Utah juniper is the most common tree in the Great Basin and is widely distributed throughout the arid West [67,80]. The tree occurs occasionally in southern Idaho, southern Montana, and western Wyoming, and is common in Colorado, Utah, Nevada, New Mexico, Arizona, and southeastern California. Utah juniper is the most common juniper species in Arizona .
Regional Distribution in the Western United States
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):
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
Occurrence in North America
AZ CA CO ID MT NV NM OR UT WY
Utah juniper is a short tree that may live as long as 650 years . Utah junipers grow less than 26.4 feet (8 m) and are often as short as 9.9 to 14.85 feet (3-4.5 m), with a trunk 4 to 7.5 inches (10-30 cm) thick [67,66,75,100]. Sometimes the tree has multiple stems .
Under severe site conditions, Utah juniper trees persist in very stunted forms. A 6-inch tree with a 24-inch (60 cm) taproot may be over 50 years old . Utah junipers grow very slowly, usually only about 0.05 inch (0.127 cm) in diameter per year [58,88].
Utah junipers have a taproot that extends deep into the soil (as far as 15 feet (4.5 m)) and lateral roots that may extend as far as 100 feet (30.3 m) from the tree, several inches below the soil surface. Most root biomass is within the first 3 feet (0.9 m) of soil, with fine roots concentrated in the uppermost 18 inches (46 cm)  or just below the soil surface . Utah juniper responds to low nutrient levels in the soil by developing extensive networks of fine roots at the base of the tree and at the end of lateral roots. These roots are in part responsible for the competitiveness of juniper versus understory species [72,78]. Junipers compete more efficiently for soil moisture than do herbaceous understory plants; therefore, over time, junipers are more likely to maintain a stable population, while understory plants decrease [8,50,114].
A Utah study concluded that Utah junipers do not use soil moisture from summer precipitation and do not have active roots in shallow soils layers during the summer .
Utah juniper is colonized by vesicular-arbuscular mycorrhizae .
Habitat and Ecology
Utah juniper thrives on very dry sites [66,80,88]. Precipitation patterns in juniper communities vary, but Utah juniper is generally found in areas of 12 to 18 inches (305-457 mm) of precipitation, with extremes of below 10 inches (254 mm)/year  to highs of 20 inches (508 mm)[31,88,114]. Utah juniper usually occurs in areas with hot, dry summers and cold, wet winters [9,59,93], although Utah juniper is also commonly found in areas of summer monsoonal precipitation in New Mexico and Arizona .
Utah juniper commonly grows on alluvial fans and dry, rocky hillsides [10,67,97,107], with shallow, alkaline soils . Utah juniper is considered a "sodium-sensitive" species [27,107]. In west-central Utah, Utah juniper is found on a range of soil textures, but most often on gravelly loams and gravelly clay loams with a pH range of 7.4 to 8.0 . In the Big Horn Mountains of Wyoming, Utah juniper dominates on limestone soils, whereas ponderosa pine (Pinus ponderosa) in the same elevations dominates on soils derived from granites and sandstones .
Decaying organic material below juniper trees may result in a 0.4 to 0.8 inch (1-2 cm) thick water-repellent soil surface [101,102]. Fire apparently destroys this water repellency .
Utah juniper occurs at 3,000 to 8,000 feet (909-2424 m) elevation in the Great Basin . In Arizona, Utah juniper occurs at 3,000 to 7,500 feet (909-2273 m) , more commonly above 5,000 feet (1515 m) . In California, the plant is common from 4290 to 8580 feet (1300-2600 m)  and found as high as 10,000 feet (3030 m) in the Sierra Nevada . In Utah, Utah juniper is found most often from 5,000 to 7,000 feet (1,500-2,100 m) . The upper limits of the pinyon-juniper zone in Utah and northeastern Arizona are from 6,500 feet (1970 m) on north-facing slopes to 8,400 feet (2545 m) on south-facing slopes .
Key Plant Community Associations
Utah juniper is a climax species in a number of pinyon-juniper (Pinus-Juniperus spp.), sagebrush (Artemisia spp.)-grassland, and shrub-steppe habitat types. At the Idaho National Engineering Laboratory Site, Utah juniper dominates with big sagebrush (A. tridentata), antelope bitterbrush (Purshia tridentata), and threetip sagebrush (A. arbuscula), on areas with bluebunch wheatgrass (Pseudoroegneria spicata), needle-and-thread grass (Hesperostipa comata), Thurber's needlegrass (Achnatherum thurberiana), and Sandberg bluegrass (P. secunda) .
In Utah pinyon-juniper sites, Utah juniper dominates with singleleaf pinyon (Pinus monophylla), Saskatoon serviceberry (Amelanchier alnifolia), threetip sagebrush, black sagebrush (Artemisia nova), big sagebrush, desert ceanothus (Ceanothus greggii), curlleaf mountain-mahogany (Cercocarpus ledifolius), true mountain-mahogany (C. montanus), green rabbitbrush (Chrysothamnus viscidiflorus), Stansbury cliffrose (Purshia mexicana var. stansburiana), antelope bitterbrush, desert snowberry (Symphoricarpos longiflorus), blue grama (Bouteloua gracilis), cheatgrass (Bromus tectorum), bottlebrush squirreltail (Elymus elymoides), sheep fescue (Festuca ovina), galleta (Hilaria jamesii), prairie junegrass (Koeleria macrantha), Indian ricegrass (Achnatherum hymenoides), western wheatgrass (Pascopyrum smithii), Sandberg bluegrass, bluebunch wheatgrass, and needle-and-thread grass .
In pinyon-juniper woodlands in southern California, Utah juniper dominates with singleleaf pinyon, Parry pinyon (Pinus quadrifolia), and California juniper (Juniperus californica). Common associates include Joshua tree (Yucca brevifolia), oaks (Quercus spp.), manzanita (Arctostaphylos spp.), Ceanothus (Ceanothus spp.), mountain-mahogany (Cercocarpus spp.), rabbitbrush (Chrysothamnus spp.), ephedra (Ephedra spp.), buckwheat (Eriogonum spp.), silktassel (Garrya spp.), snakeweed (Gutierrezia spp.), goldenweed (Isocoma spp.), bitterbrush (Purshia spp.), horsebrush (Tetradymia spp.), blackbrush (Coleogyne ramosissima), Stansbury cliffrose, Apache plume (Fallugia paradoxa), California fremont (Fremontodendron californicum), desert peach (Prunus fasciculata), skunkbush sumac (Rhus trilobata), and needlegrass (Achnatherum spp.) .
Habitat typings in which Utah juniper appears as a community dominant include:
Classification of the forest vegetation of Colorado by habitat type and community type 
Forest and woodland habitat types (plant associations) of Arizona south of the Mogollon Rim and southwestern New Mexico 
Vegetation and soils of the Coils Creek Watershed 
Vegetation and soils of the Cow Creek Watershed 
Vegetation and soils of the Crane Springs Watershed 
Vegetation and soils of the Rock Springs Watershed 
Vegetation and soils of the Duckwater Watershed 
Vegetation and soils of the Mill Creek Watershed 
Vegetation and soils of the Churchill Canyon Watershed 
Vegetation and soils of the Pine and Mathews Canyon Watersheds 
Vegetation of the Big Horn Mountains, Wyoming, in relation to substrate and climate 
Grassland, shrubland, and forestland habitat types of the White River-Arapaho National Forest 
A preliminary riparian habitat type classification system for the Bureau of Land Management Districts in southern and eastern Idaho 
Forest and woodland habitat types (plant associations) of northern New Mexico and
northern Arizona 
Flora of the Orange Cliffs of Utah 
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
FRES28 Western hardwoods
FRES30 Desert shrub
FRES34 Chaparral-mountain shrub
FRES36 Mountain grasslands
FRES40 Desert grasslands
Habitat: Rangeland Cover Types
This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):
211 Creosote bush scrub
412 Juniper-pinyon woodland
413 Gambel oak
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
417 Littleleaf mountain-mahogany
503 Arizona chaparral
504 Juniper-pinyon pine woodlands
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
220 Rocky Mountain juniper
237 Interior ponderosa pine
240 Arizona cypress
241 Western live oak
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K019 Arizona pine forest
K023 Juniper-pinyon woodland
K031 Oak-juniper woodlands
K032 Transition between K031 and K037
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
Fire Management Considerations
Juniper habitats are often burned to increase herbaceous cover for grazing or wildlife. Junipers are often difficult to ignite, and burning has been most successful when the trees themselves were lit and managers did not depend on understory fire to carry into the crowns. Often the conditions necessary to get a fire to burn in a dense juniper stand--hot, dry, windy weather--are too dangerous to allow burning [26,114].
One technique for determining whether a prescribed fire in a juniper stand is likely to succeed, at temperatures below 75° Fahrenheit (24°C) and windspeeds above 5 miles/h, was published in 1979. Add together the maximum windspeed (miles/h), air temperature (°F), and percent vegetation cover. When the total of those three numbers exceeds 110, a burn is likely to succeed, with some retorching and some mosaic burning; when the number exceeds 130, conditions are too hazardous for burning. Ideal conditions for a carrying (self-sustaining) fire exist at a score of 126-130 .
Vegetative recovery following a fire in a mature juniper site may be slow, since the prefire herbaceous cover is often sparse [45,46,48]. During this intervening period, soil erosion may be a problem [29,57]. However, Roundy and others studied erosion and infiltration rates following prescribed burns in Nevada and concluded that erosion rates would increase on interspaces, but that on coppice dunes (areas around vegetation with higher infiltration rates) erosion is not a problem.
Prediction of postfire succession is affected by prefire vegetation and its fire survivability, soil seedbank, immigrating propagules, and postfire precipitation [46,48,49,51]. Succession following fire in a climax pinyon-juniper woodland often proceeds as follows: skeleton forest and bare soil; annual stage (2-3 years); annual-perennial forb stage (3-4 years); perennial forb-grass-half-shrub phase (4-6 years); shrub stage or perennial grass stage; eventual pinyon-juniper climax [4,10,41]. However, Everett and Ward  studied 6 burned sites to determine successional pathways, and they concluded that succession starts from multiple points along a hypothetical pathway, and that early postfire communities vary considerably.
In the years following a fire, burned pinyon-juniper and juniper sites are preferred by wildlife species such as pronghorn, elk, bighorn sheep, and mule deer, due to increased understory forage . McCulloch  evaluated the effects of wildfire and prescribed burns on mule deer use of pinyon-juniper woodlands. During a mild winter, there was no significant difference between use of the burned and unburned plots, but during the following winter, a harsh one, mule deer use was significantly higher (p<0.10) on the burned than unburned sites.
Severe fires that result in soil temperatures above 122° Fahrenheit (50oC) reduce the vesicular-arbuscular mycorrhizae propagules in the soil and may restrict the ability of juniper to recolonize the site [77,76].
Utah junipers, like many other arid and semi-arid shrubs and trees, concentrate soil nutrients underneath their canopies by withdrawing them from a large area around the tree through extensive roots. Burning may result in a volatilization loss of nitrogen from a nutrient poor site. Natural nitrogen replenishment rates on these sites are low .
Plant Response to Fire
Barney and Frischknecht  evaluated 28 different burns in west-central Utah to assess vegetation changes following fire in pinyon-juniper communities. The effects of fire on Utah juniper over time were as follows:
|Approximate age of burn (yrs)||Crown cover (%)||Basal area (ft2/acre)|
Trees that established on burned sites immediately after the fire were adjacent to or underneath burned trees, suggesting they had grown from residual seed on the site. Utah junipers dominated these sites 46 to 71 years following the burn .
Rate of re-establishment of juniper depends on the age of the burned stand. More mature trees produce more seed, thereby increasing the rate at which a new stand is established [10,35]. Large rodent populations and unburned seeds or unburned patches within a burned stand will speed up re-establishment of Utah junipers .
Immediate Effect of Fire
Utah juniper is usually killed by fire [10,45], especially when shorter than 3 to 4 feet (0.9-1.2 m) [35,125]. Larger trees, above 4 feet (1.2 m) tall, are capable of surviving surface fires [24,114]. Mortality occurs when 60% or more of the crown is scorched [69,114]. Surface fires will thin a juniper stand to large trees and trees growing on rocks and in other refugia .
Tausch and West  studied fire scars of Utah junipers in a stand in southwestern Utah. Thirty-eight percent of the Utah junipers sampled were older than an approximately 146 year-old fire, and 4 trees had fire scars from a second fire 317 years before sampling.
Ground residual colonizer (on-site, initial community)
Initial off-site colonizer (off-site, initial community)
Utah juniper is usually killed by fire, especially when trees are small. However, Utah juniper habitat types rarely have sufficient fine fuels to produce severe or continuous fires. Fuel loads probably rarely exceed 1 to 3 tons per acre . Phenolic compounds produced by the trees reduce ground cover and therefore further decrease fuel loading around the tree. Sites that are most likely to burn are those with small, scattered trees with sufficient herbaceous understory, or those with large, decadent trees able to sustain a crown fire under windy conditions . Juniper stands are seldom dense enough to carry a crown fire from one tree to the next, so even if one tree is struck by lightning, a fire that burns throughout the stand may not result . One difficulty in estimating fire histories in juniper habitat types is that junipers don't usually form fire scars. If a fire is severe enough to form a fire scar, it probably will kill the cambium .
Ten to 30 years is an estimated mean fire interval for Utah juniper in Arizona, and from 11 to 23 years in southwestern Idaho. Fires were probably more common on slightly more mesic sites than on xeric sites .
More info for the terms: climax, competition, cover, fire suppression, litter, shrub
Utah juniper is not shade tolerant . It is a climax species in harsh areas where stands are open and regeneration can occur without competition for light.
Across the West, junipers have expanded their historical range in the years since European settlement [4,19,24,29,30,73,116,124], especially into sagebrush-grass communities below areas of traditional pinyon-juniper [10,36,86]. Overgrazing, fire suppression, and climatic change have been identified as potential causes of juniper invasion [19,30,33,37,42,86,95,114]. In the absence of fire or other disturbances, trees eventually dominate the site and crowd out herbaceous and shrub species [4,10,19]. On the Fort Apache Indian Reservation in Arizona, herbaceous cover on a grazed area was twice as high after clearing junipers as on control plots .
Juniper litter has an allelopathic effect on some understory species, especially Idaho fescue (Festuca idahoensis), Sandberg bluegrass, and blue grama [24,44,50,70,120]. This effect is particularly evident on heavy, poorly drained clay soils . Broadcasting grass seeds over litter appeared to lower the allelopathic effects .
Cheatgrass does not appear to suffer from allelopathic effects , and fourwing saltbush (Atriplex canescens) growth increases under juniper canopies .
Utah juniper is monoecious and sometimes dioecious [4,67,54,80,123]. It reproduces by seeds in cones and produces abundant seeds in most years  or every couple of years [9,62]. Cones have 1 or 2 seeds . The seeds have dormant embryos and impermeable seedcoats, so they need a period of "after-ripening" and usually germinate the second season following maturity .
Utah junipers begin to produce seed only when they are about 30 years old [24,58]. Utah juniper seeds are long-lived. In one study, 17% of Utah juniper seeds germinated after 45 years [4,j71]. In general, about 8 to 49% of Utah juniper seeds germinate .
Animal transport of seeds is an important factor in the dissemination of juniper seeds [9,24,88], especially by jackrabbits [10,103]. Seeds that have passed through the digestive tract of animals germinate more quickly than those that have not .
Growth Form (according to Raunkiær Life-form classification)
Life History and Behavior
|Bark begins to slip||March 25|
|Pollen shedding; seed cones open||March 25|
|Approx. start of leader elongation||April 20|
|First conspicuous new pollen cones||August 19|
|Bark begins to stick||September 15|
|Leader elongation ceases||October 19|
Molecular Biology and Genetics
Barcode data: Juniperus osteosperma
Statistics of barcoding coverage: Juniperus osteosperma
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Juniperus osteosperma is the most wide-spread species of juniper in the extensive Pinyon-Juniper woodland formation of the SW USA; it has little commercial value and occurs often on rocky escarpments and plateaus where few other plants get a foothold. It is therefore assessed as Least Concern.
- 1998Lower Risk/least concern (LR/lc)
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Currently one of the most important economic values of pinyon-juniper woodlands is for livestock grazing .
In northwest Colorado, chaining Utah juniper stands to increase livestock production resulted in a significant reduction of bird species diversity (p<0.05) and an increase in the number of small mammals .
Utah juniper is occasionally heavily infested by juniper mistletoe (Phoradendron juniperum ssp. juniperum) and dense mistletoe (P. bolleanum ssp. densum) .
Relevance to Humans and Ecosystems
Utah juniper is an important cover and shelter species for several large animals, including mule deer throughout its range, elk for winter cover in Wyoming, Utah, and New Mexico, desert bighorn sheep throughout the Southwest, bison in Utah, wild horses throughout the West, mountain lion and lynx in Utah, Wyoming and Arizona, and pronghorn in Utah and Nevada [32,43,55,82,84,87,109].
Several small animals are also commonly found in pinyon-juniper woodlands, including the porcupine, desert cottontail, deer mouse, Great Basin pocket mouse, chisel-toothed kangaroo rat, desert woodrat, and others [55,121]. A study of small mammal populations on unchained, and on 8-year-old, and 15-year-old chained pinyon-juniper woodlands in Colorado found greater species diversity on the unchained site, although lower total numbers of animals .
Many reptiles also rely on the pinyon-juniper ecosystem for habitat .
Seventy-three different bird species breed in pinyon-juniper habitat woodlands, although of those, only 5 are obligates (screech owl, gray flycatcher, scrub jay, plain titmouse, and gray vireo) and 13 semi-obligates . Ferruginous hawks nest in Utah juniper trees .
A study of chained juniper woodlands in Colorado concluded that breeding bird densities were more than double on unchained than on 8-year-old and 15-year-old chained areas. There were no breeding species in common between the 2 types of sites, since the woodland supported tree-dependent species, and the chained sites supported ground- and shrub-nesters. Species diversity was also greater on the unchained sites .
Utah juniper is only moderately nutritious forage. The tree has low concentrations of manganese, iron, potassium, and phosphorus compared to other forage. Utah juniper does have high calcium, but with a calcium to phosphorous ratio of 28 to 1, animals probably would not do well on it . Winter crude protein levels are from 6.4 to 7.9%. Eight percent protein is considered a maintenance value for mule deer . In a Utah feeding trial, Smith  concluded that Utah juniper's low protein content makes it very poor feed, especially for young animals. In vitro dry matter digestibility for Utah juniper, measured in the fall, was 44.1% in a Utah study. Fifty percent is considered to be a maintenance level for mule deer .
Nutrient content of Utah juniper is as follows :
|Crude fiber (%)||22.0|
|Ether extract (%)||16.3|
|N-free extract (%)||50.8|
Utah juniper needles contain volatile oils--monoterpene hydrocarbons, oxygenated monoterpenes, and sesquiterpenes--that, in high concentration, can be damaging to the microorganisms in a deer's rumen and prevent proper digestion of food [39,104]. In a study comparing Utah juniper oil with that of alligator juniper and Rocky Mountain juniper, Utah juniper was most inhibitory of rumen microbial activity. Deer are able to detect the volatile oil content of food and will preferentially browse foods with lower content .
Importance to Livestock and Wildlife
Utah juniper is used by many birds and animals, both wildlife and livestock, for cover and food.
Wood Products Value
Value for rehabilitation of disturbed sites
Utah juniper is generally considered too slow growing to be useful as a site rehabilitation species .
Juniper "berries" or berry-cones are eaten by jackrabbits and coyotes . Many bird species depend on juniper berry-cones for fall and winter food . The foliage is grazed by mule deer when other foliage is scarce and during periods of deep snow [67,39,43,55]. Although deer mice and other small mammals are common in Utah juniper stands, in deer mice feeding trials in Nevada, Utah juniper seeds were the least preferred food choice of 28 seeds .
Large mammal use of Utah juniper is outlined in the following table [31,55,60,74,92,91,87,109,113]:
|mule deer||medium, in winter||medium to high, in winter||low||low||high, in winter|
|elk||--||--||low||medium, in winter||low|
|domestic sheep||--||none to low||--||--|
|pronghorn||--||--||low to medium||--||--|
Juniperus osteosperma (Utah Juniper; syn. J. utahensis) is a shrub or small tree reaching 3–6 m (rarely to 9 m) tall. It is native to the southwestern United States, in Utah, Nevada, Arizona, western New Mexico, western Colorado, Wyoming, southern Montana, southern Idaho and eastern California. It grows at moderate altitudes of 1,300–2,600 metres (4,300–8,500 ft), on dry soils, often together with Pinus monophylla.
The shoots are fairly thick compared to most junipers, 1.5–2 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 millimetres (0.039–0.059 in) broad. The juvenile leaves (on young seedlings only) are needle-like, 5–10 mm long. The cones are berry-like, 8–13 millimetres (0.31–0.51 in) in diameter, blue-brown with a whitish waxy bloom, and contain a single seed (rarely two); they are mature in about 18 months. The male cones are 2–4 millimetres (0.079–0.157 in) long, and shed their pollen in early spring. It is largely monoecious with both sexes on the same plant, but around 10% of plants are dioecious, producing cones of only one sex.
The plants frequently bear numerous galls caused by the Juniper Tip Midge Oligotrophus betheli (Bibionomorpha: Cecidomyiidae); these are conspicuous pale violet-purple, produced in clusters of 5-20 together, each gall 1–2 centimetres (0.39–0.79 in) diameter, with dense modified spreading scale-leaves 6–10 millimetres (0.24–0.39 in) long and 2–3 millimetres (0.079–0.118 in) broad at the base. Seeds are dispersed by Jackrabbits (mostly the Black-tailed Jackrabbit Lepus californicus spp.) rodents and to a lesser extent by coyotes (Canis latrans).
Names and Taxonomy
The accepted scientific name for Utah juniper is Juniperus osteosperma (Torr.) Little (Cupressaceae) [66,67,75].
In northwestern Nevada, Utah juniper hybridizes with western juniper (J. occidentalis). In Arizona, Utah juniper hybridizes with oneseed juniper (J. monosperma), Rocky Mountain juniper (J. scopulorum), and alligator juniper (J. deppeana) .