Map_thumbnail_large_font

Juniperus occidentalis

Status_ne_offStatus_dd_offStatus_lc_onStatus_nt_offStatus_vu_offStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA PINOPSIDA PINALES CUPRESSACEAE

Scientific Name: Juniperus occidentalis
Species Authority: Hook.
Infra-specific Taxa Assessed:
Common Name(s):
English Western Juniper

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2013
Date Assessed: 2011-03-08
Assessor(s): Farjon, A.
Reviewer(s): Adams, R & Thomas, P.
Justification:
Juniperus occidentalis is presently increasing in abundance, spread and numbers of mature individuals. The southern subpopulations are stable, but lack of recruitment locally could pose problems following destructive events. The overall assessment of Least Concern is driven by the larger subpopulations in the north, which are all increasing.

Geographic Range [top]

Range Description: Recorded from the western USA: California, W Idaho, NW & W Nevada, Oregon, and S Washington.
Countries:
Native:
United States (California, Idaho, Nevada, Oregon, Washington)
Range Map: Click here to open the map viewer and explore range.

Population [top]

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

Habitat and Ecology [top]

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

Use and Trade [top]

Use and Trade: The wood of this juniper is still used locally for firewood, fence poles, corrals, etc. Its very durable wood is also used for special purposes such as furniture, interior panelling and decorative applications. Horticultural use is rare, but the species has value for landscaping of disturbed sites. There are a few cultivars known, one of these has conspicuously silvery glaucous foliage and is called 'Sierra Silver' and, at least for a time, retains the columnar or pyramidal habit of younger plants.

Threats [top]

Major Threat(s): Overall, the species is not threatened. However, for var. australis, due to extreme environmental limitations, recruitment and growth  are sporadic and extremely slow. In many subpopulations there are only old or senescent trees present; if these were all to die from stochastic events or an alien pathogen (not present now) this taxon could become threatened with extinction.

Conservation Actions [top]

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

Citation: Farjon, A. 2013. Juniperus occidentalis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 22 December 2014.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided