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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #178320
Title: NORTHERN JUNIPER WOODLANDS

Author
item THORNE, R - UNIV. CALIFORNIA DAVIS
item SCHOENHERR, A - UNIV. CALIFORNIA DAVIS
item Clements, Darin - Charlie
item Young, James

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/12/2005
Publication Date: 8/20/2007
Citation: Thorne, R.F., Schoenherr, A.A., Clements, C.D, Young, J.A. 2007. Northern Juniper Woodlands. In: Barbour, M.G., Keeler-Wolf, T., and Schoenherr, A.A., editors. Terrestial Vegetation of California, 3rd Edition. Berkeley, CA: University of California Press. p. 574-586.

Interpretive Summary: The northern juniper woodlands of California include two phases; 1) a western juniper (Juniperus occidentalis ssp. occidentalis) that is largely restricted to volcanic provinces of the southern Cascade and Modoc Plateau, and 2) a mountain juniper (J. occidentalis ssp. australis) that extends down the trans-Sierra. The distribution of western juniper plant communities is closely associated with the volcanic provinces of northern and northeastern California. Western juniper woodlands do finger into Ponderosa Pine (Pinus ponderosa) and Jeffrey Pine (P.jeffreyi) woodlands at higher elevations. The fingers end at lower elevations in annual grasslands and agronomic fields. Big sagebrush (Artemisia sps.) is a consistent shrub understory in these communities with bluebunch wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis), Thurber’s needlegrass (Achnatherum thurberianum), squirreltail (Elymus elymoides), and Sandberg bluegrass (Poa secunda) common perennial grass species. Mountain juniper woodlands are associated with the more mesic higher potential mountain brush communities associated with antelope bitterbrush (Purshia tridentata), curl-leaf mountain mahogany (Cercocarpus ledifolius) and aspen (Populus tremuloides) being characteristic associated plants.

Technical Abstract: The northern juniper woodlands of California are characteristically made up of a western juniper (Juniperus occidentalis ssp. occidentalis) type and a mountain juniper (J. occidentalis ssp. australis) type. The distribution of western juniper plant communities are closely related to the volcanic provinces of the southern Cascades and Modoc Plateaus of far northern and northeastern California. However, western juniper is not restricted to soils derived from volcanic rock. The western juniper woodlands are characteristically associated with the more mesic portions of the Artemisia steppe with mountain big sagebrush (Artemisia tridentata ssp. vaseyana), bluebunch wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis), Thurber’s needlegrass (Achnatherum thurberianum), squirreltail (Elymus elymoides), and Sandberg bluegrass (Poa secunda). Western juniper woodlands are typically not closed stands and are often rich with native perennial species when not degraded. Mountain juniper woodlands are commonly associated with curl-leaf mountain mahogany (Cercocarpus ledifolius), antelope bitterbrush (Purshia tridentata), snowberry (Symphoricarpus rotundifolus), and aspen (Populus tremuloides). These communities are in the higher elevations in the Sierra Nevada and where white fir (Abies concolor), and white pine (Pinus monticola) can be found as well. Pinyon/juniper woodlands are also present. This community is one in which Pinus and Juniperus species compose the landscape. These communities can result in closed stands that crowd out important grazing and browsing resources.