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Ecological Sections: Southern California Mountains and Valleys

Subsection M262Bb
Northern Transverse Ranges

This subsection is along the south-southwest side of the San Andreas fault, both northwest and southeast of the Big Pine fault.  It is on the north-northeast edge of the Transverse Ranges from the Cuyama Valley on the west-northwest to the San Francisquito Fault on the east-southeast.  The climate is mostly hot to temperate, but cold at higher elevations, and subhumid.  Most of the subsection is high enough that the climate is influenced by elevation more than by the Pacific Ocean.  MLRA 20e.

Lithology and Stratigraphy.  This subsection contains large areas of Pre-Mesozoic gneisses, Mesozoic granitic rocks, Tertiary marine and nonmarine sedimentary rocks, and Quaternary sediments.  The Tertiary marine sedimentary rocks are mostly Eocene and Oligocene, and some are Miocene and Pliocene.

Geomorphology.  This is a subsection with steep mountains with narrow to rounded summits and narrow canyons, although there are a few broad valleys with Quaternary to Recent alluvial plains.  The mountains trend east-west, except those southwest of the Cuyama River Valley which trend west-northwest.  Hills along the San Andreas fault trend west-northwest. The subsection elevation range is from about 2000 feet up to 8831 feet on Mount Pinos.  Mass wasting and fluvial erosion and deposition are the main geomorphic processes.

Soils.  The soils are mostly Lithic and shallow Typic Xerorthents, Pachic and shallow Entic Haploxerolls,  and Typic and Pachic Argixerolls on Pre-Mesozoic gneiss and Mesozoic granitic rocks; shallow Typic Xerorthents, Typic Xerochrepts, and Mollic Haploxeralfs on Tertiary sedimentary rocks; Typic Xerochrepts, Pachic Haploxerolls, and Mollic and Ultic Haploxeralfs on Pleistocene nonmarine sediments, and Xerofluvents on Recent alluvial fans and floodplains.   Most of the soils are leached free of carbonates.  The soils are well drained.  Soil temperature regimes are mostly thermic and mesic, with some frigid at higher elevations.  Soil moisture regimes are xeric.

Vegetation.  The predominant natural plant communities are California juniper series in drier areas; Jeffrey pine series and Black oak series at higher elevations; and Chamise series on shallow and very stony soils, Scrub oak series, and Mixed chaparral shrublands.  Mixed sage series is common at lower elevations in the southeast side of the subsection.  Canyon live oak series is common on steep canyon sideslopes.  Singleleaf pinyon series is common at higher elevations than the California juniper series.  Birchleaf mountain-mahogany series is common in drier areas.

    Characteristic series by lifeform include:

    Grasslands: Beaked sedge series, Bur-reed series, California annual grassland series, Tufted hairgrass series.

    Shrublands: Big sagebrush series, Bigberry manzanita series, Bitterbrush series, Black bush series, Black sagebrush series, Bladderpod - California ephedra - narrowleaf goldenbush series, California buckwheat series, Canyon live oak shrub series, Chamise series, Chamise - bigberry manzanita series, Chamise - black sage series, Chamise - Eastwood manzanita series, Chamise - wedgeleaf ceanothus series, Deerbrush series, Eastwood manzanita series, Fourwing saltbush series, Greenleaf manzanita series, Hairyleaf ceanothus series, Holodiscus series, Hop-sage series, Interior live oak - canyon live oak shrub series, Mixed saltbush series, Mixed scrub oak series, Mountain whitethorn series, Mulefat series, Parry rabbitbrush series, Rubber rabbitbrush series,  Scrub oak series, Shadscale series, Wedgeleaf ceanothus series, White sage series.

    Forests and woodlands: Bigcone Douglas-fir series, Bigcone Douglas-fir - canyon live oak series, Black cottonwood series,  Black oak series, Blue oak series, California juniper series, Canyon live oak series, Curlleaf mountain-mahogany series, Coulter pine series, Coulter pine - canyon live oak series, Holly leaf cherry stands, Incense-cedar series, Jeffrey pine series, Limber pine series, Mixed conifer series, Ponderosa pine series, Singleleaf pinyon series, White fir series.
Climate.  The mean annual precipitation is about 12 to 30  inches.  Most of it is rain at lower elevations, but much of it is snow at higher elevations .  Mean annual temperature is about 40 to 54 F.  The mean freeze-free period is about 150 to 225  days.

Surface Water.  Runoff is rapid.  All but the larger streams and those that drain watersheds that are at higher elevation are dry through the summer.  Natural lakes are absent. 

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