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Contribution of Source-Sink Theory to Conservation in Protected Areas

Contribution of Source-Sink Theory to Conservation in Protected Areas. Newly Recognized Types of Sources and Sinks. Added to source and sink are: Refuge – places where survival is high but reproduction is relatively low, so the subpopulation is a weak source.

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Contribution of Source-Sink Theory to Conservation in Protected Areas

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  1. Contribution of Source-Sink Theory to Conservation in Protected Areas

  2. Newly Recognized Types of Sources and Sinks • Added to source and sink are: • Refuge – places where survival is high but reproduction is relatively low, so the subpopulation is a weak source. • Attractive Sink – habitat quality is good allowing potentially high reproduction and high survival, but where either reproduction or survival are reduced by forces that are not detected by the organism (e.g., human persecution or harvest). • Delibes et al. 2001

  3. Protected Area as Sink Vulnerable to Loss of the Source • Sources and Sinks (Pulliam 1988): • A subpopulation in a sink could be sustained by dispersal from a source. • Loss of viability from the source due to the sink was not expected because of the assumptions that density dependent habitat selection would lead to the fittest individuals occupying the source.

  4. Protected Areas as Sinks Maintained by External Sources High Habitat quality Natural Condition Land Use Effect Low Close Far Protected Area Distance from Protected Area >1 1 <1 Lambda Sink Source High Land Use Intensity Low Close Far Protected Area Distance from Protected Area >1 1 <1 Sink Attractive Sink Lambda Extinction?

  5. Protected Area as Source at Risk from Attractive Sink • Sources and Attractive Sinks (Gunderson et al. 2001): • Rate of dispersal from source patches can increase in the presence of sink patches, there by reducing metapopulation population growth. • “ Such mortality sinks, sometimes also termed traps, may represent an actual conservation problem when animals are harvested or persecuted in habitats surrounding reserves”.

  6. Protected Areas as Sources Vulnerable to Attractive Sinks High Habitat quality Natural Condition Land Use Effect Low Close Far Protected Area Distance from Protected Area >1 1 <1 Lambda Refuge/Source Source High Land Use Intensity Low Close Far Protected Area Distance from Protected Area >1 1 <1 Sink Attractive Sink Lambda Extinction?

  7. Protected Area as Source to allow Sustainable Harvest in Surroundings • Sources and Sustainable Harvest: • Mortality levels in the sinks are managed to allow the protected area to function as a source.

  8. Protected Areas as Sources for Harvest High Habitat quality Natural Condition Land Use Effect Low Close Far Protected Area Distance from Protected Area >1 1 <1 Lambda Source Source High Land Use Intensity Low Close Far Protected Area Distance from Protected Area >1 1 <1 Source Attractive Sink Lambda Sustainable Harvest?

  9. Conclusions Concept is being widely considered for protected area establishment and management in three primary ways: Adequate demographic data are available for relatively few species. Spatially-explicit demographic models are not widely used. Specific applications and evaluations are few. Promise of greater contribution in the future.

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