Chapter 34
Ecological Subregions of the United States

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California Coastal Range Open Woodland - Shrub - Coniferous Forest - Meadow

Two Sections have been delineated in this Province:

These Sections are located in California. The area of these Sections is about 24,900 mi2 (64,500 km2).

Section M262A--Central California Coast Ranges

Geomorphology. This area has parallel ranges, and folded, faulted, and metamorhosed strata; the rounded crests are of subequal height. This Section is in the Coast Ranges geomorphic province. Elevation ranges from 500 to 3,500 ft (152 to 1,064 m).

Lithology and Stratigraphy. There are Cenozoic marine and nonmarine sedimentary rocks and alluvial deposits; late Mesozoic shelf, slope, and eugeosynclinal sedimentary rocks; and Mesozoic ultramafic rocks.

Soil Taxa. Soils include Alfisols, Aridisols, Entisols, Inceptisols, Mollisols, and Vertisols, in combination with thermic soil temperature regime and xeric and aridic soil moisture regimes.

Potential Natural Vegetation. K\"uchler mapped vegetation as blue oak-foothill pine forest, California prairie, and chaparral. Predominant potential natural communities are Blue Oak, Interior Live Oak, Valley Oak, Mixed Chaparral, Western Juniper-Pinyon Pine (southern part), Bluegrass, and Valley Needlegrass series.

Fauna. Mammals include mule deer, pronghorn, tule elk, coyote, bobcat, ground squirrel, and kangaroo rat. Birds include hawks, eagles, owls, quail, mourning dove, mockingbird, scrub jay, gulls, herons, crows, finches, and sparrows. The California condor is being re-introduced in the southern part of the Section. Introduced species include the Andean condor and feral pigs.

Climate. Precipitation ranges from 10 to 30 in (250 to 760 mm). Temperature averages 55 to 64 oF (13 to 18 oC). The growing season lasts 120 to 270 days.

Surface Water Characteristics. Few slow and moderately slow moving rivers and streams flow northerly to Monterey Bay via the Salinas River. Few streams in alluvial or weak bedrock channels flow directly toward the Pacific Ocean. Many streams that flow eastward in alluvial or weak bedrock channels to the Great Valley Section do not flow throughout the summer. Reservoirs for irrigation and flood control are common.

Disturbance Regimes. Fires are low, moderate, or high intensity ground or stand-replacing fires. This is a seismically active area with strong shaking and ground rupture. Wide fluctuations in precipitation and temperature for periods of years result in significant or catastrophic changes in biological communities.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. The introductions related to grazing and agriculture.

Cultural Ecology. Humans have been utilizing the Section for about 8,000 years, and have been an integral part of Coast Range ecology for about 2,000 years. World-renown Chumash rock art is a unique reflection of prehistoric lifestyle. Grazing is an important historic use, beginning with land grants during the Mexican period. Contemporary attitudes and beliefs are dichotomized between emphasis on values: amenity for the newcomer and commodity for the long-time resident. All are overlain by a rural lifestyle. Economic emphases are recreation, agriculture, and government.

Compiled by Pacific Southwest Region.

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Section M262B--Southern California Mountains and Valleys

Geomorphology. There are narrow ranges and broad fault blocks, alluviated lowlands, and dissected westward sloping granitic uplands. This Section is in both the Transverse and Peninsular Ranges geomorphic provinces. Elevation ranges from 500 to 11,500 ft (153 to 3,496 m).

Lithology and Stratigraphy. There are Cenozoic marine and nonmarine sedimentary rocks and alluvial deposits, and Mesozoic granitic rocks.

Soil Taxa. Soils include Alfisols, Entisols, Inceptisols, and Mollisols, in combination with thermic, mesic, and frigid soil temperature regimes and xeric and aridic soil moisture regimes.

Potential Natural Vegetation. K\"uchler mapped vegetation as southern oak forest, coastal sagebrush, chaparral and southern yellow pine forest. Predominant potential natural communities include Chamise, Ceanothus, Mixed Chaparral, Scruboak, Coast Live Oak, Englemann Oak, Needlegrass, Jeffrey Pine, Canyon Oak and Big Cone Douglas-Fir series.

Fauna. Mammals include mule deer, pronghorn, bighorn sheep, coyote, bobcat, mountain lion, ground squirrel, and kangaroo rat. Birds include hawks, eagles, owls, quail, mourning dove, mockingbird, jays, gulls, herons, crows, finches, and sparrows. Species of concern include cactus wren, California gnatcatcher, Bell's vireo, foothill and mountain yellow-legged frog, orange-throated whiptail, and California mountain kingsnake.

Climate. Precipitation ranges from 10 to 40 in (250 to 1,020 mm). Temperature averages 45 to 64 oF (7 to 18 oC). The growing season lasts 100 to 200 days.

Surface Water Characteristics. Rivers and streams are common, but most do not flow throughout the year. Rivers and streams flow in alluvial and weak bedrock channels westward to the Pacific Ocean, or eastward to basins in the Mojave Desert or Sonoran Colorado Desert Sections. Many reservoirs for municipal water supply and flood control occur below steep mountains throughout the Section.

Disturbance Regimes. There are stand-replacing fires of variable frequency, season, and intensity. This is a seismically active area with strong shaking and ground rupture. Some plant and animal species show effects of air pollution. Movement of coarse soil particles by gravity (dry ravel) is a common process in steep mountainous portions of the area.

Land Use. Composition and successional sequence of some communities have changed because of plant and animal species introduced between the mid 1800's and early 1900's. These introductions related to urbanization, grazing, agriculture, and recreational activities. Valley portions are densely populated.

Cultural Ecology. Humans have been utilizing the area for some 10,000 years; the early San Dieguito Paleo-Indian hunting assemblage is well documented at sites along the San Dieguito River. After the end of the Pleistocene, prehistoric assemblages reflect extensive practice of seasonal rounds for resource gathering. Late in the 1700's the Spanish established colonies and missions, and converted the economy of the entire area to ranching and farming; the later citrus industry became a major agricultural influence. Contemporary attitudes and beliefs are varied; lifestyle is urban. The international border and large Hispanic populations contribute to cultural diversity. The economy is varied and urban oriented; tourism and recreation are important industries.

Compiled by Pacific Southwest Region.

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