Office for Environmental Programs - Theses
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ItemIntegrating species distribution modelling and cost-efficiency analysis to prioritise Platypus habitat management activities in the greater Melbourne region( 2012)Conservation activities are restricted by budget. This fact calls for an efficient use of resources for management activities that are expected to improve the condition of conservation targets. Prioritisation of management activities based on cost-efficiency has been advocated as a means to increase efficiency and achieve larger conservation benefits at a lower cost. Cost-efficiency assessments require estimation of costs and expected benefits of management activities. If the conservation target is a particular species or a group of species, benefits can be predicted from species distribution models (SDM) which relate species' records to environmental variables. Platypus (Ornithorhynchus anatinus) distribution models were developed and embedded in a conservation investment prioritisation protocol to demonstrate how financial costs and benefits to platypus of riparian vegetation restoration could be efficiently balanced. The platypus is a unique, charismatic focal species for conservation efforts in the case study region of greater Melbourne (south-east Australia). Platypus habitat is increasingly threatened in the case study area, mostly due to urbanisation and its impacts on habitat and water quality. Development of platypus SDMs was guided by selection of predictor variables that balance ecological relevance and possibility of change via management actions (i.e. riparian vegetation cover, catchment imperviousness), with the aim of using these models to predict platypus habitat benefits from management activities, in addition to current habitat suitability. Potential locations for vegetation management activities were prioritised based on expected platypus habitat benefits which were traded against the financial costs of achieving those benefits using a benefit-cost ratio analysis. Cost-efficiency analysis was undertaken between and within catchments to identify locations in which greatest habitat benefits can be achieved at the lowest cost. Predictions from SDMs show low platypus habitat suitability for most of the study area, with the exception of the middle and upper reaches of the Yarra catchment and upper reaches of the Bunyip River. High platypus habitat suitability is restricted to non-urban areas in streams with high riparian tree cover, relatively high precipitation during dry periods and low topographic wetness index. Results of the cost-efficiency analysis show greatest habitat benefits can be achieved at the lowest cost in locations with a medium current vegetation condition (riparian tree cover between 40 and 60%) and low to medium expected vegetation change from management activities (10-20% addition to riparian tree cover). These features are found in the middle sections of the main Yarra River and in the lower sections of the Tarago River. Budget allocation based on cost-efficiency prioritisation achieves up to 26 times more habitat benefits than prioritisation based only on benefits. This effect is more pronounced for a small budget ($1 million) but makes little difference for larger budgets (>$20 million). Highest cost-efficiency of vegetation management actions is concentrated in locations within the Yarra and Westernport systems, which are between 6 and 100 times more cost-efficient than locations in the Werribee and Dandenong catchments. These results show the importance of integrating cost and benefit information when prioritising management actions, especially when costs and benefits are variable and heterogeneous across the landscape.
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