Red Cedar

Juniperus scopulorum hybridizes with its eastern relative J . virginiana in zones of contact in the Missouri River basin (C. W. Comer et al. 1982) and with J . horizontalis ( J . ´ fassettii Boivin; N. C. Fassett 1945). Relictual hybridization with J . virginiana is known in the Texas panhandle (R. P. Adams 1983).

Trees dioecious, to 20 m, single-stemmed (rarely multistemmed); crown conic to occasionally rounded. Bark brown, exfoliating in thin strips, that of small branchlets (5--10 mm diam.) smooth, that of larger branchlets exfoliating in plates. Branches spreading to ascending; branchlets erect to flaccid, 3--4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves light to dark green but often glaucous blue or blue-gray, abaxial gland elliptic, conspicuous, exudate absent, margins entire (at 20´ and 40´); whip leaves 3--6 mm, not glaucous adaxially; scalelike leaves 1--3 mm, not overlapping to overlapping by not more than 1/5 their length, keeled to rounded, apex obtuse to acute, appressed or spreading. Seed cones maturing in 2 years, of 2 distinct sizes, generally with straight peduncles, globose to 2-lobed, 6--9 mm, appearing light blue when heavily glaucous, but dark blue-black beneath glaucous coating when mature (or tan beneath glaucous coating when immature), resinous to fibrous, with (1--)2(--3) seeds. Seeds 4--5 mm. 2 n = 22.

Rocky soils, slopes, and eroded hillsides; 1200--2700 m (0 m at Vancouver Island and Puget Sound); Alta., B.C.; Ariz., Colo., Idaho, Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wash., Wyo.; n Mexico.

Sabina scopulorum (Sargent) Rydberg

The effects of fire on Rocky Mountain juniper vary according to site characteristics. The species often occurs in dry, subhumid areas with sparse undergrowth; in these habitats where surface fuels are limited, fire damage is often minor [44].

More info for the terms: fire use, prescribed fire, restoration

The Research Project Summary
Vegetation response to restoration treatments in ponderosa pine-Douglas-fir forests of western Montana
provides information on prescribed fire use and postfire response of plant community
species including Rocky Mountain juniper.

Rocky Mountain juniper

mountain red cedar

Rocky Mountain cedar

More info for the terms: presence, shrub, tree

Rocky Mountain juniper is a perennial, evergreen gymnosperm native to North America [73]. The species grows as a shrub or tree to 30 feet (10 m) or more and has thin, fibrous bark that usually shreds with age [27,78,121]. In the open, trees are stubby and broadly pyramidal with branches to ground level. In shaded areas, the trunk is less tapered and foliage arranges in "weeping sprays" [27,65,78]. Leaves are scalelike and 0.03-0.11 inch (1-3 mm) long or needlelike and 0.11-0.47 inch (3-12 mm) long [46,121].

Staminate cones are solitary at tips of branchlets, ovoid or mostly ellipsoid and 0.08-0.16 inch (2-4 mm) long [27,53,121]. Ovulate cones, or "berries", are solitary at the tips of branches and are fleshy with a resinous pulp. Berries are globose to subglobose, 0.16-0.31 inch (4-8 mm) in diameter [27,78,81,121]. Each contains 1-3 (up to 12) round seeds, 0.08-0.20 inch (2-5 mm) in diameter [27,53,65,82,121].

Rocky Mountain juniper is a long-lived species that often survives to be 250-300 years old or more [27,132]. A 36-foot (11 m) tall, 6.5-foot (2 m) diameter specimen near Logan, Utah was estimated at 3,000 years old [11,65,119,132].

Rocky Mountain juniper's morphological traits vary widely depending on climate, the presence of other species for hybridization, and other factors [28]. The preceding description provides characteristics of Rocky Mountain juniper relevant to fire ecology and is not meant to be used for identification. Detailed morphological descriptions and keys for identifying Rocky Mountain juniper are available [27,53].

Rocky Mountain juniper occurs throughout the drier mountains and foothills of British Columbia and Alberta; south through the Great Basin and Rocky Mountains to Arizona, New Mexico, and western Texas; and north across eastern Colorado, western Nebraska and North Dakota, Montana, and into Saskatchewan. It is also found on Vancouver and other Puget Sound islands, as well as the surrounding mainland [65,78,121].

Distribution of some hybrids is: Juniperus scopulorum x J. virginiana in Nebraska, North Dakota, and South Dakota [40,41,46]; J. scopulorum x J. horizontalis in Montana, North Dakota, and Alberta [1,41,46]; J. scopulorum x J. deppeana across central and north-central New Mexico, as well as in Walnut Canyon east of Flagstaff, Arizona [55,65]; J. scopulorum x J. osteosperma from Walnut Canyon north into Utah and east to Mesa Verde [55]. Distribution of Rocky Mountain juniper can also be accessed at The Plants Database.

More info for the terms: fire interval, fire regime, fire tolerant, fuel, fuel continuity, habitat type, mean fire interval, surface fire, woodland

Fire adaptations: Due to its thin bark and compact crown, Rocky Mountain juniper trees up to 3-4 feet (0.9-1.2 m) tall are easily killed by fire. Since the species grows slowly, trees are especially susceptible to fire for their first 20 years or more [26,44,57,87,89,114]. Large Rocky Mountain junipers, however, have survived at least 4-6 fires [26,44,87]. As trees mature, they develop thicker bark and a more open crown, allowing them to survive surface fires if the low, spreading branches do not carry fire to the crown [26,44,57,87]. A severe fire, however, may damage or kill such trees [44]. High volatile oil content, especially in the lower branches, also makes the trees more flammable [90,112].

FIRE REGIMES: Fire return intervals vary for habitats where Rocky Mountain juniper occurs. For example, in pinyon-juniper habitat (including Rocky Mountain juniper) of the Sacramento Mountains of New Mexico, the mean fire interval was 28 years with a range of 10-49 years, and fires that covered more than 25 acres (10 hectares) occurred at 15-20 year intervals in other areas of New Mexico. Research in the Walnut Canyon National Monument in Arizona reported surface fire intervals of 20-30 years for pinyon-juniper habitat where Rocky Mountain juniper occurs [94].

A fire history study in Mesa Verde National Park estimated the historic interval between stand-replacing fires for pinyon-juniper habitat, where Rocky Mountain juniper was a dominant, at approximately 400 years, and large fires may have not occurred for more than 600 years in some areas. In contrast, fire intervals for chaparral communities in the park were estimated at 100 years. It appears that, in this area, pinyon-juniper habitat that was burned severely was replaced by chaparral species, which are more fire tolerant. As a result, pinyon-juniper habitat is found mostly in the southern part of the park, where cliffs and sparsely vegetated slopes form a barrier to fire. Though this habitat type may support heavy fuel loads, horizontal fuel continuity remains low, so crown fires are usually confined to relatively small areas unless high winds and extreme drought occur [47].

Little information was available regarding FIRE REGIMES specific to Rocky Mountain juniper communities as of 2002. Fire return intervlas for plant communities and ecosystems in which Rocky Mountain juniper occurs are summarized below. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".

Community or Ecosystem Dominant Species Fire Return Interval Range (years) sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [94] basin big sagebrush Artemisia tridentata var. tridentata 12-43 [104] mountain big sagebrush Artemisia tridentata var. vaseyana 15-40 [10,22,85] Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40**) [124,131] saltbush-greasewood Atriplex confertifolia-Sarcobatus vermiculatus desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100  plains grasslands Bouteloua spp. 94] curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1000 [13,106] mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii western juniper Juniperus occidentalis 20-70  Rocky Mountain juniper Juniperus scopulorum 94] western larch Larix occidentalis 25-100  blue spruce* Picea pungens 35-200 [9] pinyon-juniper Pinus-Juniperus spp. 94] whitebark pine* Pinus albicaulis 50-200 [9] Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-300+ [7,9,102] Colorado pinyon Pinus edulis 10-49 [94] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [9,15,79] aspen-birch Populus tremuloides-Betula papyrifera 35-200 [33,126] mountain grasslands Pseudoroegneria spicata 3-40 (10**) [7,9] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [9,10,12] oak-juniper woodland (Southwest) Quercus-Juniperus spp. 94] Oregon white oak Quercus garryana 9] bur oak Quercus macrocarpa 126] oak savanna Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [94,126] elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. 33,126] *fire return interval varies widely; trends in variation are noted in the species summary
**mean

More info for the terms: competition, fuel, herbaceous, wildfire

Fire has long been recognized as a control mechanism for juniper [44]. In the 1950s and 1960s some pinyon-juniper elimination operations were conducted by mechanical methods and slash was piled and burned. Some areas where these large fuel loads were burned remained free of vegetation 20 years later [94].

In areas where Rocky Mountain juniper is not desirable, young trees have been killed mechanically by scorching the crown and stems [44]. Tree-by-tree burning and wildfire both control Rocky Mountain juniper effectively in juniper and sagebrush-grass types in Wyoming [45]. In central Oregon, one juniper control technique is to conduct prescribed fires several years after harvesting trees, when herbaceous vegetation will be present to provide fuel to carry fire to juniper seedlings [94]. In general, control of Rocky Mountain juniper by fire has been more effective in the southern part of its range [90].

Thinning undergrowth in pinyon-juniper woodlands favors Rocky Mountain juniper by reducing the number and intensity of fires and reducing competition for moisture [89].

More info on this topic.

More info for the term: phanerophyte

RAUNKIAER [98] LIFE FORM:
Phanerophyte

More info for the terms: tree, woodland

Topography: Rocky Mountain juniper is most abundant in dry, clay, rocky, or sandy slopes, canyons and wash areas as well as prairie hillsides, fields, pastures, and woodlands [34,53,65,72,78,81,121]. The species grows best along ravines, in canyon bottoms, and on moist, cool hillsides [65,72]. It is found on exposed bluffs, rocky points, and southern exposures throughout its range and is common on northern exposures in North Dakota and South Dakota [90].

Substrate: Rocky Mountain juniper prefers calcareous and somewhat alkaline soils and grows best on moist, deep soils [65]. The species is found on soils derived from basalt, limestone, sandstone, lavas, and shale. It also grows in many places where there is no developed soil [39,65,90].

Climate: Rocky Mountain juniper is generally found in dry, subhumid climates [90]. It also grows in moist, subhumid regions in the northern part of its range and in semiarid regions in the central and southern parts of its range [65]. The species can tolerate temperature extremes from -35 to 110º Fahrenheit (-37 to 43º C), but performs best where the average minimum temperature is greater than -10 to -5º Fahrenheit (-23 to -21º C). In its range, mean July temperatures range from 60 to 75º Fahrenheit (16 to 24 ºC) and mean January temperatures range from 15 to 40º Fahrenheit (-9 to 4º C) [65,90]. The average number of frost free days ranges from 120 in the northern Rockies to 175 at low elevations in Arizona and New Mexico [90]. Rocky Mountain juniper is adapted to dry climates and requires only about 10 inches (254 mm) of annual precipitation [11,65]. The average annual precipitation in its range varies from 12 inches (305 mm) in the Southwest, Great Basin, and eastern slope of the Rocky Mountains in Colorado to 26 inches (660 mm) in the Puget Sound area [90].

Tolerance/affinity for harsh environments: Rocky Mountain juniper is considered hardy except for "burning" of foliage on trees exposed to northwest winds during winter in the northern Great Plains [50]. It can tolerate shade when young, but becomes intolerant later in life [11,26,65]. It is more drought tolerant than eastern redcedar and less so than other tree junipers in the west [90]. In fact, during the 1930s drought, Rocky Mountain juniper woodland maintained and expanded range in the western Dakotas [107].

Elevation: Rocky Mountain juniper is found near sea level in the Puget Sound to 9,000 feet (2,700 m) in the Southwest [65,90]. Elevation ranges for Rocky Mountain juniper in some states are:

Arizona 5,000-9,000 feet (1,500-2,700 m) [65,74] Colorado 4,000-8,500 feet (1,200-2,600 m) [62,65] Idaho 2,000-5,000 feet (600-1,500 m) Montana 1,900-7,500 feet (600-2,300 m) Nevada 3,500-7,400 feet (1,000-2,000 m) [65] New Mexico 5,000-9,000 feet (1,500-2,800 m) [65,81] Texas 2,000-6,000 feet (600-1,800 m) [113] Utah 3,500-7,400 feet (1,100-2,300 m) [65]

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):

More info for the term: cover

SAF COVER TYPES [39]:




46 Eastern redcedar

206 Engelmann spruce-subalpine fir

208 Whitebark pine

209 Bristlecone pine

210 Interior Douglas-fir

212 Western larch

216 Blue spruce

217 Aspen

218 Lodgepole pine

219 Limber pine

220 Rocky Mountain juniper

221 Red alder

233 Oregon white oak

235 Cottonwood-willow

236 Bur oak

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

240 Arizona cypress

241 Western live oak

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):

More info for the term: shrub

ECOSYSTEMS [48]:




FRES17 Elm-ash-cottonwood

FRES20 Douglas-fir

FRES21 Ponderosa pine

FRES23 Fir-spruce

FRES25 Larch

FRES26 Lodgepole pine

FRES29 Sagebrush

FRES30 Desert shrub

FRES32 Texas savanna

FRES33 Southwestern shrubsteppe

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

FRES36 Mountain grasslands

FRES38 Plains grasslands

FRES39 Prairie

FRES40 Desert grasslands

More info on this topic.

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

More info for the terms: forest, shrub, woodland

KUCHLER [76] PLANT ASSOCIATIONS:




K010 Ponderosa shrub forest

K011 Western ponderosa forest

K012 Douglas-fir forest

K015 Western spruce-fir forest

K016 Eastern ponderosa forest

K017 Black Hills pine forest

K018 Pine-Douglas-fir forest

K019 Arizona pine forest

K021 Southwestern spruce-fir forest

K022 Great Basin pine forest

K023 Juniper-pinyon woodland

K024 Juniper steppe woodland

K031 Oak-juniper woodland

K032 Transition between K031 and K037

K037 Mountain-mahogany-oak scrub

K038 Great Basin sagebrush

K040 Saltbush-greasewood

K055 Sagebrush steppe

K056 Wheatgrass-needlegrass shrubsteppe

K063 Foothills prairie

K064 Grama-needlegrass-wheatgrass

K065 Grama-buffalo grass

K066 Wheatgrass-needlegrass

K067 Wheatgrass-bluestem-needlegrass

K068 Wheatgrass-grama-buffalo grass

K070 Sandsage-bluestem prairie

K098 Northern floodplain forest

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):

More info for the terms: association, cover, grassland, shrub, shrubland, woodland

SRM (RANGELAND) COVER TYPES [108]:




104 Antelope bitterbrush-bluebunch wheatgrass

105 Antelope bitterbrush-Idaho fescue

107 Western juniper/big sagebrush/bluebunch wheatgrass

109 Ponderosa pine shrubland

209 Montane shrubland

210 Bitterbrush

212 Blackbush

314 Big sagebrush-bluebunch wheatgrass

315 Big sagebrush-Idaho fescue

316 Big sagebrush-rough fescue

317 Bitterbrush-bluebunch wheatgrass

318 Bitterbrush-Idaho fescue

319 Bitterbrush-rough fescue

320 Black sagebrush-bluebunch wheatgrass

321 Black sagebrush-Idaho fescue

322 Curlleaf mountain-mahogany-bluebunch wheatgrass

401 Basin big sagebrush

402 Mountain big sagebrush

403 Wyoming big sagebrush

404 Threetip sagebrush

405 Black sagebrush

406 Low sagebrush

408 Other sagebrush types

412 Juniper-pinyon woodland

413 Gambel oak

415 Curlleaf mountain-mahogany

416 True mountain-mahogany

417 Littleleaf mountain-mahogany

421 Chokecherry-serviceberry-rose

422 Riparian

501 Saltbush-greasewood

503 Arizona chaparral

504 Juniper-pinyon pine woodland

505 Grama-tobosa shrub

509 Transition between oak-juniper woodland and mahogany-oak association

607 Wheatgrass-needlegrass

608 Wheatgrass-grama-needlegrass

612 Sagebrush-grass

613 Fescue grassland

615 Wheatgrass-saltgrass-grama

724 Sideoats grama-New Mexico feathergrass-winterfat

731 Cross timbers-Oklahoma

732 Cross timbers-Texas (little bluestem-post oak)

735 Sideoats grama-sumac-juniper

Rocky Mountain juniper is readily killed by ground fires or by low intensity surface burns [11,47]. Larger trees may survive low intensity fires due to their thicker bark and more open crown. See Fire Ecology or Adaptations for more information.

More info for the terms: cover, habitat type, tree

Rocky Mountain juniper is important forage and cover to many wildlife species [121].

Palatability/nutritional value: Waxwings are the principal consumers of Rocky Mountain juniper cones ("berries"), but numerous other birds and mammals include the berries in their diets [121]. Big sagebrush (Artemisia tridentata), bitterbrush (Purshia spp.), and Rocky Mountain juniper combined have been reported to make up 66% of winter mule deer browse [16] and Rocky Mountain juniper is considered a major component of wintering mule deer diet in the Bridger Mountains of Montana [54]. Mule deer browse the foliage moderately in winter, spring, and fall, and lightly in the summer [77]. High levels of volatile oils in Rocky Mountain juniper may cause mule deer to select against the foliage in favor of other browse when available [30]. Other animals that use Rocky Mountain juniper berries, foliage, or stems for forage include white-tailed deer, black-tailed deer, Rocky Mountain goats, ring-necked pheasant, grouse, and cattle [25,36,105,121]. Overall, it is rated good in energy value and fair in protein value [31].

Palatability of Rocky Mountain juniper is rated as follows [31]:

  CO MT ND UT WY cattle poor poor ---- poor poor domestic sheep poor poor poor fair fair horses poor poor poor poor poor antelope ---- ---- poor poor poor elk poor poor ---- fair fair mule deer poor poor fair fair good white-tailed deer ---- ---- poor ---- good small mammals good poor ---- good good small nongame birds ---- poor fair good good upland game birds ---- poor good good fair waterfowl ---- ---- ---- poor poor

Relative food and cover values of Rocky Mountain juniper for white-tailed deer and mule deer in Wyoming are as follows [91,92]:

  summer forage winter forage hiding/escape cover thermal cover fawning cover white-tailed deer fair good excellent excellent good mule deer poor fair excellent excellent good

Cover value: The dense protective shelter of Rocky Mountain juniper is especially valuable in the winter [121].

Rocky Mountain juniper woodlands provide nesting habitat, migratory corridors, and winter food and cover for birds otherwise found only in forested areas and provide needed woody cover for birds on the edges of grasslands [111]. Rocky Mountain juniper is a favored nesting tree of chipping sparrows, robins, song sparrows, and mockingbirds [121], and is used for nesting by sharp-shinned hawks in Utah [96]. Juncos, myrtle warblers, sparrows and other birds roost in the dense foliage [121].

In the northern Great Plains Rocky Mountain juniper woodlands provide habitat for bushy-tailed woodrats, white-footed mice, deer mice, prairie voles, pocket mice, and eastern cottontail [103,110]. Big game use the Rocky Mountain juniper habitat type for forage and cover [56,60].

Cover value of Rocky Mountain juniper is rated as follows [31]:

  CO MT ND UT WY pronghorn ---- ---- poor poor poor elk fair good ---- fair good mule deer good good good good good white-tailed deer ---- ---- good ---- good small mammals good fair fair good good small nongame birds good fair good good good upland game birds ---- fair fair good good waterfowl ---- ---- ---- good good antelope ---- ---- poor poor poor

More info for the terms: association, habitat type, tree, woodland

Rocky Mountain juniper is found over most of the range of pinyon (Pinus
spp.)-juniper (Juniperus spp.) woodlands [14,21,84]. It is a major tree species in the
higher elevations of pinyon-juniper woodlands in Colorado, northern New Mexico, and Arizona, and
locally in Nevada and Utah [43]. In pinyon-juniper woodlands, it is found in association with other
juniper species such as alligator juniper, oneseed juniper, and Utah juniper, as well as Colorado
pinyon (Pinus edulis), Mexican pinyon (P. cembroides), and singleleaf pinyon
(P. monophylla) [71,80,95].

Rocky Mountain juniper communities in the northern Great
Plains are often restricted to steep, north-facing slopes. Individuals may be scattered across
other areas in mountains and canyons throughout the Rocky Mountain region, such as rocky outcrops,
butte tops, draws, and floodplains [19,49,58,109]. Rocky Mountain juniper forms open woodland with
sagebrush and grasses [122], and it is often found mixed with Douglas-fir (Pseudotsuga
menziesii) [8,72,122], Gambel oak (Quercus gambelii) [26,72], or ponderosa pine
(Pinus ponderosa) [26,72,109,122]. It is also found along waterways in pure stands or as
understory in the cottonwood (Populus spp.)-willow (Salix spp.) habitat type [122].
It forms pure stands at middle and low elevations in the northern part of its range [90].

Classifications describing plant communities in which Rocky Mountain juniper
is a dominant species are as follows:

Colorado [4,66,118]

Wyoming [2,3,5,6,57,115]

Idaho [20,70,115]

Montana [57,59,60,88,101]

North Dakota [57]

South Dakota [5,57,68,117]

Utah [128]

More info for the term: tree

Tree

More info for the terms: seed, tree

Propagation:
Rocky Mountain juniper can be propagated from cuttings
or from seed [18], though it can be difficult to grow from seed due to
prolonged dormancy [99]. Trickle irrigation of wooded draws in coal-mine spoils of
the Northern High Plains increased the survival rate of Rocky Mountain juniper by
nearly 100% [18]. Wagner and others [127], Noble [90], and U.S.D.A. [121] discuss methods of artificial regeneration of Rocky
Mountain juniper.

Pests:
Rocky Mountain juniper is hearty and relatively disease resistant and insect tolerant [123].
However, several cedar foliage rusts are found on Rocky Mountain juniper. Cedar apple blight
(Gymnosporangium juniperi-virginianae), for which Rocky Mountain juniper is the alternate
host, does little harm [65,121]. Two similar rusts (G. betheli and G. nelsoni)
cause galls on stems. The extent of damage in the wild is unknown, but these rusts can be
destructive to nursery stock. Juniper mistletoes are also found on Rocky Mountain juniper in
Arizona and New Mexico, but their effects are unknown [65]. Other diseases to which the tree is
susceptible include Phomopsis blight (Phomopsis juniperovora), Cercospora blight
(Cercospora sequoiae var. juniperi), and Kabatina tip blight
(Kabatina juniperi) [65,100].

Rocky Mountain juniper is also vulnerable to attack by several insects, including the following:
roundheaded borer (Callidium californicum) in Oregon and Washington, bark beetles
(Phloeosinus scopulorum) in Washington and British Columbia, cedar twig beetles
(Phloeosinus spp.) throughout the central and southern part of its range, cedar flathead
borers (Chrysobothris spp.), and gall midges (Walshomyia insignis) [65]. Two
species of spider mites and 2 species of juniper berry mites can also cause
problems. Noble [90] discusses pests and their effects in more detail.

Control:
Rocky Mountain juniper is difficult to kill without cutting or fire, though herbicides may work to
kill individual trees [90]. A combination of tebuthiuron and picloram was somewhat effective at
controlling Rocky Mountain juniper in pinyon-juniper woodlands of New Mexico; the effectiveness of
both decreased as the size of trees increased [83]. A 2-way application of Tordon did not
significantly affect Rocky Mountain juniper [45]. Refer to Fire Effects
for information on using fire to control Rocky Mountain juniper.

Other:
Rocky Mountain juniper is susceptible to erosion damage because the species establishes on
exposed, erodable sites [65,111]. Use by animals as "rubbing posts" may also damage
stems and roots, and may provide an entryway for pathogens. Also, range animals may browse,
or "high-line", crown foliage and alter growth and vigor of trees [90]. In wet years
and near springs, use by American bison and cattle should be monitored to avoid accelerating
the erosion process by overuse [111].

AZ CO ID MT NE
NV NM ND OK OR
SD TX UT WA WY

AB BC SK

More info for the term: fuel

Rocky Mountain juniper's close-grained, durable, aromatic wood is used for furniture, interior paneling, fence posts, fuel, and novelties such as chests [11,65,121]. It is especially well-suited for fencing because the wood lasts a long time in contact with the ground. The wood is not used regularly for other products due to its small size and knotty, twisted trunks [11]. Northern Plains tribes preferred Rocky Mountain juniper branches for making bow staves [129].

Native Americans have used Rocky Mountain juniper seeds, "berries", and foliage for incense, teas, or salves to treat a variety of ailments including respiratory problems, backaches, vomiting and diarrhea, dandruff, high fever, arthritis and muscular aches, kidney and urinary ailments, and heart and circulatory problems. It has also been used to facilitate childbirth [24,37,63,120,121]. Juniper berries are also used to make gin [11].

More info on this topic.

More info for the terms: formation, tree

Pistillate flowers of Rocky Mountain juniper become conspicuous during late summer, then open the following April, when staminate flowers shed pollen [53,65,121,132]. Female cones ("berries") ripen and attain full size in the 1st autumn after pollination [65,82,121,132]. Berries mature by November or December of the 2nd year after pollination, then remain on the tree until March or April of the following spring [27,46,65,82,121]. Some may remain on the tree for up to 3 years [90].

Additional Rocky Mountain juniper phenological data from an Arizona study are [64]:
Bark begins to slip: 4/8
Pollen shedding and female flowers open: 4/15
Approximate start of leader elongation: 4/20
First conspicuous formation of male flowers: 8/26
Bark begins to stick: 9/15
Leader elongation ceases: 10/19

More info for the terms: climax, density, fire frequency, forest, frequency, grassland, seed, shrub, succession, top-kill, tree, wildfire, woodland

 
Rocky Mountain juniper does not resprout after top-kill [57,112,114,130]. Postfire re-establishment is solely by seed [47], and animal transport of seeds is an important factor [94].Numerous seedlings often germinate after burning of old trees [114,130].

Fire is a major factor controlling the distribution of Rocky Mountain juniper [114,130]. Reduced fire frequency, along with climate change and introduction of grazing, accounts for the expansion of juniper woodlands into meadows, grasslands, sagebrush communities, and aspen groves that began in the late 1800s. Prior to this time, more frequent fires probably maintained low density in woodlands and often restricted junipers to rocky sites [86]. In general, the species grows in areas that do not burn frequently or intensely.

Frequent fires in the pinyon-juniper type can maintain a grassland setting, and the absence of fire will allow conversion to woodlands [54]. Wildfire eliminated Rocky Mountain juniper for 28 years in the Missouri, Judith, and Musselshell river breaks of central Montana [35]. In many areas where Rocky Mountain juniper grows, lack of heavy fuels may limit fire activity to surface fires of low intensity, allowing the species to persist [101]. It is often found in ponderosa pine forests where fire has been absent for long periods [93,101], and the resurgence of Rocky Mountain juniper in Idaho grasslands is due to fire cessation [75]. Severe fires in Douglas fir-Rocky Mountain juniper habitats in Montana appear limited to local areas where fire is carried into the crowns of widely-spaced trees [101].

After fire in pinyon-juniper habitat, junipers will usually invade the area first, followed by pinyon, which may eventually replace juniper on higher sites [69]. The following stages have been outlined for postfire succession in southwestern Colorado climax pinyon-juniper forest (including Rocky Mountain juniper): 1) skeleton forest and bare soil, 2) annual stage, 3) perennial grass-forb stage, 4) shrub stage, 5) shrub-open tree stage, 6) climax pinyon-juniper forest [38,94]. It takes approximately 300 years to reach climax [94].

Postfire succession in western Utah juniper woodland (including Rocky Mountain juniper) takes approximately 85-90 years: 1) skeleton forest and bare soil, 2) annual stage, 3) perennial grass-forb stage, 4)perennial grass-forb-shrub stage, 5) perennial grass-forb-shrub-young juniper stage, 6) shrub-juniper stage, 7) juniper woodland [38,94].

More info for the terms: adventitious, initial off-site colonizer, secondary colonizer, seed, shrub, tree

POSTFIRE REGENERATION STRATEGY [116]:
Tree without adventitious bud/root crown
Shrub without adventitious bud/root crown
Initial off-site colonizer (off-site, initial community)
Secondary colonizer (on-site or off-site seed sources)

More info for the terms: dioecious, monoecious, seed, tree

Breeding system: Rocky Mountain juniper is mostly dioecious, though it is rarely monoecious [27,53,65].

Pollination: Pollen is distributed mainly by wind in the spring [90].

Seed production: Rocky Mountain juniper may begin bearing seeds at 10-20 years of age, but the optimum age for seed production is 50-200 years. Trees can bear seed nearly every year, but heavier crops occur every 2-5 years [65,90,121]. The species is usually a prolific seeder, especially when stunted or growing in the open. Seeds are small, at 18,000-42,000 seeds per pound (8,000-19,000 seeds/kg) [65].

Seed dispersal: Rocky Mountain juniper ovulate cones ("berries") remain on the tree through the winter, unless consumed by birds or other animals, then ripen and fall from the tree in the 2nd spring [11]. The berries are dispersed mainly by birds, whose digestive tracts pass the seeds quickly with little effect on germination capability [26,65,69,78,82,87]. Bohemian waxwings are the primary dispersers and have been reported to pass 900 seeds in just 5 hours [11]. Other avian consumers include robins, solitaires, turkey, jays, and other waxwings [26,65,69,78,82,87]. Bighorn sheep, foxes, chipmunks, and other small mammals also help disperse seeds. Gravity and run-off provide another method of dissemination for the heavy berries that would otherwise fall and remain close to the parent tree [65,69,82].

Seed banking: Rocky Mountain juniper seeds do not germinate during the 1st spring following maturity, but germinate freely during the 2nd spring. The seeds require an "after-ripening" period of 14-16 months, during which moisture and chemical changes occur within the seeds [11,65,78,132].

Germination: Germinative capacity varies from 32-58% with an average of 45% [65,132]. The seeds may germinate more readily if fleshy covering is dissolved by digestive tract of a bird or other animal [11].

Seedling establishment/growth: Rocky Mountain juniper seedlings are generally sparse, possibly due to delayed germination and an inability to establish readily on dry sites. Seedlings are most successful in rocky crevices or other pockets with trapped moisture [11,65]. In nurseries, seedlings perform best with partial shade for the 1st year [65].

Rocky Mountain juniper is a slow-growing species. The average height of 8-year-old trees is 1 foot (0.3 m) [11,65]. Saplings grow slowly and steadily until age 40, when they average 13-14 feet (3.9-4.3 m) tall. Then growth slows, and at age 80, the average height is 18 feet (5.5 m). Thereafter trees grow about 0.55 foot (17 cm) per decade and reach 30 feet (9 m) in about 300 years. Diameter growth is also slow at about 0.79 inch (2 cm) per decade until about 170 years of age. Growth then declines slowly to about 0.255 inch (0.6 cm) per decade after age 210, and 300-year-old trees average 17 inches 0.4 m) diameter at 1 foot (0.3 m) above ground [65,119,132].

Asexual regeneration: Rocky Mountain juniper does not reproduce naturally from sprouts, but may be cultivated from cuttings [65,90,127]. For more information, see Other Management Considerations.

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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):

BLM PHYSIOGRAPHIC REGIONS [17]:




1 Northern Pacific Border

2 Cascade Mountains

5 Columbia Plateau

6 Upper Basin and Range

7 Lower Basin and Range

8 Northern Rocky Mountains

9 Middle Rocky Mountains

10 Wyoming Basin

11 Southern Rocky Mountains

12 Colorado Plateau

13 Rocky Mountain Piedmont

14 Great Plains

15 Black Hills Uplift

16 Upper Missouri Basin and Broken Lands

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More info for the terms: climax, forest, series, succession, tree

Rocky Mountain juniper is usually found in long-term seral or near-climax vegetation [90]. It is often found as a climax species in juniper, pinyon-juniper, and pinyon associations in the Rocky Mountain region, and tends toward dominance at higher elevations. It is a minor component of climax or a seral species in Gambel oak and ponderosa pine associations [26,87]. The species may also be climax with Douglas-fir, or it may occur as a "pioneer" tree species in Douglas-fir succession [32]. In pinyon-juniper habitats, Rocky Mountain juniper is often the first to return after a disturbance, and it may invade sagebrush (Artemisia spp.) stands. In both habitats pinyon may follow and eventually replace it [51,52,65]. In the ponderosa pine climax series in Lolo National Forest, Montana, Rocky Mountain juniper and ponderosa pine are the only successfully reproducing conifers [29]. For postfire succession information, see Plant Response To Fire.

The currently accepted scientific name of Rocky Mountain juniper is Juniperus
scopulorum Sarg. (Cupressaceae) [27,53,62,67,74,78,81,113].

Rocky Mountain juniper hybridizes with alligator juniper (J. deppeana) [55,65],
creeping juniper (J. horizontalis) [1,41,46], oneseed juniper (J. monosperma)
[55], Utah juniper (J. osteosperma), and eastern redcedar (J. virginiana) [40,41,46].
Relictual hybridization with eastern redcedar is documented in Texas [46].
There are numerous horticultural and ornamental varieties [55,65,90].

More info for the term: tree

Rocky Mountain juniper is occasionally used for erosion control [121], and the tree has been used for revegetating mine spoils in Kansas [125]. Its dense branches, cold hardiness, drought tolerance, and relative freedom from pests make it a desirable choice for windbreaks and ornamental plantings [23,50,99]; it is the most widely planted conifer species for protective plantings in the Great Plains [123].

Rocky Mountain juniper is most common as a component of the foothills or woodland coniferous zone; in some areas it extends into the montane zone in significant amounts. It forms a distinct forest cover type, Rocky Mountain Juniper (Society of American Foresters Type 220), from northern Colorado and Utah northward. Southward it becomes associated with Pinyon-Juniper (Type 239) (27,36).

Rocky Mountain juniper, because of its scattered distribution over a broad range, is often found in complex transition zones or growing on exposed or severe sites within other forest types (27,36). In these situations, however, it is rarely more than a minor component of the forest association. Rocky Mountain juniper is found in the following forest cover types, among others:

206 Engelmann Spruce-Subalpine Fir
208 Whitebark Pine
209 Bristlecone Pine
210 Interior Douglas-Fir
212 Western Larch
216 Blue Spruce
217 Aspen
218 Lodgepole Pine
219 Limber Pine
221 Red Alder
233 Oregon White Oak
235 Cottonwood-Willow
236 Bur Oak
237 Interior Ponderosa Pine
240 Arizona Cypress
241 Western Live Oak

Differences in elevation, latitude, physiography, and soils, which affect temperature, precipitation, soil moisture, and nutrient conditions, in combination with phytozoological interactions, influence the composition of forests in which Rocky Mountain juniper grows. Furthermore, fire has influenced the development of regional differences for Rocky Mountain juniper distribution, associated complexes, and related biotic associations. Only in the northern parts of its range, at middle and lower elevations, does it form pure stands (14,21,48).

Throughout its range south to northern New Mexico and Arizona, Rocky Mountain juniper intermingles with ponderosa pine (Pinus ponderosa) on southern and western exposures and with interior Douglas-fir (Pseudotsuga menziesii var. glauca) on northern and eastern exposures where it is more abundant. At higher elevations, Rocky Mountain juniper is occasionally associated with Engelmann spruce (Picea engelmannii), subalpine fir (Abies lasiocarpa), lodgepole pine (Pinus contorta), and limber pine (P. flexilis) throughout the Rocky Mountains. In its central and southern range, Rocky Mountain juniper has been reported with white fir (Abies concolor), blue spruce (Picea pungens), aspen (Populus tremuloides), and narrowleaf cottonwood (Populus angustifolia); at higher elevations it is occasionally or rarely found with bristlecone pine (Pinus aristata) (36,42).

At higher elevations, in British Columbia, Alberta, Idaho, and western Montana, Rocky Mountain juniper is occasionally found with subalpine larch (Larix lyalli) western white pine (Pinus monticola), limber pine, or whitebark pine (P. albicaulis). It is associated with whitebark pine at higher elevations in western Wyoming. In the Pacific Northwest, Oregon white oak (Quercus garryana) and red alder (Alnus rubra) are commonly associated with Rocky Mountain juniper, along with Douglas-fir at slightly higher elevations on Vancouver Island, the San Juan Islands, and the inland area around Puget Sound (20,36,42).

Rocky Mountain juniper grades into variations of the pinyon-juniper complexes at middle to lower elevations, southward from Nevada, Utah, and Colorado. Within these complexes, Rocky Mountain juniper generally decreases in density in relation to pinyon species with an increase in elevation. The usual junipers are Utah juniper (Juniperus osteosperma), one-seed juniper (J. monosperma), and alligator juniper (J. deppeana). The pinyons may be pinyon (Pinus edulis), Mexican pinyon (P. cembroides), or singleleaf pinyon (P. monophylla). This association is well developed on the Coconino Plateau in Arizona, where it is referred to as the pygmy conifer biome (14,26,29).

Rocky Mountain juniper is often associated with open-grown scrubby ponderosa pine or bur oak (Quercus macrocarpa) growing on severe sites in the rough, broken tableland topography of western North and South Dakota and eastern Montana and Wyoming (27).

Occasionally in this area, it forms small but almost pure stands. Along stream bottoms and in protected draws, it is occasionally found with a variable but generally incomplete mixture of deciduous trees that may include cottonwood (Populus spp.), willow (Salix spp.), green ash (Fraxinus pennsylvanica), American elm (Ulmus americana), boxelder (Acer negundo), bur oak, and hackberry (Celtis occidentalis). In the Black Hills, it may, rarely, be found with white spruce (Picea glauca).

Because of Rocky Mountain juniper's association with a wide range of forest-shrub-grassland types, a complete list of understory vegetation would be too long to include here. Sparse understories are a characteristic of Rocky Mountain juniper stands, however, particularly on dry sites and where the species is dominant or codominant. Some of the shrubs reported as understory components are American plum (Prunus americana), antelope bitterbrush (Purshia tridentata), chokecherry (Prunus virginiana), creosotebush (Larrea tridentata), cliffbush (Jamesia americana), cliffrose (Cowania mexicana), red-osier dogwood (Cornus stolonifera), fernbush (Chamaebatiaria millefolium), mountain-mahogany (Cercocarpus spp.), rabbitbrush (Chrysothamnus spp.), currant (Ribes spp.), rose (Rosa spp.), sagebrush (Artemisia spp.), serviceberry (Amelanchier spp.), skunkbush sumac (Rhus trilobata), snowberry (Symphoricarpos spp.), winterfat (Eurotia lanata), and shadscale saltbush (Atriplex confertifolia). Also, it shares sites with common juniper (Juniperus communis) throughout its range and with creeping juniper (J. horizontalis) in the Dakotas, Wyoming, Montana, and Alberta (20).

Common grass and grasslike associates of Rocky Mountain juniper at lower elevations in its northern range include wheatgrass (Agropyron spp.), fescue (Festuca spp.), needlegrass (Stipa spp.), grama (Bouteloua spp.), and bluegrass (Poa spp.). In the southern Rocky Mountains, it is found with grama, galleta (Hilaria spp.), and tobosa (Hilaria mutica). Along its eastern distribution from North Dakota to Texas, Rocky Mountain juniper grows with wheatgrass, grama, buffalograss (Buchloe dactyloides), bluestem (Andropogon spp.), and sandreed (Calamovilfa spp.) (20,26).

The climate generally associated with Rocky Mountain juniper is dry and subhumid. The range of climatic conditions is broad, however, extending from maritime to subalpine to semiarid. Temperature extremes range from 43° to -37° C (110° to -35° F), but conditions are more favorable to the species when minimum temperatures exceed -23° to -21° C (-10° to -5° F). Average July temperatures in different areas vary from about 16° to 24° C (60° to 75° F), and average January temperatures from about -9° to 4° C (15° to 40° F). Average number of frost-free days varies from 120 days in parts of the northern Rocky Mountains to 175 days at lower elevations in Arizona and New Mexico. The longest growing season is near sea level in the Puget Sound area (36,39,42).

Average annual precipitation varies in amount, distribution, and type. Over much of the Rocky Mountain juniper range, precipitation averages 380 to 460 mm (15 to 18 in), with variation from 305 mm (12 in) in areas of the Southwest, Great Basin, and eastern slope of the Rocky Mountains in Colorado to 660 mm (26 in) on Vancouver Island. More than half of the precipitation occurs in late fall or early winter on the Pacific coast and west of the Continental Divide in the northern Rocky Mountains. In the northern Great Plains and east of the divide in the northern and central Rocky Mountains, the period of heaviest precipitation is spring and early summer, but this period is late summer and early fall in the Great Basin, Southwest, and southern Rocky Mountains. In general, snow accounts for about one-third to one-half of the total annual moisture, but the amount is highly variable depending upon location (44) (table 1).

Table 1- Climatic data from six regions within the range of Rocky Mountain juniper
Average Temperature
Frost-free period Average annual
precipitation Region Annual July January Rain Snowfall °C days mm cm Pacific Coast 10 17 3 200+ 810   20 Rocky Mountains    Northern   4 14 -8 120 840 135    Central   7 20 -6 130 330 130    Southern 10 22 -2 150 250   76 Northern Great Plains    Western area   7 22 -7 140 410 107 Great Basin and
Southwest
  9
21
-1
170
360
147 °F days in Pacific Coast 50 63 38 200+ 32   8 Rocky Mountians    Northern 40 58 17 120 33 53    Central 44 68 21 130 13 51    Southern 50 72 28 150 10 30 Northern Great Plains    Western area 45 27 20 140 16 42 Great Basin and Southwest
49
70
30
170
14
58 Recent paleobotanical studies indicate the macroclimate covering much of the Rocky Mountain juniper range has changed from mesic to more xeric conditions. Rocky Mountain juniper is a drought-enduring species and it is more hardy than eastern redcedar; however it is generally less drought-resistant than other western tree juniper species, and the climatic change has not been favorable for regeneration or growth. Ten-thousand years ago, during the Holocene, the species was present in the Wisconsin forests. As recently as 1,000 years ago, extensive stands of Rocky Mountain juniper were present in Western Nebraska and in the Laramie Basin of Wyoming, with specimens often reaching 131 cm (52 in) d.b.h. (38,42,45,47).

Rocky Mountain juniper is susceptible to loss from erosion simply because it often becomes established on exposed sites where soils are readily eroded. Overuse of ranges by livestock, bison (in North and South Dakota), and occasionally deer can accelerate the erosion process.

Because animals use the trees as "rubbing posts," they cause considerable physical damage to stems and roots, including wounds that may admit pathogens. In addition, they browse the foliage when range conditions are poor and animal concentrations are high. This browsing, called "high-lining," reduces crown size, ultimately affecting growth and vigor.

Rocky Mountain juniper is attacked by a complex of arachnids, insects, and nematodes (11,37). Two species of spider mites (Oligonychus ununguis and Eurytetranychus admes) feed on foliage and occasionally develop epidemic populations. Two species of juniper berry mites (Trisetacus quadrisetus and T. neoquadrisetus) that destroy the fruits have been reported in British Columbia and Oregon (35). A small red false spider mite (Pentamerismus erythreus), sometimes called red spider, is not rated as a forest pest but can be a serious problem in shelterbelts and landscape plantings.

Rocky Mountain juniper is host to several species of Coleoptera (true insects), Lepidoptera (butterflies and moths), Diptera (flies and midges), and Psyllids (jumping plant lice) that damage the roots, bole, twigs, foliage, and berries.

A nematode, Pratylenchus penetrans, has injured Rocky Mountain juniper seedlings by causing root lesions. The damage has been reported only in the nursery, where populations of the nematode have reached high levels (13).

A broad range of diseases associated with Rocky Mountain juniper attack the roots, stems, and foliage; but the most serious disease probably is a blight caused by Cercospora sequoiae. Some shelterbelts in the Great Plains have lost most of their junipers from this disease. Rocky Mountain juniper is also an alternate host for a cedar-apple rust (Gymnosporangium juniperi-virginianae) which can be a serious problem in the apple industry. The most conspicuous stem diseases are rusts caused by Gymnosporangium spp. and by mistletoes (Phoradendron spp.). These infestations generally are noted by the formation of twig excrescences, woody galls, and witches' brooms (13,19).

Seedling diseases of Rocky Mountain juniper have not been thoroughly studied. It is normally resistant to damping-off fungi; however, Rhizoctonia solani has caused losses in Texas (12). Phomopsis blight (Phomopsis juniperovora) can destroy seedlings in the nursery and reduce survival of outplanted seedlings from partial blighting of the foliage. This blight is seldom found on trees older than 4 years; the disease does not thrive under the dry conditions prevailing on most juniper sites. In some nurseries, juniper cultivars have developed magnesium-deficiency symptoms that were similar to symptoms of Phomopsis blight.

Ectotrophic mycorrhizae are rare on the Cupressaceae. Most Juniperus species examined have been primarily endomycorrhized. No fungi have been reported to form mycorrhizae with Rocky Mountain juniper. Tuber griseum and T. melanosporum have been reported with juniper species in general, however, and Elaphomyces granulatus had been reported for common juniper (13,40).

Rocky Mountain juniper is susceptible to death or severe injury from fire, primarily because the fibrous, stringy bark is thin, and the lower branches contain significant amounts of volatile oils and normally extend to the ground (13).

Rocky Mountain juniper is dioecious. Both pistillate and staminate flowers are small and are borne on the ends of short branchlets or along the branchlet from mid-April to mid-June. The greenish-yellow female flowers usually contain one or two ovules and become more conspicuous during late summer, opening the following spring before pollination. Pollen is disseminated primarily by wind from inconspicuous yellow male flowers on short branchlets, each flower usually containing six stamens. Female flowers are composed of three to eight pointed scales which become fleshy and fuse to form small indehiscent strobili, commonly called "berries" (15,18).

The berries ripen the second year after pollination from mid-September to mid-December and remain on the tree until March or April of the following spring; however, some fruits may persist on the tree for as long as 3 years (18). Immature berries are green and glaucous; ripe berries are bluish purple and covered with a conspicuous white, waxy bloom. The rounded fruit is resinous with a thin coat and averages about 5 to 8 min (0.2 to 0.3 in) in diameter.

Population Differences Information on population variability of Rocky Mountain juniper is incomplete. Undoubtedly, any species with its scattered distribution and wide elevational and latitudinal range will show differences between subsets of the total population in such features as growth, morphology, phenology, and resistance to heat and cold. Recent studies on variations of terpenoids, other volatile oils, and isozymes are providing more information about differences not only among individuals but among segments of the population (31). A study on the overlapping populations of Rocky Mountain juniper and eastern redcedar in the Missouri River Basin indicates that secondary intergradation (allopatric introgression) is occurring rather than primary intergradation (allopatric divergence), and the gene flow is primarily in an easterly direction (9).

Races and Hybrids Hybridization and the development of races of Rocky Mountain juniper are complex. The whole population within the Missouri River Basin is reported to be a hybrid swarm of Rocky Mountain juniper and eastern redcedar, with neither of the extreme parental types being found; also, the trees tend increasingly toward Rocky Mountain juniper in a line from the southeast to the northwest. It has been shown that controlled hybridization between these two species is possible. A tri-parental hybrid swarm that includes horizontal juniper and eastern redcedar (J. uirginiana) has also been reported in western portions of the northern Great Plains. In the Southwest, hybridization with alligator juniper has been reported (7,8,14,46).

No subspecies have been identified for Rocky Mountain juniper. Two naturally occurring varieties have been reported. J. scopulorum var. columnaris, a columnar form, is found only in North Dakota. A depressed shrub, J. s. var. patens, found in Wyoming and Alberta, is considered to be a hybrid with horizontal juniper (32,42).

Several horticultural and ornamental varieties have been reported. Most of these have been developed from the natural columnar variety in North Dakota and from the ornamental variety J. scopulorum var. viridifolia, called "Chandler Blue" and "Hill Silver" (16). Other varieties include "Medora," a bluish, semicolumnar compact form; "Moffet," similar to Medora but somewhat less compact; "Welch," a blue-green pyramidal type with upright branches; "Pathfinder," a silver-blue type of more open form; "Colorgreen," a reasonably compact green variety; and "Hillborn Globe," a broad, blue-green pyramid form. Most of these varieties have been introduced into the horticultural trade as grafted specimens.

Rocky Mountain juniper grows slowly and rather uniformly throughout its range; however, rates of growth have not been thoroughly studied. In the Southwest, average height at 40 years of age has been reported to be about 4 m (13 ft), indicating a growth rate of 10.3 cm (4.1 in) per year. At age 40, height growth declines to about 3.4 cm per year (1.3 in) until age 80, at which time trees average about 5 m (18 ft) tall. Thereafter, height growth is fairly uniform at 1.8 cm per year (0.7 in), producing trees 9 m (30 ft) tall at about 300 years of age. Diameter growth measured at 30 cm (12 in) above the ground (basal diameter) was also reported as slow, with a growth rate of 0.2 cm (0.08 in) per year. This growth rate is fairly uniform until the trees are about 170 years old or average about 33 cm (13 in) in basal diameter. The rate then declines over a period of about 40 years to another constant rate of about 0.08 cm (0.03 in) per year when the tree is 210 years old. This growth rate may be sustained until the tree is 300 or more years old. Basal diameters of trees 300 years old averaged 43 cm (17 in). The species is long lived, with ages of 300 years not uncommon. A relic specimen in western South Dakota was estimated to have been 750 years old when it died; one unusual specimen in Logan Canyon, UT, is reported to be 3,000 years old (4,42).

Tree growth varies considerably with location and site condition. In Canada, the trees usually grow to 30 cm (12 in) in basal diameter and 3 to 4 m (10 to 12 ft) tall, although a few trees reach 9 m (30 ft) in height. Trees on the north rim of the Grand Canyon are 5 to 6 m (15 to 20 ft) tall and 30 to 46 cm (12 to 18 in) in basal diameter. Heights of 6 to 15 m (20 to 50 ft) and basal diameters up to 46 cm (18 in) are reported from other areas of the Southwest (14,42).

Rocky Mountain juniper is not recognized as a commercial timber species, so limited volume and growth prediction data are available. Stand yield prediction equations have been developed for the species in Colorado, Idaho, Utah, and Wyoming. Most information available is generalized and related to harvesting for fenceposts and firewood and to management of stands for watershed, range, wildlife, and shelterbelts. It is a fragile forest type and overcutting or improper management for livestock use reduces wildlife habitat and damages watershed (5,30).

The future management of Rocky Mountain juniper as a forest type, of which only about 22 percent is in national forests, is unclear; furthermore, present conditions for management are not well known. As an associate of the pinyon-juniper type, the species is recommended for 200-year-rotation management and both even- and uneven-aged silvicultural systems can be applied. In the past, harvesting varied from light-cutting and high-grading to excessive overcutting; in recent years pinyon-juniper has been removed from large areas by chaining to increase forage for livestock. Except in limited areas in rather inaccessible places, few so-called virgin stands remain (1,10,30).

Rocky Mountain juniper normally is a component of long-term seral or near-climax vegetation. It is relatively shade-tolerant during the seedling and sapling stages, but it later becomes more intolerant and is unable to endure as much shade as eastern redcedar-its eastern counterpart. Rocky Mountain juniper requires top light for height growth and crown development, and trunk branches die out when it develops in overly dense, pure stands or under deep shade of other tree species. In the northern Rocky Mountains, it is considered less tolerant of shade than ponderosa pine, limber pine, or lodgepole pine but is reported to endure considerable shade from broadleaf trees in protected canyons and sheltered sites on the Pacific coast (26,42). Overall, it is most accurately classed as a very shade-intolerant species.

In Utah, junipers have been observed to invade sagebrush stands under certain conditions; pinyon generally follows and has a tendency to replace the juniper. Pinyon-juniper may encroach into grasslands that have been overused or disturbed in some manner, as juniper germination and establishment are favored by mineral soil. Rocky Mountain juniper also has allelopathic properties that can inhibit establishment of competing grasses, forbs, and shrubs. Herbicides can be used to kill individual trees, to keep chained areas from revegetating, and to restore recently invaded grasslands. However, Rocky Mountain juniper and one-seed juniper are the most difficult of the juniper species to kill (17,24,26,28,42).

Controlled burning to reduce competition from juniper species has had varied results. Insufficient ground-fuel and wide topographical and meteorological variables make it difficult to use fire throughout the entire range of Rocky Mountain juniper. Generally, fire has been more successful in the southern areas of the species' range (48).

Once established, Rocky Mountain juniper competes well with understory vegetation for water and minerals. In a shelterbelt study, its height growth exceeded Siberian pea shrub, green ash, boxelder, or American elm when competing with undisturbed sod-forming grasses. Removal of the sod did increase juniper growth, but not significantly (34).

Apparently no silvicultural guidelines or cutting methods have been developed for Rocky Mountain juniper. Its shade tolerance when young would tend to rule out the clearcut method. Development of shade intolerance with maturity might suggest a three- or four-step shelterwood system, should a need develop to grow and harvest Rocky Mountain juniper in pure stands.

Rocky Mountain juniper is considered to have a shallow but fairly extensive lateral root system, particularly where trees are growing over cemented subsoils or in rocky areas that limit depth of root penetration. The species develops a deeper root system along bottom lands with deeper soils. In the nursery, undercutting of third-year seedlings stimulates strong lateral root development (18).

Rocky Mountain juniper may begin bearing seed at 10 years of age, under favorable conditions. The optimum age for seed production is 50 to 200 years. Trees that are open grown, stunted, or under stress often are prolific seed producers. Rocky Mountain juniper is rated as a good to prolific seed producer throughout most of its range, but in parts of Idaho and Montana, production is reported as only fair. The interval between heavy seed crops varies from 2 to 5 years, but some seed is produced almost every year. Rocky Mountain juniper is as good a seed producer as its other tree associates, with the possible exception of Utah juniper and singleleaf pinyon. It is a better producer than common or creeping juniper (18,42).

Each Rocky Mountain juniper fruit usually contains one, sometimes two, and rarely three brownish seeds, and 100 kg (220 lb) of berries yields 11 to 28 kg (24 to 62 lb) of seeds. The angular, lightly grooved seeds are about 5 mm (0.2 in) in length and 3 mm (0.1 in) in thickness; they average about 59 700/kg (27,100/lb) but range from 39 200 to 92 800/kg (17,800 to 42,100/lb) (18).

Rocky Mountain juniper is considered to have a high proportion of unfilled seeds, but the number varies widely from tree to tree and from season to season. Interacting factors causing filled or unfilled seeds are only partially understood; some of the most important are stand age, structure, density, and species composition; physiography; and favorable or unfavorable weather conditions for flower development, pollination, and seed development (8,18).

Viability of Rocky Mountain juniper seed is only fair and, except for alligator juniper, is not as good as other juniper or pinyon species with which it grows. Recent studies indicate that average germinative capacity is 22 percent, with maximums rarely exceeding 35 percent; however, in one study germination averaged 45 percent and varied from 32 to 58 percent. In another study, seed stored in less than ideal conditions had 30 percent germination after 3.5 years. Under proper storage conditions, at least some of the seed may remain viable for several years (14,18).

Rocky Mountain juniper seeds are disseminated primarily by birds, secondarily by gravity and water. A few mammals play a minor role. The berries are eaten mostly during fall and winter months, when other foods are relatively scarce. Bohemian waxwings are known to eat large numbers of berries. Cedar waxwings, robins, turkeys, and the jays- Mexican, pinyon, scrub, Stellar's, and blue-have all been known to feed on the berries at times. As domestic sheep feed on juniper berries, propagation is noticeable along trails between grazing ranges (30). Bighorn sheep and deer occasionally eat the berries, but they normally browse juniper only under stress conditions. Dissemination of seeds by small mammals is thought to be insignificant (30,33,42).

Thus, natural distribution patterns are affected by bird and animal populations, their daily and migratory movements, location and prevalence of berries, and availability and desirability of other foods. These variables, combined with specific site and weather conditions for germination and establishment, are largely responsible for the scattered distribution of Rocky Mountain juniper within its total range.

Artificial regeneration of Rocky Mountain juniper is commercially significant, and large amounts of seed are required to produce the nursery stock needed for planting in shelterbelts, parks, and landscapes, and on mine spoils or other disturbed sites. Fruits should be collected early enough in the fall to avoid losses to birds and animals, but immature fruits should not be gathered because they are difficult to separate from mature fruits (18). Seeds may be stored either in the dried fruits or as cleaned seeds. A moisture content of 10 to 12 percent is considered satisfactory for long-term storage, and the clean seeds or dried fruits should be stored in sealed containers at -7° to 4° C (20° to 40° F).

Normally, Rocky Mountain juniper seeds germinate the second spring after a 14- to 16-month "after-ripening" period that breaks embryo dormancy. Low germination percentages and slow germination, with germination sometimes being delayed more than 2 years, are not unusual, however. These problems result from a combination of chemical factors in the embryo and physical factors, such as the thick, hard, outer layer of the two-layered seedcoat, which has only a very small permeable area in the hilum (1, 6).

Specific effects of passage through the digestive tract of a bird or animal on germination of Rocky Mountain juniper are not known; however, it could improve germination, as digestion acts as a scarification and acid treatment. A report on the pinyon-juniper type states that germination of juniper (species not indicated) was materially improved by such passage (30). Germination is epigeal (18).

Under natural conditions, Rocky Mountain juniper seedlings become established more readily on moist sites under partial shade; in fact, the characteristic sparseness of Rocky Mountain juniper regeneration is due partly to its inability to establish itself on drier sites. The moist sites favored by Rocky Mountain juniper often are conducive to frost-heaving, however, which can take a heavy toll of seedlings. In nurseries, seedlings are best established on mulched seedbeds under partial shade (2,18,42).

The seedlings, characterized by acicular foliage (sharp-pointed leaves), develop slowly under natural conditions. They are reported to reach a height of 30 cm (12 in) in 8 years in northern New Mexico and Arizona. Their growth is more rapid in nurseries, where they often reach 15 cm (6 in) or more in 3 years. The preferred age for nursery stock for field plantings depends on the area and includes 2-0, 3-0, 1-1, 1-2, 2-1, or 2-2 stock. Potting or balling Rocky Mountain juniper for field planting increases survival over bare root planting during dry years but adds considerably to the cost. During the fall, seedlings often change from the normal green to a bluish purple because of freezing weather, less precipitation, or changes in light intensity (18,42).

Seedlings in the juvenile stages are sometimes confused with common juniper seedlings, but they do not have the basally jointed leaves of that species (15).

Edaphic factors for Rocky Mountain juniper can be characterized as nonspecific and variable, as evidenced by the broad ecological range of the species and its adaptability to a wide variety of soils and conditions in shelterbelt reclamation and landscape plantings. Within pinyon-juniper woodlands in Arizona and New Mexico there are 5 soil orders, 10 great-groups, 40 subgroups, and 150 soil families (3,16,25,34).

Rocky Mountain juniper is most often associated with soils derived from basalt, limestone, and shale throughout its natural range, particularly in semiarid regions. Soils in the order Mollisols are commonly associated with this species. Generally, the soils are poorly developed, stony, shallow, have low moisture-holding capacities, and are easily eroded, so that in many places little or no topsoil is present. Some of the soils are calcareous or adobic, often high in clays; are slightly alkaline; and have limy, cemented subsoils. The pH of these soils is generally around 8.0 and moisture availability to plants is low (21,43).

Geology and physiography associated with Rocky Mountain juniper are varied. Throughout its range, it is often found on open exposed bluffs, rocky points, and southern exposures. It does best in sheltered areas, however, along ravines, and in canyons and draws. Its range extends from glaciated valleys in central British Columbia through the foothills of the Rocky Mountains to mesas and tablelands of the southwestern United States, and south into the Sierra Madre in Sonora, Mexico. It is found on lava beds in Idaho and eastern Washington, on limestone cliffs in southwestern Montana, on outcroppings of sandstone and limestone in the central Rocky Mountains, and on high limestone plateaus in South Dakota and Wyoming. It is common on northern aspects in the "badland" topography of both North and South Dakota. In the southern parts of its range Rocky Mountain juniper is often found on malpais derived from lava flows, and on Kaibab limestone plateaus in northern Arizona (42).

The elevational range of Rocky Mountain juniper is from near sea level to 2740 m (9,000 ft); following the general plant geography rule of decreasing elevation with increasing latitude, the range varies considerably with latitude and local climate. Aspect also has an effect on local elevations, southern exposures generally having a wider range than corresponding northern exposures. For example, in Utah and Nevada, Rocky Mountain juniper has been reported ranging generally from 1070 to 2260 m (3,500 to 7,400 ft) on southern exposures and from 1160 to 1400 m (3,800 to 4,600 ft) on northern exposures (14,42).

The early Indians made some use of juniper berries for food and decoration; the bark was woven into cradles and similar products as well as being used for torches. The most important use of Rocky Mountain juniper, however, was as firewood for cooking and heating, and today this is still a major use. Fuelwood volume tables that include Rocky Mountain juniper have been developed (14,30).

The wood is fine grained, with white sapwood and deep red heartwood with faint purplish and whitish streaks. It is slightly lighter in weight and not as hard as that of eastern redcedar, but in color, odor, figure, and strength it could be substituted for its eastern counterpart. When cured, the wood, especially the heartwood, is resistant to decay; it has been cut heavily for fenceposts, particularly before the advent of steel fenceposts (14).

The small size and rapid taper of the stems, with the consequent high cost of producing usable sawn material, have discouraged use for lumber. However, some sawn material has been cut from Rocky Mountain juniper for such use as closet lining, custom-built furniture, inlays, and cedar chests. The products are attractive; the colored heartwood also has been used for carvings and novelties, but only on a small scale (14,30).

Rocky Mountain juniper does not reproduce naturally by sprouts or layering. Cuttings can be grown satisfactorily in a rooting medium if they are given a basal treatment of indolebutyric acid in talc and misted intermittently for 3 s/min (12,42).

Cupressaceae -- Cypress family

Daniel L. Noble

Rocky Mountain juniper (Juniperus scopulorum) is one of 13 junipers native to North America. It is similar to eastern redcedar (Juniperus virginiana) but requires 2 years for seed maturity, compared to 1 year for its eastern relative. Other common names for the typical variety include Rocky Mountain redcedar, redcedar, western redcedar, river juniper, cedro rojo, and sabino (23,42,49). Rocky Mountain juniper varies in size from a shrub to a small tree. The largest specimen grows in the Cache National Forest in Utah. It measures 198 cm (78 in) in d.b.h. but is only 11 m (36 ft) tall. Much information is available about Rocky Mountain juniper as a member of a variety of habitat associations; however what is known about the silvics of the species is more limited (41).

Of 11 junipers native to the United States normally reaching tree size, Rocky Mountain juniper is the most widely distributed in western North America (22,49). Within its range the distribution is considerably scattered; however, the concentrations, from central British Columbia and southern Alberta through northwestern Montana and southeastern Idaho into Colorado and northern New Mexico, generally follow the Rocky Mountains. In addition, there are fairly extensive concentrations in western portions of the northern Great Plains, in the Uinta and Wasatch Mountains of Utah, and in a band approximately 100 km (62 mi) wide beginning near the Grand Canyon in northwest Arizona and following the Arizona Plateau southeast into the Black Mountains of southwestern New Mexico.


- The native range of Rocky Mountian juniper.

Tree, Evergreen, Dioecious, 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, Leaf apex acute, Leaf apex obtuse, Leaves < 5 cm long, Leaves < 10 cm long, Leaves blue-green, Leaves not blue-green, Scale leaves without raised glands, Scale leaf glands not ruptured, Scales leaves not or barely overlapping, Whip leaf margins entire under magnification, Twigs glabrous, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Aril exposing seed coat, Berry-like cones brown, Berry-like cones pink, Bracts of seed cone included, Seeds tan, Seeds brown, Seeds wingless.

Juniperus scopulorum, the Rocky Mountain juniper, is a species of juniper native to western North America, from southwest Canada to the Great Plains of the United States.

Foliage and cones