The California Floristic Province (CFP) is a floristic province with a Mediterranean climate located on the Pacific Coast of North America with a distinctive flora that bears similarities to floras found in other regions experiencing a winter rainfall, summer drought climate like the Mediterranean Basin.
It belongs to the Madrean Region of the Holarctic Kingdom.
With an area of 293,804 km², as defined by Conservation International, it includes 70% of California and extends into southwestern Oregon, a small part of western Nevada and northern Baja California. The province is bordered by the Rocky Mountain Region in the north. The boundary is vague and is not well-defined. Many leading geobotanists, including Robert F. Thorne (Flora of North America) and Armen Takhtajan, include Oregon and Northern California within the Rocky Mountain Province.[1]
The California Floristic Province is a world biodiversity hotspot as defined by Conservation International, due to an unusually high concentration of endemic plants: approximately 8,000 plant species in the geographic region, and over 3,400 taxa limited to the CFP proper, as well as having lost over 70% of its primary vegetation.
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The California Floristic Province is one of the five biodiversity hotspots with Mediterranean climates, and it is characterized by hot, dry summers and cool, wet winters. Many parts of the coastal areas of this hotspot, being moderated by the ocean, experience cool summers due to the regular occurrence of ocean fog. This fog sustains Redwood forests as well as many other habitats.[2]
In California, the province includes most of the state excluding the Modoc Plateau, Great Basin and deserts in the southeastern part of the state. In Oregon, the province includes the coastal mountains south of Cape Blanco and most of the Rogue River watershed.
In Baja California, the province includes the forest and chaparral belts of the Sierra Juarez and the Sierra San Pedro Martir (but excluding their desert slopes to the east), coastal areas south to about El Rosario, and Guadalupe Island.
In Nevada, the CFP includes the region of the Sierra in the vicinity of Lake Tahoe, with the eastern border with the Great Basin corresponding roughly to the location of Reno-Carson City.
Parts of the following mountain ranges are included in the province:
The Great Central Valley is also within the CFP.
Numerous plant communities exist in California and botanists have attempted to structure them into identifiable vegetation types groupings. Robert Ornduff and colleagues Phyllis M. Faber and Todd Keeler-Wolf did much work on this problem, and in the 2003 Natural History Guide Introduction to California Plant Life established a cohesive set of titles to identify California plant communities based on but somewhat different from those earlier established by California botanist Philip A. Munz.
Broken into three large groupings based on geography, the Ornduff scheme includes: the Cismontane ("this side of the mountain") west of the Sierra Nevada or San Jacinto Mountains, or North of the Transverse Ranges, Montane, and Transmontane ("the other side of the mountain"), in the rainshadow of these ranges, typically desert.
The hotspot presents a higher level of endemism in plants than in animals. Of the 7,031 vascular plants (species, subspecies or varieties) found in the hotspot, 2,153 taxa (in 25 genera) are endemic, meaning they are found nowhere else[3]. About 80,000 km², or 24.7% of the original vegetation remains in relatively pristine conditions today.
The six largest plant families in California by number of species (40% of all species of vascular plants) are:
The province notably has giant sequoia forests, California oak woodlands (All native oaks in this ecosystem are endemic) and redwood forests. Other ecosystems include sagebrush steppes, prickly pear shrublands, coastal sage scrub, chaparral, juniper-pine woodland, upper montane-subalpine forests, alpine forests, riparian forests, cypress forests, mixed evergreen forests, and Douglas fir forests, coastal dunes, mudflats and salt marshes.
A few examples of plants that are endemic to the province and are also endangered species are:
Agriculture and urban expansion are encroaching upon remaining habitats in the California Floristic Province. Commercial farming in the region generates half of all agricultural products consumed by the United States population. Other threats include invasive species colonisation, air pollution, soil contamination, wildfires (excessive heat or frequency types), and construction of building developments and roads. Global warming presents future threats.