Robert A. McQuilkin
Chestnut oak (Quercus prinus), sometimes called rock chestnut oak, rock oak, or tanbark oak, is commonly found in the Appalachian region on dry, infertile soils and rocky ridges but reaches best growth on rich well-drained soils along streams. Good acorn crops on this medium-sized, long-lived tree are infrequent, but the sweet nuts are eaten by wildlife when available. Chestnut oak is slow growing and the lumber is cut and sold as white oak.
Regularity: Regularly occurring
-The native range of chestnut oak.
Soils and Topography
In the Blue Ridge Mountains of northern Georgia, site index for chestnut oak ranges from 12 to 25 in (39 to 83 ft), and averages about 20 in (65 ft). Site index is greater on steep slopes, lower slope positions, and at elevations below 800 in (2,600 ft) than elsewhere. Other indicators of good chestnut oak sites are subsoils with more than 15 percent silt, loam or sandy loam surface soils, and sites where litter decomposes rapidly (15). Chestnut oak growth is poorest on soils of the Porters (Humic Hapludult) and Ashe (Typic Dystrochrept) series, intermediate on soils of the Hayesville and Halewood series (Typic Hapludults), and best on soils of the Tusquitee and Brevard series (Humic and Typic Hapludults, respectively) (6).
Associated Forest Cover
White Pine-Chestnut Oak (Type 51) is found in the Appalachian region from West Virginia to Georgia. It is most common in southwestern Virginia, eastern Tennessee, and western North Carolina at elevations between 360 and 1100 m (1,200 and 3,600 ft). On the drier sites, common associated species include scarlet (Quercus coccinea), white (Q. alba), post (Q. stellata), and black (Q. velutina) oaks; hickories; blackgum; sourwood (Oxydendrum arboreum); red maple; and pitch, Table Mountain, Virginia, and shortleaf pines. On more mesic sites, associated species include northern red (Quercus rubra) and white oaks, black locust (Robinia pseudoacacia), yellow-poplar, sugar and red maples, and black cherry.
Chestnut oak is also an associated species in the following cover types: Eastern White Pine (Type 21); White Pine-Hemlock (Type 22); Red Maple (Type 108); Bear Oak (Type 43); White Oak-Black Oak-Northern Red Oak (Type 52) and its variants white oak-black oak-chestnut oak, black oak-scarlet oak-chestnut oak, and scarlet oak-chestnut oak; White Oak (Type 53); Black Oak (Type 110); Pitch Pine (Type 45) and its variant pitch pine-chestnut oak; Virginia Pine (Type 79); and Virginia Pine-Oak (Type 78).
Common shrub associates of chestnut oak include highbush and lowbush blueberry (Vaccinum corymbosum and V. angustifolium), dwarf chinkapin oak Quercus prinoides), and mountain-laurel (Kalmia latifolia).
Before the demise of American chestnut (Castanea dentata), chestnut oak was an important component of the Appalachian oak-chestnut forests. Since then, hickory, chestnut oak, northern red oak, and white oak have replaced American chestnut as these stands have gradually changed to oak-hickory stands (20).
Diseases and Parasites
Chestnut oak and white oak are the two species most preferred by the gypsy moth (Lymantria dispar). Other important defoliators of chestnut oak are the spring and fall cankerworms (Paleacrita Vernata and Alsophila pometaria), the forest tent caterpillar (Malacosoma disstria) and the half-wing geometer (Phigalia titea) (1,14,34).
Chestnut oak is more resistant to wood borers than most oaks but is particularly susceptible to attack by ambrosia beetles, especially the Columbian timber beetle (Corthylus columbianus) and several species of the genera Platypus and Xyleborus; these beetles are particularly damaging to trees that have been weakened by fire or drought. The more important wood borers that attack chestnut oak are the oak timberworm (Arrhenodes minutus), the carpenterworm (Prionoxystus robiniae), and the little carpenterworm (P. macmurtrei).
Chestnut oaks are also susceptible to several gallforming wasps (Cynipidae), a pit scale (Asterolecanium quercicola), and the golden oak scale (A. variolosum). These insects may kill twigs and branches but rarely kill mature trees.
The acorns of chestnut oak are frequently infested with larvae of the nut weevils Curculio spp. and Conotrachelus spp., the moth Valentinia glandulella, and the cynipid gall wasps (Cynipidae). However, one study indicated that chestnut oak acorns may have lower insect infestation rates than acorns of other oaks (2).
Reaction to Competition
In the Appalachian region, chestnut oak typically occupies intermediate to poor sites where it is considered to be the physiographic climax. It is excluded from the more mesic sites by species that grow more rapidly in the seedling and sapling stages, such as northern red, black, and white oaks; yellow-poplar; sugar and red maples; and black cherry. The most xeric sites are typically occupied by species even better adapted to such conditions, such as scarlet oak, post oak, and pitch pine (8,21,23).
Chestnut oak seedlings maintain much higher root starch levels during the growing season than white oak or northern red oak and have a higher root-to-shoot ratio and a more rapid initial root development rate than northern red oak. These factors may partially account for the species adaptability to xeric sites (10,16).
Life History and Behavior
It has been estimated that 75 percent of the chestnut oak reproduction in the southern Appalachians is of sprout origin (4).
Germination of chestnut oak acorns is enhanced by a covering of leaf litter 2 or 3 cm (I in) deep, but a covering of more than about 5 cm (2 in) results in many etiolated seedlings. Large numbers of seedlings can become established after good seed years, but such years occur infrequently. Seedling establishment and survival are greatly reduced by dense herbaceous and shrub layers.
Chestnut oak seedlings grow slowly. In Indiana, the height of seedlings 10 years after establishment averaged 15 cm (6 in) in an uncut forest, 24 cm (9 in) where release cuttings were made, and 146 cm (58 in) in a clearcut. In contrast to this slow seedling growth, chestnut oak sprouts in the clearcut were more than 6.4 m (21 ft) tall (4). The seedlings are capable of rapid growth, however, when growing conditions are near optimal. In one nursery study, chestnut oak seedlings produced an average of 4.3 growth flushes during the first growing season and exceeded bear oak and white oak, and equaled or exceeded northern red oak in height, dry weight, and leaf area. Growth of these seedlings was highly correlated with initial leaf area, which in turn was correlated with acorn size (11).
Seed Production and Dissemination
Chestnut oak begins producing seed at about age 20, but stump sprouts as young as 3 years can produce viable seed, and coppice stands as young as 7 or 8 years can have abundant acorn production. The germinative capacity of sound acorns is around 90 percent. Dissemination is primarily by gravity and squirrels (4,22,26).
Flowering and Fruiting
Chestnut oak produces an abundant crop of aments every year, but the production of pistillate flowers varies considerably from year to year; trees that produce a large crop of flowers and acorns one year usually produce fewer flowers the following year.
Growth and Yield
Sawtimber yield from chestnut oak stands on dry slopes and ridges in the southern Appalachians is about 98.0 m³/ha (7,000 fbm/acre) at age 80. On average sites, maximum periodic growth is about 1.4 m³/ha (100 fbm/acre) per year at age 100 (4).
On the better sites, chestnut oak has good form and maintains a bole that is relatively clear of branches and sprouts, although many epicormic sprouts develop if the bole is exposed to sunlight (32).
Molecular Biology and Genetics
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Relevance to Humans and Ecosystems
Quercus prinus (syn. Quercus montana), the chestnut oak, is a species of oak in the white oak group, Quercus sect. Quercus. It is native to the eastern United States, where it is one of the most important ridgetop trees from southern Maine southwest to central Mississippi, with an outlying northwestern population in southern Michigan. It is also sometimes called "rock oak" because of montane and other rocky habitats. As a consequence of its dry habitat and ridgetop exposure, it is not usually a large tree, typically 18–22m (60–70 ft) tall; occasional specimens growing in better conditions can however become large, with trees up to 40–43 m (130–140 ft) tall known. They tend to have a similar spread of 18–22m (60–70 ft). A 10-year-old sapling will stand about 5 m (16 ft) tall. This species is often an important canopy species in an oak-heath forest.
Taxonomy and nomenclature
Extensive confusion between the chestnut oak (Quercus prinus) and the swamp chestnut oak (Quercus michauxii) has occurred, and some botanists have considered them to be the same species in the past.
The name Quercus prinus was long used by many botanists and foresters for either the chestnut oak or the swamp chestnut oak, with the former otherwise called Q. montana or the latter otherwise called Q. michauxii. The application of the name Q. prinus to the chestnut oak is now often accepted, although sometimes that name is declared to be of uncertain position, unassignable to either species, with the chestnut oak then called Q. montana, as in the Flora of North America.
The chestnut oak is readily identified by its massively-ridged dark gray-brown bark, the thickest of any eastern North American oak. The leaves are 12–20 cm long and 6–10 cm broad, shallowly lobed with 10–15 rounded lobes on each margin; they are virtually identical to the leaves of swamp chestnut oak and chinkapin oak, but the trees can readily be distinguished by the bark, that of the chinkapin oak being a light ash-gray and somewhat peeling like that of the white oak and that of swamp chestnut oak being paler ash-gray and scaly. The chinkapin oak also has much smaller acorns than the chestnut oak. The chestnut oak is easily distinguished from the swamp white oak because that tree has whitened undersides on the leaves. Another important distinction between the chestnut oak and the swamp chestnut oak is by the habitat; if it grows on a ridge, it is chestnut oak, and if it grows in wet bottomlands, it is probably the more massive swamp chestnut oak; however, this is not fully reliable.
Characteristics of the chestnut oak include:
- Bark: Dark, fissured into broad ridges, scaly. Branchlets stout, at first bronze green, later they become reddish brown, finally dark gray or brown. Heavily charged with tannic acid.
- Wood: Dark brown, sapwood lighter; heavy, hard, strong, tough, close-grained, durable in contact with the soil. Used for fencing, fuel, and railway ties. Sp. gr., 0.7499; weight of cu. ft., 46.73 lbs.
- Winter buds: Light chestnut brown, ovate, acute, one-fourth to one-half of an inch long.
- Leaves: Alternate, five to nine inches long, three to four and a half wide, obovate to oblong-lanceolate, wedge-shaped or rounded at base, coarsely crenately toothed, teeth rounded or acute, apex rounded or acute. They come out of the bud convolute, yellow green or bronze, shining above, very pubescent below. When full grown are thick, firm, dark yellow green, somewhat shining above, pale green and pubescent below; midribs stout, yellow, primary veins conspicuous. In autumn they turn a dull yellow soon changing to a yellow brown. Petioles stout or slender, short. Stipules linear to lanceolate, caducous.
- Flowers: May, when leaves are one-third grown. Staminate flowers are borne in hairy aments two to three inches long; calyx pale yellow, hairy, deeply seven to nine-lobed; stamens seven to nine; anthers bright yellow. Pistillate flowers on short spikes; peduncles green, stout, hairy; involucral scales hairy; stigmas short, bright red.
- Acorns: Annual, singly or in pairs; nut oval, rounded or acute at apex, bright chestnut brown, shining, one and a quarter to one and one-half inches in length; cup, cup-shaped or turbinate, usually inclosing one-half or one-third of the nut, thin, light brown and downy within, reddish brown and rough outside, tuberculate near the base. Scales small, much crowded toward the rim sometimes making a fringe. Kernel white, sweetish.
The acorns of the chestnut oak are 1.5–3 cm long and 1–2 cm broad, among the largest of native American oaks, surpassed in size only by the bur oak and possibly swamp chestnut oak,
|This section requires expansion. (October 2011)|
This species is a predominant ridge-top tree in eastern North American hardwood forests. It often grows with multiple trunks, often as a result of prior injury to the main stem. It is a long-lived tree, with high-quality timber when well-formed. The acorns of the chestnut oak are a valuable wildlife food.
Chestnut oak trees are generally not the best timber trees because they are usually branched low and not very straight, but when they grow in better conditions, they are valuable for timber, which is marketed as 'mixed white oak'.
- The Natural Communities of Virginia Classification of Ecological Community Groups (Version 2.3), Virginia Department of Conservation and Recreation, 2010
- Schafale, M. P. and A. S. Weakley. 1990. Classification of the natural communities of North Carolina: third approximation. North Carolina Natural Heritage Program, North Carolina Division of Parks and Recreation.
- ITIS (the Integrated Taxonomic Information System) accepts Q. prinus as the accepted name for the chestnut oak.
- The confusion arose from differing identifications of the type specimens for the Linnaean name, by some (but not all) botanists considered resolved by close examination of the leaf pubescence, which differs in the two species.
- "Quercus montana". Flora of North America. Retrieved 8 October 2011.
- Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons. pp. 338–344.
- Flora of North America: Quercus montana RangeMap
- ITIS Taxonomic Report: Quercus prinus L.
- ITIS Taxonomic Report: Quercus montana (synonum of Quercus prinus L.)
- USDA Plants Profile: Quercus prinus L.
|Wikimedia Commons has media related to Quercus montana (syn: Quercus prinus).|
The four species of the chestnut oak group in eastern North America ( Quercus montana , Q . michauxii , Q . muhlenbergii , and Q . prinoides ) are somewhat difficult to distinguish unless careful attention is paid to features of leaf vestiture and fruit and cup morphology. Attempts to identify these species mostly or solely on basis of leaf shape and dentition (as in many other oak species complexes) have resulted in a plethora of misidentified material in herbaria and erroneous reports in the literature. The closely appressed, asymmetric trichomes on the abaxial surface of the mature leaf, in combination with longer simple hairs along the midvein, are unique to Q . montana among North American species of Quercus . Immature leaves and densely shaded leaves sometimes exhibit a more erect trichome that could be confused with the longer, felty hairs of Q . michauxii , so it is important to evaluate mature sun leaves when possible.
Names and Taxonomy
Comments: This species is called Quercus montana in many floras. The name Quercus prinus is considered ambiguous by Flora North America vol. 3 (1997), possibly applying instead to the plant otherwise known as Q. michauxii. However, this name, Q. prinus, has never been formally rejected, and is applied by Kartesz to this taxon (LEM 6Dec93).
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