Rocky Mountain juniper

Rocky Mountain juniper (Jr) - Juniperus scopulorum

Page Index

Geographic Range & Ecological Amplitudes

Description

Rocky Mountain juniper varies in size from a shrub to small-sized (rarely >10 m tall) tree. It is an evergreen, scale-leaved conifer, at maturity with a tapered stem, long branches, and fibrous stringy bark. In British Columbia, it is not used for any wood products; however its wood is attractive—fine grained, with white sapwood and deep red heartwood, is resistant to decay, and very fragrant.

Geographic Range 

Geographic element:
Western North American/mainly Cordilleran and less Pacific

Distribution in Western North America:
(central) in the Pacific region; central and south in the Cordilleran region

Ecological Amplitudes 


Rocky Mountain Juniper

Climatic amplitude:
montane boreal - cool temperate - cool semiarid - cool mesothermal

Orographic amplitude:
submontane - montane

Occurrence in biogeoclimatic zones:
(BWBS), (MS), (SBS), (SBPS), (BG), (PP), IDF, ICH, CDF, (southern CWH)

Edaphic Amplitude

Range of soil moisture regimes:
very dry - moderately dry - slightly dry - (fresh)

Range of soil nutrient regimes:
poor - medium - rich - very rich; calciphyti
top  

Tolerances and Damaging Agents

 
Root System Characteristics Rocky Mountain juniper has a shallow but fairly extensive lateral root system. Roots are associated with vesicular-arbuscular mycorrhizae.
Tolerances
tolerance to tolerance class comments
Low light L rarely grows in closed-canopy stands
Frost H tolerates growing season frost
Heat H Frequent on insolated sites.
Water deficit H Frequent on excessively dry sites.
Water surplus L Probably low; absent on water-surplus sites.
Nutrient (mainly N) deficiency H Common on poor sites but absent in acid, very poor soils; tolerates alkaline soils.
top  
Damaging Agents
damaging agent resistance class comments
Snow L uncommon in high snow fall areas
Wind H common on wind exposed sites
  risk class  
Fire H not a fire resistant species
Insect L Not a serious concern.
Fungi M Not a serious concern; juniper blight.
Associated tree species and successional role In British Columbia, Rocky Mountain juniper grows in isolated clumps of one or several trees, rarely in open-canopy stands. Occasionally, it associates with Pacific madrone, Subalpine larch, Whitebark pine, Western white pine, Trembling aspen, and Common douglas.

top

Silvical Characteristics

 
characteristic interpretive class comments
Reproduction capacity H Seed produced at 10 years of age; heavy seed crops are frequent.
Seed dissemination capacity H Dispersal mainly by birds.
Potential for natural regeneration in low light L Practically nil; a shade-intolerant and exposure-requiring species.
Potential for natural regeneration in the open H an exposure-requiring species
potential initial growth rate (<5 years) L Height increment <5 cm/yr.
Response of advance regeneration to release na Advance regeneration does not develop in the absence of adequate light and seedbeds.
Self-pruning capacity in dense stands na Grows exclusively in open-canopy, park-like stands.
Crown spatial requirements H individuals are well spaced
Light conditions beneath closed-canopy, mature stands na Grows exclusively in open-canopy, park-like stands.
Potential productivity na Non-crop species; site index functions are not available; the species was recommended for 200 year rotation in southwestern US.
Longevity M Commonly >300 years; the maximum reported age 3,000 years (Logan, Utah).

top

Genetics and Notes

Genetics & Notes
Genetics Information on population variability of Rocky Mountain juniper is incomplete. Hybridization with other junipers is common and complex. No subspecies have been identified but several horticultural and ornamental varieties have been reported.
Notes Noble, D.L. 1990. Juniperus scopulorum. Pp. 116-126 in R.M. Burns and B.H. Honkala (technical coordinators) Silvics of North America, Vol. 1. Agri. Handbook 654, USDA For. Serv., Washington, D.C.

In addition to Rocky Mountain juniper, there are two shrub junipers native to British Columbia: creeping savin juniper (Juniperus horizontalis Moench) and the wide-spread mountain juniper (Juniperus sibirica Burgds.); the former is restricted to the BWBS zone, the latter occurs throughout the province. More detailed silvics information is given by:

Rocky Mountain juniper is not grown for timber production anywhere in its range. It is used mainly in landscape, restoration, and reclamation planting.
top