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Western juniper foliage is not easily ignited and/or scorched when moist [17]. Western junipers under 4 to 6 feet (1.2-1.8m) tall are readily killed by fire [64,17]. A more severe fire is necessary to kill taller trees [64].
Recovery time depends on the size of burn, location of seed source, stand maturity, and presence of animal dispersers [19]. Postburn succession in western juniper communities depends on season of burn, postfire mortality, and on seed of associated species present in the preburn community. Postfire succession is also related to the effects of competition from herbaceous species and shrubs as well as drought. Large burns and long distances from seed sources slow recovery rates. According to Bunting and others [17] "because these factors vary widely early seral community composition is highly variable." Fire scars have been observed on western junipers found growing in fire-resistant low sagebrush communities lacking perennial grass cover [103].
Western juniper provides perching and nesting sites for at least 27 species of birds, as well as cover and hibernation sites for small mammals [68]. In southeastern and south-central Oregon western juniper provides excellent hiding and thermal cover for mule deer [61,62]. In parts of Nevada, it also provides some cover for pronghorn [101]. Western juniper also provides shade for domestic livestock [22].
Decadent trees provide nesting cavities for mountain chickadees and mountain bluebirds, and hibernation sites for several species of bats. Thirty percent of these species nest in cavities while 70 percent nest in open nests [68]. Lewis' woodpecker and the northern flicker nest in western juniper [54,90].
Western juniper is a tree that typically grows 15 to 30 feet (4.6 to 9.1 m) [87]. It rarely exceeds 60 feet (18.3 m) in height. The largest recorded specimen is 86 feet tall (26 m), with a circumference of 480 inches (1,219 cm) and crown spread of 58 feet (18 m) [12]. Trees develop full crowns and heavy limbs at maturity [22].
Varieties differ with respect to growth characteristics. The variety Juniperus occidentalis var. australis reaches an average height of 26 feet (7.9 m), with a maximum height of 50 feet (15.2 m), whereas J. occidentalis var. occidentalis typically grows to 23 feet (7.0 m) in height, and rarely grows over 40 feet (12.2 m). Average circumference of the largest stem 5 feet (1.5 m) above the ground of J. occidentalis var. australis is 84 inches (213 cm), while only 42 inches (107 cm) for J. occidentalis var. occidentalis [98].
Bark is furrowed and shreddy [31]. Taproots average 51 inches (130 cm) in depth [55]. Root-to-shoot ratios decrease with age giving western juniper the ability to outcompete species such as big sagebrush [55].
Western juniper is slow growing and long lived [31]. Individuals can survive for 1,000 years or longer [87]. The Bennett juniper, which grows near Sonora Pass, California, is believed to be 3,000 to 6,000 years old [4,12]. Annual growth of mature western juniper is as follows [28]:
Stand Height Diameter
inch cm inch cm
Open, dominant 3.5 9 0.3 0.8
Closed, subdominant 3.5 9 0.1 0.4
Closed, young 1.2 3 0.05 0.2
Highest rate 4.3 11 0.5 1.3
Western juniper occurs from southeastern Washington and Oregon southward to the upper slopes of the Sierra Nevada and San Bernardino Mountains of southern California [87]. It occurs along the western edge of the Great Basin in southwestern Idaho and northwestern Nevada [70].
The subspecies J. occidentalis var. australis occurs most commonly in the subalpine zone to forested uplands of the northern Coast Ranges and the Sierra Nevada Mountains of California, southward to California's San Bernardino, San Gabriel and various desert mountain ranges westward into Nevada [44,98,103,106]. The variety J. occidentalis var. occidentalis occurs from the Cascade Range through the Modoc Plateau into adjacent parts of Washington, Oregon, and Idaho, and southward into northwestern Nevada [44]. It reaches its greatest extent in central Oregon east of the Cascade Range [103].
During the past 150 years, western juniper has extended its range and now occupies approximately 42 million acres (17 million hectares) in the Intermountain West [16,36]. It grows over approximately 4 million acres (1.6 million hectares) in the Pacific Northwest [29].
Young western junipers have thin bark and are readily killed by surface fires. "Older" trees with thicker bark are described as "moderately resistant" to fire [87]. In general, the taller the juniper, the greater the severity of the fire required to kill it [64]. Western juniper does not sprout [19]. Reestablishment is through seed that is dispersed fairly slowly by water and animals.
FIRE REGIMES in western juniper communities: When fires occurred at 10 to 25 year intervals, western juniper was restricted to protected microsites [1]. Belsky [8] reports that "at current levels of livestock grazing and fire control, western juniper woodlands represent the final phase of vegetative succession in parts of Oregon, California, and Idaho." In climax western juniper communities, all age classes are typically represented from seedlings to trees several hundred years in age [96].
Fire return intervals in western juniper communities range from 7 to 25 years to more than 100 years [2]. Mean fire interval for western juniper within the Columbia River Basin is estimated at 52 years [6]. Fire return intervals within western juniper communities have been reported as follows:
California: 7-17 years
southwestern Idaho: 25 years
Nevada: 15-20 years [1]
southwestern Oregon: < 20 years [19]
In western juniper woodlands of the San Bernardino Mountains of California, infrequent canopy fires produce a mosaic of fairly small scattered patches within uniform stands [99].
FIRE REGIMES in other communities: The range of fire intervals reported for some species that dominate communities where western juniper occurs are listed below. To learn more about the FIRE REGIMES in those communities refer to the FEIS summary for that species, under "Fire Ecology or Adaptations."
Pacific ponderosa pine (Pinus ponderosa var. ponderosa): 2-42 years
red fir (Abies magnifica var. magnifica): 10-65 years
(Abies magnifica var. shastensis): 70-130 years
Western juniper sites with less than 1,322 pounds per acre (600 kg/ha) of fine fuels are difficult to burn
[16]. As the crown of an established western juniper expands over time,
herbaceous production declines from the combined effects of shading, litter accumulation,
and soil moisture [1]. Trees create their own fine fuel break,
so these stands may be virtually "fireproof" except under the "most severe burning conditions"
[1,103].
Many western juniper woodlands have advanced to a point where prescribed fire is no longer
a viable management option. For example, in extremely dense stands, prescribed burning would be
both hazardous and expensive. In some cases, weedy annuals prevent the establishment of more
desirable perennial species after fire [16].
However, prescribed burning can in some instances be used to reduce western juniper
dominance [20,66]
and may offer the best means of control.
in areas of western juniper invasion. Fall and spring prescribed fires in in a basin big sagebrush community in
east-central Oregon, for example, killed 100% of western juniper seedlings on
study plots [83]. See the Research Project Summary
of this study for more information on fire effects
on western juniper and 60 additional shrubs, grasses, and forbs.
Warm dry conditions are necessary for fire to carry in western juniper woodlands.
Often mature open stands can be used as fuel breaks. Steady winds greater than 5 miles per hour (8.1 k/h), temperatures of at least 68 degrees Fahrenheit (20oC), and relative humidity of less than 25% are generally required for a successful burn [15]. Generally, where tree cover is greater than 30%, there is so little herbaceous understory that extremely high winds are needed to support a burn [70]. Thirty- to 50-year-old western junipers under 10 feet (3.1 m) in height and with an understory are fairly easy to burn, as are dense, uneven-aged mature stands [15].
Western juniper slash can be burned where fine fuels average 400 to 700 pounds per acre (181-318 kg/ha), and where slash fuel ? to 3+ inches (0.6->8 cm) totals at least 4 tons per acre (11 Mg/ha). For best results, trees should retain their needles and fuels should be fairly continuous. A rest from grazing followed by a late summer to fall burn can produce better results due to more continuous fine fuels [63].
Western juniper tends to have more resinous foliage than many other species. Ash and heat content values are as follows [97]:
foliage litter cones woody fuel
average ash content (%) 4.26 5.31 3.42 1.35-2.80
average heat content
with ash (mJ/kg) 23.64 22.53 23.68 20.04-20.27
average heat content
without ash (mJ/kg) 24.70 23.79 24.51 20.31-20.66
Van Wagtendonk and others [97] recommend adjusting fire spread models for use with Sierra Nevada conifers. If standard fuel models are used, they suggest adjusting fire front with the following "correction factors:"
heat per Unit Area fireline intensity flame length
(reaction intensity)
0.98 0.95 0.9
Western juniper-low sagebrush communities that have been invaded by medusahead (Taeniatherum caput-medusae) are often extremely "fire hazardous" [103].
Western juniper occurs in open stands on mountain slopes and high plateaus [87]. It grows as scattered individuals on rimrock or rock outcrops and in higher densities along streams, on scablands, and lower slopes where water has dispersed the seed [28]. It has remained dominant in shifting sand dune communities of south-central Washington where fire is unlikely [1].
The growth of western juniper is favored by long, dry summers and cold winters with little moisture [87]. Western juniper often occurs in a zone between desert, shrub-steppe, or grassland below and ponderosa pine (Pinus ponderosa) or sagebrush (Artemisia spp.) desert above [37,87]. Cold winter temperatures may restrict its occurrence at higher elevations [73]. It occurs in the most xeric tree-dominated zone of the Pacific Northwest [37]. Soil, climate, topography, fire, and biotic factors all contribute to the distribution of western juniper, but moisture is thought to be the primary determinant [23].
Average annual precipitation ranges from approximately 10 to 13 inches (250-330 mm), with the bulk occurring as winter snow. Temperature ranges from 36 to 105 degrees Fahrenheit (2-41oC), with an average July temperature of 66 degrees Fahrenheit (19oC). The growing season rarely exceeds 130 days [87].
Western juniper generally grows on soils that are shallow, stony, and low in organics [82,95]. Western juniper grows on soils derived from basalt, andesite, rhyolite, pumice, volcanic ash, tuff, welded tuff, colluvial, alluvial, or eolian mixtures [23]. In the Sierra Nevada, Sierra juniper grows on granitic crevices on windswept ridges [87]. Surface soils supporting western juniper are often slightly acid to moderately acidic sandy loams or coarse sands with little organic matter (1 to 4%) [37,95]. Western juniper also grows on finely-textured calcareous soils [3]. Levels of calcium, potassium, and pH are higher under mature western juniper than in the interspaces [22,23]. Soil depth ranges from 10 to 15 inches (25-38 cm) to more than 48 inches (122 cm). The subsoil is typically broken and indurated with cracked bedrock below [23]. Western juniper is best adapted to soils exhibiting rapid infiltration, deep percolation, low evaporation, and low soil moisture tension [5]. Western juniper is often found on a perched water table [37].
Western juniper grows from near sea level to more than 10,000 feet (3050 m) [87]. Elevational ranges are as follows [42,87]:
3,000 to 10,000 feet (915-3050 m) in California
3,000 to 7,500 feet (915-2288 m) in central Oregon
600 to 1,800 feet (183-549 m) in eastern Washington
205 Mountain hemlock
207 Red fir
208 Whitebark pine
211 White fir
218 Interior Douglas-fir
237 Interior ponderosa pine
238 Western juniper
247 Jeffrey pine
250 Blue oak-gray pine
256 California mixed subalpine
FRES21 Ponderosa pine
FRES23 Fir-spruce
FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES29 Sagebrush
FRES35 Pinyon-juniper
K007 Red fir forest
K008 Lodgepole-pine-subalpine forest
K011 Western ponderosa forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodland
K030 California oakwoods
107 Western juniper/big sagebrush/bluebunch wheatgrass
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
201 Blue oak woodland
209 Montane shrubland
210 Bitterbrush
212 Blackbush
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
412 Juniper-pinyon woodland
415 Curlleaf mountain-mahogany
Western juniper is a nonsprouter that is generally killed by severe fires [11]. Younger trees have thin bark and are readily killed by surface fires [87]. Older trees with thicker bark, little fuel near the stem, and higher foliage are moderately resistant to fire [38,87]. Fire may not carry in open stands of mature trees with sparse understory vegetation [15].
Western juniper provides food and cover for a variety of bird and mammal species [94]. It is browsed to some extent by mule deer and elk [68]. In parts of California, mule deer feed on small amounts of western juniper during winter and spring [10,59]. In the high desert of Oregon, western juniper is an important winter pronghorn food [86]. Western juniper is used primarily as an emergency food source by most classes of livestock and many big game species [77]. In California, it may be an important critical deer food source during severe winters; at these times, it is consumed in large quantities [59].
Domestic goats consume foliage and bark of western juniper [35].
Western juniper seed cones or cone-berries are an important winter food source for migratory birds such as the American robin and Townsend solitaire [28,26]. In Oregon, blue grouse feed on western juniper cone-berries during the fall [21]. Lewis' woodpecker, scrub jay, and Stellar's jay feed on the cone-berries [54,29]. The northern flicker nests and feeds in western juniper communities of the Blue Mountains of Oregon [90].
The foliage and cone-berries of western juniper are important foods for a number of mammals. Mule deer, elk, mountain cottontail, and coyote consume western juniper cone-berries [84]. Western juniper cone-berries are the primary food source of the dusky-footed woodrat [68].
Western juniper is an indicator of climax in a variety of sagebrush (Artemisia spp.) grassland, shrub-steppe, and dry coniferous habitat types. It occurs as a codominant with singleleaf pinyon (Pinus monophylla), big sagebrush (A. tridentata), gray low sagebrush (A. arbuscula ssp. arbuscula), stiff sagebrush (A. rigida), curlleaf mountain-mahogany (Cercocarpus ledifolius), antelope bitterbrush (Purshia tridentata), rubber rabbitbrush (Chrysothamnus nauseosus), green rabbitbrush (C. viscidiflorus), arrowleaf balsamroot (Balsamorhiza sagittata), Sandberg bluegrass (Poa secunda), Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Pseudoroegneria spicata), smilo grass (Piptatherum micranthum), and Thurber needlegrass (Achnatherum thurberiana). Western juniper also occurs with spiny hopsage (Grayia spinosa), gray horsebrush (Tetradymia canescens), junegrass (Koeleria macrantha), needle-and-thread grass (Hesperostipa comata), bottlebrush squirreltail (Elymus elymoides), and other grasses [27,37,87].
Western juniper has been described as an indicator or dominant in the following published classifications:
A relict area in the central Oregon juniper zone [25]
Plant communities and habitat types in the Lava Beds National Monument, California 1979 [30]
Great Basin pinyon and juniper communities and their response to management [33]
Plant communities of the Blue Mountains in eastern Oregon and southeastern Washington [41]
Plant associations of south Chiloquin and Klamath Ranger Districts, Winema National Forest [46]
Plant associations of the Fremont National Forest [47]
Vegetation types of the San Bernardino Mountains [49]
Plant associations of the Wallowa-Snake Province: Wallowa-Whitman National Forest [51]
Woodland classification: the pinyon-juniper formation [52]
Preliminary classification for the coniferous forest and woodland series of Arizona and New Mexico [58]
Forest/environment relationships in Yosemite National Park, California USA [76]
A vegetation classification system applied to southern California [79]
In western juniper woodlands, wet to moderately wet soils grazed during the early spring are subject to damage through increased soil compaction. Grazing on dry or frozen soils causes fewer negative effects [13]. At least 3 years of rest from grazing is suggested after seeding in western juniper [82].
Fire suppression, overgrazing, and climatic factors have led to an expansion of western juniper into adjacent grass and shrublands [70]. This juniper invasion has dramatically reduced the understory and thus the forage base in many areas. From 1940 to 1960, when heavy emphasis was placed on livestock management, individual tree removal, cabling, chaining, and herbicides were widely used in an attempt to reduce western juniper woodlands [8,71]. Various means of mechanical control have been examined in detail [102,105]. For mechanical control to be effective, the heavy support roots must be broken and the tree uprooted [105].
Detailed information on chemical control is available [32,71,102].
Detailed information on silvicultural methods pertaining to western juniper harvest has been examined. Both even and uneven-aged methods have been used, but no one method is best suited for all situations and it is important to consider local needs and conditions [31].
Western juniper is fairly nutritious for mule deer and other large
mammals, but is not highly digestible [60].
Crude protein (%) is as follows [10]:
January 6.9
February 5.6
March 7.2
April 7.0
May 8.3
August 7.5
October 7.8
November 8.5
December 7.0
Nutritive values vary by season and plant part. Protein and ash
content (%) is as follows [35]:
crude protein ash
green foliage 8.1 3.9
cured foliage 7.6 4.2
bark 3.2 7.1
CA ID NV OR WA
Western juniper has been cultivated as an ornamental since 1840 [50]. The wood is used in toys, sporting goods, jewelry boxes, suitcase and closet liners, inlay products, clocks, decorative items, and pencils [43,77]. Pipe bowls are made from the roots of western juniper, and pet bedding from the shavings [43]. Juniper boughs have been used for Christmas wreaths and other decorations. Over 100 tons of boughs from central Oregon were sold in 1983 at 1 to 2 cents per pound [77].
The essential oils of western juniper are used for flavoring or scenting agents in medicines, beverages, condiments, aerosols, insecticides, soaps, and men's cosmetics [43]. The cone-berries of western juniper are edible and taste best when dried [48]. Western juniper foliage has been added to chicken feed to produce gin-flavored eggs for human consumption [43].
Some Native American peoples traditionally used western juniper wood in making bow staves [100].
Western juniper is palatable browse for elk, mule deer, mountain cottontails, porcupines and black-tailed jackrabbits [68]. However, palatability of western juniper varies by individual tree [87] and Rosentreter and Jorgensen [82] describe overall palatability as "low."
Western juniper cone-berries provide food for coyotes, and small mammals such as deer mice, yellow-pine chipmunks, and golden-mantled ground squirrels [68]. Western juniper cone-berries are at least moderately palatable to wintering birds such as the American robin and Townsend solitaire [28].
In Oregon, leaf elongation begins in June with 15 to 20% annual leaf turnover [72]. Western juniper cones develop from mid-April to mid-May and pollen is shed in May [50,72,87]. Seed cones ripen in mid-September after the second growing season [50]. Cones may persist on the trees for 2 to 3 years [69]. Most germination occurs during the spring [87]. In Oregon, most natural germination occurs during April [22].
Mature trees are somewhat resistant to fire if the crown is not scorched, so some larger trees may survive low-severity fires and serve as a seed source [67]. Western juniper first becomes dominant 30 to 50 years after fire [15]. Reoccupation of a site occurs fairly slowly through dispersed seed [19,25].
Tree without adventitious bud/root crown
Initial off-site colonizer (off-site, initial community)
Secondary colonizer - off-site seed
FIRE REGIMES: Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Western juniper regenerates through seed. Green pistillate megastrobili form seed cones in abundance [87,92]. Female cones first develop 2 weeks after the male cones, and seed cones remain on the tree for 2 years until mature [72,84]. Seed cones generally ripen in mid-September. Seed cones are blue-green prior to ripening, and bluish-black and glaucous when ripe [50]. Cone-berries contain 1 to 4 (more rarely up to 12) brownish seeds [69]. Western juniper is monoecious or dioecious [92]. Many plants have the capacity to shift their sex from year to year, depending on conditions. Trees bordering roads or clearings typically produce much greater numbers of female cones than do trees within stands [28].
Seed production typically begins at 20 years of age or more, but few seed cones are produced until the tree reaches 50 to 70 years of age [28,29]. Full reproductive potential is achieved at 50 years or older [73]. Western juniper produces an abundance of seed cones nearly every year after maturity [87].
The germination of most species of juniper is delayed due to embryo dormancy, impermeable seedcoats, or temperature constraints. Western juniper seed is dormant when freshly harvested. Germination of juniper seed has been described as "erratic and unpredictable" [104]. Specific information on germination characteristics is available [50,104]. Tueller [91] reports that germination in junipers (Juniperus spp.) "is not a straight-forward process, but one that requires a specific sequence of environmental conditions for natural germination and seedling establishment." Mineral soil may be required for best seedling establishment [92].
Seed of western juniper is dispersed by birds, mammals, water, and gravity [69]. In a southwestern Idaho study, western juniper seed dispersed an average of 4.7 feet (1.42 m) downslope and 2.0 feet (0.60 m) upslope during a 4-month summer period, and an average of 4.2 feet (1.29 m) during a 6-month winter period. More distant seed dispersal in summer is due to animals. Most, if not all, uphill seed movement can be attributed to animal dispersal. Livestock may aid in dispersal by kicking or rolling seeds [19]. The seeds of many juniper species are thought to germinate faster after the seed cone has been consumed by animals [88]. Rabbits, ground squirrels, woodrats and other rodents, mule deer, elk, coyotes, and domestic livestock are all dispersal agents for western juniper [19,84]. Schupp and others [84] report that although rabbits, deer, and other mammals consume cone-berries; coyotes are the most important of the mammalian dispersers.
Wintering birds such as the American robin, Stellar's jay, scrub jay, and Townsend solitaire eat and disseminate large numbers of western juniper cone-berries [28,68,75]. Burkhardt and Tisdale [19] maintain that the proportion of long-range seed dispersal, at least in southwestern Idaho, is low as evidenced by the lack of disjunct stands of western juniper.
Water dispersal accounts for a large percentage of downslope seed movement. Spring runoff traveling across frozen soil compacted by livestock may account for high densities of western junipers along waterways [28]. Seed establishment is favored in deeper valleys or in areas rich in forbs [19].
Western juniper seedlings establish more rapidly under big sagebrush, bunchgrasses, or under existing trees. In a central Oregon study, seedlings established as follows [28]:
with big sagebrush - 47%
with western juniper - 15%
with bunchgrasses - 14%
in the open - less than 1%
Burkhardt and Tisdale [19] found that most seedlings established on the north side of existing trees where the young plants were protected from intense solar radiation. Seedlings are often found along fences, hedges, or under taller trees where large numbers of birds perch [69,87,103].
Western juniper does not reproduce vegetatively [22].
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
Western juniper is a highly competitive invasive species [81]. It is found on all exposures and slopes but is relatively intolerant of shade [22,23]. This long-lived species has been expanding its range into adjacent shrub-steppes, grasslands, and savannas during the past 100 to 150 years [8]. It has doubled its range in central and eastern Oregon during the past 80 to 100 years [81]. Expansion into low sagebrush communities has been slower than into big sagebrush communities [2]. Expansion into shrub steppe communities in Nevada has reduced understory diversity and productivity [7]. Western juniper expansion has been attributed to livestock grazing and associated reductions in fine fuels, climatic changes (mild temperatures and above average precipitation in the late 1880s and early 1900s), and reduction in fire frequency due to fire suppression and cessation of Native American burning [8,29,74,75].
Climax stands are generally restricted to rimrock and the edges of mesas, whereas seral communities can dominate slopes and valley bottoms adjacent to older western juniper stands [95]. Old growth western juniper is generally found in "firesafe" spots [103]. This tree was formerly restricted to rocky ridges and outcrops, deep pumice soils and on fractured bedrock. Western juniper remains a climax dominant in rimrock and similar sites due to the rocky substrate and lack of fuels needed to carry an intense fire [1,18]. Western juniper is an indicator of climax in a number of sagebrush-grassland, shrub-steppe, and drier conifer habitat types. Some communities represent topo-edaphic climaxes [65].
Western juniper survives on harsh sites and is increases in many early seral communities. In seral communities near Prineville, Oregon, young classes of western juniper predominate with a maximum age of nearly 100 years in these seral stands. In non-seral communities western junipers are at least several hundred years in age [96].
The scientific name of western juniper is Juniperus occidentalis Hook. (Cupressaceae) [44,45,53]. The following varieties of western juniper are recognized:
Juniperus occidentalis var. australis (Vasek) A. Holmgren & N. Holmgren, Sierra juniper [44,106,107,108]
Juniperus occidentalis var. occidentalis, western juniper (typical variety)
Varieties are referred to by their common names in this review. "Western juniper" applies to the species as a whole.
Western juniper may hybridize with Utah juniper (J. osteosperma) where the two species occur together in northwestern Nevada east of California's Warner Mountains. Relict individuals in the White Mountains of California may also be hybrids of western and Utah juniper [22].
Western juniper can be propagated from cuttings or by layering [22,87]. Trees have been used as riprap for stabilizing streambanks [22].
Western juniper has been used since historic times for firewood, charcoal, corrals, poles, and fence posts [22]. The wood is extremely durable and resistant to rot [77]. Juniper wood splits easily, burns clean and produces little ash [22,43]. Western juniper woodlands can produce 8 to 11 cords of firewood per acre. However, it is estimated that 7 hours of labor are required per cord to cut, limb, pile slash, and gather the wood [14]. Western juniper dulls saws since wind-blown sand particles readily adhere to its shaggy bark [43].
In recent times, western juniper has been used for paneling, interior studs, particleboard, veneer, plywood, and other lumber products. Western juniper logs brought to mills are short with a rapid taper. Most logs are limby and bark inclusions extend deep into the wood. Western juniper wood requires slow and careful kiln drying to prevent warping [43]. It tends to be difficult to plane [22].
Qərb ardıcı (lat. Juniperus occidentalis) - sərvkimilər fəsiləsinin ardıc cinsinə aid bitki növü.
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Qərb ardıcı (lat. Juniperus occidentalis) - sərvkimilər fəsiləsinin ardıc cinsinə aid bitki növü.
Juniperus occidentalis o ginebre occidental (en anglès western juniper o Sierra juniper) és una planta nativa de l'oest dels Estats Units, és un arbre o arbust que creix entre els 800 i els 3.000 metres d'altitud, rarament es troba per sota dels 100 m.
Les fulles es disposen en parells de verticils de tres fulles esquamoses d'1–2 mm de llargada, fins a 5 mm en els brots principals. Les fulles juvenils són aciculars. Els fruits semblen baies de 5–10 mm de diàmetre de color blavenc-marronós i maduren en 18 mesos.
Els fruits alimenten i són dispersats per diversos ocells. Les plantes sovint presenten agalles de l'insecte Oligotrophus betheli (Bibionomorpha: Cecidomyiidae).
Hi ha dues varietats de Juniperus occidentalis tractades com subespècies per alguns botànics:
El Bennett Juniper de Stanislaus National Forest de Califòrnia es considera que té 3000 anys d'edat i presenta una alçada de 26 m i un diàmetre de 3,88 m.[1]
Juniperus occidentalis normalment creix en llocs secs i rocosos on no té competència amb altres espècies d'arbres. De vegades es presenten híbrids naturals amb Juniperus osteosperma.
Juniperus occidentalis o ginebre occidental (en anglès western juniper o Sierra juniper) és una planta nativa de l'oest dels Estats Units, és un arbre o arbust que creix entre els 800 i els 3.000 metres d'altitud, rarament es troba per sota dels 100 m.
Der Westamerikanische Wacholder (Juniperus occidentalis), auch Westlicher Wacholder genannt, ist eine Pflanzenart aus der Familie der Zypressengewächse (Cupressaceae). Sie ist im westlichen Nordamerika heimisch.
Der Westamerikanische Wacholder wächst als immergrüner Baum. Das Erscheinungsbild sowie die Wuchshöhe hängen stark von der Höhenlage, der Niederschlagsmenge und den Bodenverhältnissen ab. Auf tiefgründigen Böden und in geschützter Lage kann er eine maximale Wuchshöhe von 22 Metern erreichen. Altbäume, die nahe der Waldgrenze wachsen, besitzen ungewöhnlich starke, drehwüchsige Stämme und breite, vom Wind zerzauste Kronen, die mit vielen Trockenästen versehen sind.
Der Westamerikanische Wacholder besitzt ein sehr kräftiges, tief- und weitreichendes Wurzelsystem. Es ist in der Lage, selbst in Felsspalten Halt zu finden und den Baum mit Wasser zu versorgen.
Die rotbraune Borke ist längsrissig und bedeckt den Stamm von stark exponierten Altbäumen nur mehr in schmalen Streifen. Die graubraune Borke von Jungbäumen löst sich in großen Schuppen ab. Kräftige Zweige besitzen eine rotbraune Rinde, die sich in dünnen und papierartigen Schuppen ablöst.
Das fast weiße Splintholz umgibt das harte und relativ schwere rötliche Kernholz. Es ist sehr dauerhaft und riecht sehr aromatisch.
Die zahlreichen, gegenständig oder zu dritt in Wirteln, dicht an kräftigen Zweigen angeordneten Schuppenblätter sind grau-grün, etwa 3 Millimeter lang und besitzen einen fein gezähnten Rand. Bei jungen und kräftigen Zweigen stehen die Blattspitzen etwas ab. Die von einem dicken Häutchen (Cuticula) umgebenen Blätter besitzen als Anpassung an das trockene Klima keine Spaltöffnungen. Auf der gewölbten Rückseite der Schuppenblätter befindet sich eine deutlich zu erkennende Harzdrüse, die im Herbst eine harzartige Flüssigkeit ausscheidet. Sämlinge besitzen rund 1,3 Zentimeter lange, sehr spitze und pfriemlich geformte Nadeln.
Der Westamerikanische Wacholder ist meist einhäusig (monözisch), selten zweihäusig (diözisch) getrenntgeschlechtig. Die Blütezeit erstreckt sich von April bis Mai. Die männlichen Blüten besitzen 12 bis 18 Staubblätter. Die weiblichen Zapfenblüten haben spitz eiförmige Samenanlagen, die nach der Bestäubung von fleischigen Schuppenblättern umschlossen werden. Die 6 bis 8 Millimeter dicken Beerenzapfen reifen im Herbst des zweiten Jahres. Sie sind zur Reife blauschwarz und weiß bereift. Das dünne und harzige „Fruchtfleisch“ wird von einer festen Schale umgeben. Sie verbleiben im Winter am Baum. Jeder Beerenzapfen enthält zwei bis drei hartschalige Samen, die circa 3 Millimeter lang werden. Sie sind etwas zugespitzt und weisen eine erhabene Rücken- und eine flache Vorderseite auf. Das Tausendkorngewicht beträgt rund 37 Gramm. Die Ausbreitung der Diasporen erfolgt großteils über Vögel (Ornithochorie).
Die Chromosomenzahl beträgt bei der Nominatform 2n = 22.[1]
Der Schwerpunkt des Verbreitungsgebietes des Westamerikanischen Wacholders liegt in den sehr trockenen Steppen des mittleren und südlichen Oregons. Den nördlichsten Punkt des natürlichen Vorkommens bilden isolierte Kleinvorkommen im mittleren und südlichen Washington. Die Ostgrenze bildet eine ebenfalls isolierte Population im äußersten Südwesten Idahos. Die Südgrenze verläuft durch das im nördlichen Kalifornien gelegene Lassen County und den Norden Nevadas. Sein Verbreitungsgebiet überlappt sich mit dem des Rocky-Mountain-Wacholders (Juniperus scopulorum).
Diese Art gilt als lichtbedürftig, dürrebeständig, anspruchslos und widerstandsfähig gegenüber Kälte, Hitze, Wind, Schneestürmen und Sommergewitterstürmen mit Blitzschlag und den daraus entstehenden Bränden. Sie besiedelt Standorte mit Jahresniederschlägen von rund 230 bis 355 mm und kommt in Höhen von 200 bis 3.100 Metern vor. Selbst stark exponierte Felsen werden besiedelt. Der Westamerikanische Wacholder bildet kaum Mischbestände mit anderen Baumarten. An Begleitbaumarten werden die Gelb-Kiefer (Pinus ponderosa) oder Cercocarpus ledifolius beobachtet. In den höheren Besiedlungslagen werden die Küsten-Kiefer (Pinus contorta subsp. latifolia) und die Gebirgs-Douglasie (Pseudotsuga menziesii var. glauca) genannt.
Aufgrund der unzugänglichen Standorte kommt dem Westamerikanischen Wacholder kaum eine wirtschaftliche Bedeutung zu. Da das Holz selbst bei Bodenkontakt sehr widerstandsfähig ist, werden gelegentlich Zaunpfähle daraus hergestellt. Es wäre des Weiteren zur Herstellung von Möbeln, Paneelen und Furnieren geeignet. Das ätherische Öl, das aus dem Kernholz dieser und anderer Wacholderarten gewonnen werden kann, findet als Geruchskomponente bei Seifen, Sprays und Desinfektionsmitteln sowie als Immersionsöl in der Mikroskopie Verwendung. Das Harz soll von den kalifornischen Indianern benutzt worden sein, um Federn an ihren Pfeilen zu befestigen.
Juniperus occidentalis wird innerhalb der Gattung Juniperus der Untergattung Sabina und der Sektion Occidentalis zugeordnet. Die Arten dieser Sektion besitzen fein gezähnte Blätter und die Beerenzapfen sind bei der Reife dunkelblau. Andere Quellen allerdings führen die Untergattung Sabina als Sektion Sabina ohne weitere Unterteilungen. Ein Synonym für Juniperus occidentalis Hook. ist Juniperus andina Nutt.
Verschiedene Quellen teilen die Art in die zwei Unterarten Juniperus occidentalis Hook. subsp. occidentalis – die Nominatform – und die südliche Unterart Juniperus occidentalis Hook. subsp. australis Vasek. Nach neuen Untersuchungen wurde dieser Unterart aber Artstatus als Juniperus grandis R.P.Adams zuerkannt.[2]
Der Westamerikanische Wacholder wird von der Weltnaturschutzunion IUCN zwar in der Roten Liste gefährdeter Arten geführt, aber als nicht gefährdet („Least Concern“) bezeichnet. Es wurde festgestellt, dass Bestand und Verbreitung der Art stark zunehmen, da die Beweidung durch Nutztiere rückläufig ist, wodurch Sämlinge besser vor Witterungseinflüssen und Pflanzenfressern geschützt sind.[3]
In den USA wird diese Wacholderart im Bundesstaat Nevada durch Einschränkung der Nutzung unter Schutz gestellt.[4]
Der Westamerikanische Wacholder (Juniperus occidentalis), auch Westlicher Wacholder genannt, ist eine Pflanzenart aus der Familie der Zypressengewächse (Cupressaceae). Sie ist im westlichen Nordamerika heimisch.
Шунды пуксён пал сусыпу (лат. Juniperus occidentalis ) – Cupressaceae семьяысь Америкалэн Огазеяськем Штатъёсаз будӥсь сусыпу. Ӝуждалаез ог 26—30 м.
Шунды пуксён пал сусыпу (лат. Juniperus occidentalis ) – Cupressaceae семьяысь Америкалэн Огазеяськем Штатъёсаз будӥсь сусыпу. Ӝуждалаез ог 26—30 м.
Juniperus occidentalis, known as the western juniper, is a shrub or tree native to the Western United States, growing in mountains at altitudes of 800–3,000 meters (2,600–9,800 ft) and rarely down to 100 m (330 ft). It is listed as Least Concern on the IUCN Red List because it is a widespread species with an increasing population.[1]
Juniperus occidentalis is a shrub or small tree 4–15 meters (13–49 ft) tall. Exceptionally tall specimens can be found in the John Day area of Oregon in excess of 26–28 m (85–92 ft) tall.
The shoots are of moderate thickness among junipers, at 1–1.6 millimeters (1⁄32–1⁄16 in) diameter. The juvenile leaves (on young seedlings only) are needle-like and 5–10 mm (3⁄16–13⁄32 in) long. Arranged in opposite decussate pairs or whorls of three, the adult leaves are scale-like, 1–2 mm long (5 mm on lead shoots) and 1–1.5 mm broad. The cones are berry-like, 5–10 mm in diameter, blue-brown with a whitish waxy bloom,[2] and mature in about 18 months. The male cones are 2–4 mm long and shed their pollen in early spring. The plants are about half monoecious (with both sexes on the same plant) and half dioecious (producing cones of only one sex).
The cones contain 1–3 seeds, the majority of which germinate in springtime. In Oregon, where most of the species resides, seeds germinate in April and the foliage emerges in June.[3] Seed dispersal is conducted by water runoff, gravity, and animals.[3]
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Form
Berry-like female cones
Leaves and cones
Further to the south, Juniperus grandis (the Sierra juniper) is sometimes treated as a variety of J. occidentalis (as J. occidentalis var. australis).[4][5] J. grandis is 12–26 m (39–85 ft) tall with a trunk up to 3 m (10 ft) in diameter. The cones are 5–9 mm (3⁄16–11⁄32 in) wide. Most plants are dioecious, but about 5–10% are monoecious. The two plants are also chemically distinct.[6] J. grandis can be found in California and westernmost Nevada, south of 40° 30' N latitude in the Sierra Nevada and San Bernardino Mountains. The oldest and largest specimen of J. grandis is 26 m (85 ft) tall and 3.88 m (12 ft 9 in) wide, perhaps 3,000 years old, and located in California's Stanislaus National Forest.[7]
J. occidentalis can be found in the Western United States—specifically southeast Washington, eastern and central Oregon, southwest Idaho, northeastern California and extreme northwest Nevada, north of 40° 30' N latitude, east of the Cascade Range.
It usually occurs on dry, rocky sites where there is less competition from larger species like ponderosa pine and coast Douglas-fir. Annual precipitation can be as low as 20 centimetres (7+7⁄8 in).[2] In very exposed positions at high altitude, it can assume a krummholz habit, growing low to the ground even when mature with a wide trunk. Hybrids with J. osteosperma are occasionally found.
In the John Day area of Oregon, it competes for sunlight among ponderosa pines at the bottom of some deep side canyons. However, it more commonly reaches 4–15 m (13–49 ft) with a bushier growth habit on open and barren ground.
The cones are an important food for several birds, including American robin, Clark's nutcracker, phainopepla and cedar waxwing; these digest the fleshy cone scales and disperse the seeds in their droppings.
The plants often bear galls caused by the juniper tip midge, Oligotrophus betheli. These are violet-purple fading to brown, 1–2 cm (3⁄8–13⁄16 in) in diameter, with dense modified spreading scale-leaves 6–10 mm (1⁄4–3⁄8 in) long and 2–3 mm broad at the base.
In the past two decades, sagebrush steppe ecosystems have witnessed an expansion of Juniper throughout the western U.S.[8] This alteration of vegetation change can be associated with the decreased fire frequency, overgrazing of livestock, and an alteration of climate that transformed into a more wet and mild climate.[8]
Fire scar data was collected and dated to display the expansion of western juniper. It started between 1875 and 1885, with a pinnacle rate of development between approximately 1905 and 1924.[8]
Since the 1990s use of prescribed fires to control expansion of the species has increased. The results of increased prescription fires show a positive effect on plant communities.[9]
Like other junipers, J. occidentalis produces a crop of cones called a juniper berry. While original European gins used berries from J. communis, several distilleries—particularly in Bend, Oregon—have used local western juniper to flavor their gin.[10][11]
While not common as a lumber source, Oregon State University has sponsored research into the use of western juniper for commercial applications such as sign posts and guard rails.[12][13] Western juniper lumber is noted for its durability and high compression strength.[14]
{{cite web}}: CS1 maint: multiple names: authors list (link) Juniperus occidentalis, known as the western juniper, is a shrub or tree native to the Western United States, growing in mountains at altitudes of 800–3,000 meters (2,600–9,800 ft) and rarely down to 100 m (330 ft). It is listed as Least Concern on the IUCN Red List because it is a widespread species with an increasing population.
Juniperus occidentalis
Le Genévrier occidental (Juniperus occidentalis) est un arbre appartenant au genre Juniperus et à la famille des Cupressaceae.
Juniperus occidentalis, lokalt kalt "Western Juniper " eller «Sierra Juniper», er en art av bartrær som tilhører einerslekten Juniperus i sypressfamilien. Den vokser i 800-3 000 meters høyde i det vestlige USA. Den tåler tørke godt og kan konkurrere med større trær mange steder.
Det er to varianter av arten:
Juniperus occidentalis var. occidentalis – «Western Juniper» – vokser i det nordvestre USA nord for 40° 30' N, og er en busk eller et tre 4-15 meter høyt, ytterst sjelden inntil 26-28 meter i Oregon. Den har grå-grønne, skjellaktige nåler inntil 1–2 mm lange. Unge nåler er inntil 5–10 mm lange. Den er i halvparten av tilfellene særbu med hann- og hunnblomster på ulike individer. Bærkonglene modner på 18 måneder til et brun-blå, 7–10 mm stort bær med hvitt vokslag, og 1-3 frø. Hannkonglene er 2–4 mm store og sprer sitt pollen i februar-mars.
Juniperus occidentalis var. australis – «Sierra Juniper» – vokser i California og vestre Nevada sør for 40° 30' N, og er et tre 12-26 meter høyt. Diameteren kan bli hele 3,88 meter. Den har brun-rød, langsgående strimlet bark og skjellaktige nåler inntil 1–2 mm lange. Unge nåler er inntil 5–10 mm lange. Den er i 90-95 % av tilfellene særbu med hann- og hunnblomster på ulike individer. Bærkonglene modner på 18 måneder til et brun-blå, 5–9 mm stort bær med hvitt vokslag, og 1-3 frø. Hannkonglene er 2–4 mm store og sprer sitt pollen i februar-mars.
Juniperus occidentalis, lokalt kalt "Western Juniper " eller «Sierra Juniper», er en art av bartrær som tilhører einerslekten Juniperus i sypressfamilien. Den vokser i 800-3 000 meters høyde i det vestlige USA. Den tåler tørke godt og kan konkurrere med større trær mange steder.
Det er to varianter av arten:
Juniperus occidentalis var. occidentalis – «Western Juniper» – vokser i det nordvestre USA nord for 40° 30' N, og er en busk eller et tre 4-15 meter høyt, ytterst sjelden inntil 26-28 meter i Oregon. Den har grå-grønne, skjellaktige nåler inntil 1–2 mm lange. Unge nåler er inntil 5–10 mm lange. Den er i halvparten av tilfellene særbu med hann- og hunnblomster på ulike individer. Bærkonglene modner på 18 måneder til et brun-blå, 7–10 mm stort bær med hvitt vokslag, og 1-3 frø. Hannkonglene er 2–4 mm store og sprer sitt pollen i februar-mars.
Juniperus occidentalis var. australis – «Sierra Juniper» – vokser i California og vestre Nevada sør for 40° 30' N, og er et tre 12-26 meter høyt. Diameteren kan bli hele 3,88 meter. Den har brun-rød, langsgående strimlet bark og skjellaktige nåler inntil 1–2 mm lange. Unge nåler er inntil 5–10 mm lange. Den er i 90-95 % av tilfellene særbu med hann- og hunnblomster på ulike individer. Bærkonglene modner på 18 måneder til et brun-blå, 5–9 mm stort bær med hvitt vokslag, og 1-3 frø. Hannkonglene er 2–4 mm store og sprer sitt pollen i februar-mars.
Країни зростання: Сполучені Штати Америки (Каліфорнія, Айдахо, Невада, Орегон, Вашингтон). Діапазон висот 200–1200 м (var. occidentalis) і 1980–3100 м (var. australis). В хвойному лісі зазвичай росте там, де виходи скельних порід викликають дрібний ґрунт, на великих висотах зазвичай рослини можна знайти серед гранітних валунів або навіть в ущелинах на голому граніті. Клімат коливається від напівпосушливого до каскадів дощової тіні з опадами в основному у вигляді снігу взимку.
Однодомні або дводомні вічнозелені дерева 10–15(-30) м у висоту і 30–100(-250) см діаметра, як правило, з одним стовбуром. Гілки товсті, висхідні або розпростерті, часто вигнуті або перекручені, утворюючи пірамідальну крону у молодих деревах, ставючи округлої і неправильної форми на старих деревах. Кора спершу гладка, рожево-коричнева, потім стає сірою і лущиться; потім волокниста, від червоно-коричневого до коричневого кольору, розшаровуючись тонкими смужками. Листя темно-зелене, батігоподібни листки 3–6 мм, не тьмяні зверху; лускоподібні листки 2–3 × 2 мм, яйцевидно-ромбічні, гострі або тупі, не перекриваються. Пилкові шишки численні, від майже кулястих до яйцеподібно-довгастих, 3–5 × 2–3 мм, жовто-зелені, після дозрівання жовто-коричневі. Шишки зріють 2 роки, спочатку діаметром 2 мм, росте в два сезони від пурпурно-червоного до синього або фіолетового кольору з тьмяним нальотом, від майже кулястої до еліпсоїдної форми, розміром (6-)7–9(-10) × (5-)6–8 мм, м'ясисті, більш-менш смолисті, в кінцевому рахунку, сухі, падають незабаром після дозрівання. Насіння 1–2 на шишку, яйцевидної або напів-яйцеподібної форми, 5–6(-7) × 4–5 мм, з неглибокими канавками і смолистими ямами, жовтувато-коричневі.
Підвид occidentalis часто (50%) однодомний. Зрілі насіннєві шишки в середньому діаметром 7,5 мм. Саджанці в основному мають 2 сім'ядолі. Підвид australis у першу чергу (90%) дводомний. Зрілі насіннєві шишки в середньому діаметром 8,5 мм. Саджанці часто мають 3–4 сім'ядолі.
Зафіксоване довголіття для підвиду australis 2675 років; для підвиду occidentalis 1600 років.
Деревина цього ялівцю досі використовується локально на дрова, стовпи паркану, загонів тощо. Його дуже довговічна деревина також використовується для спеціальних цілей, таких як меблі, внутрішньої обшивки та декоративних цілей. Садівниче використання є рідким, але вид має значення для озеленення порушених ділянок. Є кілька відомих сортів, один з них має явно сріблясте тьмяне листя і називається 'Sierra Silver' і, принаймні, на деякий час, зберігає стовпчасту або пірамідальну звичку молодих рослин.
В цілому, нема серйозних загроз виду.
Juniperus occidentalis là một loài thực vật hạt trần trong họ Cupressaceae. Loài này được Hook. mô tả khoa học đầu tiên năm 1838.[1]
Juniperus occidentalis là một loài thực vật hạt trần trong họ Cupressaceae. Loài này được Hook. mô tả khoa học đầu tiên năm 1838.
Встречается в американских штатах Вашингтон, Орегон, Айдахо, Невада и Калифорния. Растёт на сухих скалистых участках, где меньше конкуренции с более крупными деревьями, такими как сосна жёлтая и псевдотсуга Мензиса (Pseudotsuga menziesii).
В Национальном лесу Станислаус (англ. Stanislaus National Forest) в Калифорнии растёт дерево, чей возраст определяется примерно в 3 000 лет. Высота этого дерева 26 м, толщина 3,88 м.
Шишкоягодами можжевельника западного питаются некоторые виды птиц, включая странствующего дрозда (Turdus migratorius), чёрного свиристеля (Phainopepla nitens) и кедрового свиристеля (Bombycilla cedrorum). Птицы хорошо переваривают мясистые чешуйки шишек и в дальнейшем способствуют распространению неперевариваемых семян.
Растения часто становятся жертвой корневого рака, возникающего в результате заражения грибком Oligotrophus betheli.
Различают две разновидности можжевельника западного:
Встречается в американских штатах Вашингтон, Орегон, Айдахо, Невада и Калифорния. Растёт на сухих скалистых участках, где меньше конкуренции с более крупными деревьями, такими как сосна жёлтая и псевдотсуга Мензиса (Pseudotsuga menziesii).
В Национальном лесу Станислаус (англ. Stanislaus National Forest) в Калифорнии растёт дерево, чей возраст определяется примерно в 3 000 лет. Высота этого дерева 26 м, толщина 3,88 м.
