Serpentine Land Use and Health Concerns

Soils developed from serpentine (ultramafic) substrates are noted for their meager and strange biomass. The chemical infertility is the main controlling factor in the development of plants in serpentine soils (Proctor and Woodell 1975, Kruckeberg 1984, Brooks 1987). Botanists have recognized the unusual nature of the endemic plants and this has led to preserving serpentine tracts that contain rare plant species. The evolution of plant species that are restricted to serpentine has produced remarkable adaptations to survival on serpentine substrates. Kruckeberg (1984) pointed out that the long-term habitat attrition on these rare natural serpentine ecosystems requires conservation initiatives to insure their preservation. In California, private and public land managers are required to develop environmental impact studies before disturbing tracts containing serpentine bedrock and its overlying soils (Clinkenbeard et al. 2003). The U.S. Fish and Wildlife Service (USFWS 1998) carried out a recovery plan for 28 species of plants and animals that occur exclusively or primarily on serpentine soils and grasslands in the San Francisco Bay area. The strategy was to provide detailed actions needed to achieve self-sustaining populations of endangered species so they will no longer require protection under the Endangered Species Act. Serpentine land tracts within metropolitan areas have come under closer regulation, as there is concern of releasing naturally occurring asbestos during construction disturbances. Typical examples of disturbance would be construction sites, new road construction, and quarry excavation. Of particular concern are the large amounts of dust produced in quarry operations or unpaved gravel roads consisting of crushed serpentine rock. The dust from such sites may contain airborne asbestos fibers released from the serpentine. This asbestos-bearing dust may pose a toxic threat to the construction workers and to later occupants of homes, schools, and office buildings occupying serpentine tracts. Asbestos is the blanket term for a group of naturally occurring silicate minerals that can be separated into fibers. The fibers are strong, durable, and resistant to extreme heat. Because of these qualities, asbestos has been used in industrial, maritime, automotive, scientific, and building products.