Indicator ES.2.b Acres of significant natural areas

ES.2.b Acres of significant natural areas

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Data Source

Natural area and acreage accessed from San Francisco Recreation and Park Department, August 6, 2009.

Explanation and Limitations

The Open Space Element of the City's General Plan (as amended in 1991) requires the City to preserve and protect the Significant Natural Resource Areas (Policy 13). The policy identifies the following criteria used to determine a Significant Natural Area:
  1. Relatively undisturbed remnants of San Francisco's original landscape that either support diverse and significant indigenous plant and wildlife habitats or contain rare geologic formations or riparian zones;
  2. Sites that contain rare, threatened, or endangered species or areas likely to support these species; and
  3. Areas adjacent to other protected natural resource areas.
In San Francisco these communities may include oak woodlands, creeks, lakes, grasslands, dunes, scrub and rock outcrops. In many cases these nature preserves are the only places where wildlife such as the Red-tailed Hawk, Gray Fox, Great-horned Owl, and San Francisco garter snake still reside, reproduce and play. Not all significant natural area acreage is accounted for in this data. Significant natural areas not publicly owned have not been accounted for.

Acres of significant natural areas alone is not the only measure in appraising a city's natural areas system. Further analysis of San Francisco's natural area system is needed to determine the quality and accessibility of the space. For example, although significant natural areas are present, resources may not be available for its upkeep and maintenance. Not all significant natural areas acreage is accounted for in this data. Significant natural areas not publicly owned have not been accounted for.

Why is this a Community Health Indicator?

Parks and natural open space areas promote physical activity and social interaction. Areas with natural vegetation also have direct effects on physical and mental health. One review of studies showed that access to places for physical activity combined with outreach and education can produce a 48% increase in the frequency of physical activity.a Exposure to greenery and the natural world has additional benefits to health. More generally, living in proximity to green space is associated with reduced self-reported health symptoms, better self-rated health, and higher scores on general health questionnaires.b Trees and green space also improve the physical environment by removing air pollution from the air and mitigating the urban heat island effect produced by concrete and glass.c
  1. Kahn EB. The effectiveness of interventions to increase physical activity. American Journal of Preventative Medicine. 2002; 22: 87-88.
  2. Vries S, de Verheij RA, Groenewegen PP, Spreeuwenberg P. Natural environments - healthy environments? An exploratory analysis of the relationship between green space and health. Environment and Planning A. 2003;35:1717-1731.
  3. Parks for People: Why America Needs more City Parks and Open Space. San Francisco: The Trust for Public Land, 2003.