蜜桃av

Quercus rubra, the听northern red oak, is an听听tree in the听听group (Quercus听section听Lobatae). It is a native of North America, in the eastern and central United States and southeast and south-central Canada. It has been introduced to small areas in Western Europe, where it can frequently be seen cultivated in gardens and parks. It prefers good soil that is slightly听. Often simply called听red oak, northern red oak is so named to distinguish it from听听(Q.听falcata), also known as the Spanish oak. Northern Red Oak is sometimes called听champion oak.

Description

In many forests,听Quercus rubra听grows straight and tall, to 28 metres (92 feet), exceptionally to 43听m (141听ft) tall, with a trunk of up to 50鈥�100 centimetres (20鈥�39 inches) in diameter. Open-grown trees do not get as tall, but can develop a stouter trunk, up to听2听m (6+1鈦�2听ft) in diameter. It has stout branches growing at right angles to the stem, forming a narrow round-topped head.

Under optimal conditions and full sun, northern red oak is fast growing and a 10-year-old tree can be 5鈥�6听m (16鈥�20听ft) tall.听Trees may live up to 400 years;听a living example of 326 years was noted in 2001.

Northern red oak is easy to recognize by its听, which features ridges that appear to have shiny stripes down the center. A few other oaks have bark with this kind of appearance in the upper tree, but the northern red oak is the only tree with the striping all the way down the trunk.

As with most other deciduous oaks, leafout takes place in spring when day length has reached 13 hours鈥攊t is tied entirely to听听and will take place regardless of air temperature. As a consequence (see below), in cooler regions, northern red oaks often lose their flowers to late spring frosts, resulting in no seed crop for the year. The catkins and leaves emerge at the same time. The听听develop on the tree for two growing seasons and are released from the tree in early October, and leaf drop begins when day length falls under 11 hours. The timing of leafout and leaf drop can vary by as much as three weeks in the northern and southern US. Seedlings emerge in spring when soil temperatures reach 21听掳C (70听掳F).[]

• Bark: Dark reddish gray brown, with broad, thin, rounded ridges, scaly. On young trees and large stems, smooth and light gray. Rich in tannin. Branchlets slender, at first bright green, shining, then dark red, finally dark brown. Bark is brownish gray, becoming dark brown on old trees.
• Wood: Pale reddish brown, sapwood darker, heavy, hard, strong, coarse-grained. Cracks in drying, but when carefully treated could be successfully used for furniture. Also used in construction and for interior finish of houses. Sp. gr., 0.6621; weight of cu. ft., 41.25听lbs.
• Winter buds: Dark chestnut brown (reddish brown), ovate, acute, generally听6听mm (1鈦�4听in) long
• Leaves and acorns: Alternate, seven to nine-lobed, oblong-ovate to oblong, five to ten inches long, four to six inches broad; seven to eleven lobes tapering gradually from broad bases, acute, and usually repandly dentate and terminating with long bristle-pointed teeth; the second pair of lobes from apex are largest; midrib and primary veins conspicuous. Lobes are often less deeply cut than most other oaks of the red oak group. Leaves emerge from the bud convolute, pink, covered with soft silky down above, coated with thick white tomentum below. When full grown are dark green and smooth, sometimes shining above, yellow green, smooth or hairy on the axils of the veins below. In autumn they turn a rich red, sometimes brown. Often the petiole and midvein are a rich red color in midsummer and early autumn, though this is not true of all red oaks. The acorns mature in about 18 months after听; solitary or in pairs, sessile or stalked; nut oblong-ovoid with broad flat base, full, with acute apex, one half to one and one-fourth of an inch long, first green, maturing nut-brown; cup, saucer-shaped and shallow,听2听cm (3鈦�4听in) wide, usually covering only the base, sometimes one-fourth of the nut, thick, shallow, reddish brown, somewhat downy within, covered with thin imbricated reddish brown scales. Its kernel is white and very bitter.

Red oak acorns, unlike the white oak group, display听听and will not germinate without a minimum of three months' exposure to temperatures below 4听掳C (40听掳F). They also take two years of growing on the tree before development is completed.

Distribution and habitat

The species grows from the north end of the听, east to听, south as far as听,听,听, and听, and west to听,听,听, and听.

It grows rapidly and is tolerant of many soils and varied situations, although it prefers the glacial drift and well-drained borders of streams.听In the southeastern United States, it is frequently a part of the canopy in an听, but generally not as important as some other oaks.

Northern red oak is the most common species of oak in the northeastern US after the closely related听听(Q.听palustris). The red oak group as a whole are more abundant today than they were when European settlement of North America began as forest clearing and exploitation for lumber much reduced the population of the formerly dominant white oaks.[]

Ecology

Over the last few decades, the northern red oak has dealt with several environmental factors, mainly disease, predation by insects, and limited opportunities for dispersal. These stresses have impacted the species' ability to proliferate in both the Northeast and Europe.听The various environmental responses observed in听Quercus rubra听across several temperate environmental conditions have allowed for it to serve as a model organism for studying symbiotic relationships, dispersal, and habituation between tree species.

Pests and diseases

Canker pathogen,听,听has become a major pathogen to the species over the last decade, causing leaf browning, bark cracking and bleeding, and high rates of tree mortality across the northeastern United States.听The northern red oak is also characterized as one of the most susceptible species to plant fungi听听补苍诲听,听which have caused severe, red-black cankers in the trunk region of the species.听Both听P. cinnamomi听补苍诲听P. ramorum听grow under warmer temperature conditions; as a result, northern red oak trees found in California, France, and northern Spain all have a higher incidence of fungal infection.听Oak Wilt caused by the fungus听听is a major pathogen found in eastern North America that can kill trees quickly.

Abiotic stresses

Northern red oak seedlings have been known to have a high mortality rate in northeast regions prone to spring freeze, particularly in Massachusetts. Acorns produced by oaks in this region are typically smaller in size as an adaptation to frost produced in high latitudes; however, the resulting smaller seedlings have produced limited opportunities for animal consumption and dispersal.听Flooding along the continental United States has been shown to be a major issue for the northern red oak, in which decreased听听transport and photosynthetic activity has been observed, but only after multiple days of flooding, indicating that the northern red oak has adapted moderate resistance to excess water exposure.听The northern red oak has also developed tolerance mechanisms for heat stress, particularly observed in deciduous forests in the Southeastern United States, where, during summer heat waves, temperatures can exceed 40听掳C (104听掳F). The leaves of the northern red oak have been observed to have an acclimation to听听activase activity that is directly correlated to acclimations with repeated exposure to heat waves. Consistent photosynthetic activity in the red oak has also been observed in the presence of high carbon dioxide levels that often occur as a result of elevated temperatures.

Animals

Northern red oak kernels have highly concentrated amounts of bitter-tasting听, a biochemical classified as a predator deterrent, which has limited appeal for consumption among animals. Despite this, the acorns are eaten by听,听听补苍诲听.听In Europe, the acorns are consumed by several moth species, particularly听听补苍诲听, which increases their niche breadths and reduces their competition with听听飞别别惫颈濒蝉.听Due to this, germination rates among the northern red oak acorns have decreased significantly and resulted in less seed dispersal by animals within Poland. In addition, limited opportunities for dispersal have become costly for the northern red oak in Europe. European animals known for dispersing tendencies, such as the听听补苍诲听, have been found to be more attracted to local oak species.

Fungi

Quercus rubra听has effective听听relationships that have been correlated with increased growth rates. Northern red oak trees have been shown to increase growth in the presence of various听听that coil at the base of the oak trunk. The fungi, which eventually proliferate at the stumps of deciduous trees, have been found to be host-specific to both听Quercus rubra听补苍诲听听and primarily promote growth upon infection.

Invasiveness in Europe

It was introduced to Europe in the 1700s and has naturalized throughout most of western and central Europe.听Across western and central Europe, the northern red oak has become the fourth-most significant invasive species, colonizing several regions across听,听,听,听,听,听,听,听听补苍诲听). The northern red oak is primarily found on the edges of woodland reserves in Europe, where light availability, tannin concentration, and animal dispersal are the most necessary component for the species' longevity and survival.听The high influx of the species in Europe is primarily based on its economic productivity as a fast-growing source of听; however, it has been linked to lower percentages of trace elements and minerals found in the surrounding soil and reduced听听among native oak species such as听.

Uses

The northern red oak is one of the most important oaks for 听production in North America. Quality red oak is of high value as lumber and veneer, while defective logs are used as听. Other related oaks are also cut and marketed as red oak, although their wood is not always of as high a quality. These include听,听,听,听,听听and other species in the red oak group. Construction uses include flooring, veneer, interior trim, and furniture. It is also used for lumber, railroad ties, and fence posts.[]

Red oak wood grain is so open that smoke can be blown through it from end-grain to end-grain on a flat-sawn board. For this reason, it is subject to moisture infiltration and is unsuitable for outdoor uses such as boatbuilding or exterior trim.[]

The acorns can be collected in autumn, shelled, tied up in a cloth, and leached to remove bitterness. They can then be eaten whole or ground into meal.

Ornamental use

Quercus rubra听is grown in parks and large gardens as a specimen tree.听It is not planted as often as the closely related听听as it develops a听听and quickly becomes difficult to transplant, however modern growing pots have made starting seedlings with taproots easier than in the past.

Culture

It is the听听of听听and the听听of听.

Famous specimens

• 听鈥� A very large Northern Red Oak in听, Connecticut. The tree has suffered falling limbs because of its great age. However, this tree is still a sight to behold; the trunk is 8听m (26听ft) in circumference and the root-knees are also particularly impressive. The oak is located on Giant Oak Lane off听. There are several other large oaks in the area.
• 听鈥� This forest tree is located on a very rich steep slope in听,听. It is a high-stump听听with three leads. It was the state champion oak in Maryland in 2002. The circumference at breast height is 6.7听m (22听ft 0听in), the height 41.5听m (136听ft 2听in) and the spread 29.9听m (98听ft 1听in)
• 听鈥� This majestic red oak tree is located on Shelby Street in the South Frankfort neighborhood in听,听, and is the largest red oak tree in the oldest neighborhood in听,听. It is in the backyard of a house built in 1914 by architect Arthur Raymond Smith, who at one time worked for D.X. Murphy & Bros., famed architects that designed the twin spires at听. The circumference at breast height is 6.4听m (21听ft 0听in), with the trunk reaching higher than 12听m (40听ft) before the branches begin and an estimated height of 40听m (130听ft).
• 听鈥� At over 250 years old, this tree is among the oldest in Toronto. The trunk has a circumference of 4.95听m (16听ft 3听in) and the canopy is over 24听m (79听ft) tall. The lot where the tree stands has been purchased by the City of Toronto to be turned into a public park.