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North America Regional Centre of Endemism: CPD Site NA16

California and Oregon, U.S.A.
and Baja California, Mexico

Location: California west of the deserts and small areas in Oregon and Baja California, at latitudes c. 30°-42°N and longitudes 115°-124°W.
324,000 kmē.
0-4418 m.
Vegetation: Montane coniferous and mixed evergreen forests, oak woodlands, chaparral, coastal scrubs, annual grassland; more locally other types.
3488 native species; of which 2124 are endemic; 565 taxa within the Californian part of the area are threatened or endangered.
Useful plants:
Timber trees, agricultural rootstocks (e.g. Vitis californicus for grape vines), ornamentals, medicinals.
Other values:

Threats: Population growth, fuelling many activities threatening the flora, including conversion of land for agricultural or urban uses, dam construction, excessive groundwater abstraction, recreation and mining. The deliberate starting of fires is a serious problem.
Many protected areas, including 29,000 kmē devoted primarily to biodiversity protection (but many threats to the flora remain).

Map 4: CPD Site NA16



The California Floristic Province (CFP) lies on the west coast of North America, mostly within the state of California (U.S.A.); however, small portions of south-western Oregon (U.S.A.) and north-western Baja California (Mexico) are included on the basis of similarities in flora and climate (Map 4)..

In California the CFP includes all areas west of the Sierra Nevada-Cascade mountain crests and the islands off the shore of southern California. In Oregon the CFP includes the coastal mountains south of Cape Blanco and most of the Rogue River watershed. In Baja California the CFP includes the forest and chaparral belts of the Sierra Juarez and the Sierra San Pedro Martir (but not their desert slopes to the east), coastal areas south to about El Rosario, and Guadalupe Island. The CFP is approximately 324,000 kmē in area: 285,000 kmē in California, 25,000 kmē in Oregon and 14,000 kmē in Baja California (Raven and Axelrod 1978).

Major physiographic regions within the CFP include all or portions of four coastal mountain ranges, a large interior valley and two interior mountain ranges. These regions are: (1) the Klamath Mountains (in south-east Oregon and north-west California) (see Data Sheet NA16c); (2) the Coast ranges (from about Trinidad Head to Point Arguello); (3) the Transverse ranges (from Point Arguello and San Miguel Island east into the deserts); (4) the Peninsular ranges (from the Los Angeles Basin and San Nicolas Island south into Baja California); (5) the Central (or Great) Valley (the Sacramento Valley east of the North Coast ranges and the San Joaquin Valley east of the South Coast ranges); (6) the Cascade range (mostly volcanic mountains from Mt Lassen north into Oregon); and (7) the Sierra Nevada (mostly granitic mountains from near Mt Lassen south to the Mojave Desert). Physiographic regions east of the CFP are the Great Basin, Mojave and Colorado deserts (Norris and Webb 1990).

The coastal slopes of the CFP drain directly to the Pacific Ocean by many perennial and seasonal rivers and streams. The interior slopes of the North and South Coast ranges and the west slopes of the Sierra Nevada and southern Cascade mountains drain by numerous tributary rivers to the Sacramento and San Joaquin rivers, through the Sacramento and San Joaquin valleys to the inland delta where these two rivers meet, and finally to the ocean through San Francisco Bay.

The climate throughout the CFP is Mediterranean, characterized by cool, wet winters and warm-to-hot, dry summers. Local climatic conditions within the CFP vary on several axes: (1) from relatively wet and temperate at the northern end to relatively dry and subtropical at the southern end; (2) from relatively moderate daily and annual temperature variations with cooling summer fogs along the coast to more extreme daily and annual temperature variations with intense summer heat in the interior; and (3) from long, hot summers and short, mild winters in the interior lowlands to short, mild summers and long, frigid winters in the high mountains (Major 1977; Barbour et al. 1991).

Geology and soils are extremely varied within the CFP. Granitic, volcanic and marine sedimentary rocks occupy large portions of the region. Serpentinite, limestone, several unusual rock types, and soils ranging from very young to very old and from highly acidic to highly alkaline contribute to habitat diversity (Stebbins and Major 1965; Stebbins 1978a).

Diversity in topography, climate, geology and soils are the main factors leading to the unusual diversity of habitats and plants in the CFP. The CFP exceeds the other four Mediterranean climate regions of the world in diversity of soil types and available moisture regimes (Stebbins 1978a). The newest manual for the California flora recognizes 28 non-overlapping floristic subregions within the CFP of California (Hickman 1989). The CFP also includes portions of 17 different horticultural zones (Sunset Books 1986).

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Numerous vegetation classifications have been proposed in the CFP (Munz and Keck 1959; Cheatham and Haller 1975; Kuchler 1977; Matyas and Parker 1980; Barry 1985; Holland 1986), but no single system is widely accepted. One of the most detailed recognizes over 210 separate plant communities in the California portion of the CFP (Holland 1986). General vegetation types covering extensive areas of the CFP and their most common dominant species are listed below.

1. Montane coniferous forests (5,937,000 ha): Pinus ponderosa, P. contorta subsp. murrayana, P. jeffreyi, P. coulteri, Abies concolor, A. magnifica, Pseudotsuga menziesii, Calocedrus decurrens, Juniperus occidentalis and others (Rundel, Parsons and Gordon 1977; Thorne 1977).

2. Oak woodlands (3,809,000 ha): Quercus agrifolia, Q. wislizenii, Q. douglasii, Q. lobata, Q. garryana, Q. engelmanii and Pinus sabiniana (Griffin 1977).

3. Mixed evergreen forests (829,000 ha): Pseudotsuga menziesii, Quercus kelloggii, Q. chrysolepis, Lithocarpus densiflorus, Arbutus menziesii, Heteromeles arbutifolia and others (Sawyer, Thronburgh and Griffin 1977).

4. Chaparral (3,141,000 ha): Adenostoma fasciculatum, Arctostaphylos spp., Ceanothus spp., Quercus dumosa, Q. durata, Eriogonum spp., Toxicodendron diversilobum and others (Hanes 1977).

5. Montane chaparral (420,500 ha): Arctostaphylos patula, Castanopsis sempervirens, Quercus vaccinifolia and Ceanothus velutinus (Hanes 1977).

6. Northern and southern coastal scrubs (1,015,000 ha): Northern coastal scrub: Baccharis pilularis, Mimulus (=Diplacus) aurantiacus, Ceanothus thyrsiflorus, Gaultheria shallon, Lupinus arboreus, Eriophyllum stoechadifolium, Rubus spp., Pteridium aquilinum, Castilleja latifolia, Heracleum lanatum and others. Southern coastal scrub: Artemisia californica, Salvia mellifera, S. leucophylla, Eriogonum fasciculatum, Eriophyllum confertiflorum, Encelia californica, Haplopappus spp. and others (Heady et al. 1977; Mooney 1977).

7. Annual grassland (3,502,000 ha) (picture): Bromus mollis, B. diandrus, B. rubens, Avena fatua, A. barbata, Lolium multiflorum, Hordeum spp., Vulpia spp., Taeniatherum asperum, Erodium botrys, E. cicutarium, Centaurea solstitialis, Medicago spp., Trifolium spp. and other non-native species (Heady 1977).

Several less extensive vegetation and habitat types that contribute significantly to diversity and endemism within the CFP include:

1. Valley and montane riparian habitats (20,000 and 35,000 ha, respectively): Quercus lobata, Acer negundo, Fraxinus latifolia, Alnus rhombifolia, A. rubra, Cephalanthus occidentalis, Platanus racemosa, Populus fremontii, P. trichocarpa, Juglans hindsii, Salix spp., Rubus spp. and others (Holstein 1984).

2. Closed-cone pine and cypress forests (32,000 ha, combined): The pines are Pinus attenuata, P. muricata, P. remorata, P. contorta subsp. contorta, P. contorta subsp. bolanderi, P. radiata and P. torreyana. Common cypresses are Cupressus macnabiana and C. sargentii; rare cypresses are C. forbesii, C. stephansonii, C. macrocarpa, C. goveniana, C. pygmaea, C. abramsiana, C. nevadensis and C. bakeri (Vogl et al. 1977).

3. Alkali sink, grassland and scrub communities (area undetermined): Allenrolfea occidentalis, Distichlis spicata, Sporobolus airoides, Suaeda fruticosa, Atriplex spinifera and A. polycarpa (Griggs and Zaninovich 1984; Coates, Showers and Pavlik 1989).

4. Coastal salt marsh (20,600 ha): Salicornia virginica, Spartina foliosa, Frankenia grandifolia, Distichlis spicata, Atriplex patula, Batis maritima, Scirpus robustus, Grindelia spp. and others (MacDonald 1977).

5. Coastal dunes (area undetermined): Native dominants: Abronia latifolia, Ambrosia chamissonis, Calystegia soldanella, Camissonia cheiranthifolia, Elymus mollis and Poa douglasii (foredune habitats); Artemisia pycnocephala, Baccharis pilularis, Croton californicus, Ericameria ericoides, Eriogonum latifolium, Haplopappus venetus, Lathyrus littoralis, Lupinus arboreus, L. chamissonis and Scrophularia californica (backdune habitats). Introduced dominants: Ammophila arenaria, Cakile maritima and Mesembryanthemum spp. (Holland 1986; Barbour and Johnson 1977).

Two habitat types especially notable for their high levels of endemism in the CFP, serpentine soils and vernal pools, are described in separate Data Sheets (NA16e and NA16g).

The extent and character of natural vegetation throughout the CFP have changed dramatically in the last two centuries (Table 17). The most serious losses of habitat important to plant diversity include a 91% loss of wetlands (due to filling and draining for urban and agricultural growth), an 89% loss of riparian woodlands (due to agricultural and urban development, river channelization and diversions), a >90% loss of native perennial grasslands (through urbanization, conversion to agriculture and a conversion to non-native annual grassland mediated by overgrazing) and a >30% loss of the most diverse conifer forests (through conversion to less diverse forest-scrub, montane chaparral and clear-cut habitats by logging).

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Size and degree of endemism

The flora of the CFP is well documented, but remains fertile ground for research and discovery. Major Floras have been published for California (Jepson 1925; Munz and Keck 1959; Munz 1968), southern California (Munz 1974), Oregon (Peck 1961) and Baja California (Wiggins 1980). A completely new manual of the California flora was published in 1993 (Hickman 1993). New taxa continue to be described, especially from the southern Sierra Nevada. Between 1968 and 1986, 219 taxa (116 species and 103 lower taxa) were described or renamed in the CFP (Shevock and Taylor 1986; J. Shevock, pers. comm.).

As of 1978, the flora of the CFP was estimated to include 794 genera and 4452 species; about 3488 species (78.3%) are native. Fifty-two genera (6.5%) (Table 18) and 2124 species (47.7%) are endemic (Raven and Axelrod 1978; Howell 1957). This flora is nearly as large as that of the entire central and north-eastern U.S.A. and adjacent Canada (5523 species, of which 4425, 80.0%, are native) (Fernald 1970), an area over 6 times as large as the CFP. The largest families in the CFP (in order of decreasing size) are: Asteraceae, Poaceae, Fabaceae, Scrophulariaceae, Brassicaceae, Cyperaceae, Polygonaceae, Polemoniaceae, Boraginaceae and Hydrophyllaceae. The largest genera are: Carex, Astragalus, Phacelia, Lupinus, Eriogonum and Mimulus (Smith and Noldeke 1960). Of the 964 or so introduced species, about 672 (15.1% of the flora) are weedy (Raven and Axelrod 1978).

Floristic affinities

Evergreen sclerophyll vegetation in the CFP (mixed evergreen forest, live-oak woodland, chaparral, closed-cone pine and cypress forests, and the soft-leaved coastal scrub) are derived from Eocene floras of the south-western U.S.A. and north-western Mexico which lived in a warm, summer-moist climate. Conifer forests of the Sierra Nevada and more southerly ranges are derived from Miocene forests of the Great Basin and Columbia Plateau, where the climate was also warm and moist. Conifer forests of the north coast are more closely related to forests of the Miocene north-west, which flourished in a cooler climate (Raven and Axelrod 1978; Axelrod 1977).

Increasing topographic relief, climatic fluctuations and climatic heterogeneity during the Miocene and Pliocene promoted migration, mixing, segregation and differentiation among these floras throughout western North America. Coastal and interior floras became distinct, and the mosaic of lowlands and mountains became complex. As the Sierra Nevada uplifted and the Mediterranean climate developed fully during the Pleistocene, the rich Tertiary floras became progressively impoverished, but new species evolved from Tertiary ancestors to occupy new habitats. The Xerothermic period of the early Holocene, warmer and drier than the present, established many of the plant distributional patterns seen today (Raven and Axelrod 1978; Axelrod 1977).

Thus, the CFP emerged as a recognizable entity during the Quaternary, enriched by both old and young species with both northern and southern affinities. Numerous Tertiary relicts (mostly trees and some shrubs) have survived in several coastal and montane mild-climate refugia. Many plants (especially herbs) that became isolated in topographic, edaphic, or other ecological islands in the CFP have diverged from their closest relatives in other physiographic or floristic provinces to become local endemics. Many of the most notable narrow endemics evolved by adapting to unusual combinations of soil and climate that were too physiologically stressful or disturbance-prone for many more common plants to tolerate (Raven and Axelrod 1978; Axelrod 1977).

Numbers of rare and endangered species

Approximately 565 taxa within the CFP of California are recognized by conservation organizations as threatened or endangered. About 32 are believed to be extinct. Approximately 453 more are taxa of limited distribution and 122 are taxa of uncertain but potentially threatened status (Smith and Berg 1988; M. Skinner, pers. comm.). In the California portion of the CFP, 24 plants are listed as threatened or endangered under the federal Endangered Species Act; 191 are listed under the California Endangered Species Act (California Department of Fish and Game 1991). More species are proposed and listed each year. Several additional rare plants occur in the Oregon portion of the Klamath region (see Klamath-Siskiyou region Data Sheet NA16c). Approximately 150 Baja California endemics occur in the CFP of Mexico (R. Thorne, pers. comm.), of which many are rare or threatened.

Centres of diversity and endemism

Floristic diversity in the CFP is highest in the Sierra Nevada and Transverse ranges and nearly as high in the Klamath Mountains and Coast ranges (Stebbins 1978a; Richerson and Lum 1980). Endemism is highest regionally in the Transverse and Peninsular ranges, Coast ranges and Klamath Mountains (Stebbins and Major 1965), although local centres of endemism are widely scattered throughout the CFP. Major centres of endemism within the CFP are listed below, together with their locally endemic plants. Endemism associated with the Klamath-Siskiyou region, serpentine soils and vernal pools are listed in separate Data Sheets (NA16c, NA16e and NA16g).

NA16a - Big Bear Valley and Baldwin Lake area
Neighbouring sites in the eastern Transverse ranges with 11 local endemics on Pleistocene clay deposits: Arabis parishii, Arenaria ursina, Castilleja cinerea, Eriogonum kennedyi subsp. austromontanum, Linanthus killipii, Mimulus exiguus, Pyrrocoma uniflora subsp. gossypina, Senecio bernardinus, Sidalcea pedata, Taraxacum californicum and Thelypodium stenopetalum; and 4 local endemics on limestone formations: Astragalus albens, Lesquerella kingii subsp. bernardina, Erigeron parishii and Eriogonum ovalifolium var. vimineum (Krantz 1983, 1988). Plants endemic to the pebble plain and adjacent habitats are relatively well protected in private and state preserves, although populations on national forest lands are not adequately protected. Plants endemic to the limestone habitats are seriously threatened by mining and lack of attention by the local national forest authorities. Five of these plants were proposed for endangered status under the federal Endangered Species Act in November 1991. If these plants are listed as endangered, they will receive significant legal protection on federal lands.

NA16b - Guadalupe Island
A mountainous Pacific island 265 km off Baja California at 29°N, 118°17'W, with 17 local endemics (Baeriopsis guadalupensis, Castilleja guadalupensis, Dudleya virens, Eriogonum zapotense, Erysimum moranii, Erythea edulis, Euphorbia pondii, Hemizonia palmeri, Lavatera lindsayi, Lupinus niveus, Mirabilis heimerlii, Phacelia phyllomanica, Senecio palmeri, Sphaeralcea palmeri, S. sulphurea, Stephanomeria guadalupensis and Talinum guadalupense) (Wiggins 1980). Guadalupe Island is entirely unprotected and is probably the most seriously threatened centre of diversity in the CFP. The island is sparsely settled and mostly undeveloped, but is severely overgrazed by feral goats. The grazing allows little or no successful reproduction among many native woody plants. If goat populations are not reduced and sensitive sites fenced before existing mature plants die, numerous extinctions are likely.

NA16d - Santa Lucia Range and Monterey Peninsula (picture)
A large, rugged and vegetationally diverse coastal mountain range near the middle of the CFP, with the coastal scrub, dunes and forests of the Monterey Peninsula at its northern end. At least 50 plants are locally endemic, including Abies bracteata, Allium hickmanii, Arctostaphylos (10 taxa), Bloomeria humilis, Brodiaea lutea var. cookii, Carex obispoensis, Ceanothus maritimus, C. rigidus, Centrostegia vortriedei, Chlorogalum purpureum, Chorizanthe breweri, Cirsium fontinale var. obispoense, Clarkia jolonensis, Collinsia antonina, Delphinium huthchinsoniae, D. umbraculorum, Dudleya bettinae, D. abramsii var. murina, Eriogonum butterworthianum, Galium californicum subsp. luciense, G. clementis, G. hardhamae, Hemizonia paniculata subsp. cruzensis, Layia jonesii, Lupinus abramsii, L. cervinus, Malacothamnus jonesii, M. palmeri (3 varieties), Malacothrix saxatalis (2 varieties), Mimulus guttatus subsp. arenicola, Monardella antonina, M. palmeri, M. subglabrata, Orthocarpus densiflorus var. obispoensis, Pogogyne clareana, Ribes menziesii var. hystrix, R. sericeum and Sidalcea hickmanii. At least 7 more are endemic to Monterey Peninsula: Astragalus tener var. titi, Brodiaea versicolor, Cupressus macrocarpa, C. goveniana, Haplopappus eastwoodiae, Lupinus tidestromii var. tidestromii, Trifolium polyodon and T. trichocalyx (Rogers 1991). Approximately 8% of this area is protected in State Parks and National Forest Wilderness Areas. Another 8% is on non-wilderness national forest land. Many endemic plants occur in these areas, but important sites on the Monterey Peninsula and at two large military reservations are threatened by urban growth and military training activities.

NA16f - Kern Plateau and Southern Sierra Nevada
Rugged and diverse mountains with the highest local floristic diversity in the CFP (approximately 2200 species on the Kern Plateau) and over 75 local endemics, including Abronia alpina, Allium shevockii, Angelica callii, Arabis pygmaea, Astragalus ertterae, A. ravenii, A. shevockii, A. subvestitus, Brodiaea insignis, Calochortus westonii, Calyptridium pulchellum, Camissonia kernensis, C. sierrae subsp. alticola, Carpenteria californica, Castilleja praeterita, Ceanothus fresnensis, C. pinetorum, Clarkia springvillensis, Cordylanthus eremicus subsp. kernensis, Cupressus nevadensis, Delphinium purpusii, Dicentra nevadensis, Draba cruciata (2 varieties), Dudleya calcicola, D. cymosa subsp. costafolia, Erigeron aequifolius, E. multiceps, Eriogonum (9 taxa), Eriophyllum lanatum var. obovatum, Erythronium pluriflorum, E. pusaterii, Eschscholzia procera, Frasera tubulosa, Fritillaria brandegei, F. striata, Galium angustifolium subsp. onycense, Horkelia tularensis, Ivesia purpurascens, Linanthus oblanceolatus, L. serrulatus, Lomatium rigidum, L. shevockii, Lupinus citrinus, L. culbertsonii, L. padre-crowleyi, Mimulus norisii, M. pictus, M. shevockii, Monardella beneolens, Nemacladus twisselmannii, Oreonana clementis, O. purpurascens, Phacelia novenmillensis, P. orogenes, Ribes tularense, Sidalcea keckii, Silene aperta, Streptanthus cordatus var. piutensis, S. fenestratus, S. gracilis and Trifolium bolanderi (J. Shevock, pers. comm.; Twisselman 1972). Approximately 60% of this area is protected in National Parks and National Forest Wilderness Areas. Most of the rest is on non-wilderness forest land. Overall protection is high, but some endemic plants are threatened by grazing, development and other land uses.

Lesser centres of endemism in the CFP include Pine Hill, the Pitkin-Bodega area, Suisun Bay-west delta area, Ione chaparral, Diablo range, Santa Cruz Mountains, Pajaro dunes, southern San Joaquin Valley and Carrizo plains, Channel Islands and Sierra San Pedro Martir (Emory 1989; Stebbins and Major 1965; Hoover 1937). In addition to its local endemics, each centre of endemism hosts several other rare CFP endemics.

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Useful plants

Plants native or endemic to the CFP have been used for wood products, agricultural rootstocks, ornamental plants and sources of medicine. The Monterey pine (Pinus radiata), endemic to 3 small areas on the central coast of California, has become a major component of the forest products industries in New Zealand and Australia. Sugar pine (P. lambertiana) and giant sequoia (Sequoiadendron giganteum, a CFP endemic), were once major suppliers of wood products. The endemic coast redwood (Sequoia sempervirens) and other more widespread native conifers (especially Abies, Pinus and Pseudotsuga spp.) are the base of a major forest products industry.

California wild grape (Vitis californicus) has been used in developing disease-resistant rootstocks for European grapes that support a major wine industry in California. California black walnut (Juglans hindsii) is widely used as a disease-resistant rootstock for locally grown European walnuts.

The horticultural industry in California and throughout the world has been enriched by many contributions from the CFP. Prized horticultural subjects include: members of several endemic genera (especially Carpenteria, Dendromecon, Lyonothamnus, Romneya, Sequoia, Sequoiadendron and Umbellularia); many species of Arctostaphylos, Ceanothus, Clarkia, Fremontodendron , Iris, Lupinus, Penstemon, Rhamnus, Salvia and Zauchneria; most other native or endemic trees; numerous bulbs (especially Brodiaea, Calochortus, Erythronium and Fritillaria); many annuals; and others (Schmidt 1980). Many native grasses, shrubs and trees are valued for use in erosion control, revegetation and wildlife habitat improvement.

Native Americans in the CFP used many local plants as remedies for illness. Among the most important were yerba santa (Eriodictyon californicum), yerba mansa (Anemopsis californica) and cascara (Rhamnus purshiana) (Balls 1962). Modern medicine has scarcely explored the medicinal potential of the CFP flora, but Pacific yew (Taxus brevifolia), native to the northern CFP and Pacific Northwest, is the source of a potential new anticancer drug called taxol. Vast quantities of bark are being collected for research and, although the species will stump-sprout, it grows very slowly and some populations are threatened (Scher 1991).

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Social and environmental values

Individuals, businesses and industries throughout the CFP enjoy substantial social and environmental benefits from its native vegetation and diversity of habitats. Economically and socially important benefits include moderation of local climate, protection of watersheds and water resources, flood abatement, nonpoint source pollution abatement, habitat for wild pollinators of food crops, habitat for a diverse non-game fauna that includes many rare and endangered species, critical links in the Pacific flyway, commercial and recreational fisheries, large and small game for hunters, many forms of passive recreation and opportunities for education and research.

Economic assessment

California is the largest agricultural producer (200 crops worth $1690 million in 1988) and forest products producer (about 4450 million board feet annually) in the U.S.A. (Jones and Stokes Associates 1992). Although made possible by the region's abundance of water, fertile soils and forests, not all of this production can be considered sustainable. For example, the water that irrigates up to 75% of California's cropland is supplied through state and federal water projects that are heavily subsidized by taxpayers, promote agriculture on marginal lands, and have caused many kinds of impacts on native biological resources (El-Ashry and Gibbons 1986).

Amenity values of natural habitats in the CFP are extremely high to residents of, and visitors to, this very populous and mostly affluent region. The CFP contains one of the most visited National Parks in the U.S.A. (Yosemite) and the national forest most used for recreation (San Bernardino) (Jones and Stokes Associates 1992). California's state parks and recreation areas (not counting National Parks) received 10% of all park use in the U.S.A. in 1988. The tourism industry was valued at $3990 million in 1989. During the late 1980s, approximately 2.4 million fishing licenses and 420,000 hunting licenses were purchased annually in California (Jones and Stokes Associates 1992).

The monetary value of the social and environmental values described above is undoubtedly astronomical, but few efforts at quantification have been made. One recent survey of households to assess the "existence value" of wildlands indicated that Californians would be willing to pay $1.5 billion annually to maintain wetlands and $2.4 billion annually for ecological restoration of wetland habitats (Jones and Stokes Associates 1990).

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California is the most populous State in the U.S.A. (about 29,976,000 in 1990), with over 10% of the U.S. population. Most of these people (over 29,000,000) live in the CFP portion of the state. Approximately 182,000 and 800,000-900,000 people live in the Oregon and Baja California portions of the CFP, respectively. The highest population densities occur along the south coast (Santa Barbara to Tijuana), central coast (San Francisco Bay and Monterey Bay areas) and the California state capital area (Sacramento and vicinity). California's population is projected to grow 1-2% per year to about 39,000,000 by 2005 and over 44,000,000 by 2035 (California Department of Finance 1991).

Population growth is the driving force behind nearly all the direct causes of habitat loss, fragmentation and degradation in the CFP today. Threats to plant diversity in the CFP include habitat conversion, water use and water projects, unsustainable natural resource harvest and extraction, abusive recreation and vandalism, biological invasions, and others (Jensen, Torn and Harte 1990). Habitats on undeveloped lands are being widely converted to agricultural and urban uses. An estimated 1.7 million acres will be converted to agricultural uses and 1 million acres to urban and rural uses between about 1986 and 2000. Water projects have disrupted flow, degraded water quality and flooded canyons on most rivers in the CFP. Over 100 major and 1200 minor dams exist in California and over 30 more major dams are proposed. Groundwater overdraft has caused and continues to cause wetland and riparian loss throughout the region and land subsidence in the Sacramento-San Joaquin Delta. Marginally productive soils are destroyed through heavy irrigation and fertilization leading to salinization. Off-road vehicle activity degrades many sand-dune and serpentine barren habitats. Although much vegetation in the CFP is fire-adapted, fires caused by arson and accident are unnaturally damaging to biodiversity where many years of fire suppression have led to excessive fuel accumulations. Forests, especially old growth, are being cut faster than they will regrow and are being converted to types less supportive of indigenous biodiversity. Livestock overgrazing damages range and riparian vegetation. Mining of precious metals devastates many serpentine areas. Sand and gravel mining has degraded many riparian and coastal dune areas. Invasive exotic plants (especially Bromus, Cortaderia, Cytisus, Ilex, Mesymbryanthemum, Carpobrotus and Senecio mikanioides) outcompete much native vegetation, and some animals present in large numbers (especially introduced feral pigs) cause much direct damage to vegetation.

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Status of land protection

Plants and other elements of natural diversity are protected to varying degrees in dozens of federal, state, regional and private parks and preserves ranging in size from a fraction of a hectare to over 300,000 hectares. Lands devoted primarily to biodiversity protection include: National Parks, Monuments, seashores and recreation areas; National Forest Research Natural Areas, Special Interest Areas and Wilderness Areas; California ecological reserves and state preserves; University of California natural reserves; and Nature Conservancy preserves. Lands managed for mixed uses (recreation, hunting, etc.) in addition to biodiversity protection include National Wildlife Refuges, State Wildlife Areas, and State Parks, beaches and recreation areas.

No database has been compiled that summarizes land protection in the CFP separately from other parts of the state of California, or by vegetation type or bioregion within the CFP. Summary data from Jensen, Torn and Harte (1990), revised to exclude several large sites in the California deserts and including a Wilderness Area in Oregon and two National Parks in northern Baja California, result in the following figures: approximately 2.9 million ha in sites devoted primarily to biodiversity protection and approximately 0.7 million ha protected in mixed-management sites (together, about 3.6 million ha, or 11% of the CFP). Areas of selected vegetation types protected in the state of California include: 83,970 ha of subalpine conifer forests (91% of the habitat in California); 252,600 ha of lodgepole pine forest (83%); 377,900 ha of red fir forest (49%); 1655 ha of closed-cone pine and cypress forests (13%); 494,620 ha of mixed conifer forests (12%); 69,890 ha of redwood forests (11%) (picture); 60,870 ha of coastal scrub (6%); 119,200 ha of valley-foothill hardwoods (4%); and 390 ha of valley riparian (2%) (Jensen, Torn and Harte 1990; Forest and Rangeland Resources Assessment Program 1988).

Barriers to progress

A legal basis for biodiversity protection exists in California and Oregon through a variety of federal, state, and local laws and regulations, including endangered species acts (both California and federal), the National Environmental Policy Act, the National Forest Management Act, California Environmental Quality Act, state fish and game department codes, and the open space and conservation elements of county and city general plans (Jones and Stokes Associates 1992). Although significant protection has been achieved through these laws and regulations, protection measures are too often uncoordinated, slow, overly bureaucratic, poorly or unevenly implemented, underfunded and weakened by loopholes.

While public interest in biodiversity protection is growing in the CFP, losses of habitat and diversity continue to accelerate. Jensen, Torn and Harte (1990) identified a variety of legal, social, and scientific barriers that limit progress in biodiversity protection in the state of California:

  • California lacks a state policy mandating conservation of biodiversity;
  • legislative protection focuses on species, not ecosystems;
  • conservation interests are under-represented in resource policy-making bodies in California state government, while industries and special interest groups that extract goods and values from biological resources are over-represented;
  • responses to threats are mostly local and reactive, not regional and anticipatory;
  • some diverse ecosystems are seriously under-represented on public lands and in protected areas;
  • serious gaps remain in knowledge of the status, ecological requirements, and management needs of plants and other biodiversity in the CFP;
  • environmental and scientific illiteracy among many private landowners, responsible officials, and elected representatives hinders wise resource stewardship.

In Baja California, relatively few laws are available to support biodiversity protection and the two designated National Parks are not fully protected from grazing and timber extraction. The Mexican government is encouraging many people to move to Baja California from other parts of Mexico and establish new settlements. These settlements and the agriculture that supports them are eliminating much of the species-rich coastal scrub in north-western Baja California (Thorne and Moran, pers. comm.).

Current actions and recommendations for the future

Existing and emerging efforts to improve biodiversity protection in the CFP are too numerous and diverse to describe here. Most are occurring in the state of California and are the result of combined governmental and private efforts. Some of the more promising programmes and mechanisms include informal management agreements, memoranda of understanding, transfer of development rights, habitat conservation plans, mitigation banking, open space and conservation easements (Jones and Stokes Associates 1992). Memoranda of understanding are frequently used by the California Department of Fish and Game to enforce implementation of protection and mitigation measures by landowners whose activities impact state-listed threatened or endangered plants.

Ecological and social-economic guidelines have been identified that would improve site selection and management planning for biodiversity protection (Jones and Stokes Associates 1992; J. Shevock, pers. comm.). General ecological guidelines include the following: (1) emphasize contiguous blocks of habitat area; (2) select habitat blocks that are close together; (3) protect blocks of habitat large enough to contain large populations of species; (4) connect habitat blocks that support similar habitats; (5) maintain a broad distribution of protected areas; and (6) ensure adequate representation of all major plant community types in protected areas. Rare plants with narrow distributions and very specific habitat requirements will often need more focused efforts.

Two general social and economic guidelines are: (1) incorporate and maximize compatibility with current patterns of ownership and land use, projected future land use needs and the management objectives of private landowners, public land managers and regulatory agencies and (2) identify the roles and responsibilities of land owners, managers and regulatory agencies early in the planning process. New initiatives for biodiversity conservation must be increasingly strategic (rather than opportunistic), because of competing interests, multiple uses and complex ownership and use patterns on most of the lands now targeted for protection and enhancement.

Further recommendations for improving protection of all biodiversity in California focus on immediate actions, institutional changes and anticipatory actions (Jensen, Torn and Harte 1990): (1) establish a state policy mandating protection of biodiversity; (2) establish a habitat protection act; (3) establish a biodiversity conservation board (a state governmental agency) to coordinate, advocate, administer and enforce biodiversity protection laws and policies; (4) establish a biodiversity research institute; (5) ensure implementation and enforcement of existing laws; (6) acquire significant natural areas and provide additional funding for parkland operations and maintenance; (7) reduce environmental illiteracy by increasing requirements for high school and college-level courses in biology and environmental issues, and increase training of teachers in these fields; (8) broaden representation on state policy-making bodies; (9) close loopholes in the California Endangered Species Act, including those that permit destruction of endangered plants and their habitats; and (10) protect biological diversity in the face of global atmospheric change by mitigating impacts and providing leadership in slowing the rate of atmospheric change. Little action has been taken yet on any of these recommendations.

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Map 4. California Floristic Province, U.S.A. and Mexico (CPD Site NA16)

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This Data Sheet was written by Tim Messick (Jones and Stokes Associates, 2600 V Street, Suite 100, Sacramento, CA 95818-1914, U.S.A.).


Mr Messick thanks Reid Moran, Jim Shevock, Mark Skinner, Robert Thorne and Roger Trott for providing information and comments.

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