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Quercus taxonomy
Quercus chrysolepis Liebm.
EOL Text
General: Canyon live oak is an evergreen tree with a rounded, dense crown, growing from 6 to 20 m tall. It also may be a low shrub in dry, open habitats. The mature bark is gray and scaly. Like all oaks, it is monoecious and wind-pollinated. Leaves are oblong to elliptic, 2 to 3 cm long, flat, firm, with entire to toothed margins. Although dark green and shiny above, their lower surfaces are paler, grayish, and covered with a yellow “felt.” Like all oaks, it is monoecious and wind-pollinated. Acorn cups are composed of thick, tubercled scales. The one-seeded nuts are 2 to 6 cm long, oblong to elliptic, and mature in less than 2 years. On average, trees have high acorn production once every 2 to 3 years. Flowering takes place from March to May. Fruits mature between August and October.
Like most oaks, it has an obligate relationship with mycorrhizal fungi, which provide critical moisture and nutrients. Seedlings and saplings are shade tolerant and often occur under the canopy of older trees.
Propagation by seed: Oak seeds do not store well and consequently seeds should be planted soon after maturity. Nuts are considered ripe when they separate freely from the acorn cap and fall from the tree. Care should be taken to collect local fruits, because they may be adapted to local environmental conditions. Viable nuts are green to brown and have unblemished walls. Nuts with discoloration, sticky exudates, or small holes caused by insect larvae should be discarded.
Direct Seeding: Seeds may be planted at the beginning of the winter. Once a site is chosen, prepare holes that are 10 inches in diameter and 4 to 5 inches deep. One gram of a slow-release fertilizer should be placed in the bottom and covered by a small amount of soil. Place 6 to 10 acorns in each hole at a depth of 1 to 2 inches. Rodents or birds should use temporary enclosures to minimize herbivory. A simple enclosure can be constructed from a 1-quart plastic dairy container with the bottom removed and a metal screen attached. Near the end of the first season, seedlings should be thinned to 2 or 3 per hole and to 1 seedling by the second season. Supplemental watering may be necessary if a drought of 6 weeks or more occurs during the spring.
Container Planting: Seeds may be planted in one-gallon containers, using well-drained potting soil that includes slow-release fertilizer. Tapered plastic planting tubes, with a volume of 10 cubic inches, also may be used. Seeds should be planted 1 to 2 inches deep and the soil kept moist. Seedlings should be transplanted as soon as the first true leaves mature. Planting holes should be at least twice as wide and deep as the container. Seedlings may require watering every 2 to 3 weeks during the first season. Care should be taken to weed and mulch around young plants until they are 6 to 10 inches tall.
Canyon live oak reproduces by sprouts that develop from dormant buds under the bark at the base of trees. Sprouts may form after a minor injury, such as browsing, or when the aerial parts of a tree are destroyed by fire or harvesting (21).
Sprouts develop from any size tree or shrub immediately after an injury. Older, less vigorous trees may produce only stool sprouts or none. The size and vigor of the parent tree or shrub determine the early height growth and number of sprouts per clump. Sprout development is greater on larger, more vigorous parent trees. Sprout growth of 0.5 to 1 m (1.6 to 3.3 ft) has been measured the first year. The number of sprouts per clump is gradually reduced as growth is concentrated on the dominant members. When nearly 100 years old, a parent tree may have three to five stems per clump. Individual stems in these clumps are seldom as large as single trees (13).
General: Canyon live oak is not perceived as declining throughout much of its natural range. Significant loss of habitat is unlikely since this species occurs primarily on mountain slopes and canyons on public lands. Nevertheless, where fuel loads are high, fire may cause local extirpation. However, regeneration by seeds appears to be one of the highest reported for western oaks.
United States
Origin: Unknown/Undetermined
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
In southwestern Oregon, canyon live oak is primarily associated with Douglas-fir, tanoak, giant chinkapin (Castanopsis chrysophylla), and Pacific madrone (Arbutus menziesii) in the mixed evergreen forests. In these forests it is a codominant tree and a shrub in the Pseudotsuga menziesii-Quercus chrysolepis-Lithocarpus densiflorus/Quercus chrysolepis-Lithocarpus densiflorus climax community type. On steep canyon slopes, it is dominant in the Quercus chrysolepis-Lithocarpus densiflorus-Pseudotsuga menziesii/Rhus diversiloba/ moss community. On benches and ridgetops, canyon live oak along with tanoak occupies the lower tree canopy of the Pseudotsuga, -menziesii-Pinus spp./Lithocarpus densiflorus-Quercus chrysolepis-Castanopsis chrysophylla /Pteridium aquilinum community. Canyon live oak also is a major codominant in the successional evergreen chaparral, along with hoary manzanita (Arctostaphylos canescens) and greenleaf manzanita (A. patula). In the mixed conifer zone of the western slope of the Cascade Range, canyon live oak primarily grows in semipermanent fire chaparral associated with snowbrush ceanothus (Ceanothus velutinus) (6).
In the Klamath region of northern California, canyon live oak is an occasional small tree or shrub throughout the Abies concolor zone of the montane or mixed conifer forest of the interior side of the Coast Ranges and Klamath Mountains. In the Abies concolor /Arbutus menziesii/Corylus cornuta type, canyon live oak is a codominant lower canopy tree under ponderosa pine, sugar pine, and white fir (Abies concolor). The associated codominant lower canopy trees are giant chinkapin, bigleaf maple, and Pacific dogwood (Cornus nuttallii) (10). It is also an understory tree in the Abies concolor/Vicia americana, Abies concolor/Chimaphila umbellata, Abies concolorlBerberis nervosa, and Abies concolor/Ceanothus prostratus types (1) and, at lower elevations, in the forest cover types Pacific Ponderosa Pine-Douglas-Fir (Society of American Foresters Type 244) and Pacific Ponderosa Pine (Type 245) (5).
In the Coast Ranges of northern California, canyon live oak is a major component of the mixed evergreen forest or Douglas-Fir-Tanoak-Pacific Madrone (Type 234). In these forests, it is associated with bigleaf maple, California-laurel, coast live oak Quercus agrifolia), Douglas-fir, madrone, and tanoak. Canyon live oak is not usually found in the modal mixed evergreen community dominated by Douglas-fir and tanoak; however, it is dominant on steep, southwestern slopes associated with Douglas-fir and madrone in a Quercus chrysolepis/Pseudotsuga menziesii type. In the southern portion of the mixed evergreen forests, canyon live oak assumes more importance along with ponderosa pine. On serpentine soils, canyon live oak is a minor climax associate in the Pinus ponderosa/Ceanothus cuneatus, Pseudotsuga menziesii/Corylus cornuta, and Lithocarpus densiflorus/Gaultheria shallon types (20).
In the central Coast Ranges of California, canyon live oak is a codominant in the mixed hardwood forests (Blue Oak-Digger Pine, Type 250), associated with coast live oak, blue oak (Quercus douglasii), interior live oak (Q. wislizeni), California black oak (Q. kelloggii), madrone, tanoak, California laurel, and Digger pine (Pinus sabiniana). In this area, it also occurs in successional chaparral associated with Eastwood manzanita (Arctostaphylos glandulosa). At higher elevations, canyon live oak is dominant in the canyon live oak-Coulter pine forest (Canyon Live Oak, Type 249).
In the Sierra Nevada of California, canyon live oak is found in several forest types. In the low-elevation foothill woodland forest, it is occasionally found on steep, north-facing slopes associated with interior live oak, blue oak, and Digger pine. In the mixed oak woodland, canyon live oak is a codominant with interior live oak, along with a prominent understory of manzanita, toyon, and western poison-oak (Rhus diversiloba). In the more mesic mixed oak forest, canyon live oak is a codominant with interior live oak, California black oak, bigleaf maple, and California-laurel (17).
Above the foothill woodland zone, canyon live oak is a codominant in the mixed oak-evergreen forest where it associates with ponderosa pine, Douglas-fir, and California black oak. Still higher in elevation in the mixed conifer forest, canyon live oak occurs in small groves with an understory of poison-oak and swordfern (Polystichum munitum), or in groves of mixed oak. It is also an understory small tree or shrub in the lower portion of the mixed conifer forests (17).
In the Transverse Range of southern California, canyon live oak is an important subdominant of the yellow pine forest on steep, south-facing slopes where it associates with ponderosa pine, Jeffrey pine (Pinus jeffreyi), and California black oak. In moister, cooler areas, canyon live oak is the major dominant in the stable bigcone Douglas-fir-canyon live oak forests (13). Canyon live oak is also found in the western juniper woodlands where it is associated with Jeffrey pine, singleleaf pinyon (Pinus monophylla), California black oak, and curlleaf cercocarpus (Cercocarpus ledifolius). Woodland chaparral is the only chaparral type in which canyon live oak is consistently present; it grows with manzanita, ceanothus, birchleaf cercocarpus, interior live oak, and scrub oak (11).
Throughout California, canyon live oak is an associate in the cypress groves of Santa Cruz cypress (Cupressus goveniana var. abramsiana), Tecate cypress (C. guadalupensis var. forbesii), Sargent cypress (C. sargentii), and Cuyamaca cypress (C. arizonica var. stephensonii). It is associated with singleleaf pinyon in the eastern-southern Sierra Nevada. In the Mojave Desert, canyon live oak is a minor associate of the montane white fir forests (1).
In Arizona, canyon live oak is a minor climax species in the montane Douglas-fir and pinyon forests. It is an understory component in pure stands of Douglas-fir. At lower elevations, it is also a major shrub in oak-chaparral communities, associated with Gambel oak (Quercus gambelii), New Mexico locust (Robinia neomexicana), buckthorn cercocarpus, silk-tassel bush (Garrya flavescens), Gregg ceanothus (Ceanothus greggii), and manzanita (17).
In Baja California, Mexico, canyon live oak is found in three habitats: in a scrub-chaparral type, as a shrub associated with manzanita and buckwheats (Eriogonum spp.); in groves on steep canyon slopes, as a small tree associated with Baja oak (Quercus peninsularis), buckthorn, manzanita, and ceanothus; and at higher elevations, as a small tree in Jeffrey pine forests (17).
In stands of canyon live oak, seedling regeneration can be very dense and evenly distributed. Seedlings show little seedbed preference, but they do best under an overstory or on the shaded overstory fringe. The best seedbed is moist soil covered with leaf litter. Few uncovered acorns germinate. Germination is hypogeal, and a short, cold stratification pretreatment helps to break dormancy. Germination occurs in early spring, and the percentage of seed germinating is moderate. The juvenile root penetrates moist soil rapidly, and survival is high under the shade of dense stands. Competition from grass can cause a complete failure in dry years.
Early seedling growth is slow, and large numbers of seedlings accumulate in some stands (7,13).
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Canyon live oak acorns were eaten by Native Americans in the Sierra Nevada and southern California [9,24,51,253]. Because canyon live oak often grows in steep and inaccessible locations, the acorns may have been used less than acorns from other California oaks [49,51]. Canyon live oak acorns may be bitter or possibly poisonous when raw [6,49,51]. The meal from canyon live oak acorns may require more washing than the acorn meal from other oak species [51].
Canyon live oak wood is the highest quality of all western oaks [221]. The wood is particularly hard and is sometimes referred to as "rock oak" or "maul oak". It has been used for axles, tool handles, mauls, wagon tongues, plow beams, ship frames, and wheels [124,161,187]. Wedges made from canyon live oak were used to split redwood into railroad ties [127]. Today, its commercial value is limited by the small quantities available [161,221].
Canyon live oak is an attractive landscaping tree [93,120,219] and an important source of firewood in southern California [184,239].
United States
Origin: Unknown/Undetermined
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
Canyon live oak seedlings and saplings are browsed by deer. In some areas, as many as 40 percent of all seedlings were browsed (8). In most situations, however, growth is not seriously retarded. Young stands of canyon live oak are relatively vulnerable to ground and crown fires. The combustion of ground fuels and brush during light fires singes and kills the crown foliage and burns through the thin, flaky bark. Repeated fires tend to convert canyon live oak trees to shrubs (18). In southern California, crown-sprouting associates-such as coast live oak and bigcone Douglas-fir-remain as trees after repeated fires, whereas canyon live oak becomes a shrub (14).
Little insect damage has been observed on canyon live oak compared with other oaks. Occasional localized damage is caused by California oakworm (Phryganidia californica) in wet years; in dry years ' the Pacific oak twig girdler (Agrilus angelicus) causes some damage. Other insects reported to do minor damage on canyon live oak are Pacific tent caterpillar (Malacosoma constrictum), western tussock moth (Orgyia vetusta), carpenterworm (Prionoxystus robiniae), ribbedcase maker (Bucculatrix albertiella), oak bark beetles (Pseudopityophthorus sp.), and a false powderpost beetle (Melalgus confertus) (3).
Acorns are destroyed by the filbert weevil (Curculio uniformis) and the filbertworm (Melissopus latiferreanus) (22). Often entire crops are riddled by insects. During some years an entire crop of acorns is used as food by squirrels, deer, and birds.
Numerous pathogens are found on canyon live oak throughout its range, the most serious being various heart rots. Diseases of canyon live oak are relatively unimportant under natural conditions. A rust fungus, Cronartium quercuum, and the mistletoe Phoradendron villosum subsp. villosum cause witches' brooms.