Introduction: In the Pacific Northwest of North America, research addressing lentic-breeding amphibian populationvulnerability has emphasized aquatic habitats, frequently neglecting terrestrial habitats. Consequently,...Introduction: In the Pacific Northwest of North America, research addressing lentic-breeding amphibian populationvulnerability has emphasized aquatic habitats, frequently neglecting terrestrial habitats. Consequently, wetlandprotection and restoration often fails to preserve or restore adjacent uplands required by lentic-breeding amphibians.Inattention to the juxtaposition and connectivity of uplands to wetlands could locally extirpate lentic-breedingamphibians. The objective of this research is to identify the relative importance of juxtaposed terrestrial and aquatichabitats in a lentic-breeding amphibian, the northern red-legged frog (Rana aurora), by evaluating the relationshipbetween its occurrence and abundance with its aquatic and terrestrial habitats. To accomplish this, egg mass countswere used to quantify R. aurora populations in 30 stillwater habitats across an urbanization gradient. Using aGeographic Information System, seven descriptors of aquatic and surrounding terrestrial habitats were measured toevaluate their relationships to R. aurora occurrence and abundance.Results: Rana aurora occurrence and breeding abundance both reflect the forested area around wetland breedingsites and forest connectivity to those sites. Rana aurora breeding abundance also strongly reflects the percent offorested perimeter around wetland breeding sites. The forest habitat most important for R. aurora breeding abundanceseems to be > 200 m from the breeding wetlands. The American bullfrog presence and the two aquatic parametersmeasured, wetland area and vegetated area, were unrelated to R. aurora occurrence and breeding abundance.Conclusions: Area and connectivity of juxtaposed forested terrestrial habitat may represent a basic control on R. aurorapresence and population size. Urban development policies should consider preservation and restoration of uplandforest habitats beyond current fixed-width buffers and wetland habitat area at landscape scales.展开更多
文摘Introduction: In the Pacific Northwest of North America, research addressing lentic-breeding amphibian populationvulnerability has emphasized aquatic habitats, frequently neglecting terrestrial habitats. Consequently, wetlandprotection and restoration often fails to preserve or restore adjacent uplands required by lentic-breeding amphibians.Inattention to the juxtaposition and connectivity of uplands to wetlands could locally extirpate lentic-breedingamphibians. The objective of this research is to identify the relative importance of juxtaposed terrestrial and aquatichabitats in a lentic-breeding amphibian, the northern red-legged frog (Rana aurora), by evaluating the relationshipbetween its occurrence and abundance with its aquatic and terrestrial habitats. To accomplish this, egg mass countswere used to quantify R. aurora populations in 30 stillwater habitats across an urbanization gradient. Using aGeographic Information System, seven descriptors of aquatic and surrounding terrestrial habitats were measured toevaluate their relationships to R. aurora occurrence and abundance.Results: Rana aurora occurrence and breeding abundance both reflect the forested area around wetland breedingsites and forest connectivity to those sites. Rana aurora breeding abundance also strongly reflects the percent offorested perimeter around wetland breeding sites. The forest habitat most important for R. aurora breeding abundanceseems to be > 200 m from the breeding wetlands. The American bullfrog presence and the two aquatic parametersmeasured, wetland area and vegetated area, were unrelated to R. aurora occurrence and breeding abundance.Conclusions: Area and connectivity of juxtaposed forested terrestrial habitat may represent a basic control on R. aurorapresence and population size. Urban development policies should consider preservation and restoration of uplandforest habitats beyond current fixed-width buffers and wetland habitat area at landscape scales.
