Juniperus occidentalis subsp. australis
Sierra juniper (Peattie 1950).
The type of subsp. australis was collected in 1961 by F.C. Vasek (Vasek 610929-38) along Poligue Canyon Road to Holcomb Valley in the San Bernardino Mountains. This collection was near the southern limit of the species' range (Farjon 2005).
Synonymy for subspecies australis (Farjon 2005):
See Juniperus occidentalis. Subsp. australis is primarily (90%) dioecious. Branchlets mostly have 4 scale leaves per whorl. Mature seed cones average 8.5 mm diameter. Seedlings often have 3-4 cotyledons (Adams 1993, Farjon 2005).
USA: California, at 1000-3000 m elevation on dry rocky slopes (Adams 1993).
In the Sierra Nevada, in grows on shallow soils, often with Abies magnifica, Pinus albicaulis, Pinus contorta subsp. murrayana, Pinus jeffreyi, or Tsuga mertensiana (Sowder and Mowat 1965). At the southern extension of its range in San Bernardino County, it generally grows at a higher elevation than Juniperus californica and J. osteosperma (Munz and Keck 1959). This is the only documented area where J. occidentalis and Pinus monophylla grow together in a piñon-juniper woodland, although their distributions overlap geographically near the west edge of Nevada and from east-central to southern California (Griffin and Critchfield 1972, Horton 1960).
The "Scofield Juniper" has yielded a crossdated age of 2,675 years (Miles and Worthington 1998, cited in RMTRR 2006). The "Bennett Juniper," mentioned above, has yielded a crossdated age of 1,220 years and was estimated by the analyst, Peter Brown, to be about 2,200 years old (RMTRR 2006).
Dendrochronologically useful. The most noted use to date has probably been a temperature reconstruction done by Graumlich (1991).
Little used. They are a popular subject for bonsai.
Readily seen in Yosemite National Park, for example in the Tuolumne Meadows area, and in the high country of Sequoia and Kings Canyon National Parks.
"The top is almost always dead in old trees. Some are mere weathered stumps, decorated with a few leafy sprays, reminding one of the crumbling towers of some ancient castle" (Muir 1894).
Graumlich, Lisa J. 1991. Subalpine tree growth, climate, and increasing CO2: An assessment of recent growth trends. Ecology 72(1): 1-11. Abstract: Five tree-ring series from foxtail pine (Pinus balfouriana), lodgepole pine (P. murrayana), and western juniper (Juniperus occidentalis) collected in the Sierra Nevada, California, were analyzed to determine if the temporal and spatial patterns of recent growth were consistent with the hypothesized CO2-induced growth enhancement. Specifically, the author addresses the following questions: (1) can growth trends be explained solely in terms of climatic variation; (2) are recent growth trends unusual with respect to long-term growth records. While the results offer no support for the hypothesized CO2 fertilization effect, they do provide insights into the response of subalpine conifers to climatic variation. Response surfaces demonstrate that precipitation during previous winter and temperature during the current summer interact in controlling growth and that the response can be nonlinear. Although maximum growth rates occur under conditions of high winter precipitation and warm summers for all three species, substantial species-to-species variation occurs in the response to these two variables.
Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Technical Paper 44. Berkeley, CA: USFS Pacific Southwest Forest and Range Experiment Station. 29 p.
Miles, D.H. and M.J. Worthington. 1998. Sonora Pass junipers from California USA: construction of a 3,500-year chronology. In V. Stravinskiene and R. Juknys, editors. Dendrochronology and Environmental Trends - Proceedings of the International Conference 17-21 June 1998, Kaunas, Lithuania. Vytautas Magnas University.
Munz, Philip A. and David D. Keck. 1959. A California flora. Berkeley, CA: University of California Press. 1,681 p.
Sowder, James E. and Edwin L. Mowat. 1965. Western juniper (Juniperus occidentalis Hook.), p. 223-225 in H.A. Fowells (ed.), Silvics of forest trees of the United States. Agriculture Handbook 271. Washington, DC: U.S. Department of Agriculture.
Dealy, J.E. 1990. Western juniper, in Burns and Honkala (1990).
Tresidder, Mary Curry. 1948. Sierra Juniper (accessed 2009.04.13), an online excerpt from the book Trees of Yosemite. Nice woodcut illustrations.
Last Modified 2012-11-23