Overview

Brief Summary

Cupressaceae -- Cypress family

    J. Edward Dealy

    Western juniper (Juniperus occidentalis) is also called Sierra  juniper. There are two subspecies separated geographically, occidentalis  in the northern part and australis in the southern part of its  range. Unless specifically identified, both are included in the following  discussion. One of the largest western junipers recorded grows on the  Stanislaus National Forest in California. It measures 414 cm (163 in) in  d.b.h., is 26.5 m (87 ft) tall, and has a crown spread of 15.5 m (51 ft).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5



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].

  • 103. Young, James A.; Evans, Raymond A. 1981. Demography and fire history of a western juniper stand. Journal of Range Management. 34(6): 501-505. [2659]
  • 106. Zanoni, T. A. 1978. The American junipers of the section Sabina (Juniperus, Cupressaceae) -- a century later. Phytologia. 38(6): 433-454. [4954]
  • 16. Bunting, Stephen C. 1990. Prescribed fire effects in sagebrush-grasslands and pinyon-juniper woodlands. In: Alexander, M. E.; Bisgrove, G. F., technical coordinator. The art and science of fire management: Proceedings of the 1st Interior West Fire Council annual meeting and workshop; 1988 October 24-27; Kananaskis Village, AB. Information Rep. NOR-X-309. Edmonton, AB: Forestry Canada, Northwest Region, Northern Forestry Centre: 176-181. [15519]
  • 29. Eddleman, Lee E.; Miller, Patricia M.; Miller, Richard F.; Dysart, Patricia L. 1994. Western juniper woodlands (of the Pacific Northwest): Science assessment. Walla Walla, WA: Interior Columbia Basin Ecosystem Management Project. 131 p. [27969]
  • 36. Ferry, Gardner W.; Clark, Robert G.; Montogmery, Roy E.; [and others]. 1995. Altered FIRE REGIMES within fire-adapted ecosystems. In: LaRoe, Edward T.; Farris, Gaye S.; Puckett, Catherine E.; [and others], eds. Our living resources: A report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems. Washington, DC: U.S. Department of the Interior, National Biological Service: 222-224. [27123]
  • 44. Hickman, James C., ed. 1993. The Jepson manual: Higher plants of California. Berkeley, CA: University of California Press. 1400 p. [21992]
  • 70. Meeuwig, Richard O.; Murray, Robert B. 1978. Current research on pinyon-juniper in the Great Basin. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 97-103. [1636]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]
  • 98. Vasek, Frank C. 1966. The distribution and taxonomy of three western junipers. Brittonia. 18: 350-372. [2426]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Regional Distribution in the Western United States

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):


1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Occurrence in North America


CA ID NV OR WA

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Western juniper is found intermittently from latitude 34° N. in  California to latitude 46° 37' N. in southeastern Washington, in a  narrow belt from longitude 117° W. in Idaho and California to  longitude 123° W. in northern California, and in sparse, scattered  stands in south-central and southeastern Washington, southeastern Oregon,  and the northwest corner of Nevada. In southwestern Idaho, it grows on  approximately 162 000 ha (400,000 acres) (2). Western juniper reaches its  greatest abundance as extensive and continuous stands in central Oregon.  Stands more limited in size extend up the valleys and foothills of the  southern Blue Mountain region, and small groups or individuals are  scattered sparsely through the northern Blue Mountains. Extensive stands  are common on the plains and in the foothills of north-central Oregon, and  large stands occur down the high plains and foothills of south-central  Oregon (5,6). From north-central through south-central Oregon, western  juniper grows in various densities on roughly 1 140 000 ha (2,816,000  acres) (5). It is found near Mount Ashland in southwestern Oregon (10),  the only native stand documented west of the Cascade Range in Oregon. It  grows in scattered locations west of the Cascades in northern California  and extends south to Trinity County. Western juniper is present in  extensive stands from the Oregon border south through the Pit River Valley  in northeastern California and continues intermittently as sparse stands  in a narrow corridor along eastern California south to disjunct stands in  the San Bernardino Mountains (17). The eastern limits of this species are  in San Bernardino County, CA, and Owyhee County, ID. The western limit is  Trinity County, CA.

     
- The native range of western juniper.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Physical Description

Morphology

Description

More info for the term: tree



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

  • 12. Bronaugh, Whit. 1993. The biggest western juniper. American Forests. 99(9-10): 41. [29157]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 28. Eddleman, Lee E. 1984. Ecological studies on western juniper in central Oregon. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 27-35. [847]
  • 31. Evans, Raymond A. 1988. Management of pinyon-juniper woodlands. Gen. Tech. Rep. INT-249. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 34 p. [4541]
  • 4. Arno, Stephen F.; Hammerly, Ramona P. 1977. Northwest trees. Seattle, WA: The Mountaineers. 222 p. [4208]
  • 55. Kramer, S.; Miller, P. M.; Eddleman, L. E. 1996. Root system morphology and development of seedling and juvenile Juniperus occidentalis. Forest Ecology and Management. 86(1-3): 229-240. [28919]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]
  • 98. Vasek, Frank C. 1966. The distribution and taxonomy of three western junipers. Brittonia. 18: 350-372. [2426]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Physical Description

Tree, Evergreen, Dioecious, Monoecious, Habit erect, Trees without or rarely having knees, Tree with bark shaggy or peeling, Young shoots in flat sprays, Young shoots 3-dimensional, Buds not resinous, Leaves scale-like, Whip leaves present, Leaves of two kinds, Leaves opposite, Leaves whorled, Non-needle-like leaf margins entire, Non-needle-like leaf margins dentate or serrate, Leaf apex acute, Leaf apex obtuse, Leaves < 5 cm long, Leaves < 10 cm long, Leaves not blue-green, Scale leaves without raised glands, Scale leaf glands ruptured, Scales leaves not or barely overlapping, Whip leaf margins denticulate under magnification, Twigs glabrous, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Aril completely enclosing seed coat, Berry-like cones brown, Berry-like cones pink, Bracts of seed cone included, Seeds tan, Seeds brown, Seeds wingless.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

Stephen C. Meyers

Source: USDA NRCS PLANTS Database

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Description

Trees monoecious or dioecious, to 20(--30) m, single-stemmed; crown rounded to conical. Bark red-brown to brown, exfoliating in thin strips, that of small branchlets (5--10 mm diam.) smooth, that of larger branchlets exfoliating in scales or flakes. Branches spreading to ascending; branchlets erect, 3--4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves green, abaxial glands ovate to elliptic, conspicuous, with yellow or white exudate, margins denticulate (at 20´); whip leaves 3--6 mm, not glaucous adaxially; scalelike leaves 1--3 mm, not overlapping, rounded, apex acute to obtuse, appressed. Seed cones maturing in 2 years, of 2 distinct sizes, with straight peduncle, ovoid, 5--10 mm, blue to blue-black, glaucous, fleshy and resinous, with 2(--3) seeds. Seeds 2--4 mm.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA

Source: Missouri Botanical Garden

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Type Information

Type material for Juniperus occidentalis Hook.
Catalog Number: US 280590
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Verified from the card file of type specimens
Preparation: Pressed specimen
Collector(s): D. Douglas
Locality: Base of Rocky Mts., the Columbia., Washington, United States, North America
  • Type material: Hooker, W. J. 1838. Fl. Boreali-Amer. (Hooker). 2: 166.
Creative Commons Attribution 3.0 (CC BY 3.0)

© Smithsonian Institution, National Museum of Natural History, Department of Botany

Source: National Museum of Natural History Collections

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
In the northern part of its range (var. occidentalis) Western Juniper often forms single species stands, or it is associated with Pinus ponderosa. Here it is most frequently found on flood plains, terraces, and grassy plateaux and uplands. In E Oregon it is also spreading onto abandoned agricultural fields and rangeland, partly as a result of a decreasing frequency of wildfires. In the Sierra Nevada (var. australis) it can grow with Pinus jeffreyi, P. albicaulis, P. monticola, P. contorta, Abies magnifica, Calocedrus decurrens, and Tsuga mertensiana. The most common understorey shrub in its entire range is Seriphidium tridentatum (Artemisia tridentata); in the north also Chrysothamnus spp., Purshia tridentata, Ribes cereum, in the south Arctostaphylos spp., Ceanothus sp., and several others. The altitudinal range is 200-1,200 m a.s.l. (var. occidentalis) and 1980-3100 m a.s.l. (var. australis). In coniferous forest it usually occurs where rock outcrops cause shallow soils, at higher altitudes in the Sierras it can usually be found among granite boulders or even in crevices on bare granite domes. In the north it grows on xeric soils, often derived from volcanic rock, or from non-calcareous sediment. The climate ranges from semi-arid in the rain shadow of the Cascades (15-45 cm p/a) in the north to mesic in the Sierras, with precipitation mostly in the form of winter snow.

Systems
  • Terrestrial
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Habitat characteristics

More info for the term: xeric



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

  • 1. Agee, James K. 1994. Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades. Gen. Tech. Rep. PNW-GTR-320. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 52 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment). [23656]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 23. Dealy, J. Edward; Geist, J. Michael; Driscoll, Richard S. 1978. Communities of western juniper in the Intermountain Northwest. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 11-29. [784]
  • 28. Eddleman, Lee E. 1984. Ecological studies on western juniper in central Oregon. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 27-35. [847]
  • 3. Anderson, E. William. 1956. Some soil-plant relationships in eastern Oregon. Journal of Range Management. 9(4): 171-175. [314]
  • 37. Franklin, Jerry F.; Dyrness, C. T. 1973. Natural vegetation of Oregon and Washington. Gen. Tech. Rep. PNW-8. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 417 p. [961]
  • 42. Hall, Frederick C. 1978. Western juniper in association with other tree species. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 31-36. [1060]
  • 5. Barrett, Hugh. 1984. Western juniper and the range site concept. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University Extension Service, Department of Rangeland Resources: 23-26. [398]
  • 73. Miller, Richard F.; Rose, Jeffery A. 1995. Historic expansion of Juniperus occidentalis (western juniper) in southeastern Oregon. The Great Basin Naturalist. 55(1): 37-45. [25666]
  • 82. Rosentreter, Roger; Jorgensen, Ray. 1986. Restoring winter game ranges in southern Idaho. Tech. Bull. 86-3. Boise, ID: U.S. Department of the Interior, Bureau of Land Management, Idaho State Office. 26 p. [5295]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]
  • 95. Vaitkus, Milda R. 1986. Effect of western juniper on understory herbage production in central Oregon. Corvallis, OR: Oregon State University. 101 p. Thesis. [3835]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Key Plant Community Associations

More info for the terms: climax, codominant, formation, relict, series



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]

  • 25. Driscoll, Richard S. 1964. Vegetation-soil units in the central Oregon juniper zone. Res. Pap. PNW-19. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 59 p. [823]
  • 27. Eckert, Richard E., Jr. 1957. Vegetation-soil relationships in some Artemisia types in northern Harney and Lake Counties. Corvallis, OR: Oregon State College. 208 p. Dissertation. [837]
  • 30. Erhard, Dean H. 1979. Plant communities and habitat types in the Lava Beds National Monument, California. Corvallis, OR: Oregon State University. 173 p. Thesis. [869]
  • 33. Everett, Richard L. 1985. Great Basin pinyon and juniper communities and their response to management. In: Symposium on the cultural, physical and biological characteristics of range livestock industry in the Great Basin: Proceedings, 38th annual meeting of the Society for Range Management; 1985 February 11-14; Salt Lake City, UT. Denver, CO: Society for Range Management: 53-62. [889]
  • 37. Franklin, Jerry F.; Dyrness, C. T. 1973. Natural vegetation of Oregon and Washington. Gen. Tech. Rep. PNW-8. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 417 p. [961]
  • 41. Hall, Frederick C. 1973. Plant communities of the Blue Mountains in eastern Oregon and southeastern Washington. R6-Area Guide 3-1. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 82 p. [1059]
  • 46. Hopkins, William E. 1979. Plant associations of south Chiloquin and Klamath Ranger Districts--Winema National Forest. R6-Ecol-79-005. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 96 p. [7339]
  • 47. Hopkins, William E. 1979. Plant associations of the Fremont National Forest. R6-ECOL-79-004. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 106 p. [7340]
  • 49. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687]
  • 51. Johnson, Charles G., Jr.; Simon, Steven A. 1987. Plant associations of the Wallowa-Snake Province: Wallowa-Whitman National Forest. R6-ECOL-TP-255A-86. Baker, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, Wallowa-Whitman National Forest. 399 p. [9600]
  • 52. Johnston, Barry C. 1989. Woodland classification: the pinyon-juniper formation. In: Ferguson, Dennis E.; Morgan, Penelope; Johnson, Frederic D., compilers. Proceedings--land classifications based on vegetation: applications for resource management; 1987 November 17-19; Moscow, ID. Gen. Tech. Rep. INT-257. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 160-166. [6958]
  • 58. Layser, Earle F.; Schubert, Gilbert H. 1979. Preliminary classification for the coniferous forest and woodland series of Arizona and New Mexico. Res. Pap. RM-208. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 27 p. [1428]
  • 76. Parker, Albert J. 1989. Forest/environment relationships in Yosemite National Park, California USA. Vegetatio. 82: 41-54. [11055]
  • 79. Paysen, Timothy E.; Derby, Jeanine A.; Black, Hugh, Jr.; [and others]. 1980. A vegetation classification system applied to southern California. Gen. Tech. Rep. PSW-45. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 33 p. [1849]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Habitat: Rangeland Cover Types

More info on this topic.

This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):


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

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Habitat: Ecosystem

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):



FRES21 Ponderosa pine

FRES23 Fir-spruce

FRES26 Lodgepole pine

FRES28 Western hardwoods

FRES29 Sagebrush

FRES35 Pinyon-juniper

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Habitat: Cover Types

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):


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

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Habitat: Plant Associations

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):



K007 Red fir forest
K008 Lodgepole-pine-subalpine forest
K011 Western ponderosa forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodland
K030 California oakwoods

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Soils and Topography

Western juniper grows on soils developed in parent materials originating  from metamorphic, sedimentary, and igneous sources. Included are tuff,  welded tuff, pumice, volcanic ash, rhyolite, andesite, granite, basalt,  and eolian soils, and colluvial or alluvial mixtures of these soils.  Western juniper forms complex patterns on zonal, intrazonal, and azonal  soils. Profile development is often weak. Soils are generally stony but  can be nearly free of stones. They are commonly shallow (25 to 38 cm; 10  to 15 in) but range to deep (more than 122 cm or 48 in). Fractured bedrock  or broken indurated subsoil layers commonly occur under shallow  overburdened soils. Surface horizons are often of medium texture, and  subsoils of medium to fine texture; however, textures can vary from sandy  to clayey. Indurated layers can occur and are associated with  accumulations of clay, calcium carbonate, and silica. They may be less  than 1.5 cm (0.6 in) to several centimeters thick (5,6,8).

    Under mature western juniper trees in central Oregon, soil Ca, K, and pH  are higher than in inter-space soils and soils under young trees. These  changes appear to increase the ability of western juniper to compete with  other vegetation (7).

    Soils supporting juniper at high densities are frequently Mollisols.  Argixerolls, Haploxerolls, and Haplaquolls are common great groups. Soils  supporting scattered juniper are commonly Aridisols-including Camborthids,  Durargids, and Haplargids however, Argixerolls are also common. Other  soils on which western juniper can be found are Durixerolls and  Cryoborolls of the order Mollisols, Torriorthents of the order Entisols,  and Chromoxererts of the order Vertisols (5,6).

    Western juniper is found on all exposures and slopes. In central Oregon,  it is common in large continuous stands on level to gentle topography. In  other areas, it grows less continuously on terraces, moderately sloping  alluvial fans, canyon slopes, and steep, rocky escarpments (5,6,8).  Elevations at which western juniper is found range from about 185 m (600  ft) along the Columbia River to more than 3050 m (10,000 ft) in the Sierra  Nevada (24). In central Oregon, there are large, continuous stands between  670 and 1525 m (2,200 and 5,000 ft) (8).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Climate

Northern populations of western juniper grow in a climate characterized  as continental. The climate is semiarid with typical intermountain  characteristics of dry hot summers, cold winters, and precipitation of 230  to 355 mm (9 to 14 in), which occurs principally as snow during the winter  and as rain in the spring and fall (5). Precipitation is generally sparse  in the summer. Frost can occur during any month in central Oregon, the  area of western juniper's most extensive stands; however, July and August  are generally frost free. Temperatures in central Oregon range from a  record low of -32° C (-26° F) during January to a record high of  41° C (105° F) during August. The average temperature in January  is -1° C (30° F) and in July, 18° C (64° F). Southern  populations of western juniper grow in a similar climate; however, winter  temperatures are less extreme than in northern areas. Summer lightning  storms are common in the western juniper zone and result in natural fires  which have historically had a major influence on distribution and past  occurrence of juniper.

    Although western juniper grows in extensive stands in a narrow range of  precipitation (230 to 355 mm; 9 to 14 in) in central Oregon, it is a minor  species in many upper elevation areas of higher precipitation. The latter  areas have shallow, rocky soils too droughty to support other more common  upper-slope conifers.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Associations

Associated Forest Cover

Western juniper is a single species overstory in many northern stands.  In ecotones or transitions, ponderosa pine (Pinus ponderosa) and  curlleaf mountain-mahogany (Cercocarpus ledifolius) are the most  common tree associates at the lower edge of the conifer zone (5,6). At  upper elevations, western juniper often grows in narrow ecotones where  deep, forested soils grade into shallow, rocky scab flats. Small stands or  groups of trees commonly grow where rock outcrops produce shallow soil  inclusions in ponderosa pine, Douglas-fir (Pseudotsuga menziesii),  white fir (Abies concolor), lodgepole pine (Pinus  contorta), and other forest types (5,6,11). In the Sierra Nevada,  western juniper may be found on shallow soils with Jeffrey pine (Pinus  jeffreyi), California red fir (Abies magnifica), whitebark  pine (Pinus albicaulis), mountain hemlock (Tsuga mertensiana),  or lodgepole pine (24). At the southern extension of its range in San  Bernardino County, it generally grows at a higher elevation than  California juniper (Juniperus californica) and Utah juniper (J.  osteosperma) (20). This is the only documented area where western  juniper and singleleaf pinyon (Pinus monophylla) grow together in  a pinyon-juniper woodland vegetation type, although distributions are  known to overlap geographically near the west edge of Nevada and from  east-central to southern California (10,13). Western juniper is the  associate of singleleaf pinyon only in the high altitude section of the  type, primarily near Big Bear Lake, CA (13).

    Western juniper is recognized in five forest cover types (9). It is the  dominant species in Western Juniper (Society of American Foresters Type  238); an associate species in Interior Ponderosa Pine (Type 237) and  Jeffrey Pine (Type 247); and a minor or occasional species in Blue  Oak-Digger Pine (Type 250) and California Mixed Subalpine (Type 256).

    Big sagebrush (Artemisia tridentata) is the most common shrub  species associated with western juniper throughout its range. Other shrubs  common to western juniper communities in the northern portion of its range  are gray rabbitbrush (Chrysothamnus nauseosus), green rabbitbrush  (C. viscidiflorus), antelope-brush (Purshia tridentata), wax  currant (Ribes cereum), and horsebrush (Tetradymia spp.).  Less common shrubs are low sagebrush (Artemisia arbuscula), stiff  sagebrush (A. rigida), spiny hopsage (Atriplex spinosa), broom  snakeweed (Gutierrezia sarothrae), prickly phlox (Leptodactylon  pungens), and desert gooseberry (Ribes velutinum) (2,5,8).

    Common grass or grasslike species in northern areas are bluebunch  wheatgrass (Agropyron spicatum), cheatgrass (Bromus tectorum),  Idaho fescue (Festuca idahoensis), prairie Junegrass (Koeleria  cristata), Sandberg bluegrass (Poa sandbergii), bottlebrush  squirreltail (Sitanion hystrix), and Thurber needlegrass (Stipa  thurberiana). Less common are threadleaf sedge (Carex filifolia),  Ross sedge (C. rossii), sixweeks fescue (Festuca octoflora),  needle-and-thread (Stipa comata), and western needlegrass (S.  occidentalis). Forb species common to northern communities include  western yarrow (Achillea millefolium), milkvetch (Astragalus  spp.), littleflower collinsia (Collinsia parviflora), obscure  cryptantha (Cryptantha ambigua), lineleaf fleabane (Erigeron  linearis), woolly eriophyllum (Eriophyllum lanatum), spreading  groundsmoke (Gayophytum diffusum), lupine (Lupinus spp.),  a suffrutescent wild buckwheat (Eriogonum spp.), and tufted phlox  (Phlox caespitosa). Less common associates are sulfur eriogonum  (Eriogonum umbellatum), small bluebells (Mertensia  longiflora), and Hooker silene (Silene hookeri) (2,5,8).

    Major western juniper associations in central Oregon include  Juniperus/Artemisia/Festuca, Juniperus/Artemisia/Festuca-Lupinus,  Juniperus/ Festuca, Juniperus/Artemisia/Agropyron-Chaenactis, Juniperus/  Artemisia/Agropyron, Juniperus/Artemisia/Agropyron-Astragalus,  Juniperus/Artemisia-Purshia, Juniperus/Agropyron, and Juniperus/  Agropyron-Festuca (8).

    In one treatment of vegetation types in the conterminous United States,  western juniper is considered the dominant species in the Juniper Steppe  Woodland (Juniperus-Artemisia-Agropyron), number 24, and is a  secondary species in the Juniper-Pinyon Woodland (Juniperus-Pinus),  number 23 (8,10,17).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Diseases and Parasites

Damaging Agents

Because of the characteristic wide spacing in  most stands, the short stature of the trees, and the extensive, strong  root systems that often penetrate cracked rock under the soil mantle,  western juniper is very resistant to wind. Most damage from wind occurs as  top breakage in mature and overmature trees, and little damage occurs in  young stands. Fire resistance varies with age. Seedlings, saplings, and  poles are highly vulnerable to fire (18). Mature trees have some   resistance to fire because they have little fuel near the stem and  relatively thick bark, and because foliage is fairly high above the  ground. Old-growth stands remain in existence because, historically,  intense natural fires have not occurred and human-caused fires have been  controlled (2,3,5,6). Because of effective fire controls, young stands are  expanding into shrublands that would otherwise be maintained by periodic  natural fires (2). Where desired, it is easiest to control or eliminate  western juniper on rangelands with fire management when trees are less  than 2 m (6 ft) tall. The taller the trees become, the more intense the  fire must be to obtain good control. If a site has developed a dense stand  of large trees, fuel consisting of shrubs and bunchgrass is often  inadequate for burning trees under any weather conditions that management  can safely tolerate (18).

    Because the species has relatively little commercial value, little  attention has been given to the identification or effect of insects that  attack western juniper. Serious damage in western juniper by insects is  infrequent. The juniper bark beetle (Phloeosinus serratus) can  cause mortality, particularly to trees in a weakened condition, during a  drought (24). Gall midges feed on western juniper and produce galls;  however, their effect on productivity has not been studied. Although  termites are not considered a problem in use of products made from western  juniper wood, an unidentified species of termite has been observed in dead  material on lower portions of overmature trees, as well as in juniper  fenceposts in central Oregon.

    The principal damaging agents to western juniper are a white trunk rot  (Pyrofomes demidoffii) that attacks living trees and an  unidentified brown cubicle rot usually found in the basal portions of the  trunk (24). These rots cause high losses and have prevented the use of  western juniper wood for pencils. A single sporophore in evidence usually  indicates a tree is unmerchantable. The endophytic fungi Retinocyclus  abietis anamorpha and Hormoneme sp.have been found on  the foliage of western juniper. Infection rates increase with age,  density, and purity of stands. In general, western juniper is minimally  susceptible to infection (22). Two mistletoes, identified as constricted  mistletoe (Phoradendron ligatum) and dense mistletoe (P.  densom), cause lower vigor, deformity of branches, and brooming of the  foliage (12). A third mistletoe, R. juniperinum (Viscaceae),  also occurs on western juniper (25). Brooming of foliage is also caused by  the stem rusts Gymnosporangium kernianum and G. betheli. One  other rust of the same genus has been reported (12). Except for the white  trunk rot and the unidentified brown one, none of the diseases that attack  western juniper has been assessed.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

General Ecology

Fire Management Considerations

More info for the terms: cover, fireline intensity, flame length, forbs, fuel, litter, prescribed fire, shrubs, tree



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 Fire Case Study and 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 ¼ 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 0.98

Western juniper-low sagebrush communities that have been invaded by medusahead (Taeniatherum caput-medusae) are often extremely "fire hazardous" [103].

  • 1. Agee, James K. 1994. Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades. Gen. Tech. Rep. PNW-GTR-320. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 52 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment). [23656]
  • 103. Young, James A.; Evans, Raymond A. 1981. Demography and fire history of a western juniper stand. Journal of Range Management. 34(6): 501-505. [2659]
  • 15. Bunting, Stephen C. 1984. Prescribed burning of live standing western juniper and post-burning succession. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service; Oregon State University, Department of Rangeland Resources; 69-73. [557]
  • 16. Bunting, Stephen C. 1990. Prescribed fire effects in sagebrush-grasslands and pinyon-juniper woodlands. In: Alexander, M. E.; Bisgrove, G. F., technical coordinator. The art and science of fire management: Proceedings of the 1st Interior West Fire Council annual meeting and workshop; 1988 October 24-27; Kananaskis Village, AB. Information Rep. NOR-X-309. Edmonton, AB: Forestry Canada, Northwest Region, Northern Forestry Centre: 176-181. [15519]
  • 20. Clements, Charlie D.; Young, James A. 1997. A viewpoint: rangeland health and mule deer habitat. Journal of Range Management. 50(2): 129-138. [28429]
  • 63. Lent, Steve. 1984. Developing prescriptions for burning western juniper slash. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 77-90. [1440]
  • 66. Martin, Robert E.; Dell, John D. 1978. Planning for prescribed burning in the Inland Northwest. Gen. Tech. Rep. PNW-76. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 67 p. [18621]
  • 70. Meeuwig, Richard O.; Murray, Robert B. 1978. Current research on pinyon-juniper in the Great Basin. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 97-103. [1636]
  • 83. Sapsis, David B. 1990. Ecological effects of spring and fall prescribed burning on basin big sagebrush/Idaho fescue--bluebunch wheatgrass communities. Corvallis, OR: Oregon State University. 105 p. Thesis. [16579]
  • 97. van Wagtendonk, Jan W.; Sydoriak, Walter M.; Benedict, James M. 1998. Heat content variation of Sierra Nevada conifers. International Journal of Wildland Fire. 8(3): 147-158. [29410]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Broad-scale Impacts of Plant Response to Fire

More info for the terms: competition, cover, presence, shrubs, succession



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].

  • 103. Young, James A.; Evans, Raymond A. 1981. Demography and fire history of a western juniper stand. Journal of Range Management. 34(6): 501-505. [2659]
  • 17. Bunting, Stephen C.; Peters, Erin F.; Sapsis, David B. 1994. Impact of fire management on rangelands of the Intermountain West. Scientific Contract Report: Science Integration Team, Terrestrial Staff, Range Task Group. Walla Walla, WA: Interior Columbia Basin Ecosystem Management Project. 32 p. [26452]
  • 19. Burkhardt, Wayne J.; Tisdale, E. W. 1976. Causes of juniper invasion in southwestern Idaho. Ecology. 57: 472-484. [565]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Plant Response to Fire



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].

  • 15. Bunting, Stephen C. 1984. Prescribed burning of live standing western juniper and post-burning succession. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service; Oregon State University, Department of Rangeland Resources; 69-73. [557]
  • 19. Burkhardt, Wayne J.; Tisdale, E. W. 1976. Causes of juniper invasion in southwestern Idaho. Ecology. 57: 472-484. [565]
  • 25. Driscoll, Richard S. 1964. Vegetation-soil units in the central Oregon juniper zone. Res. Pap. PNW-19. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 59 p. [823]
  • 67. Martin, Robert E.; Johnson, Arlen H. 1979. Fire management of Lava Beds National Monument. In: Proceedings of the 1st conference on scientific research in the National Parks: vol. 2; 1976 November 9- 12; San Francisco CA. Washington, DC: U.S. Department of the Interior, National Park Service: 1209-1217. [1537]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Broad-scale Impacts of Fire



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].

  • 17. Bunting, Stephen C.; Peters, Erin F.; Sapsis, David B. 1994. Impact of fire management on rangelands of the Intermountain West. Scientific Contract Report: Science Integration Team, Terrestrial Staff, Range Task Group. Walla Walla, WA: Interior Columbia Basin Ecosystem Management Project. 32 p. [26452]
  • 64. Martin, Robert E. 1978. Fire manipulation and effects in western juniper (Juniperus occidentalis Hook.). In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 121-136. [1531]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Immediate Effect of Fire

More info for the term: fuel



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].

  • 11. Blackburn, W. H.; Beall, R.; Bruner, A.; [and others]. 1975. Controlled fire as a management tool in the pinyon-juniper woodland, Nevada. Annual Progress Report FY 1975. Unpublished report on file with: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. 77 p. [453]
  • 15. Bunting, Stephen C. 1984. Prescribed burning of live standing western juniper and post-burning succession. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service; Oregon State University, Department of Rangeland Resources; 69-73. [557]
  • 38. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others]. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Post-fire Regeneration

More info for the term: adventitious



Tree without adventitious bud/root crown

Initial off-site colonizer (off-site, initial community)

Secondary colonizer - off-site seed

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Fire Ecology

More info for the terms: climax, fire interval, mean fire interval, phase, severity, succession



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

  • 1. Agee, James K. 1994. Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades. Gen. Tech. Rep. PNW-GTR-320. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 52 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment). [23656]
  • 19. Burkhardt, Wayne J.; Tisdale, E. W. 1976. Causes of juniper invasion in southwestern Idaho. Ecology. 57: 472-484. [565]
  • 2. Agee, James K. 1996. Fire in the Blue Mountains: a history, ecology, and research agenda. In: Jaindl, R. G.; Quigley, T. M., eds. Search for a solution: sustaining the land, people and economy of the Blue Mountains. Washington, DC: American Forests: 119-145. [28827]
  • 6. Barrett, Stephen W.; Arno, Stephen F.; Menakis, James P. 1997. Fire episodes in the Inand Northwest (1540-1940) based on fire history data. Gen. Tech. Rep. INT-GTR-370. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 17 p. [27453]
  • 64. Martin, Robert E. 1978. Fire manipulation and effects in western juniper (Juniperus occidentalis Hook.). In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 121-136. [1531]
  • 8. Belsky, A. Joy. 1996. Viewpoint: western juniper expansion: is it a threat to arid northwestern ecosystems? Journal of Range Management. 49(1): 53-59. [26572]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]
  • 96. Vaitkus, Milda R.; Eddleman, Lee E. 1991. Tree size and understory phytomass production in a western juniper woodland. The Great Basin Naturalist. 51(3): 236-243. [16869]
  • 99. Wangler, Michael J.; Minnich, Richard A. 1996. Fire and succession in pinyon-juniper woodlands of the San Bernadino Mountains, California. Madrono. 43(4): 493-514. [27891]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Successional Status

More info on this topic.

More info for the terms: climax, fire frequency, fire suppression, frequency, invasive species, shrub, tree



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].

  • 1. Agee, James K. 1994. Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades. Gen. Tech. Rep. PNW-GTR-320. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 52 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment). [23656]
  • 103. Young, James A.; Evans, Raymond A. 1981. Demography and fire history of a western juniper stand. Journal of Range Management. 34(6): 501-505. [2659]
  • 18. Burkhardt, J. Wayne; Tisdale, E. W. 1969. Nature and successional status of western juniper vegetation in Idaho. Journal of Range Management. 22(4): 264-270. [564]
  • 2. Agee, James K. 1996. Fire in the Blue Mountains: a history, ecology, and research agenda. In: Jaindl, R. G.; Quigley, T. M., eds. Search for a solution: sustaining the land, people and economy of the Blue Mountains. Washington, DC: American Forests: 119-145. [28827]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 23. Dealy, J. Edward; Geist, J. Michael; Driscoll, Richard S. 1978. Communities of western juniper in the Intermountain Northwest. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 11-29. [784]
  • 29. Eddleman, Lee E.; Miller, Patricia M.; Miller, Richard F.; Dysart, Patricia L. 1994. Western juniper woodlands (of the Pacific Northwest): Science assessment. Walla Walla, WA: Interior Columbia Basin Ecosystem Management Project. 131 p. [27969]
  • 65. Martin, Robert E. 1980. Western juniper. In: Eyre, F.H., ed. Forest cover types of the United States and Canada. Washington, D.C.: 115-116. [1532]
  • 7. Bates, Jon D.; Miller, Richard F.; Svejcar, Tony. 1998. Understory patterns in cut western juniper (Juniperus occidentalis spp. Occidentalis Hook.) woodlands. The Great Basin Naturalist. 58(4): 363-374. [29093]
  • 74. Miller, Rick; Rose, Jeff. 1998. Pre- and post-settlement fire return intervals on Intermountain sagebrush steppe. In: Annual report: Eastern Oregon Agricultural Research Center. Corvallis, OR: Oregon State University, Agricultural Experiment Station: 16-17. [29194]
  • 75. Miller, Rick; Rose, Jeffrey; Svejcar, Tony; [and others]. 1995. Western juniper woodlands: 100 years of plant succession. In: Shaw, Douglas W.; Aldon, Earl F.; LoSapio, Carol, technical coordinators. Desired future conditions for pinon-juniper ecosystems: Proceedings of the symposium; 1994 August 8-12; Flagstaff, AZ. Gen. Tech. Rep. RM-258. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 5-8. [24790]
  • 8. Belsky, A. Joy. 1996. Viewpoint: western juniper expansion: is it a threat to arid northwestern ecosystems? Journal of Range Management. 49(1): 53-59. [26572]
  • 81. Rose, Jeffrey A.; Eddleman, Lee E. 1994. Ponderosa pine and understory growth following western juniper removal. Northwest Science. 68(2): 79-85. [23145]
  • 95. Vaitkus, Milda R. 1986. Effect of western juniper on understory herbage production in central Oregon. Corvallis, OR: Oregon State University. 101 p. Thesis. [3835]
  • 96. Vaitkus, Milda R.; Eddleman, Lee E. 1991. Tree size and understory phytomass production in a western juniper woodland. The Great Basin Naturalist. 51(3): 236-243. [16869]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Regeneration Processes

More info for the terms: dioecious, forbs, monoecious, natural, tree



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].

  • 103. Young, James A.; Evans, Raymond A. 1981. Demography and fire history of a western juniper stand. Journal of Range Management. 34(6): 501-505. [2659]
  • 104. Young, James A.; Evans, Raymond A.; Budy, Jerry D.; Palmquist, Debra E. 1988. Stratification of seeds of western and Utah juniper. Forest Science. 34(4): 1059-1066. [6597]
  • 19. Burkhardt, Wayne J.; Tisdale, E. W. 1976. Causes of juniper invasion in southwestern Idaho. Ecology. 57: 472-484. [565]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 28. Eddleman, Lee E. 1984. Ecological studies on western juniper in central Oregon. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 27-35. [847]
  • 29. Eddleman, Lee E.; Miller, Patricia M.; Miller, Richard F.; Dysart, Patricia L. 1994. Western juniper woodlands (of the Pacific Northwest): Science assessment. Walla Walla, WA: Interior Columbia Basin Ecosystem Management Project. 131 p. [27969]
  • 50. Johnsen, Thomas N., Jr.; Alexander, Robert A. 1974. Juniperus L. juniper. In: Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 460-469. [1268]
  • 68. Maser, Chris; Gashwiler, Jay S. 1978. Interrelationships of wildlife and western juniper. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 37-82. [1541]
  • 69. McCaughey, Ward W.; Schmidt, Wyman C.; Shearer, Raymond C. 1986. Seed-dispersal characteristics of conifers. In: Shearer, Raymond C., compiler. Proceedings--conifer tree seed in the Inland Mountain West symposium; 1985 August 5-6; Missoula, MT. Gen. Tech. Rep. INT-203. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 50-62. [12593]
  • 72. Miller, Richard F. 1984. Water relations in western juniper. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 36-44. [1650]
  • 73. Miller, Richard F.; Rose, Jeffery A. 1995. Historic expansion of Juniperus occidentalis (western juniper) in southeastern Oregon. The Great Basin Naturalist. 55(1): 37-45. [25666]
  • 75. Miller, Rick; Rose, Jeffrey; Svejcar, Tony; [and others]. 1995. Western juniper woodlands: 100 years of plant succession. In: Shaw, Douglas W.; Aldon, Earl F.; LoSapio, Carol, technical coordinators. Desired future conditions for pinon-juniper ecosystems: Proceedings of the symposium; 1994 August 8-12; Flagstaff, AZ. Gen. Tech. Rep. RM-258. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 5-8. [24790]
  • 84. Schupp, Eugene W.; Gomez, Jose M.; Jimenez, Jaime E.; Fuentes, Marcelino. 1997. Dispersal of Juniperus occidentalis (western juniper) seeds by frugivorous mammals on Juniper Mountain, Oregon. The Great Basin Naturalist. 57(1): 74-78. [27379]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]
  • 88. Springfield, H. W. 1976. Characteristics and management of Southwestern pinyon-juniper ranges: the status of our knowledge. Res. Pap. RM-160. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 32 p. [2216]
  • 91. Tueller, Paul T. 1976. Secondary succession, disclimax, and range condition standards in desert scrub vegetation. In: Hyder, D. N., ed. Arid shrublands--Proceedings of the third workshop of the United States/Australia rangelands panel; 1973 March 26 - April 5; Tucson, AZ. Denver, CO: Society for Range Management: 57-65. [3790]
  • 92. Tueller, Paul T.; Clark, James E. 1975. Autecology of pinyon-juniper species of the Great Basin and Colorado Plateau. In: The pinyon-juniper ecosystem: a symposium; 1975 May; Logan, UT. Logan, UT: Utah State University, College of Natural Resources, Utah Agricultural Experiment Station: 27-40. [2368]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Growth Form (according to Raunkiær Life-form classification)

More info on this topic.

More info for the term: phanerophyte



Phanerophyte

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life Form

More info for the term: tree



Tree

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Reaction to Competition

Western juniper is intolerant of shade  and competes poorly with conifers on upper slope sites. Although many  individual specimens are found growing as seedlings or saplings in upper  slope conifer communities with moderate to dense crowns, they are usually  small and suppressed and have low vigor. Establishment of western juniper  in this situation apparently occurs when the stand is opened by  disturbance.

    Western juniper is intolerant of fire and historically was kept in  restricted sites by natural fires. Since the advent of effective fire  control and intensive livestock grazing (reducing ground fuel and  understory competition), regeneration and establishment of western juniper  have expanded into suitable sites previously dominated by mountain big  sagebrush (Artemisia tridentata spp. vaseyana). This  expansion of young stands is common in Oregon, Idaho, and northeastern  California (2,3,5,6).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Rooting Habit

Seedlings of western juniper, typical of and site  species, produce rapid spring root extension with minimal top growth.  There is a greater downward growth than lateral growth of roots, again  characteristic of and site species. As seedlings become established, their  roots extend laterally to take maximum advantage of nutrients and seasonal  moisture in upper soil horizons. As a mature tree, western juniper lacks a  central taproot. It has roots that are wide spreading and strong, often  penetrating deep into cracks of bedrock.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History and Behavior

Cyclicity

Phenology

More info on this topic.

More info for the term: natural



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].

  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 50. Johnsen, Thomas N., Jr.; Alexander, Robert A. 1974. Juniperus L. juniper. In: Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 460-469. [1268]
  • 69. McCaughey, Ward W.; Schmidt, Wyman C.; Shearer, Raymond C. 1986. Seed-dispersal characteristics of conifers. In: Shearer, Raymond C., compiler. Proceedings--conifer tree seed in the Inland Mountain West symposium; 1985 August 5-6; Missoula, MT. Gen. Tech. Rep. INT-203. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 50-62. [12593]
  • 72. Miller, Richard F. 1984. Water relations in western juniper. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 36-44. [1650]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Reproduction

Vegetative Reproduction

Planting stock has been successfully  grafted and cuttings have been successfully rooted in experimental trials.  Some stock has been developed by layering (24).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Seedling Development

Natural germination of western juniper  occurs during April in Oregon. Germination is epigeal. How long after  fruit ripening germination occurs and what dormancy characteristics are  present are not known. Seeds of many juniper species show delayed  germination because of dormant embryos or hard seed coats. Seeds of  western juniper are thought to have both these characteristics.  Stratification of seeds should be conducted in a sand or peat medium. A  warm stratification is suggested for western juniper, fluctuating from 20°  C (68° F) at night to 27° C (81° F) during the day for 45  to 90 days, and then cold stratification of approximately 4° C (39°  F) to induce germination (14). After stratification, seeds can be sown in  the fall or spring. For spring planting, seeds should be sown before air  temperatures reach 21° C (70° F).

    Bare mineral soil seedbeds are reported as best for successful  germination of seed and establishment of seedlings (24). Young plants are  normally vigorous, single stemmed, and have pyramidal forms.

    Western juniper is very hardy in the early growth stage, resists disease  and insect attacks well, and is not preferred as a food item by domestic  or wild animals. Considerable browsing, however, occurs on deer winter  ranges when other forage is limited; heavy use results in a hedged growth  form.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Seed Production and Dissemination

Good seed production in  western juniper occurs nearly every year. Seed yield from 45 kg (100 lb)  of fruit averages 9 kg (20 lb). Cleaned seeds average 27 000/kg  (12,300/lb) and range from 17 600 to 35 000/kg (8,000 to 15,860/lb) (14).

    Seeds are disseminated during the fall, primarily by birds and mammals.  Animals ingest the fruit but do not digest the seeds. Dissemination of  seeds by animals is evidenced by seed-filled droppings, particularly from  robins and coyotes. Western juniper is often found growing along fence  rows, seeds having been deposited there by perched birds (14,19,24).

    Fruit can be collected after it has fallen from the tree or by  handpicking it from the tree. Care must be taken when collecting fruit  directly from the tree because the new, unripe crop and the 2-year-old,  ripe crop are mixed. Fruit should be collected as soon after ripening as  possible to prevent removal by animals. It should be stored in shallow  trays or piles to prevent excessive heating until seeds are extracted.

    Seeds of western juniper may be extracted from fruit by use of a  macerator or hammermill in conjunction with water. Because of its resinous  nature, pulp is more easily removed from the seeds if berries are  presoaked in a lye solution consisting of 1.25 grams of sodium hydroxide  or potassium hydroxide per liter (1 teaspoon to 1 gallon) of water for 1  to 2 days. After they are cleaned, seeds should be washed to remove the  lye and then stored dry in sealed containers at -2° to 4° C (29°  to 40° F) and with a moisture content of approximately 10 percent  (14).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Flowering and Fruiting

The northern Juniperus occidentalis  ssp. occidentalis is submonoecious; the southern subspecies australis  is dioecious.

    In Oregon and Washington, western juniper flowers in spring and sheds  pollen in May. Yellowish-brown staminate cones are terminal, ovoid, and 3  to 4 mm (0. 12 to 0. 16 in) long. They have 12 to 15 microsporophylls.  Ovulate cones are 6 to 8 mm. (0.24 to 0.31 in) long, subglobose to  ellipsoid, bluish-black when mature, and very glaucous. Ovulate cones,  referred to as berries, have resinous pulp and mature in September of the  second season in Oregon, Washington, and Idaho. Ovulate cones commonly  have two to three developed seeds, rarely one. The seed has a thick, bony  outer coat and a thin, membranous inner coat. The membranous coat  surrounds a fleshy endosperm within which a straight embryo with  cotyledons occurs (4,14,24,26).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Growth

Growth and Yield

In the sapling and pole stages, western  juniper has straight holes, and the crown varies from medium tapered to  round. Early growth rate varies by site; however, growth throughout its  range is poor, relative to most conifer species.

    Height of mature trees ranges from 4 to 10 in (13 to 33 ft), with  exceptions at both ends of the spectrum, depending on site conditions.  Occasionally, trees reach exceptional heights, such as one recorded as  26.5 in (87 ft) tall and 396 cm (156 in) in d.b.h.; and another, 26.5 in  (87 ft) tall and 414 cm (163 in) in d.b.h. (4,21). Boles of mature trees  are massive and more tapered than those of many conifer species, and the  butt section is often slightly fluted. This species commonly develops full  crowns and heavy limbs at maturity and, in the overmature stage, has a  ragged, dead-topped, gnarled appearance. Western juniper is a long-lived  and ruggedly picturesque species, reaching ages estimated to be more than  1,000 years (24). Old-growth stands in central Oregon are between 200 and  400 years old.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Molecular Biology and Genetics

Genetics

Two subspecies of western juniper have been identified, Juniperus  occidentalis ssp. occidentalis and ssp. australis. Distribution  of the former is in south-central and southeastern Washington, eastern  Oregon, southwestern Idaho, northeastern California, and the northwestern  corner of Nevada; that of the latter is near Susanville in Lassen County,  CA, south to San Bernardino County, CA (4,10,20,23,26). The only other  divergence reported is a variant that has a narrow spirelike habit and  occurs in a very restricted location in central Oregon (24).

    Western juniper may be hybridizing with Utah juniper where the two  species grow together in northwestern Nevada east of California's Warner  Mountains. Two relict individuals in the White Mountains of California may  be hybrids of western juniper and Utah juniper (26).

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Molecular Biology

Barcode data: Juniperus occidentalis

The following is a representative barcode sequence, the centroid of all available sequences for this species.


Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Statistics of barcoding coverage: Juniperus occidentalis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2013

Assessor/s
Farjon, A.

Reviewer/s
Adams, R & Thomas, P.

Contributor/s

Justification
Juniperus occidentalis is presently increasing in abundance, spread and numbers of mature individuals. The southern subpopulations are stable, but lack of recruitment locally could pose problems following destructive events. The overall assessment of Least Concern is driven by the larger subpopulations in the north, which are all increasing.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

National NatureServe Conservation Status

United States

Rounded National Status Rank: N5 - Secure

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Population

Population
Locally common with subpopulations expanding in some areas. An aggressive juniper, invading grasslands in eastern Oregon. Current control/ eradication programs are unlikely to control it, as fire control is so good (and desired by the public).

Population Trend
Increasing
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Threats

Major Threats
Overall, the species is not threatened. However, for var. australis, due to extreme environmental limitations, recruitment and growth are sporadic and extremely slow. In many subpopulations there are only old or senescent trees present; if these were all to die from stochastic events or an alien pathogen (not present now) this taxon could become threatened with extinction.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Management

Conservation Actions

Conservation Actions
This is one of the (few) conifers which is dramatically increasing its extent of occurrence and area of occupancy, mainly due to decreasing pressure from grazing by livestock, as agricultural economies and practices shift away from massive cattle raising and/or sheep herding. Where past overgrazing has greatly increased woody low shrubs such as Artemisia tridentata (“sage brush”) a nursing environment has been created providing shelter from sun and weather (and herbivores) to juniper seedlings.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Management considerations

More info for the term: tree



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].

  • 102. Young, James A.; Evans, Raymond A.; Budy, Jerry D.; Torell, Allen. 1982. Cost of controlling maturing western juniper trees. Journal of Range Management. 35(4): 437-442. [2645]
  • 105. Young, James A.; Evans, Raymond A.; Easi, Debra A. 1984. Stem flow on western juniper (Juniperus occidentalis) trees. Weed Science. 32: 320-327. [3850]
  • 13. Buckhouse, John C. 1984. Characteristics of watershed occupied by western juniper. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University Extension Service; Department of Rangeland Resources: 46-47. [551]
  • 31. Evans, Raymond A. 1988. Management of pinyon-juniper woodlands. Gen. Tech. Rep. INT-249. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 34 p. [4541]
  • 32. Evans, Raymond A.; Young, James A. 1985. Plant succession following control of western juniper (Juniperus occidentalis) with picloram. Weed Science. 33(1): 63-68. [882]
  • 70. Meeuwig, Richard O.; Murray, Robert B. 1978. Current research on pinyon-juniper in the Great Basin. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 97-103. [1636]
  • 71. Miller, P. M.; Eddleman, L. E.; Miller, J. M. 1991. The response of western juniper (Juniperus occidentalis) to reductions in above-ground and below-ground tissue. Canadian Journal of Forest Research. 21: 207-216. [15490]
  • 8. Belsky, A. Joy. 1996. Viewpoint: western juniper expansion: is it a threat to arid northwestern ecosystems? Journal of Range Management. 49(1): 53-59. [26572]
  • 82. Rosentreter, Roger; Jorgensen, Ray. 1986. Restoring winter game ranges in southern Idaho. Tech. Bull. 86-3. Boise, ID: U.S. Department of the Interior, Bureau of Land Management, Idaho State Office. 26 p. [5295]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Relevance to Humans and Ecosystems

Benefits

Value for rehabilitation of disturbed sites

More info for the term: layering



Western juniper can be propagated from cuttings or by layering [22,87]. Trees have been used as riprap for stabilizing streambanks [22].

  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Cover Value

More info for the terms: cover, hibernation



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].

  • 101. Yoakum, Jim. 1980. Habitat management guides for the American pronghorn antelope. Tech. Note 347. Denver, CO: U.S. Department of the Interior, Bureau of Land Management, Denver Service Center. 77 p. [23170]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 54. Koehler, Gary M. 1981. Ecolog. requirements for Lewis' woodpecker (Melanerpes lewis), potential impacts of surface mining on their habitat and recommendations for mitigation. Unpublished report prepared for the U.S. Fish and Wildlife Service. On file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. [20542]
  • 61. Leckenby, Donavin A.; Sheehy, Dennis P.; Nellis, Carl H.; [and others]. 1982. Wildlife habitats in managed rangelands--the Great Basin of southeastern Oregon: mule deer. Gen. Tech. Rep. PNW-139. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 40 p. [1432]
  • 62. Leckenby, Donavin A.; Toweill, Dale E. 1983. Response of forage species seeded for mule deer in western juniper types of southcentral Oregon. Journal of Range Management. 36(1): 98-103. [8098]
  • 68. Maser, Chris; Gashwiler, Jay S. 1978. Interrelationships of wildlife and western juniper. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 37-82. [1541]
  • 90. Thomas, Jack Ward; Miller, Rodney J.; Black, Hugh,; [and others]. 1976. Guidelines for maintaining and enhancing wildlife habitat in forest management in the Blue Mountains of Oregon and Washington. In: Transactions, 41st North American wildlife and natural resources conference; [Date of conference unknown]; [Location of conference unknown]. Washington, DC: Wildlife Management Institute: 452-456. [16734]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Palatability

More info for the term: tree



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].

  • 28. Eddleman, Lee E. 1984. Ecological studies on western juniper in central Oregon. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 27-35. [847]
  • 68. Maser, Chris; Gashwiler, Jay S. 1978. Interrelationships of wildlife and western juniper. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 37-82. [1541]
  • 82. Rosentreter, Roger; Jorgensen, Ray. 1986. Restoring winter game ranges in southern Idaho. Tech. Bull. 86-3. Boise, ID: U.S. Department of the Interior, Bureau of Land Management, Idaho State Office. 26 p. [5295]
  • 87. Sowder, James E.; Mowat, Edwin L. 1965. Western juniper (Juniperus occidentalis) Hook.). In: Fowells, H. A., compiler. Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture, Forest Service: 223-225. [17608]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Importance to Livestock and Wildlife

More info for the term: cover



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].

  • 10. Bissell, Harold D.; Strong, Helen. 1955. The crude protein variations in the browse diet of California deer. California Fish and Game. 41(2): 145-155. [10524]
  • 21. Crawford, John A.; Van Dyke, Walt; Meyers, S. Mark; Haensly, Thomas F. 1986. Fall diet of blue grouse in Oregon. The Great Basin Naturalist. 46(1): 123-127. [14176]
  • 26. Eastman, William R., Jr. 1960. Eating of tree seeds by birds in central Oregon. Res. Note 42. Corvallis, OR: Oregon Forest Research Center, Forest Lands Research. 24 p. [8284]
  • 28. Eddleman, Lee E. 1984. Ecological studies on western juniper in central Oregon. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 27-35. [847]
  • 29. Eddleman, Lee E.; Miller, Patricia M.; Miller, Richard F.; Dysart, Patricia L. 1994. Western juniper woodlands (of the Pacific Northwest): Science assessment. Walla Walla, WA: Interior Columbia Basin Ecosystem Management Project. 131 p. [27969]
  • 35. Fajemisin, B.; Ganskopp, D.; Cruz, R.; Vavra, M. 1996. Potential for woody plant control by Spanish goats in the sagebrush steppe. Small Ruminant Research. 20(3): 229-238. [29196]
  • 54. Koehler, Gary M. 1981. Ecolog. requirements for Lewis' woodpecker (Melanerpes lewis), potential impacts of surface mining on their habitat and recommendations for mitigation. Unpublished report prepared for the U.S. Fish and Wildlife Service. On file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. [20542]
  • 59. Leach, Howard R. 1956. Food habits of the Great Basin deer herds of California. California Fish and Game. 38: 243-308. [3502]
  • 68. Maser, Chris; Gashwiler, Jay S. 1978. Interrelationships of wildlife and western juniper. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 37-82. [1541]
  • 77. Parker, Douglas; Ziegler, Maurice. 1984. Values of western juniper products and a method estimating juniper cordwood. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 55-60. [1815]
  • 84. Schupp, Eugene W.; Gomez, Jose M.; Jimenez, Jaime E.; Fuentes, Marcelino. 1997. Dispersal of Juniperus occidentalis (western juniper) seeds by frugivorous mammals on Juniper Mountain, Oregon. The Great Basin Naturalist. 57(1): 74-78. [27379]
  • 86. Sneva, Forrest A.; Vavra, M. 1978. Botanical composition of feces from pronghorn antelope grazing the Oregon high desert. In: Proceedings of the eighth biennial pronghorn antelope workshop; 1978 May 2-4; Jasper, AB. Edmonton, AB: Alberta Recreation, Parks, and Wildlife, Fish and Wildlife Division: 78-93. [3404]
  • 90. Thomas, Jack Ward; Miller, Rodney J.; Black, Hugh,; [and others]. 1976. Guidelines for maintaining and enhancing wildlife habitat in forest management in the Blue Mountains of Oregon and Washington. In: Transactions, 41st North American wildlife and natural resources conference; [Date of conference unknown]; [Location of conference unknown]. Washington, DC: Wildlife Management Institute: 452-456. [16734]
  • 94. U.S. Department of Interior, Bureau of Land Management, Boise District Office; Golden Eagle Audubon Society. 1997. Breeding bird survey of old-growth/seral, prescribed burn, and clearcut stands of western juniper. Technical Bulletin 97-12. Boise, ID: U.S. Department of Interior, Bureau of Land Management, Idaho State Office. 19 p. [27645]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wood Products Value



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].

  • 14. Budy, Jerry D. 1984. Biomass and harvesting systems for western juniper. In: Proceedings--western juniper management short course. 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 53-54. [553]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 43. Herbst, John R. 1978. Physical properties and commercial uses of western juniper. In: Matin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 169-177. [1137]
  • 77. Parker, Douglas; Ziegler, Maurice. 1984. Values of western juniper products and a method estimating juniper cordwood. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 55-60. [1815]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Other uses and values



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].

  • 100. Wilke, Philip J. 1988. Bow staves harvested from juniper trees by Indians of Nevada. Journal of California and Great Basin Anthropology. 10(1): 3-31. [10870]
  • 43. Herbst, John R. 1978. Physical properties and commercial uses of western juniper. In: Matin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 January; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 169-177. [1137]
  • 48. Hopkins, William E.; Kovalchik, Bernard L. 1983. Plant associations of the Crooked River National Grassland. R6 Ecol 133-1983. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 98 p. [1193]
  • 50. Johnsen, Thomas N., Jr.; Alexander, Robert A. 1974. Juniperus L. juniper. In: Schopmeyer, C. S., tech. coord. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 460-469. [1268]
  • 77. Parker, Douglas; Ziegler, Maurice. 1984. Values of western juniper products and a method estimating juniper cordwood. In: Proceedings--western juniper management short course; 1984 October 15-16; Bend, OR. Corvallis, OR: Oregon State University, Extension Service and Department of Rangeland Resources: 55-60. [1815]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Nutritional Value


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

  • 10. Bissell, Harold D.; Strong, Helen. 1955. The crude protein variations in the browse diet of California deer. California Fish and Game. 41(2): 145-155. [10524]
  • 35. Fajemisin, B.; Ganskopp, D.; Cruz, R.; Vavra, M. 1996. Potential for woody plant control by Spanish goats in the sagebrush steppe. Small Ruminant Research. 20(3): 229-238. [29196]
  • 60. Leckenby, Donavin A. 1978. Western juniper management for mule deer. In: Martin, Robert E.; Dealy, J. Edward; Caraher, David L., eds. Proceedings of the western juniper ecology and management workshop; 1977 Jan.; Bend, OR. Gen. Tech. Rep. PNW-74. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station: 137-161. [1430]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Special Uses

Western juniper has had no widespread commercial value. During the  pioneer era, it was important as firewood and as poles for fences,  corrals, and simple shelters. Locally, it is still important for many of  the same uses (5). Heartwood is extremely durable and far outlasts other  local materials in northern areas when placed in contact with the ground.  It probably equals durability of other junipers and of cedars in more  southern areas.

    Western juniper logs are difficult to process. They are rough, limby,  short, and have rapid taper. They also have bark inclusions deep in the  wood. Juniper is reputed to be difficult to cure because it twists and  warps while drying, and to be difficult to plane, splitting easily. The  reputation is undeserved-local specialty manufacturers have been  air-drying this wood successfully for many years (12). Thin boards can be  kiln-dried successfully without checking. In fact, any slow drying process  works well. Local manufacturers use western juniper for making furniture,  novelty items, toys, tongue-and-groove interior paneling, fenceposts, and  firewood. Products experimentally manufactured that are considered  commercially feasible include hardboard, particle board, veneer, and  exposed and decorative interior studs. Research in extracted essential  oils indicates that cedrol, used in scenting and flavoring, could be  extracted in quantities and would be of a quality to be commercially  competitive with cedrol from other juniper species (1,12).

    Western juniper is valuable for wildlife cover, food (primarily  berries), and nest sites, and as shade for livestock (16,19). Also,  management agencies use harvested trees as riprap for stabilizing  streambanks. Natural stands in developing areas are highly valuable for  landscaping homesites, but the species has not been popular for  horticultural uses.

  • Burns, Russell M., and Barbara H. Honkala, technical coordinators. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods.   Agriculture Handbook 654 (Supersedes Agriculture Handbook 271,Silvics of Forest Trees of the United States, 1965).   U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 pp.   http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm External link.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

J. Edward Dealy

Source: Silvics of North America

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Juniperus occidentalis

Juniperus occidentalis (Western Juniper or Sierra Juniper) is a shrub or tree native to the western United States, growing in mountains at altitudes of 800–3,000 metres (2,600–9,800 ft) and rarely down to 100 metres (330 ft).

Description[edit]

Distinctive bark of Juniperus occidentalis var. australis, eastern Sierra Nevada, Rock Creek Canyon, California.

The Juniperus occidentalis shoots are of moderate thickness among junipers, 1-1.6 mm diameter. The leaves are arranged in opposite decussate pairs or whorls of three; the adult leaves are scale-like, 1–2 mm long (to 5 mm on lead shoots) and 1-1.5 mm broad. The juvenile leaves (on young seedlings only) are needle-like, 5–10 mm long. The cones are berry-like, 5–10 mm in diameter, blue-brown with a whitish waxy bloom, and contain one to three seeds; they are mature in about 18 months. The male cones are 2–4 mm long, and shed their pollen in early spring.

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 (Bibionomorpha: Cecidomyiidae); these are violet-purple fading to brown, 1–2 cm diameter, with dense modified spreading scale-leaves 6–10 mm long and 2–3 mm broad at the base.

Varieties[edit]

There are two Juniperus occidentalis varieties, treated as subspecies by some botanists:

  • Juniperus occidentalis var. occidentalis Western Juniper. 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. A shrub or small tree 4–15 m tall. Exceptionally tall specimens can be found in the John Day area of Oregon well in excess of 26–28 m tall (80–90 feet+) competing for sunlight among Ponderosa Pines at the bottom of some deep side canyons, but on open and barren ground 4–15 m with a bushier growth habit is more common. Cones 7–10 mm diameter. About 50% of plants are monoecious with both sexes on the same plant, 50% dioecious, producing cones of only one sex.
  • Juniperus occidentalis var. australis Sierra Juniper. California and westernmost Nevada, south of 40° 30' N latitude in the Sierra Nevada and San Bernardino Mountains. A medium-sized tree 12–26 m tall with a stout trunk up to 3 m diameter. Cones 5–9 mm diameter. Most plants dioecious, but about 5-10% are monoecious.

Ancient tree[edit]

The Bennett Juniper in the Stanislaus National Forest of California is considered the oldest and largest example at possibly 3000 years old, with a height of 26 m and a diameter of 3.88 m.[1]

Habitat[edit]

Juniperus occidentalis usually occurs on dry, rocky sites where there is less competition from larger species like Ponderosa Pine and Coast Douglas-fir. In very exposed positions at high altitude, they can assume a krummholz habit, growing low to the ground even when mature with a wide trunk (see image at left). Hybrids with Juniperus osteosperma are occasionally found.

References[edit]

Further reading[edit]

Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Names and Taxonomy

Taxonomy

Comments: Comprised of two varieties (FNA 1993; Kartesz 1999), which perhaps have hybrid populations in some Nevada mountain ranges (Charlet 1996).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

More info for the term: relict



The scientific name of western juniper is Juniperus occidentalis Hook. (Cupressaceae) [44,45,53]. The following varieties of western juniper are recognized:

J. occidentalis var. australis (Vasek) A. Holmgren & N. Holmgren  (Sierra juniper) [44,106]

J. occidentalis var. occidentalis

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].

  • 106. Zanoni, T. A. 1978. The American junipers of the section Sabina (Juniperus, Cupressaceae) -- a century later. Phytologia. 38(6): 433-454. [4954]
  • 22. Dealy, J. Edward. 1990. Juniperus occidentalis Hook. western juniper. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 109-115. [13375]
  • 44. Hickman, James C., ed. 1993. The Jepson manual: Higher plants of California. Berkeley, CA: University of California Press. 1400 p. [21992]
  • 45. Hitchcock, C. Leo; Cronquist, Arthur. 1973. Flora of the Pacific Northwest. Seattle, WA: University of Washington Press. 730 p. [1168]
  • 53. Kartesz, John T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. Volume I--checklist. 2nd ed. Portland, OR: Timber Press. 622 p. [23877]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Common Names

western juniper

Sierra juniper

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Synonyms

Juniperus occidentalis ssp. australis (Vasek) A. Holmgren & N. Holmgren

Juniperus occidentalis ssp. occidentalis [40,98]
  • 40. Griffin, James R.; Critchfield, William B. 1972. The distribution of forest trees in California. Res. Pap. PSW-82. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 118 p. [1041]
  • 98. Vasek, Frank C. 1966. The distribution and taxonomy of three western junipers. Brittonia. 18: 350-372. [2426]

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!