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:
Mixed evergreen forests in the California Coast Ranges vary in species related to coastal (Outer Ranges) or inland (Inner Ranges) climate influences. It usually happens in the elevation from 0 meter to 500 meters high. Mountains in the San Francisco Bay Area frequently support mixed evergreen forests. Generally the moister the forest habitat the greater the understory density. Coast mixed evergreen is drier than coast redwood and it is a four-layer forest structure. The conifers are usually emergent as canopy layer and broad-leaf evergreen trees emerge as sub-canopy layer. The shrubs occur as the understory species.
Those closer to the coast receiving adequate fog moisture and high rainfall generally will feature the following species:
Further inland, on north facing slopes or protected canyons, these forests are drier and generally lack tanoak, Douglas fir, and coast redwood. Species typical of the drier neighboring oak woodlands join the mix:
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 predominance of broadleaf trees provide a greater abundance of food sources.
Southern Coast, Transverse, and Peninsular Ranges mixed evergreen forest