Objectives for multiple-species conservation planning

The Ecology Centre, School of Integrative Biology, University of Queensland, St Lucia, Queensland 4072, Australia.
Conservation Biology (Impact Factor: 4.32). 07/2006; 20(3):871-81. DOI: 10.1111/j.1523-1739.2006.00369.x
Source: PubMed

ABSTRACT The first step in conservation planning is to identify objectives. Most stated objectives for conservation, such as to maximize biodiversity outcomes, are too vague to be useful within a decision-making framework. One way to clarify the issue is to define objectives in terms of the risk of extinction for multiple species. Although the assessment of extinction risk for single species is common, few researchers have formulated an objective function that combines the extinction risks of multiple species. We sought to translate the broad goal of maximizing the viability of species into explicit objectives for use in a decision-theoretic approach to conservation planning. We formulated several objective functions based on extinction risk across many species and illustrated the differences between these objectives with simple examples. Each objective function was the mathematical representation of an approach to conservation and emphasized different levels of threat. Our objectives included minimizing the joint probability of one or more extinctions, minimizing the expected number of extinctions, and minimizing the increase in risk of extinction from the best-case scenario. With objective functions based on joint probabilities of extinction across species, any correlations in extinction probabilities had to be known or the resultant decisions were potentially misleading. Additive objectives, such as the expected number of extinctions, did not produce the same anomalies. We demonstrated that the choice of objective function is central to the decision-making process because alternative objective functions can lead to a different ranking of management options. Therefore, decision makers need to think carefully in selecting and defining their conservation goals.

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Available from: Emily Nicholson, Jul 28, 2015
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    • "Implicit in this management decision is that habitat characteristics may simultaneously, and perhaps negatively, influence non-target taxa, perhaps including other taxa of conservation concern. Therefore, to reduce conservation conflict it is important to consider critical habitat and extirpation risks for multiple species in management plans (Lambeck 1997; Nicholson & Possingham 2006). However, while potential conflicts involving the management of threatened taxa have been reported (Roemer & Wayne 2003; Livezey 2010), these typically involve direct manipulations of the taxa rather than habitat restoration efforts. "
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    ABSTRACT: Although examples are rare, conflicts between species of conservation concern can result from habitat restoration that modifies habitat to benefit a single taxon. A forest restoration program designed to enhance habitat for endangered red‐cockaded woodpeckers (Picoides borealis) may be reducing available habitat for the eastern spotted skunk (Spilogale putorius), a forest‐adapted sympatric species of conservation concern that occurs in the Ouachita National Forest, Arkansas, U.S.A. At small scales, eastern spotted skunks select early successional forest with structural diversity, whereas red‐cockaded woodpeckers prefer mature pine (Pinus spp.) habitat. We surveyed for eastern spotted skunks at 50 managed forest stands, modeled occupancy as a function of landscape‐level habitat factors to examine how features of restoration practices influenced occurrence, and compared known occupied forest stands to those where active red‐cockaded woodpecker nesting clusters were located. The most‐supported occupancy models contained forest stand age (negatively associated) and size (positively associated); suggesting eastern spotted skunks primarily occupy large patches of habitat with dense understory and overhead cover. Red‐cockaded woodpecker nesting clusters were located in smaller and older forest stands. These results suggest that increased overhead cover, which can reduce risk of avian predation, enhances occupancy by small forest carnivores such as eastern spotted skunks. Management activities that increase forest stand rotation length reduce the availability of young dense forest. The practice may enhance the value of habitat for red‐cockaded woodpeckers, but may reduce the occurrence of eastern spotted skunks. Implementing plans that consider critical habitat and extinction risks for multiple species may reduce such conservation conflict.
    Restoration Ecology 03/2013; 21(2). DOI:10.1111/j.1526-100X.2012.00880.x · 1.99 Impact Factor
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    • "As such, it can serve as an example of nature conservation and management of Mediterranean ecosystems in Israel and the region. Here, we demonstrate a stakeholder engagement process for identifying conservation objectives (sensu Nicholson and Possingham, 2006) and targets (sensu Sanderson, 2006), using realistic working definitions of benefits and costs. "
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    ABSTRACT: Active and dynamic management of biodiversity is of utmost importance in the face of increasing human pressures on nature. Current approaches for site selection of protected areas often assume that both conservation features and management actions are fixed in space and time. However, this approach should be revised to allow for spatio-temporal shifts of biodiversity features, threats and management options. Our aim here was to demonstrate a novel approach for systematic conservation planning at a fine scale that incorporates dynamic ecological processes (e.g., succession), biodiversity targets and management costs. We used the new ‘Marxan with Zones’ decision support tool to spatially redistribute the major structural types of vegetation within a privately-owned nature park in Israel and facilitate the achievement of multiple conservation targets for minimum cost. The park is located in the Mediterranean climate region of the eastern Mediterranean Basin, one of Earth’s richest biodiversity hotspots. This small park alone (4.5 km2) holds 660 species of native plants and six structural types of vegetation. The region has been subject to manifold human pressures such as grazing, clearing and fire for millennia and is currently threatened by a range of modern human-related activities (e.g., invasive alien species). By spatially redistributing the six structural vegetation types under three scenarios, representing different conservation objectives (no change, equal distribution – evenness of structural types, preference to early succession stages) within three budget frameworks, we identified a set of near-optimal conservation strategies that can be enacted over time. The current spatial distribution of structural types and the cost of changing one structural type into another via management actions had a major impact on the spatial prioritization outcomes and management recommendations. Notably, an advanced successional stage (dense Mediterranean garrigue) tended to dominate a large portion of the landscape when the available budgets were low because it is a relatively inexpensive structural type to maintain. The approach presented here can be further applied to spatially prioritize conservation goals in the face of shifting environments and climates, allowing dynamic conservation planning at multiple spatial scales.
    Biological Conservation 02/2013; 158:371-383. DOI:10.1016/j.biocon.2012.08.032 · 4.04 Impact Factor
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    • "In particular, controlling a charismatic species such as sea otters may be an unpopular conservation measure. Societal or economic values can be easily incorporated in our framework through the definition of the reward function (Nicholson & Possingham 2006). Frameworks such as ours are useful for considering and setting recovery targets and evaluating the success of different management strategies. "
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    ABSTRACT: Failure to account for interactions between endangered species may lead to unexpected population dynamics, inefficient management strategies, waste of scarce resources, and, at worst, increased extinction risk. The importance of species interactions is undisputed, yet recovery targets generally do not account for such interactions. This shortcoming is a consequence of species-centered legislation, but also of uncertainty surrounding the dynamics of species interactions and the complexity of modeling such interactions. The northern sea otter (Enhydra lutris kenyoni) and one of its preferred prey, northern abalone (Haliotis kamtschatkana), are endangered species for which recovery strategies have been developed without consideration of their strong predator-prey interactions. Using simulation-based optimization procedures from artificial intelligence, namely reinforcement learning and stochastic dynamic programming, we combined sea otter and northern abalone population models with functional-response models and examined how different management actions affect population dynamics and the likelihood of achieving recovery targets for each species through time. Recovery targets for these interacting species were difficult to achieve simultaneously in the absence of management. Although sea otters were predicted to recover, achieving abalone recovery targets failed even when threats to abalone such as predation and poaching were reduced. A management strategy entailing a 50% reduction in the poaching of northern abalone was a minimum requirement to reach short-term recovery goals for northern abalone when sea otters were present. Removing sea otters had a marginally positive effect on the abalone population but only when we assumed a functional response with strong predation pressure. Our optimization method could be applied more generally to any interacting threatened or invasive species for which there are multiple conservation objectives.
    Conservation Biology 10/2012; 26(6). DOI:10.1111/j.1523-1739.2012.01951.x · 4.32 Impact Factor
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