most common form of estuary along wave- dominated microtidal coastlines globally. In Australia, they are prominent along portions of the coast which where the relative tidal range (RTR) is <1.5 and as this increases over 1.5, estuaries become tide-dominated and permanently open. In Victoria, 91 % of all estuaries are identified as ICOLLs and within these there are a diverse range of morphologies and entrance opening regimes. A classification model identifies that there are a suite of three types of ICOLLs present in Victoria. The basin accommodation space of the estuarine lagoon, channel dimensions, and catchment size and topography are factors which control the frequency and duration of entrance closures. A field campaign was undertaken to identify the geomorphic drivers of entrance closure and opening under different marine and fluvial conditions. Closure processes include lateral or vertical accretion which can occur independently or together over a closure cycle. Entrance opening is a result of an increase in water depth within the estuarine lagoon by either fluvial discharge or wave overwash. The rate of entrance closure is largely dependent on the dominant marine processes driving deposition within the channel. The highest rates of deposition occur by vertical accretion and during storms (Hs = >4 m) and the slowest during low swells and when lateral accretion becomes the dominant mechanism of sedimentation. Using a combination of field measurements and observations, the six distinct stages of entrance condition were recognised showing that the precise threshold between closure and opening is controlled by a ratio between the berm crest elevation and basin water level. Within this sequence, the relative balance of wave, tidal and fluvial energy vary throughout, with fluvial dominance driving erosional processes and waves and tides driving deposition. The findings of this study present a better understanding regarding both the wider scale boundary conditions and the specific processes controlling opening and closure of estuaries thereby providing a background for better management in estuaries of this type.
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    Dynamics of nitrogen between organic and inorganic phases in soil
    Wang, Weijin ( 2002)
    Accurate prediction of mineral N dynamics in soil is important for sustainable management of land resources towards stable plant productivity, least greenhouse gas (N20) emission, and minimum water system contamination. Our ability to achieve this is largely limited by inadequate understanding of soil N cycling processes in relation to substrate quality and quantity, soil properties and the environmental conditions. This research aimed to improve our understanding of the role of the basic N turnover processes in determining mineral N accumulation in soils, and to look into the biologically labile fractions of soil organic N as estimated-with physical, chemical, biological, isotopic equilibrium, and long-term incubation techniques. Gross N mineralisation, immobilisation in and loss from soils during waterlogged and aerobic incubation were differentiated and quantified using 15N isotope dilution techniques and five different types of analytical equations. The relative magnitude of gross N mineralisation -between waterlogged and aerobic incubations was soil-dependent, whereas gross immobilisation tended to be greater under aerobic than under waterlogged conditions. The total amounts of N consumption by immobilisation and loss were equivalent to 17 - 90 % of the mineralised N during waterlogged incubation and 23 - 59 % during aerobic incubation. Several indices of N mineralisation capacity were evaluated using the gross N mineralisation as a reference criterion, including total organic N, water-soluble organic N, NaOH-hydrolysable N, hot HC1-hydrolysable N, hot KC1-hydrolysable N, microbial biomass, and N in the light organic matter fraction. All indices except light fraction N were significantly related to gross N mineralisation during the 2-wk waterlogged and aerobic incubations of rewetted dry soils. However, none of the chemically hydrolysed N fractions showed closer relationships with N mineralisation than did total or water-soluble organic N, suggesting that these chemical methods could not selectively extract a biologically labile fraction of soil organic N. The isotopic equilibrium technique for estimating active organic N was assessed in a long-term (333 d) incubation following addition of 15N-labelled NH4+ and glucose at different C/N ratios. The estimated "active organic N" in soil at each periodic sampling (OT*) and in the original soil (OT#) increased with incubation time and was affected by the amounts of labelled N and available C addition. Considerable amounts of mineralised N were derived from other than OT* fraction of organic N, but N mineralisation from the OT* pool was much faster than from the bulk soil organic matter. The results supported the concept that soil organic N exists in a continuum of degradability. A more standardised procedure and suitable formulae were proposed for determining 074 as a relative index of the active organic N in soil. Eighteen soils were incubated at 35 C and 55 % water-holding capacity for 41 wk and two soils at different temperature and moisture combinations for 29 wk to examine the concept of potentially mineralisable N (N0) and its determination procedures. It was shown that N0 and the mineralisation rate constant k estimated with the conventional model-fitting technique varied significantly with incubation time, temperature, and moisture in unpredictable manners. These problems persisted with the double exponential model that divides the mineralisable organic N into an active (Na) and a slow (Ns) pool, although it accommodated the initial mineralisation flush very well. Modifications of this technique were proposed to explicitly estimate soil-specific organic N pools and their temperature- and moisture-dependent rate constants, including (i) use of standardised incubation temperature (35 C), moisture (55 % WHC, field capacity, or 30 kPa), and length of time (>20 wk); (ii) use of fixed rate constants in the non-linear regression (k - = 0.054 wk-1 for N0, or k - a = 0.693 for Na and k - s= 0.054 wk-1 for Ns) to estimate the pool sizes with data obtained under the optimum conditions; and (iii) use of fixed N0, or Na and NS values to estimate their rate constants under non-standard conditions. The pool sizes obtained with the modified technique provided unequivocal measures of soil N mineralisation capacity, and the rate constants showed consistent and close relationships with temperature and moisture. Using the parameters. estimated from laboratory incubation, satisfactory prediction of outdoor net N mineralisation was achieved. The No pool could reliably be estimated with water-soluble organic N and microbial biomass in soil samples, but estimation of NS needs a combination of several indices including net N mineralisation from day 14-28.
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    Tools for the conservation management of wildlife under uncertainty
    Todd, Charles Robert ( 2001)
    This thesis explores the kinds of models that may be built to support environmental decisions when direct data are scarce and understanding of the ecology of a problem is incomplete. It explores empirically the effects of structural, parameter, shape and dependency uncertainty using explicit population models of a threatened Victorian species, the eastern barred bandicoot (Perameles gunnii) and the nationally endangered species trout cod (Maccullochella macquariensis). In particular, the thesis examines the sensitivity of management decision for these species to assumptions about dependencies, their implementation in standard computer programs, decisions about structural alternatives, assumptions about shapes of statistical distributions used to reflect uncertainties, and the choices of parameters values. The empirical exploration of these features in two different ecological, management, and data contexts sheds light on the ways in which models may be used effectively to support pragmatic management decisions for threatened species. One of the uses of population models is to assess the relative risks of extinction faced by a suite of species. The assessments are used to classify species into various categories of threat, and to create lists for management action. Such lists are used for state of the environment reporting, and to set priorities for protection and recovery actions. In many circumstances, there is insufficient time to develop explicit models. In their place, various expert or rule-based systems have been developed to assess conservation status. They use a suite of population attributes including population size, geographic extent, population subdivision, and rates of change in these attributes as surrogates for extinction risk. However, these systems have, until recently, ignored uncertainties inherent in the data used to make the classifications. This thesis also explores the theoretical underpinning of dealing with uncertainty in rule-based systems, so that they may better reflect the reliability with which assessments are made.