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)