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Southern California Mountains

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NameColor on MapEPA Code‡
Western Transverse Range Lower Montane Shrub and Woodland8a
Western Transverse Range Montane Forest8b
Arid Montane Slopes8c
Southern California Subalpine/Alpine8d
Southern California Lower Montane Shrub and Woodland8e
Southern California Montane Conifer Forest8f
Northern Transverse Range8g

† Status: ✓ = Complete ○ = Needs Image … = Incomplete ∅ = Stub Only

This code refers to the US EPA's Level 4 ecoregion codes for the continental U.S., see here.


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About the Southern California Mountains

The Southern California Mountains, also referred to in some documents as Southern and Baja California Pine-Oak Mountains (Montañas con bosques de pino y encino de Baja California y sur de California) are an area of mountains including both the transverse range (Santa Ynez, San Gabriel, and San Bernardino mountains) and the Peninsular range (San Jacinto Mountains, Laguna Mountains, Sierra Juárez, and Sierra San Pedro Martír.) Towards the south end of the Peninsular range, this region only includes sparser, higher-elevation areas, whereas in the north this area is more extensive and encompassess a broader region.

The terrain here is irregular, with high, steep, and narrow mountain ranges, some plateaus, and narrow valleys filled with coarse sediments originating uphill. Faulting and earthquakes have broken up the landscape, and many slopes are unstable, subject to landslides and other forms of mass wasting.

The average climate here is a mild, semi-arid Mediteranean climate, but varies considerably by elevation and orientation relative to the topography. The climate tends towards a desert climate at lower elevations in the south and on the eastern side of the ranges; near the ocean it is mild but rainfall is low. At higher elevations, precipitation increases significantly, summers become hotter, and winters colder; the highest elevations reach an alpine climate with cool summers and cold winters. Summers are thus hottest at mid-elevations. Low elevations are nearly frost-free whereas highest elevations can experience frost during nearly two-thirds of the year, and experience significant snowfall, with snow cover often persisting into warmer months but eventually melting. The higher precipitation supports richer forests than exist elsewhere in southern California.

Vegetation cover is diverse, changing extensively with elevation. Cover begins with chapparal at low elevations, progressing through oak woods, to mixed conifer-broadleaf forests, subalpine forests of lodgepole pine and limber pine at high elevations. Forest fires are common.

This is the least-developed area of Mediterranean California, owing to its steep topography. There is some forestry, a small amount of agriculture and rural residential development, and some recreation and tourism. Much of the area is preserved in national forests.

This area extends to the coast in a small area. In most areas though it is bordered to the west by the California Coastal Sage, Chaparral, and Oak Woodlands. To the east it is bordered by the Mojave Basin and Range, produced in large part by the rain shadow from these mountains. Farther south, it is surrounded at lower elevations by the Coastal Sage, Chaparral, and Oak Woodlands, and does not directly border desert, although moving east not far one finds the Sonoran Basin and Range.

Plant Lists & In-Region Search

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Warning! This region extends outside the continental US. We have only built range maps for the portion of plant ranges in the continental US; these lists and searches may thus have major omissions for species which only occur in the portion of this region outside the continental US.


1. Wiken, E., Griffith, G. "North American Terrestrial Ecoregions - Level III", Commission for Environmental Cooperation, (2011) Web.