Michael Bode

University of Melbourne, Melbourne, Victoria, Australia

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Publications (55)372.74 Total impact

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    ABSTRACT: Protected area networks are designed to restrict anthropogenic pressures in areas of high biodiversity. Resource users respond by seeking to replace some or all of the lost resources from locations elsewhere in the landscape. Protected area networks thereby perturb the pattern of human pressures by displacing extractive effort from within protected areas into the broader landscape, a process known as leakage. The negative effects of leakage on conservation outcomes have been empirically documented and modeled using homogeneous descriptions of conservation landscapes. Human resource use and biodiversity vary greatly in space, however, and a theory of leakage must describe how this heterogeneity affects the magnitude, pattern, and biodiversity impacts of leakage. We combined models of household utility, adaptive human foraging, and biodiversity conservation to provide a bioeconomic model of leakage that accounts for spatial heterogeneity. Leakage had strong and divergent impacts on the performance of protected area networks, undermining biodiversity benefits but mitigating the negative impacts on local resource users. When leakage was present, our model showed that poorly designed protected area networks resulted in a substantial net loss of biodiversity. However, the effects of leakage can be mitigated if they are incorporated ex-ante into the conservation planning process. If protected areas are coupled with nonreserve policy instruments such as market subsidies, our model shows that the trade-offs between biodiversity and human well-being can be further and more directly reduced.Una Estrategia de Planificación de la Conservación para Mitigar los Impactos de Fugas en Redes de Áreas ProtegidasResumenLas redes de áreas protegidas están diseñadas para restringir las presiones antropogénicas en áreas de alta biodiversidad. Los usuarios de los recursos responden al buscar reemplazar algunos o todos los recursos perdidos en otras localidades del terreno. Por esto las redes de áreas protegidas perturban el patrón de presiones humanas al desplazar el esfuerzo extractivo dentro de las áreas protegidas hacia un terreno más amplio, un proceso conocido como fuga. Los efectos negativos de la fuga sobre los resultados de conservación han sido documentados empíricamente y modelados usando descripciones homogéneas de terrenos de conservación. El uso de recursos por los humanos y la biodiversidad varían ampliamente en el espacio, sin embargo, y una teoría de fuga debe describir cómo esta heterogeneidad afecta a la magnitud, el patrón y a los impactos de la fuga sobre la biodiversidad. Combinamos modelos de utilidad del hogar, búsqueda adaptativa de alimento por humanos y conservación de la biodiversidad para proporcionar un modelo bio-económico de fuga que represente la heterogeneidad espacial. La fuga tuvo impactos fuertes y divergentes sobre el desempeño de las redes de áreas protegidas, debilitando a los beneficios de la biodiversidad pero mitigando los impactos negativos sobre los usuarios locales de recursos. Cuando la fuga estuvo presente, nuestros modelos mostraron que las redes de áreas protegidas diseñadas pobremente resultaron en una pérdida neta sustancial de biodiversidad. Sin embargo, los efectos de la fuga pueden mitigarse si se incorporan ex-ante al proceso de planificación de la conservación. Si las áreas protegidas se emparejan con instrumentos de política ajena a las reservas, como los subsidios de mercado, nuestro modelo muestra que las compensaciones entre la biodiversidad y el bienestar humano puede reducirse más y de manera más directa.
    Conservation Biology 12/2014; · 4.36 Impact Factor
  • Christopher M. Baker, Michael Bode
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    ABSTRACT: Background/Question/Methods Choosing effective management strategies for invasive species is a global challenge. The invasive species problem comprises a huge number of species, and modelling every invasive species to determine appropriate management strategies is impractical. There is a pressing need to provide general guidelines for invasive species managers that can easily be applied in a range of locations and scenarios. We use a reaction-diffusion model and optimal control theory to determine optimal management strategies in a range of invasive species scenarios. We demonstrate how to adjust control effort through time for an island eradication; how control efforts should vary through space around high-value conservation assets; and how to vary control efforts through space and time to eradicate a new invasion. By estimating relatively few parameters, our solutions give managers a strong platform on which to base strategic decisions. Our methods can also be applied to specific situations, and we demonstrate this with a case study of a tropical fire ant (Solenopsis geminata) eradication on Ashmore Reef. Results/Conclusions Our results show a very clear relationship between population spread rate, population growth rate and the diminishing returns of control effectiveness. For island eradications we find that it is optimal to start with a relatively small amount of control and increase through time. The optimal eradication time depends on growth rate and the diminishing returns parameter. If a population grows quickly or large control efforts can be applied effectively, then it is best to eradicate it quickly. Otherwise, longer eradications result in lower overall costs. For spatial suppression around high conservation assets, the most important quantity is the ratio of the spread and growth rates. If the ratio is large, then it is optimal to target a large section of the surrounding landscape, while if the ratio is small it is best to focus control efforts near the conservation asset. Controlling a spreading invasion incorporates principles from both temporal eradication and spatial control problems. Control efforts should initially be focussed at the main infestation and then increased in the surrounding region through time.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Background/Question/Methods The eradication of invasive species from uninhabited islands presents an immense opportunity for conservation. Islands hold a disproportionate percent of global biodiversity, there has been historically less human intervention on island ecosystems, and the native species of islands have unique, divergent evolutionary histories. Despite this, a high proportion of animal extinctions have occurred on islands due to invasive vertebrates. Unfortunately, island conservation actions are unusually expensive, so it is imperative that the limited finances available are spent on eradications that maximise conservation benefits. Therefore to ensure investments in invasive eradication are spent wisely, the cost-efficiency and feasibility of actions must be considered transparently and defensibly, with a rational treatment of uncertainties. We propose a general method for prioritizing the eradication of multiple invasive species across multiple islands for a fixed budget. Rather than focusing on islands as management units, this method prioritises portfolios of eradication actions targeting different subsets of invasive species. This better reflects the variety of options available to managers, and the range of ecological dynamics that can result from perturbing an insular system. Results/Conclusions We present a case study prioritization of 23 potential action packages on four Australian islands: Macquarie, Tasman, Faure and Hermite Islands. By including the possibility to only eradicate a subset of invasive species on each island, we find that there are measurable increases in the total expected conservation benefit. The optimal prioritization action for some budgets is to leave some invasive species present on one of the islands (often mice due to the high cost and low feasibility of eradication) in favour of eradicating a more ecologically harmful invasive species on another island.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Background/Question/Methods Unsustainable exploitation of the oceans has led to widespread degradation of marine ecosystems. In order to maintain the primary benefits humans derive from the sea, namely food supply and biodiversity that generates other ecosystem services, the ocean is divided into three general management regimes: open–access areas with no restrictions, managed areas that control aspects of gear and fishing effort that damage habitat, and reserved or protected areas that prohibit all extractive uses. Using a theoretical example of a fish stock that depends on habitat type, we explore the conditions under which is it better to spare the sea, by investing more in no take marine reserves, to share the sea by investing in gear management to maintain habitat quality over a larger area, or a mixed strategy. We model the fraction of the seascape in each management regime given a fixed budget and a minimum food supply. Our objective is to create a plausible model with a simple analytic answer for the purpose of allowing people to choose broad policy options. Results/Conclusions We explored the range of parameters where no-take marine reserves may be favoured over habitat protection with fishing and vice versa. The relative costs of no-take reserves vs. habitat protection, the growth rate of the fish population, the effectiveness of habitat protection and the amount of self-recruitment all influence this decision. For example, preliminary results suggest that intermediate levels of self-recruitment favour a mixed strategy of some no-take reserves and habitat management areas. Obviously, when the cost of reserving area increases in relation to managing an area to reduce habitat loss, we prefer a management regime that protects habitat. We are working on a simple rule of thumb that determines the optimal management strategy given our constraints.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Background/Question/Methods: Conservation management decisions are often implemented to reflect human scales, rather than the scale of the relevant ecological dynamics. Research frequently points out the loss in efficiency that results from this scale mismatch. However, the scale of management is influenced by social, economic and political constraints on management actors; by the higher implementation costs of spatially-variable management plans; and by the divergent objectives of the actors in different regions. The critical question is not whether conservation benefits would increase if management were planned at ecological scales, but whether such benefits are sufficient to justify the cost of alignment. Fishery management often has strong spatial components, with harvest quotas, gear restrictions, and marine protected areas applying to specific locations. Such spatial management decisions are generally implemented at spatial scales that have a coarser resolution than the underlying population dynamics. We use a spatially-explicit bioeconomic metapopulation model of a line fishery within the Great Barrier Reef Marine Park to explore the relationship between scale mismatches and management efficiency, and to quantify the benefits that result from an increased alignment between management actions and key ecological scales. In this system, the management scales are defined by the boundaries of total allowable catch regions, while the important ecological scales are defined by complex biophysical connectivity between reef populations. Results/Conclusions: Given a particular scale of management (defined by the number of separate catch quotas), our approach identifies (1) the distribution of harvest efforts, and (2) the location of management boundaries, that maximise the profitability of the fished metapopulation. Assessing a range of management scales allows us to characterise the relationship between the size of the mismatch between ecological and management scales, and the magnitude of the resulting inefficiency. We further contrast the locations of the resulting boundaries with natural ecological boundaries created by the dispersal network that connects the reef populations. Decreasing the mismatch between management and ecological scales yields only diminishing efficiency returns, while incurring accelerating transaction costs. The result is that management efficiency is maximised by a management scale (or alternatively, a management resolution) that is much larger than the underlying ecological process: effectively, an optimal scale mismatch.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Background/Question/Methods Ecological systems are dynamic and policies to manage them need to respond to that variation. However, policy adjustments will sometimes be costly, which means that fine-tuning a policy to track variability in the environment very tightly will only sometimes be worthwhile. We use a classic fisheries management question – how to manage a stochastically varying population using annually varying quotas in order to maximize profit - to examine how costs of policy adjustment change optimal management recommendations. Costs of policy adjustment (here changes in fishing quotas through time) could take different forms. For example, these costs may respond to the size of the change being implemented or there could be a fixed cost any time a quota change is made. Results/Conclusions We show how different forms of policy costs have contrasting implications for optimal policies. While some types of cost act to smooth out variation in quotas and stock sizes, as one might have expected, others can actually increase variation in stock sizes and quotas through time. We also show that the potential economic impact on the fishery of managers assuming policy adjustment costs are present when in fact they are absent is much smaller than the impact of managers assuming such costs are absent if they are present.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Background/Question/Methods Much ecological theory underpinning studies in ecosystem management and life history evolution draws on a body of mathematics known as optimal control. In one set of applications, ecosystems managers are assumed to be seeking ‘optimal’ decisions over how to allocate and manage natural resources; in the other, an ‘optimal’ behavior or phenotype is predicted given the particular ecological conditions that an organism will face. In both situations, the underlying ecological systems involved can be noisy, high dimensional and nonlinear; they also vary over multiple space and time scales and are only ever observed imperfectly. However, much of this richness is assumed away in theoretical ecology in a quest to identify optimal solutions. Instead, what is needed is a theoretical approach that embraces the messy complexity of ecological questions without giving up on the optimizers’ drive to find effective management or life history strategies. Results/Conclusions We will present a series of such approaches that together offer an alternative to traditional optimal control. When taken together, we refer to these alternatives as ‘pretty darn good’ control. We will illustrate pretty darn good control through a series of applications in marine ecology and marine ecosystem management. Some recurring lessons from our efforts to apply pretty darn good control to ecological questions include that i) behaviors that can seem suboptimal when compared to simplified problem formulations might instead be rational and effective once a fuller representation of the relevant optimization problem is considered. ii) the detailing of how you represent constraints and limitations on the choice sets that individuals face is very important for obtaining sensible predictions from your model. iii) only some sources of ecological variation need to be reflected in a pretty darn good life history or management strategy and only some entry-points of uncertainty need to be resolved to deliver effective performance. iv) and finally, when developing a strategy that can respond to ecological variation, a small amount of responsiveness earns big pay-offs, but finessing further offers comparatively little gain.
    99th ESA Annual Convention 2014; 08/2014
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    ABSTRACT: Growing threats and limited resources have always been the financial realities of biodiversity conservation. As the conservation sector has matured, however, the accountability of conservation investments has become an increasingly debated topic, with two key topics being driven to the forefront of the discourse: understanding how to manage the risks associated with our conservation investments and demonstrating that our investments are making a difference through evidence-based analyses. A better understanding of the uncertainties associated with conservation decisions is a central component of managing risks to investments that is often neglected. This focus issue presents both theoretical and applied approaches to quantifying and managing risks. Furthermore, transparent and replicable approaches to measuring impacts of conservation investments are noticeably absent in many conservation programs globally. This focus issue contains state of the art conservation program impact evaluations that both demonstrate how these methods can be used to measure outcomes as well as directing future investments. This focus issue thus brings together current thinking and case studies that can provide a valuable resource for directing future conservation investments.
    Environmental Research Letters 08/2014; 9(8):085002. · 3.58 Impact Factor
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    ABSTRACT: A range of mathematical models has been developed to infer whether a species is extinct based on a sighting record. Although observations have variable reliability, current methods for detecting extinction do not differentiate observation qualities.
    Journal of Applied Ecology 02/2014; 51(1). · 4.74 Impact Factor
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    ABSTRACT: Policy documents advocate that managers should keep their options open while planning to protect coastal ecosystems from climate-change impacts. However, the actual costs and benefits of maintaining flexibility remain largely unexplored, and alternative approaches for decision making under uncertainty may lead to better joint outcomes for conservation and other societal goals. For example, keeping options open for coastal ecosystems incurs opportunity costs for developers. We devised a decision framework that integrates these costs and benefits with probabilistic forecasts for the extent of sea-level rise to find a balance between coastal ecosystem protection and moderate coastal development. Here, we suggest that instead of keeping their options open managers should incorporate uncertain sea-level rise predictions into a decision-making framework that evaluates the benefits and costs of conservation and development. In our example, based on plausible scenarios for sea-level rise and assuming a risk-neutral decision maker, we found that substantial development could be accommodated with negligible loss of environmental assets. Characterization of the Pareto efficiency of conservation and development outcomes provides valuable insight into the intensity of trade-offs between development and conservation. However, additional work is required to improve understanding of the consequences of alternative spatial plans and the value judgments and risk preferences of decision makers and stakeholders. Minimizando el Costo de Mantener Opciones Abiertas para la Conservación en un Clima Cambiante.
    Conservation Biology 01/2014; · 4.36 Impact Factor
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    ABSTRACT: Ecologists are often required to estimate the number of species in a region or designated area. A number of diversity indices are available for this purpose and are based on sampling the area using quadrats or other means, and estimating the total number of species from these samples. In this paper, a novel theory and method for estimating the number of species is developed. The theory involves the use of the Laplace method for approximating asymptotic integrals. The method is shown to be successful by testing random simulated datasets. In addition, several real survey datasets are tested, including forests that contain a large number (tens to hundreds) of tree species, and an aquatic system with a large number of fish species. The method is shown to give accurate results, and in almost all cases found to be superior to existing tools for estimating diversity.
    Proceedings of the Royal Society B: Biological Sciences 01/2014; 281(1779):20133009. · 5.68 Impact Factor
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    ABSTRACT: REDD+ presents novel options for conservation in the tropics, yet it is unclear how biodiversity-focused organizations or actors should react to these carbon-focused opportunities. Here, we critically assess for the first time the expected outcomes of five contrasting scenarios of engagement between a biodiversity actor and REDD+. We discover that in the Berau regency, Indonesia, it is usually beneficial for a biodiversity actor to react in some way to REDD+, but the preferred reaction depends on whether a REDD+ project is already developing in the region, and the scale and type of conservation objectives. In general, from a strict biodiversity perspective, the most cost efficient reaction to the presence of REDD+ is to use biodiversity funds to protect areas neglected by REDD+. Our results demonstrate that if biodiversity actors fail to adapt the way they pursue conservation in the tropics, REDD+ opportunities could go largely untapped.
    Conservation Letters 11/2013; 6(6). · 4.36 Impact Factor
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    ABSTRACT: The conservation of many threatened species can be advanced by the eradication of alien invasive animals from islands. However, island eradications are an expensive, difficult and uncertain undertaking. An increasingly common eradication strategy is the construction of ‘interior fences’ to partition islands into smaller, independent eradication regions that can be treated sequentially or concurrently. Proponents argue that, while interior fences incur substantial up front construction costs, they reduce overall eradication costs. However, this hypothesis lacks an explicit theoretical or empirical justification.We formulate a general theory that relates the number of interior fences to the magnitude and variation of the economic cost of island eradication. We use this theory to explore the conditions under which interior fences represent a defensible management strategy, under cost and risk minimisation objectives. We then specifically consider the forthcoming eradication of cats Felis catus from Dirk Hartog Island, Western Australia, by parameterising our general theory using published data on the cost and success of previous projects.Our results predict that under a wide range of reasonable conditions, interior fences can reduce the expected cost of a successful invasive alien animal eradication from large islands. On Dirk Hartog Island, interior fences will marginally reduce eradication costs, with two fences reducing expected costs by 3%. Interior fences have a much more substantial effect on the variability of eradication costs: two fences reduce the width of the 95% confidence bounds by more than one‐third and halve the size of the average project cost overrun/underrun.Our results reveal that the construction of interior fences is a defensible management strategy for eradicating alien invasive species from islands. However, the primary benefit of interior fences will be risk management, rather than a reduction in expected project costs.
    Methods in Ecology and Evolution 09/2013; 4(9). · 5.92 Impact Factor
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    ABSTRACT: Background/Question/Methods Can size and spacing rules provide guidelines for marine spatial planning? The complexity and temporal variability of coral reef systems make predictions for spatial planning challenging. General guidelines offer a solution if they predictably deliver benefits. However, are general guidelines, such as rules for the size and spacing of protected areas predictable and distinguishable enough to be useful? Using a population dynamics model of coral trout on the Great Barrier Reef, we simulated marine protected areas with variation across size and spacing rules. The model imitates realistic dispersal conditions using results of biophysical dispersal models. With each simulation, we track two long term outcomes: average annual catch (a fishery objective) and remaining abundance on the reef (a conservation objective). By tracking these two outcomes over many simulations, we evaluate the experimental size and spacing guidelines. Results/Conclusions Our results indicate that size and spacing guidelines can reveal tradeoffs in management objectives. On average, smaller, more disperse protected area configurations perform better for fishery objectives. This pattern is observed across a range of total protected area coverage (%10-40 of reef area protected). Regardless, a large amount of variation in the measured objectives weakens the ability to delineate between expected outcomes on the tradeoff. The overall usefulness of general guidelines in this model is diminished because the noise of the system drowns out the difference in outcomes for alternate guidelines. This may provide some evidence that simple guidelines are impractical for management of complex, dynamic reef systems.
    98th ESA Annual Convention 2013; 08/2013
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    ABSTRACT: Background/Question/Methods Most studies addressing the optimal balance between the size and number of offspring a mother should produce typically focus on the effects of habitat quality, such as food availability, competitors, or predators. In many species, offspring disperse from their parents before the effects of habitat quality can be seen. Such dispersal in animals is often energetically or physiologically demanding. Longer dispersal durations can increase mortality after settlement when dispersal experiences ‘carry-over’ to influence survival in adult habitat. We predicted that smaller offspring with fewer resources might not have the stamina to survive after finally reaching distant habitat compared to larger offspring with more resources. To test this prediction, we experimentally delayed the settlement of larvae of marine bryozoan (Bugula neritina) in the laboratory and recorded subsequent growth and survival in the field. We then developed a theoretical model, based on a well-known optimality model, of how selection on offspring size is expected to change with dispersal distance. Results/Conclusions We found that smaller larvae had lowered post-settlement survival compared to larger larvae. This was probably because the energy a mother gives to smaller offspring is used to prolong the larval stage at the expense of being used by offspring for growth and development after colonization. Larger offspring on the other hand, may have more ‘fuel in the tank’ to cope with the energetic demands of dispersal. Our model predicted that, even when habitat quality does not vary, more isolated habitats favor the production of fewer, larger offspring when smaller offspring incur greater deferred costs of dispersal. Taken together, our results indicate that the spatial pattern of suitable habitat could impose very different selective regimes on offspring size compared to the effects of habitat quality. Furthermore, our predictions contrast to those predicted for seed size and dispersal in plants, where the production of smaller, more numerous seeds is often a more efficient way for mothers to access distant, suitable habitat.
    98th ESA Annual Convention 2013; 08/2013
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    ABSTRACT: 1. Much of the theory on offspring size focuses on the effects of habitat quality on the relationship between offspring size and fitness. Habitat spacing may be another important factor that affects selection on offspring size when offspring disperse prior to colonization and accrue deferred costs that are mediated by offspring size. 2. We developed a theoretical model, based on a well-known optimality model, of how selection on offspring size changes with dispersal distance. The model assumes that offspring fitness depends on both offspring size and dispersal duration and that dispersal time and distance are positively related. Such assumptions are based on thousands of marine invertebrate species with non-feeding larvae, but our model also applies more generally to any organism where offspring size modifies the energetic costs of dispersal, and there is a positive relationship between dispersal duration and distance. 3. Our model predicts that, even when habitat quality does not vary, more isolated habitats may favour the production of fewer, larger offspring if smaller offspring incur greater deferred costs of dispersal. We then empirically demonstrate that offspring size and dispersal duration have interactive effects on post-settlement survival in a marine invertebrate (Bugula neritina), and such size-dependent deferred costs of dispersal are of a magnitude sufficient enough to potentially favour larger offspring in isolated habitats. 4. Together, our results indicate that the spatial pattern of suitable habitat could impose very different selective regimes on offspring size compared with the effects of habitat quality. Furthermore, our predictions contrast to those predicted for seed size and dispersal in plants, where the production of smaller, more numerous seeds is often a more efficient way for mothers to access distant, suitable habitat.
    Functional Ecology 06/2013; 27(3):757-765. · 4.86 Impact Factor
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    ABSTRACT: Abstract Although ecological assemblages frequently depart from neutral model predictions, these discrepancies have not been unambiguously attributed to neutral theory's core assumption: that community structure is primarily the result of chance variation in birth, death, speciation, and dispersal, rather than the manifestation of demographic differences among species. Using coral communities in Barbados from four time periods during the Pleistocene, we demonstrate that the neutral theory cannot explain coral community similarity distributions, species' regional abundance distributions, or their local occupancy. Furthermore, discrepancies between the neutral theory and the observed communities can be attributed to violation of the core assumption of species equivalence. In particular, species' variable growth rates are driving departures from neutral predictions. Our results reinforce an understanding of reef coral community assembly that invokes trade-offs in species' demographic strategies. The results further suggest that conservation management actions will fail if they are based on the neutral assumption that different coral species are equally able to create live coral cover in the shallow-water reef environment. These findings highlight the importance of developing biodiversity theory that can parsimoniously incorporate species differences in coral reef communities, rather than further elaborating neutral theory.
    The American Naturalist 11/2012; 180(5):577-88. · 4.55 Impact Factor
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    ABSTRACT: Context: Exclosure fences are widely used to reintroduce locally extinct animals. These fences function either as permanent landscape-scale areas free from most predators, or as small-scale temporary acclimatisation areas for newly translocated individuals to be ‘soft released’ into the wider landscape. Existing research can help managers identify the best design for their exclosure fence, but there are currently no methods available to help identify the optimal location for these exclosures in the local landscape (e.g. within a property).
    Wildlife Research. 05/2012; 39(3):192-201.
  • Michael Bode, Karl E. C. Brennan
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    ABSTRACT: Malleefowl Leipoa ocellata populations across Australia are declining and the range of the species is contracting. Despite a century of research much uncertainty remains about which factors are driving this decline. Consequently, it is also unclear which conservation actions will reduce the species’ extinction risk. In particular, we lack a quantitative understanding of malleefowl population dynamics. Here we use estimates derived from the literature to provide the first parametrization of a population viability analysis (PVA) for malleefowl. This model creates a quantitative framework for synthesizing existing information and comparing potential management strategies, and will help guide research activities by identifying critical aspects of the malleefowl’s life history. We model population dynamics as stochastic events that depend on individual characteristics, weather conditions and local management actions. Our PVA indicates that an isolated population of 32 adult birds would almost certainly decline to extinction over a 20-year period. Translocating and releasing captive-bred juveniles slows this rate of decline and intensively baiting for foxes can reverse it. Adult mortality rates have the greatest influence on population viability, and land managers should therefore prioritize conservation actions that target adult survivorship over actions that benefit earlier life stages. Quantitative research on the malleefowl should focus on the demographics of the adult life stage, their dispersal and the impacts of fire and grazing. Our analysis highlights the role of PVA models in assessing the cost-effectiveness of alternative management actions, and framing future research priorities for threatened species.
    Oryx 09/2011; 45(04):513 - 521. · 1.62 Impact Factor
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    Michael Bode, Lance Bode, Paul R Armsworth
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    ABSTRACT: The coexistence of multiple species on a smaller number of limiting resources is an enduring ecological paradox. The mechanisms that maintain such biodiversity are of great interest to ecology and of central importance to conservation. We describe and prove a unique and robust mechanism for coexistence: Species that differ only in their dispersal abilities can coexist, if habitat patches are distributed at irregular distances. This mechanism is straightforward and ecologically intuitive, but can nevertheless create complex coexistence patterns that are robust to substantial environmental stochasticity. The Great Barrier Reef (GBR) is noted for its diversity of reef fish species and its complex arrangement of reef habitat. We demonstrate that this mechanism can allow fish species with different pelagic larval durations to stably coexist in the GBR. Further, coexisting species on the GBR often dominate different subregions, defined primarily by cross-shelf position. Interspecific differences in dispersal ability generate similar coexistence patterns when dispersal is influenced by larval behavior and variable oceanographic conditions. Many marine and terrestrial ecosystems are characterized by patchy habitat distributions and contain coexisting species that have different dispersal abilities. This coexistence mechanism is therefore likely to have ecological relevance beyond reef fish.
    Proceedings of the National Academy of Sciences 09/2011; 108(39):16317-21. · 9.81 Impact Factor

Publication Stats

895 Citations
372.74 Total Impact Points

Institutions

  • 2008–2014
    • University of Melbourne
      • School of Botany
      Melbourne, Victoria, Australia
    • University of California, Davis
      • Department of Environmental Science and Policy
      Davis, CA, United States
  • 2006–2014
    • University of Queensland
      • • ARC Centre of Excellence for Environmental Decisions
      • • The Ecology Centre
      Brisbane, Queensland, Australia
  • 2009
    • University of Tasmania
      Hobart Town, Tasmania, Australia