Blue oak woodland is found in the inner coast ranges and the Sierra Nevada foothills, surrounding the Central Valley. It forms "one of the largest ecosystems in California". Primary species are blue oak and interior live oak, together with valley oak, canyon live oak, California scrub oak, gray pine, California buckeye, and western redbud.
Coast live oak woodland is widespread in northern and southern California, and is dominated by coast live oak, together with California buckeye, Pacific madrone, California bay, and California walnut.
Interior live oak woodland is found in north and south mountain ranges of California. It is dominant by interior live oaks,'' blue oaks, foothill pine and shrubs in common with blue oak woodland.
Valley oak woodland is found in the interior valleys of northern, central and southern California, and is dominated by valley oak and coast live oak, together with gray pine and Coulter pine.
Island oak woodland is found on the California Channel Islands, and is made up primarily of island oak and coast live oak, together with canyon live oak, MacDonald scrub oak, Catalina ironwood, and bishop pine.
Engelmann oak woodland is found in a few locations in the northern Peninsular Ranges of Southern California, including the Santa Rosa Plateau and San Gabriel Mountains foothills. It consists mostly of Engelmann oak together with coast live oak.
Status and future of California oak woodlands
Blue oak woodlands cover about of the state, and of this area about 79%, or, shows no evidence of past cutting of trees. Recent research by the University of Arkansas Tree-Ring Laboratory has studied several unlogged stands of blue oak woodlands, and suggests that the state may harbor over of such old growth forests. This would make California's oak woodlands some of the most extensive old growth forests left in the state. However, most oaks of full tree size are more than one hundred years old, and few saplings are ever produced, because cattle often tear the plants to pieces. The Oaks 2040 survey estimates that of California oak woodlands are seriously threatened by 2040 as a burgeoning state population makes ever more use of the wildland. This comprehensive survey includes oak woodland maps and inventory data for the ten oak types found in California. By evaluating this new information against current State of California economic growth projections, the location and extent of oak woodlands most at risk of development are identified.
Dallman, Peter R.. Plant Life in the World's Mediterranean Climates. California Native Plant Society–University of California Press; Berkeley.
Gaman, Tom and Firman, Jeffrey. Oaks 2040: The Status and Future of Oaks in California. Published by the California Oak Foundation, Oakland.
Pavlik, Bruce M., Pamela C. Muick, Sharon G. Johnson, and Marjorie Popper. Oaks of California. Cachuma Press and the California Oak Foundation; Los Olivos, California.
