low-density urbanization and critical habitats
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Low-Density Urbanization and Critical Habitats
Steven GuerryUP206a
Winter 2011
ObjectiveHighlight specific urbanized areas within Southern
California where projected low-density growth is most likely to threaten critical habitats.
MetricsUrbanization and Growth (Source: U.S. Census Bureau)• Areas categorized as “urbanized” in 2000• Population Density in 2000• Projected Total Population Growth for 2010 and 2015
Low-Density (Source: U.S. Census Bureau)• Percentage of housing composed of detached single-unit
structures
Critical Habitats (U.S. Department of Fish and Wildlife)• Areas the Endangered Species Act deems “(I) essential to the conservation of
the species and (II) which may require special management considerations or protection” for species classified as “Endangered” or “Threatened”.
Introduction to Region of Analysis
Overview of Urbanized Land and Critical Habitats
Population Density vs. Total Population
Aggregate #1
Method• Total Population of Census Tract multiplied by
percentage of housing categorized as “occupied structure with 1 unit detached”
Comparison between Density and Aggregate #1
Aggregate #2: Growth 2010 - 2015
Projecting Low-density Growth• Based on Census estimates for 2010 and 2015• Total Population Increase multiplied by percentage
increase of “occupied structure with 1 unit detached”
• Exclusion: Census tracts that underwent (a) negative population growth AND (b) percentage of low-density housing decreased
1-mile buffer around Critical Habitats
Greatest Future Threats to Critical Habitats
Requirements• within 1-mile buffer of Critical Habitats• Located on land designated as urbanized by the 2000 census• Located within the top two quantiles as determined by
Aggregate #2 (Total Population Growth multiplied by percentage growth of low-density housing)
Skills1. Inset2. Aggregating attribute fields3. Attribute sub-selections
• Urban areas map was created by selecting areas classified as “urban” (U) from a map featuring both urban and rural areas.
4. Boundary sub-set selections• Urban areas map further trimmed to only include urbanization within
five miles of critical habitats.
5. Buffering6. Geoprocessing
• Dissolved all Census Tracts in CA into a 10-county “Southern California” region
• Upper two quantiles from aggregate #2 clipped by urban areas
Potential Themes for Future Analysis Within Threatened Areas
• Zoning• Average household income• Commuting distance to work and number of
residents who work in surrounding area• Land Value• Resource consumption (energy and water)
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