Resource Management and Geography - Theses
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ItemTools for the conservation management of wildlife under uncertainty( 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.
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ItemSpatial distribution and scaling of avulsions on the King and Ovens River, Victoria, Australia( 2015)Anabranching is a multi-channel river system identified by in-stream vegetated islands or stable alluvial sediment. Avulsions require the abandonment of a river course in favour of a new, more efficient path, generally on the lowest point on the flood plain. Two styles of avulsions exist, progradational and incisional with the former requiring significant flood plain deposition (usually crevasse splays). The Ovens and King River of Northeast Victoria display characteristics of incisional avulsions which need overbank flooding to scour a new channel through surrounding flood plain. The study area of this paper provides a region, unaltered by human interference, to measure all avulsions and their relative distance downstream, an angle which previous literature has not taken up as yet. Results of longitudinal slope, stream discharge, relative flood plain height and sinuosity were based on analysing LiDAR data. Avulsion lengths and distance downstream showed very little correlation (R=2%) and although maximum lengths of avulsions showed greater correlation (R=54%) it still was not strong. Longitudinal slope decreased rapidly from -1.50 m/km to -0.29 m/km after approximately 70 km which correlated to the plateauing for maximum length avulsions. Although shear stress was not measured in this study, its ability to induce knickpoint migration is greater in lower slope regions, providing potential for longer avulsions. Valley-lengths of avulsions also exhibited similar patterns between the Ovens and the King with maximum in lengths at approximately 55 km, which correlated to a plateau in valley-length longitudinal slope. In conclusion, longitudinal slope was the main factor affecting avulsion length. Sinuosity of the Ovens River increased (1.34 to 1.65) whilst avulsion sinuosity decreased suggesting the current channel may avulse to new courses, or existing paleo-channels. The presence of paleo-channels on the wide expanse of flood plain of the lower regions, have a high tendency to attract flow into old conduits instead of scouring new channels for avulsions. Therefore, likelihood is high of reoccupation for avulsions along the Ovens River approximately from Wangaratta preventing the creation of long, whole-system avulsions. Finally, scale invariance of this study can be applied to expectations of avulsion lengths in other anabranching systems which must be considered for town-planning and risk-management. Therefore, providing the tools for predicting avulsions are necessary for future systems.
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ItemAltitudinal distribution of vegetation in the headwaters of the Wongungarra River, Victoria( 1993)Changes in vegetation composition with respect to altitude were investigated in the sclerophyllous forests of the Australian mountain region. Vegetation was surveyed at 148 sites along two transects which were located to maximise variation in altitude and minimise the influence of environmental factors not directly related to altitude. The measurement, simulation, and estimation of environmental variables revealed that this aim was met except at the end-points of the transects where secondary influences are present.
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ItemThe impact of kangaroo grazing on sediment and nutrient mobilisation( 2000-05)The adverse impacts on vegetation and soils due to livestock grazing have been extensively studied for many years. The extent to which native wildlife may also be causing change to their environment, as a result of local increases in population density, has been the subject of debate in a number of countries. In Australia there has been a growing awareness in recent years that native herbivores, particularly kangaroos and wallabies, may also be causing changes to ecosystem dynamics. Environmmental changes, produced firstly by the aboriginal people and then by Europeans, have favoured the larger macropods, resulting in increased population levels. These impacts can also be seen in areas around cities, where pressure from urbanisation has restricted populations to smaller and smaller patches of remnant vegetation and reserves, increasing the pressure on diminishing food resources within these patches. This study focuses on one of the areas that supplies drinking water to Melbourne, the Yan Yean Reservoir catchment, which is situated 37 km north east of Melbourne. This study adds to our understanding of the impacts of native wildlife populations by investigating the extent of some of these possible changes to ecosystem dynamics.
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ItemEstablishment of grassland forbs in modified urban environments( 1998-04)The use of nature-like plantings to ameliorate degraded public landscapes in Europe and North America is extensive. There is a growing trend towards the use of ecological urban landscape design in Australia. Meadow landscape may have broad applications in the treatment of degraded landscapes in Australia. An examination of suitable establishment and management techniques for flowering grasslands was undertaken at Fawkner Memorial Park. This site contains large areas of severely disturbed and degraded soils, due to past burial practices. Trials on the establishment of forbs via direct seeding and plug planting were undertaken. The management of bulb species by mowing was examined through foliage removal treatments post anthesis. The management of grass biomass through herbicides was also examined. (For complete abstract open document)
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ItemLost waters of West Moorabool: a history of a community and its catchment( 2004)Conflict around the allocation of the water resource cannot satisfactorily be reduced to a gradual decline of resource availability. This research explores the sources and mechanics of water conflict in a case study of the West Moorabool catchment, one recently designated as 'stressed'. Although situated in the temperate southeast zone of Australia, the loss of water from a predominantly rural catchment across a catchment divide to the urban centre of Ballarat has been a n1atter of continuing tension since the gold discoveries gave geographical definition to this part of European Victoria. As the demands for water increase, the political imperative to reappraise current water portioning gives full exposure to a conflict that, without historical investigation, could be oversimplified as a resource battle between urban recipients and rural donors. This history encapsulates the perspective of a changing rural community in a water supply catchment, by tracing the transition from a landscape of unallocated waters to one of overallocated water. The process whereby Ballarat water interests incrementally extended across the catchment had social consequences that polarised and entrenched the water conf1ict in this region. Although a homogeneous entity cannot be assumed, the rural community experienced a graduated decline in self-determination that has been more central to its water history than the loss of a physical resource. With water allocation being raised in many policy forums, there exists the potential to address a social agenda alongside assessments of resource capacity in a way that challenges the perpetuation of a traditional hierarchy of interests between rural communities and the inevitably more dominant and thirsty urban ones. A second but related dimension of 'loss' experienced by this catchment community concerns its increasing disconnection with the local waterways. Rivers, creeks, springs and reservoirs became less visible and accessible, flowing unseen behind reserve fences and closed roads. Relative to its more urban neighbour, the catchment community has, ironically, become physically dislocated from the water that has been of such defining significance from the first intrusion of Ballarat's powerful mining and municipal interests at Beales Swamp. An understanding of past linkages between a community and its waterways highlights the contemporary loss of connection and suggests a means of valuing 'water assets' for social and cultural meaning. Emphasis on water as a resource with volumetric attributes currently generates a negative culture around water, one that is not tempered by the creation and active management of a negotiated, watered landscape. For West Moorabool, the largely unquestioned expropriation of water from one catchment to supply another, the severance of waterways from many in the community, and the ongoing scientific investigations to reallocate a capped resource, combine to filter water of its social properties. This historical research infuses the politics of water with the memory and experience of one catchment community. It demonstrates a complexity that challenges the representation of water allocation as a problem of natural resource management with solutions more in hydrological modelling than agreed social outcomes.
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ItemThe physiography of coastal dunes, East Gippsland, Victoria( 1978)Coastal Dunes – East Gippsland. Coastal dunes occur extensively in south-east and East Gippsland, Victoria (Fig 1.1). Bird (1965, 1978) and Jenkin (1968) discuss the geomorphology and Quaternary history of the Gippsland Lakes region, outlining several stages of barrier and dune formation. The outermost barrier extends from Corner Inlet to Red Bluff as the gently curving Ninety Mile Beach, interrupted only by intermittent stream outlets and the artificial opening at Lakes Entrance. Along its entire length the barrier is surmounted by dunes behind which lie elongated lagoons and salt marsh. Landward of these are earlier formed barriers. The coastal hinterland is a lowland with relict coastal terraces mantled by fluvial and Aeolian deposits. Active dunes are confined to the narrow outer barrier but older stabilized dune systems occur on the earlier barriers and the coastal terraces. The East Gippsland coast is here considered to extend from Lake Tyers to Cape Howe at the New South Wales border. East of Lake Tyers, the foothill ranges of the Eastern Highlands are closer to the coast and Palaeozoic and Tertiary rocks form bluffs and bold headlands. The sequence of parallel barriers and lagoons is less well defined and the zone of Quaternary coastal deposits less continuous. Sandy shoreline however is dominant – of the 185 kilometres of ocean coast between Lake Tyers and Cape Howe, approximately 145 kilometres (78%) is backed by sand deposits that range from a mere fringe to a broad zone up to 7 kilometres wide. (From Introduction)