Chapter 11: Conservation Planning to Ensure Viability of Populations and Metapopulations


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BOOK EXCERPT: An important (if not the ultimate) goal of conservation planning is to preserve natural populations - that is, to prevent the extinction of species. Assessing viability is the most direct way of measuring how close to this goal your conservation plan is, or will be in the future, when the planned conservation actions are in place. Viability is the likelihood that a species (or a population) will remain extant. Population viability analysis (PVA) is a method for calculating this likelihood, either under current conditions, or under assumed future changes. At this stage in your conservation planning, you should have a good understanding of the landscape, what focal species you might use to represent ecosystems of conservation concern in your area, and the habitat available to those species. You even may have mapped out areas of suitable habitat and analyzed the connectivity between potential conservation areas. However, merely protecting areas of suitable habitat does not necessarily ensure that the amount and configuration of habitat patches will be sufficient for the long-term survival of the focal species. Likewise, even if sufficient amounts of suitable habitat are available, species may still decline due to threats unrelated to habitat loss, such as harvesting, introduced predators, competitors, or diseases. To analyze the impact of those threats, information about the species’ demography also should be considered. Population viability analysis (PVA) provides a method to link demographic data with habitat maps to address questions about the prospects for recovery, longevity, and resilience specific to your focal species in your landscape. PVA also can be particularly useful when evaluating different management options or proposed reserve design configurations, and for prioritizing research and data collection needs through the use of sensitivity analysis...An important advantage of PVA compared to alternative methods of assessment is that it can incorporate the effects of multiple impacts and conservation measures. Thus, a model can simulate effects of habitat loss (through decrease in carrying capacity of affected populations), harvest or poaching (through reduced survival rates in populations targeted), climate change (by changes in several model parameters, as discussed above), as well as conservation actions that are designed to mitigate against these threats, such as reintroductions, translocations, protected areas, habitat corridors and habitat restoration and improvement. In some cases, different threats may exacerbate each other’s impact. For example, habitat loss may result in smaller populations, which may make them more vulnerable to effects of hunting (e.g., due to Allee effects) or climate change. Thus, it is important to build PVAs that incorporate all known threats to the populations of the species, rather than focusing on one threat or one conservation measure.


Jessica Stanton
Department of Ecology and Evolution
Stony Brook University
Stony Brook, New York 11794 USA
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H. Resit Akçakaya
Department of Ecology and Evolution
Stony Brook University
Stony Brook, New York 11794 USA



ADDITIONAL RESOURCES: INTERACTIVE MAPS of Population/Viability (click to pan & zoom, 'view larger' to open window)

Mapping (view larger)



3-Scale & Time
4-Land Cover
5-Land Use
6-Focal Species
7-Habitats: Terrestrial
8-Habitats: Marine/Aq
9-Habitat Cores
11-Viability Analysis
13-Climate Change
14-Processes & Tools

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