Pristine landscapes are decreasing throughout the world, and many of Earth's species can no longer survive exclusively in the remaining small and isolated reserves. At the same time, urban landscapes are increasing, and can serve as potential habitat for many wildlife species. Amphibians are facing striking global declines and are particularly impacted by urban development as they often reside in areas attractive for human settlements such as flat, productive lowland areas with abundant fresh water. My dissertation aims to increase understanding of amphibian use of these landscapes and how management and planning can adapt to benefit their persistence. I conducted observational studies of amphibians and associated habitat features in two very difference landscapes and constructed experimental ponds to examine relationships between a native frog, a common pollutant, and common urban wetland plants. One observational study was in Portland, Oregon where formerly abundant wetlands have been destroyed and altered while many have also been restored or created. The other was throughout the relatively understudied urban and agricultural centers of Vietnam where biodiversity and human population growth are high. In both Portland and Vietnam I found that most regionally occurring native amphibians were breeding within city landscapes and in human-constructed water bodies. A common pollutant, nitrate, was strongly negatively associated with amphibians in Portland. In a mesocosm experiment I found that correlated contaminants are likely driving the pattern. In both Portland and Vietnam, presence of aquatic vegetation and amount of surrounding upland habitat were highly influential for native amphibians. Aquatic vegetation can take many forms, and in urban areas is often dominated by introduced species. I conducted experimental ponds studies to examine the relationship between a native frog and common native and introduced aquatic plant species. I found that the frog preferred and performed better in introduced reed canary grass than any other plants offered. This demonstrates that introduced plants are not universally detrimental to native wildlife species, and that management of these plants should consider the potential negative effects of control actions, especially in urban areas where restoration to a former pristine state is unlikely. Urban areas do not have to be devoid of diverse native amphibian communities, and instead should be viewed as potential habitat for conservation and environmental education. Amphibian use of human-constructed ponds, potted ornamental plants, and introduced reed canary grass demonstrates the adaptability of many species and the need for an integrated view of conservation that includes non-pristine areas. Using the information from this dissertation, city planners and managers can maintain and improve human-dominated landscapes to benefit native amphibians and promote their continued coexistence with humans in these areas.
|Advisor:||Lawler, Sharon P.|
|Commitee:||Moyle, Peter B., Shaffer, Howard B.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 76/04(E), Dissertation Abstracts International|
|Subjects:||Wildlife Conservation, Conservation, Urban planning|
|Keywords:||Frog, Human-dominated, Land-use, Landscape, Reconciliation ecology, Salamander|
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