Open Space as an Armature for Urban Expansion: A Future Scenarios Study to Assess the Effects of Spatial Concepts on Wildlife Populations
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Urbanization is one of the biggest threats to biodiversity. To address this problem, landscape planners have increasingly adopted landscape ecology as a theoretical basis for planning. They use spatial concepts that express principles of landscape ecology in diagrammatic form to create frameworks for planning. This dissertation presents a quantitative approach to evaluate the application of spatial concepts developed to create an armature of open space in areas subject to urbanization. It focuses on the predicted urban expansion of Damascus, Oregon, as a case study. An alternative futures study was used to test three open space spatial concepts for patches, corridors and networks in combination with compact and dispersed urban development patterns. The resulting eight scenarios of land use and land cover were then modeled for the year 2060 to evaluate their effects on habitat quantity, quality and configuration and to identify tradeoffs between urban development and conservation for three focal wildlife species: Red-legged frog, Western meadowlark, and Douglas squirrel. Open space spatial concepts strongly influenced habitat quantity and quality differences among future scenarios. Development patterns showed less influence on those variables. Scenarios with no landscape ecological spatial concept provided the most land for urban development but reduced habitat quantity and quality. Greenway scenarios showed habitat increases but failed to provide sufficient habitat for Western meadowlark. Park system scenarios showed habitat increases, but high-quality habitats for Western meadowlark and Red-legged frog decreased. Network scenarios presented the best overall amount of habitats and high-quality habitats for the three species but constrained urban development options. Next, I used an individual-based wildlife model, HexSim, to simulate the effects of habitat configuration and to compare and contrast resulting wildlife population sizes among the eight future scenarios with the ca. 2010 baseline landscape. Network scenarios supported the largest number of Red-legged frog breeders. Park scenarios performed best for meadowlarks, while greenway scenarios showed the largest populations of squirrels. Four of the eight scenarios sustained viable populations of Western meadowlarks. Compact development scenarios performed best for most indicators, but dispersed development scenarios performed better for Western meadowlarks. This dissertation includes both previously published and unpublished material.