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Schellhorn, N. A.

Publications and source records attributed to Schellhorn, N. A..

2 recordsLinked to original sources

Taking a landscape approach to conservation goals: designing multi-objective landscapes

Designing landscapes to accommodate both humans and nature poses huge challenges, but is increasingly recognised as an essential component of conservation and land management. The land-sparing land-sharing framework has been proposed as a tool to address this challenge. However, it has been largely criticised for its simplicity. We provide a new conceptual framework amenable to the application of structured decision-making that moves beyond the dichotomy of land-sparing or land-sharing. Using this new framework, we present a general system model that can be used to make land management decisions for the conservation of species, ecosystem services and production land at different spatial scales. The model can be parameterised for specific systems using information about: the current state of the landscape, the rates of change between landscape states, and the cost and effectiveness of taking actions. To demonstrate the utility of the model we apply it to three different landscape types. Across our three case studies, we show that investment into one of three management actions (varying degrees of management and restoration) can move the system towards more biodiversity or more managed land depending on the objectives of the land manager. We show that the dynamic and flexible nature of the landscape is important to take into account rather than a static snapshot in time. Rather than focusing on establishing the perfect landscape with a set proportion dedicated to production and to biodiversity conservation, we argue that a more useful approach is to establish incremental movements towards a landscape that meets the goals of multiple objectives. Our framework can be used to illustrate to decision makers the costs and trade-offs of different actions and help them determine land management policy.

ecology↗

Life on the margin: rainwater tanks facilitate overwintering of the dengue vector, Aedes aegypti, in a sub-tropical climate.

A key determinant of insect persistence in marginal habitats is the ability to tolerate environmental extremes such as temperature. Aedes aegypti is highly invasive and little is known about the physiological sensitivity of the species to fluctuating temperature regimes at the lower critical threshold. This has implications that limit establishment and persistence of the species in sub-optimal regions. Daily winter temperatures were measured in common Australian larval habitats, replicated in environmental chambers, and used to investigate the effect of fluctuating temperatures on the development and survival of tropical and subtropical strains of Australian Ae. aegypti. Development was slow for all treatments but both strains were able to complete development to the adult stage, suggesting previous models underestimate the potential for the species to persist in eastern Australia. Results suggested that thermal buffering in large volume habitats, and water that persists for greater than 32 days, will facilitate completion of the life cycle during sub-tropical winters. Furthermore, we provide a non-linear estimate of the lower critical temperature of Ae. aegypti that suggests the current threshold may be incorrect. Our study demonstrates that the current re-introduction of water storage containers such as rainwater tanks, into major Australian population centres will increase the risk of Ae. aegypti establishment by permitting year-round development south of its current distribution.

zoology↗