California coastal prairie

California coastal prairie, also known as northern coastal grassland, is a grassland plant community of California and Oregon. It is found along the Pacific coast, from perhaps as far south as Los Angeles, California to southern Oregon. Wind, salt spray, fire, and grazing are evolutionary disturbance regimes that impacted shrubs and tree growth to maintain more open grasslands. In the absence of grazing and/or fire, many areas of coastal prairie are being lost to shrub and tree encroachment (Ford and Hayes 2007). The accumulated organic matter from centuries produce a rich, dark prairie soil. Coastal prairie often forms a landscape mosaic with northern coastal scrub.

California's coastal prairies are the most species rich grassland types in North America (Stromberg et al 2002). Coastal prairie is also the single most urbanized major vegetation type in the U.S.: 24% of the habitat has been lost to pavement (Loveland, 1995).

Characteristic species of this community include (Ornduff 2003):

• Perennial grasses (Danthonia, Festuca, etc.)
• Bracken fern (Pteridium aquilinum)
• Douglas iris (Iris douglasiana)
• Blue dicks (Dichelostemma capitatum)
• Blue-eyed grass (Sisyrinchium bellum)

The endangered species Santa Cruz Tarweed (Holocarpha macradenia) is found in limited locations. Other rare and endangered species found in coastal prairie include: Ohlone tiger beetle (Cicindela ohlone), San Francisco garter snake, San Francisco popcornflower (Plagiobothrys diffusus), Robust spineflower (Chorizanthe robusta robusta), Artist's popcornflower (Plagiobothrys chorisianus), Pt. Reyes meadowfoam, Santa Cruz clover (Trifolium buckwestiorum), Indian clover (Trifolium amoenum), Gray's clover (Trifolium grayii), and San Francisco owl's clover. Many of the rarest plant species in coastal prairie exist mainly on land currently being grazed by livestock; these species have been disappearing when land is set aside for conservation and the livestock are removed (Hayes and Holl 2003).

Unlike many other mediterranean climate grasslands, the mostly perennial grasses stay green all summer, which makes the coastal prairies attractive for grazing cattle and sheep. Other impacts to this plant community include agriculture and development. California's coastal prairie, like most other California grasslands, has been greatly impacted by the invasion of non-native species, including earthworms, snails, slugs, pill bugs, earwigs, and annual Mediterranean grasses. Most recently, invasive perennial grasses are the greatest threat. These include velvet grass (Holcus lanatus), tall fescue (Festuca arundinacea), and Harding grass (Phalaris aquatica); the impact of these species can be somewhat ameliorated by well planned livestock grazing, which can reduce these species' cover, and allow native species to persist.

References

• Ornduff, Robert. (2003) Introduction to California Plant Life. Revised by Phyllis M. Faber and Todd Keeler-Wolf. University of California Press.
• Plant Communities of Santa Cruz County, Santa Cruz Chapter, California Native Plant Society.
• Hayes, G., and K. D. Holl. 2003. Cattle grazing impacts on annual forbs and vegetation composition of mesic grasslands in California. Conservation Biology 17:1694 - 1702.
• Stromberg, M. R., P. Kephart, and V. Yadon. 2002. Composition, invasability, and diversity in coastal California grasslands. Madroño 48:236-252.
• Loveland, T. R., and H. L. Hutcheson. 1995. Monitoring Changes in Landscapes from Satellite Imagery. Pages 468-473 in U. S. G. Society, editor. Our Living Resources: A Report to the Nation on the Distribution, Abundance, and Health of U.S. Plants, Animals, and Ecosystems. U.S. Department of Interior, National Biological Service, Washington, D.C.
• Ford, L. D., and G. F. Hayes. 2007. Northern coastal scrub and coastal prairie. in M. G. Barbour, T. Keeler-Wolf, and A. A. Schoenherr, editors. Terrestrial vegetation of California. University of California Press., Berkeley.