6 - Ecological factors in population persistence

6 Ecological factors in population persistence

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Unformatted text preview: versity of Ottawa M6.16 BIO 3115 Conservation Biology Effect of configuration of suitable and unsuitable habitat patches on population of Spotted Owls, Strix occidentalis (McKelvey et al. 1993) Question: How does configuration of suitable and unsuitable habitats affect population response of Spotted Owls? Authors conducted a simulation study using data on Spotted Owls from southern California The simulation model incorporates the actual locations of the owls, suitable patches of habitat, and explicitly considers movements of owls among patches The model simulates habitat-specific demography and the dispersal behavior of owls on computer representations of real landscape. M6.33 BIO 3115 Université d’Ottawa / University of Ottawa Effect of configuration of suitable and unsuitable habitat patches on population of Spotted Owls, Strix occidentalis (McKelvey et al. 1993) In the simulated landscape, each cell = 1 territory (1000 ha) Model varied only the configuration of suitable and unsuitable habitat patches; 3 situations were simulated: (1) Suitable patches (black cells) randomly distributed; (2) Suitable patches in one large block; (3) Suitable patches in clusters surrounded by marginal habitat Given the three situations, persistence of the owl population over 100 yrs was examined. M6.34 BIO 3115 Université d’Ottawa / University of Ottawa M6.17 BIO 3115 Conservation Biology Effects of habitat distribution on persistence of Spotted Owls: random distribution Population 110 50 0 0 50 100 Time (years) M6.35 BIO 3115 Université d’Ottawa / University of Ottawa Suitable habitat arrayed in one large block Population 110 50 0 0 50 100 Time (years) M6.36 BIO 3115 Université d’Ottawa / University of Ottawa M6.18 BIO 3115 Conservation Biology Clusters of suitable habitat are surrounded by marginal habitat (buffers) Population 80 50 0 0 50 100 Time (years) M6.37 BIO 3115 Université d’Ottawa / University of Ottawa Spotted owls: Conclusions/Recommendations Random distribution results in a fast decline in N, clearly leading to extinction of the local population. Clusters of suitable habitats surrounded by marginal habitats result in increasing chances of local extinction. If suitable habitat in 1 block, chances of persistence remain high even after 100 yrs! Biologists suggested that spotted owl reserves should have “hard boundaries” (i.e. reserves should be separated from similar looking sink habitat so that dispersing birds will not settle in unproductive territories) M6.38 BIO 3115 Université d’Ottawa / University of Ottawa M6.19...
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This document was uploaded on 03/11/2014 for the course BIO 3115 at University of Ottawa.

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