California coastal prairie, also known as northern coastal grassland, is a grassland plant community of California and Oregon in the temperate grasslands, savannas, and shrublands biome. It is found along the Pacific Coast, from as far south as Los Angeles in Southern California up into southern Oregon.
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 percent of the habitat has been lost to pavement.
Wind, salt spray, fire, and grazing are evolutionary disturbances which affected shrubs and tree growth maintaining more open grasslands. In the absence of grazing and/or fire, many areas of coastal prairie are being lost to shrub and tree encroachment. The accumulated organic matter from centuries produce a rich, dark prairie soil (mollisol). Coastal prairie often forms a landscape mosaic with the Northern coastal scrub plant community.
Characteristic species of this community include:
Many of the rarest plant species in the 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.
Rare and endangered species found in the coastal prairie include:
Unlike many other Mediterranean climate grasslands, the mostly perennial bunch grasses stay green all summer, which makes the coastal prairies attractive for grazing cattle and sheep. Other effects to this plant community include agriculture and development. California's coastal prairie, like most other California grasslands, has been greatly affected by the invasion of non-native species, including earthworms, snails, slugs, pill bugs, earwigs, and annual Mediterranean grasses.
Most recently, invasive perennial grasses (see invasive grasses of North America) 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.
California's coastal prairies are protected by the California Coastal Act, which considers these habitat types to be Environmentally Sensitive Habitat Areas (ESHA). Akin to the endangered species act for habitat types on California's coast, ESHA protections disallow any harm to so designated habitats, except where such harm is necessary to otherwise restore the habitat as a whole (e.g., prescribed fire, grazing).