Over 300 species of vertebrates depend on oak woodlands for their survival and those animals contribute their part to the ecosystem in complex interrelationships that are necessary, though often not well understood. There is not just one, but rather a large number of unique hardwood ecosystems. Oak woodlands are found in the foothills as well as at lower elevations. These lands are dominated by oak species and have historically been managed primarily for grazing. Over 50 distinct oak habitat types have been described.
Hardwoods are also an integral component of the higher elevation mixed coniferous forests.
There they can be found in various assemblages, although seldom as pure stands of one species. Riparian zones are another hardwood domain. Riparian species help stabilize banks and reduce erosion in addition to providing some of the most important habitat for wildlife. Economically, the California hardwood industry has lagged far behind its successful eastern counterpart. The lack of interest in hardwoods has been due in large part to the fact that high-quality softwood timber could be logged easily and in large volumes.