Калифорнийский чёрный дуб (Quercus kelloggii)

Species of oak tree

Quercus kelloggii, the California black oak or Kellogg oak, is an oak in the red oak section (genus Quercus, section Lobatae, series Agrifoliae) native to western North America. Although genetically separated from them for more than 20 million years, its leaves (though not its fruit) are remarkably similar in appearance to several other members of the red oak section including the red oak (Quercus rubra) and the black oak (Quercus velutina) found in eastern and central North America.

Quercus kelloggii typically grows from in height and from in diameter. Large trees may exceed in height and diameter, with the record holder measuring 124 feet (38 m) tall and thick (in the Siskiyou National Forest in Oregon). The species also grows in shrubby scrub oak form on poor sites. In open areas, the crown is broad and rounded, with lower branches nearly touching the ground or forming a browse line. In closed stands, the crown is narrow and slender in young trees and irregularly broad in old trees. Trunks are usually free of branches on the lower in closed stands. Acorns are relatively large in this species, from long It can be found at altitudes of up to , for example near Mount Shasta. and California black oak occupies more total area in California than any other hardwood species. Livestock also make heavy use of this species for food and cover. Older trees affected by heart rot have cavities which provide den or nest sites Acorns are heavily used by livestock, mule deer, feral pigs, rodents, mountain quail, Steller's jays, and woodpeckers. Acorns constitute an average of 50% of the fall and winter diets of western gray squirrels and black tailed deer during good mast years. Fawn survival rates increase or decrease with the size of the acorn crop. It is a preferred foraging substrate for many birds. All of 68 bird species observed in oak woodlands of the Tehachapi Mountains of California used California black oak for part of their foraging activities. Acorn woodpecker, Bullock's oriole, and Nashville warbler show strong preferences for California black oak. The parasitic plant Pacific mistletoe (Phoradendron villosum), which commonly grows on this oak, produces berries that attract birds, as well.

Some California Native Americans prefer California black oak acorns over those of other species for making acorn meal. Historically, this acorn was a staple food for many Native American groups, who usually leached out the bitter tannin. Native Americans recognized the importance of fire to this oak, and purposely lit fires in oak woodlands to promote its health and ensure their food source. The wood is used for making furniture, pallets, and construction timber. The tree is used as an ornamental.

California black oak comprises a total volume of 29% of California's hardwood timber resources, and is the major hardwood sawn into lumber there. The total estimated area of species occurrence is 361,800 hectares (3,618 square kilometers or 894,000 acres); 239,200 ha (2,392 km2 or 591,000 acres) of timberland and 122,600 ha (1,226 km2 or 303,000 acres) of woodland. Of this land 60% is privately owned, 31% is in National Forests, and 9% is on other public lands. It has greatly decreased from its historic abundance. This is due to a number of factors, including drought, disease, animal foraging, logging practices, fire suppression, and a variety of other human impacts. Cutting green trees for fuelwood has contributed to the decline of this species, and illegal harvesting of green trees from public lands is a continuing problem. It was long considered by foresters and government agencies to be a weed tree. In its earlier years, its only use to settlers was to feed the boilers of donkey engines bringing in the valuable pine and fir logs. For a period in the mid 1960s, the U. S. Forest Service policy in California's National Forests was systematic extermination of California black oak by girdling the trees. The objective was to make room for more coniferous growth. In the rush to use the pines, firs, and redwoods, the dense hardwoods were looked on with contempt. Like a few other visionaries in the 1960s, Guy Hall thought the California black oak presented a beautiful challenge that deserved better than eradication. In 1965, Hall convinced federal agencies to cease their extermination policies. Plantations of California black oak have been successfully established in clearcuts from acorn plantings. Thinning such stands promotes stand productivity and wood quality, and is recommended when trees are from tall or when stand density (basal area) exceeds 29 m2/ha (125 ft2/acre). This tree has also been managed for hardwood production by maintaining scattered pure stands within coniferous forests. Stands of this species often establish on poorer sites, where conifer seedling establishment has not been successful.

Q. kelloggii is cultivated in the specialty horticulture trade as an ornamental tree for native plant, drought tolerant, water conserving, and habitat gardens, and various types of municipal, commercial, and agency sustainable landscape and restoration projects.