Cold Canyon, Vaca Range, California, USA Photograph by David Olson   Western North America: Western United States Mediterranean Forests, Woodlands, and Scrub   24,900 square miles (64,600 square kilometers) -- slightly larger than West Virginia Vulnerable

· Loads of Oaks
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Loads of Oaks

If you were to visit this ecoregion, you would likely see one of the many species of oaks that live here: blue, scrub, coast live, canyon live, golden-cup, valley, interior live, and maul.

Special Features

In several areas within this ecoregion, a base of serpentine rock supports several species of pines and cypresses, including Sargent and McNab cypress, as well as leather oak, interior silktassel, milkwort streptanthus, and Muir's hairstreak, all plants that thrive in areas where this type of rock is common.

	Acorn woodpeckers have an amazing strategy for storing food. If you happened upon a tree with hundreds of holes drilled into the bark, you probably found an acorn woodpecker cache. The birds chip out holes in the wood with their bills and pound an acorn into each one.

Wild Side

Mammals are diverse in this area, making up 10 percent of the 60 endemic species found here -- the largest number of endemic mammals in any ecoregion in the United States or Canada. Sonoma chipmunks, Suisun shrews, salt marsh harvest mice, and many species of kangaroo rats all call the area home. A variety of plethodontid, or lungless, salamanders also live here, including five endemics. (Lungless salamanders breathe through their moist skin.) Scrub jays, acorn woodpeckers, and wrentits are three of the area's 100 species of birds. Unusual invertebrates found here include army ants, ancient bristletails, and land snails.

This ecoregion supports 2036 species of plants other than trees. This is probably due to the fact that the area is a mosaic of grasslands, chaparral shrublands, open oak savannas, oak woodlands, serpentine communities, closed-cone pine forests, pockets of montane conifer forests, wetlands, salt marshes, and riparian forests. The ecoregion also ranges in elevation from 300 feet (90 m) to 3,000 feet (900 m). Oak woodland and chaparral are the most common plant communities. In the ecoregion's valleys you will find foothill pines, California buckeye, manzanita, redbud, and chamise.

Cause for Concern

Approximately 30 percent of this ecoregion remains intact, particularly the steep foothill and mountain areas. Valley oak savannas and woodlands are virtually gone. Many trees are cut down for firewood and pasture. Introduced species are also a problem because they often take over areas from native species. This ecoregion has approximately 2,100 introduced species representing 30 percent of the total plants found here--a sad claim to fame and the highest of any ecoregion in the United States or Canada. Because few of the natural predators of the area are left, increased native deer and rodent populations, as well as sheep and cattle, are over-eating the plants. Building of roads, golf courses, and housing developments breaks the habitat into small pieces. More and bigger farms also take over natural habitat, while off-road vehicle use is allowed in the Clear Creek Recreation Area, threatening its globally unique serpentine communities.

Some pines need the heat produced by fires to trigger the opening of their cones and the release of their seeds. This group of species is referred to as closed-cone pines. Historically, these pines experienced natural fires every 25-50 years, but practices of fire suppression and changes in fire frequency threaten the survival of closed-cone pines.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.