California mixed evergreen forest
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California mixed evergreen forest is an ecoregion, of the temperate broadleaf and mixed forests biome, that occurs in the Pacific Coast Ranges of southwestern Oregon and western California in the Coast, Transverse, and Peninsular Ranges in California. Mixed evergreen forests occur in small areas of the Klamath-Siskiyou forests, Northern California coastal forests, and California chaparral and woodlands ecoregions. The forests of each ecoregion have a somewhat different plant community composition.
Klamath-Siskiyou mixed evergreen forest
The mixed evergreen forests of the Klamath Mountains-Siskiyou Mountains occur above 300 meters (1000 ft) elevation, and are of four main types. Douglas-fir forests are found on gentle slopes, north-facing slopes, ridges with deep soil, and river terraces with deep sediments, usually underlain with sedimentary rocks. Coast Douglas-fir (Pseudotsuga menziesii ssp. menziesii) is the predominant tree, occupying up to 70% of the forest cover. Broadleaf evergreen trees are relatively few. Tree species of secondary importance are:
On granite soils, a similar species composition predominates, but with more broadleaf evergreens, chiefly:
- Tanoak (Lithocarpus densiflora) and
- Canyon live oak (Quercus chrysolepis), along with
- Giant chinquapin (Chrysolepis chrysophylla).
On steep, well drained slopes, canyon live oak is the dominant species, with coast Douglas-fir in a minor role.
On serpentine soils, mixed evergreen forests are made up of:
- moister areas
- Lawson's cypress (also known as Port Orford cedar, Chamaecyparis lawsoniana) and
- Western white pine (Pinus monticola)
- drier areas
- Incense cedar (Calocedrus decurrens),
- Jeffrey pine (Pinus jeffreyi),
- Knobcone pine (Pinus attenuata).
Northern and Central Coast Range mixed evergreen forest
These forests vary the further inland you go. Many sites in the San Francisco Bay Area host these forests. The moister the forest the more lush the understory.
- Those closer to the coast receiving adequate fog moisture and high rainfall generally will have:
- Coast Douglas-fir,
- Coast redwood (Sequoia sempervirens)
- Tanoak, (Notholithocarpus densiflorus)
- Pacific madrone (Arbutus menziesii),
- California bay laurel (Umbellularia californica),
- Canyon live oak (Quercus chrysolepis),
- Interior live oak (Quercus wislizenii),
- Coast live oak (Quercus agrifolia),
- Black oak (Q. kelloggii),
- Oregon oak (Q. garryana)
- Big leaf maple (Acer macrophyllum).
- Further inland, on north facing slopes or protected canyons, these forests are drier and lack tanoak, Douglas fir, and coast redwood. There also occur species typical of the even drier oak woodlands:
Common wildlife include Steller's jay, chestnut-backed chickadee, western gray squirrel, raccoon and many others. These forests are more diverse in animal life than those having only conifers. The dominance of broadleaf trees offers more food sources. These forests offer a feel of broadleaf deciduous forests though evergreen trees dominate.
Southern Coast, Transverse, and Peninsular Ranges mixed evergreen forest
Also called southern mixed evergreen forests, the mixed evergreen forests of the southern California Coast Ranges, the Transverse Ranges, and the northern Peninsular Ranges, are restricted to cooler north-facing slopes at higher elevations.
- Predominant tree species include:
- Tanoak (Notholithocarpus densiflorus)
- Madrone (Arbutus menziesii)
- Canyon live oak (Quercus chrysolepis)
- Coast live oak (Quercus agrifolia)
- California bay laurel (Umbellularia californica)
- Jeffrey pine (Pinus jeffreyi)
- Coulter pine (Pinus coulteri)
- Bigcone Douglas-fir (Pseudotsuga macrocarpa).
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