Можжевельник виргинский: описание и особенности

Species of conifer tree

Juniperus virginiana, also known as eastern redcedar, red cedar, Virginian juniper, eastern juniper, red juniper, and other local names, is a species of juniper native to eastern North America from southeastern Canada to the Gulf of Mexico and east of the Great Plains. It is not to be confused with Thuja occidentalis (eastern white cedar).

Juniperus virginiana is a dense slow growing coniferous evergreen tree with a conical or subcylindrical shaped crown that may never become more than a bush on poor soil, but is ordinarily from tall, with a short trunk in diameter, rarely to in height and in diameter. The oldest tree reported, from West Virginia, was 940 years old. The bark is reddish brown, fibrous, and peels off in narrow strips. The leaves are of two types; sharp, spreading needle like juvenile leaves long, and tightly adpressed scale like adult leaves long; they are arranged in opposite decussate pairs or occasionally whorls of three. The juvenile leaves are found on young plants up to 3 years old, and as scattered shoots on adult trees, usually in shade. The seed cones are long, berry like, dark purple blue with a white wax cover giving an overall sky blue color (though the wax often rubs off); they contain one to three (rarely up to four) seeds, and are mature in 6–8 months from pollination. The juniper berry is an important winter food for many birds, which disperse the wingless seeds. The pollen cones are long and broad, shedding pollen in late winter or early spring. The trees are usually dioecious, with pollen and seed cones on separate trees, south to central Florida and west to southeast Texas. Cones are smaller, ; scale leaves are blunt at apex and the bark is orange brown. It is treated by some authors at the lower rank of variety, while others treat it as a distinct species.

Eastern Red Cedar is a pioneer species, meaning that it is one of the first trees to repopulate disturbed sites. It is unusually long lived among pioneer species, with the potential to live over 900 years. It is commonly found in prairies or oak barrens, old pastures, or limestone hills, often along highways and near recent construction sites. Eastern Red Cedar grows in a wide range of climatic and soil conditions. The tree is extremely tolerant of drought due to its extensive, fibrous root system and reduced leaf area. It can be found from droughty, rocky soils with few nutrients to rich alluvial soils with abundant moisture. However, Eastern Red Cedar is almost never dominant on such rich mesic sites due to intense competition with faster growing, more shade tolerant hardwood trees. Outside of its native range it is considered an invasive species, and it can be aggressive even within its range. It is fire intolerant, and was previously controlled by periodic wildfires. Low branches near the ground burn and provide a ladder that allows fire to engulf the whole tree. Grasses recover quickly from low severity fires that are characteristic of prairies that kept the trees at bay. With the urbanization of prairies, the fires have been stopped with roads, plowed fields, and other fire breaks, allowing J. virginiana and other trees to invade. Trees are destructive to grasslands if left unchecked, and are actively being eliminated by cutting and prescribed burning. The trees also burn very readily, and dense populations were blamed for the rapid spread of wildfires in drought stricken Oklahoma and Texas in 2005 and 2006. On the Great Plains, expanding red cedar populations are altering the plains ecosystem: a majority of the region's bird species are not present in areas where the tree's land cover exceeds 10 percent, and most small mammal species are not present where land cover exceeds 30 percent. Eastern juniper benefits from increased CO2 levels, unlike the grasses with which it competes. Many grasses are C4 plants that concentrate CO2 levels in their bundle sheaths to increase the efficiency of RuBisCO, the enzyme responsible for photosynthesis, while junipers are C3 plants that rely on (and may benefit from) the natural CO2 concentrations of the environment, although they are less efficient at fixing CO2 in general. Alterations of prairie ecosystems by J. virginiana include outcompeting forage species in pastureland. The low branches and wide base occupy a significant portion of land area. The thick foliage blocks out most light, so few plants can live under the canopy. The needles that fall raise the pH of the soil, making it alkaline, which holds nutrients such as phosphorus, making it harder for plants to absorb them. However, studies have found that Juniperus virginiana forests that replace grasslands have a statistically insignificant decrease to a significant increase

The pollen of Juniperus virginiana var. virginiana is a known allergen. The nominate variety is native to Eastern North America, north of Mexico, with the pollen releasing at various points in the spring, variable by latitude and elevation.

The fragrant, finely grained, soft, brittle, very light, pinkish to brownish red heartwood is very durable, even in contact with soil. Because of its resistance to decay, the wood is often used for fence posts. Moths avoid the aromatic wood, and therefore it is in demand as lining for clothes chests and closets, which are often denominated "cedar closets" and "cedar chests". If correctly prepared, excellent English longbows, flatbows, and Native American sinew backed bows can be made from it. It is marketed as "eastern redcedar" and "aromatic cedar". The best portions of the heartwood are one of the few woods that are suitable for making pencils, however the supply had so diminished by the 1940s that the wood of the incense cedar largely replaced it. The fruits also yield an essential oil which contains mostly D Limonene. The oil derived from foliage and twigs has two main constituents: safrole and limonene. One minor compound is the podophyllotoxin, a non alkaloid toxin lignan. Native American tribes have historically used poles of juniper wood to demarcate agreed tribal hunting territories. French traders named Baton Rouge, Louisiana, which denotes "red stick", from the reddish color of these poles. Some nations continue to use it ceremonially. The Cahokia Woodhenge series of timber circles that the pre Columbian Mississippian culture in western Illinois erected were constructed of massive logs of eastern juniper. One iteration of such a circle, Woodhenge III, which is thought to have been constructed circa 1000 AD, had 48 posts in the circle of 410 feet (125 m) in diameter and a 49th pole in the center. Among many Native American cultures, the smoke of burning eastern juniper is believed to expel evil spirits prior to conducting a ceremony, such as a healing ceremony. During the Dust Bowl drought of the 1930s, the Prairie States Forest Project encouraged farmers to plant shelterbelts, i. e. wind breaks, of eastern juniper throughout the Great Plains of the US. The trees thrive in adverse conditions. Tolerant of both drought and cold, they grow well in rocky, sandy, and clayey soils. Competition between individual trees is minimal, and therefore they can be closely planted in rows, in which situation they still grow to full height, creating a solid windbreak in a short time. A number of cultivars have been selected for horticulture, including 'Canaertii' (narrow conical; female) 'Corcorcor' (with a dense, erect crown; female), 'Goldspire' (narrow conical with yellow foliage), and 'Kobold' (dwarf). Some cultivars previously listed under this species, notably 'Skyrocket', are actually cultivars of J. scopulorum. In the Arkansas, Missouri, and Oklahoma Ozarks, eastern juniper is commonly used as a Christmas tree. This is the most widely used wood for making blocks for recorders. There are numerous properties that it possesses that make it uniquely suitable for this, such as good moisture absorption, low expansion when wet (so it does not crack the recorder head), and mild antiseptic properties. Eastern red cedar is considered effective as a shelter belt tree and for erosion control. Being coniferous, red cedar has dense evergreen foliage which makes it an ideal windbreak. The tree's extensive root system allows it to survive drought, and helps to retain surrounding topsoil during dry, windy conditions.