Introduction
Quercus chrysolepis, or canyon live oak (also known as gold-cup oak, laurel oak, or maul oak), occurs in a greater variety of habitats than any other California oak. It is present in forest, woodland, and chaparral areas on a large variety of parent materials and soil types. Canyon live oak extends from southwest Oregon to Baja California and east to Arizona over a broad elevational range. The species commonly occurs in narrow canyon bottoms, on steep side slopes and in sheltered coves. However, it is best developed in the canyons of the coast and transverse ranges.
Canyon live oak is one of eight native California oaks that grow to tree size, but the species can grow in a variety of forms ranging from shrub to tree. Fire can be deleterious to individual canyon live oak trees, but is essential for the health of the stand as a whole. The species response to fire is basal sprouting, and with short fire intervals the species may never achieve tree from. The thin, flaky, bark of canyon live oak makes it especially sensitive to fire.
Canyon live oak is an evergreen species, and the upper age limits reached are not known. The acorns mature in 2 years but the crop varies from year to year and tree to tree. Native Americans in California used acorns of other species (valley oak, black oak and tanoak) more commonly for food even though the acorns of canyon live oak can be quite large, and acorns supplied more than 50% of the diet of California’s Native Americans at one time. Early settlers in California used the wood from canyon live oak for making farm tools, including wagon wheels, mauls, and axles, building ships, making furniture, and as a fuel.
Today the most common sues for canyon live oak include wildlife habitat, watershed and fuelwood. Acorns from this species are an important food for gray squirrels, ground squirrels, deer, mice, Steller’s jay, scrub jay, and pigeons. In the San Bernardino Mountains, a large majority of the black bear denning sites were fond in canyon live oak stands. Canyon live oak has a deep penetrating root in its juvenile stages and is a good soil stabilizer as it commonly grows on steep, rocky, and unstable slopes. Its high BTU rating and rapid sprouting also make it a good fuel wood. In addition, canyon live oak is an attractive urban tree.
Over one million acres of California timberland and woodland are occupied by canyon live oak (second only after blue oak) with a volume of over 2 million board feet (second only to black oak). Canyon live oak contributes 17% of the total hardwood timberland volume in California. However, there is difficult in utilizing this resource because of three factors: problems in harvesting, sawing, and drying the logs.
Recent studies on canyon live oak being conducted by scientists at the Riverside Fire Lab are looking at the effects of thinning, clearcutting, and burning on sprout and tree growth and survivorship, understory vegetation, soil chemistry and insect fauna. Preliminary results indicate clearcutting produces the most vigorous sprouts (number and height), while thinning led to more vigorous sprouts on residual trees. Other field studies on canyon live oak include acorn outplanting in thinned and clearcut oak stands and the development of wood biomass equations.
Greenhouse studies being conducted on canyon live oak are examining how the presence or absence of mycorrhizal fungi influence the growth of oak seedlings and their ability to withstand water stress. Results of these studies showed that the total and the dry weight of plants were positively correlated with the rate of fungal colonization. Mycorrhizal infection appears to slightly stimulate growth under low water stress and we hypothesize that this infection may substantially increase growth under water stress due to enhanced water uptake. This information has important application in the establishment of new canyon live oak stands through outplanting.
Susan C. Barro
Botanist
Melody A. Lardner
Ecologist, USDA
Forest Service
prepared and edited by John M. Harper, Richard B. Standiford, and John W. LeBlanc