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Artemisia tridentata spp. tridentata/Elymus cinereus

basin big sagebrush/basin wildrye

Classification Comments: Artemisia tridentata spp. tridentata/Elymus cinereus is included in Hironaka et al. (1983) as a habitat type known to be present in Idaho and adjacent states that was not studied as part of their classification. This association has recently been described in Nevada (Weixelman et al. 1996) and Idaho (Moseley 1998). A considerable amount of literature refers to plant associations with Artemisia tridentata as the dominant shrub. However, identification to the subspecies has not always occurred. The National Vegetation Classification (Anderson et al. 1998) recognizes a broadly defined Artemisia tridentata/Elymus cinereus association that is used when subspecies is unknown. When subspecies is known the Artemisia tridentata spp. tridentata/Elymus cinereus and Artemisia tridentata ssp. vaseyana/Elymus cinereus plant associations should be recognized.

Distribution: This plant association has been reported from Colorado, Wyoming, Nevada, Idaho, Oregon, and possibly Wyoming (Hironaka et al. 1983; Weixelman et al. 1996; Anderson et al. 1998).

Soils: The surface soil material is silty loam to sandy loam and can be very deep. Where coarse fragments occur in the soil profile, they are generally less than 60% by volume in any given horizon. In some stands surface soils are moist into late summer and depth to field capacity moisture is within a meter of the surface in the summer. On deep alluvial terraces along larger rivers, this depth may be as deep as 3 m and the surface soils are dry by late summer. Soils at higher elevation sites in Nevada have been classified as Cryoborolls, while at lower elevations in Idaho they are Haploxerolls (Weixelman et al. 1996; Fisher and Moseley 1997).

Environment: This association is often in the transition zone between drier upland associations and the wetter riparian zone. Artemisia tridentata ssp. tridentata is an indicator of deep soil. It is most often found in areas of deep alluvial deposition on the valley bottom, usually on stream terraces, but also has been observed on toeslopes. Seasonal flooding on these sites is rare. Occurrences are generally below 6,000 feet in the north (Idaho) and 8,000 feet in the south (Nevada).

Vegetation Composition: Artemisia tridentata ssp. tridentata dominates the shrub layer and a mixture of graminoids and forbs dominate the herbaceous layer in stands of high ecological condition, however, Elymus cinereus usually is the most abundant species, sometimes reaching near 100% cover. Basin big sagebrush generally has a canopy of 10-50%. It has a stout taproot which grows to a depth of 1 to 4 m and is able to tap moisture deep in the soil profile. Therefore, basin big sagebrush is considered to be a phreatophyte. Cover of Chrysothamnus spp. is low in high quality stands. Total graminoid cover can be as high as 70%, with Elymus cinereus comprising most of this. Total forb cover is generally between 5 and 20% (Weixelman et al. 1996).

Wildlife Functions: Artemisia tridentata is not preferred browse but is a very important emergency food during winter months. Sage grouse, mule deer, elk, and pronghorn will forage on plants. Pygmy rabbits forage extensively on big sagebrush. This plant association does provide cover for upland game birds and small mammals (USDA 2000).

Successional Dynamics: Indicators of disturbance in this association, such as heavy livestock grazing or fire, include high coverage of species such as Chrysothamnus spp., Iva axillaris, Iris missouriensis, and Bromus tectorum (Weixelman et al. 1996). At low elevations in southwestern Idaho, Sarcobatus vermiculatus can occur in stands with canopy cover equal to the Artemisia. It is unknown if this reflects a successional stage due to livestock grazing.

Management Considerations: The diagnostic shrub and graminoid are only moderately palatable. During much of the year Elymus cinereus is course and unpalatable, it can however be damaged if young spring and fall growth is grazed. Spring and winter rest periods are needed to replenish the root reserves of Elymus cinereus. Elymus cinereus is generally resistant to fire, but can be eliminated in hot fires when soils are very dry. Artemisia tridentata will decrease with fire. Prescribed burns should be used only when soil moisture is high and at sites that have remnants of palatable grasses. Livestock should be excluded from burned sites to allow root reserves to build up and to prevent premature utilization of new shoots. Both Elymus cinereus and Artemisia tridentata ssp. tridentata can be used for range restoration and soil stabilization (Kittel et al. 1999).

References:

Anderson, M., P. Bougeron, M. T. Bryer, R. Crawford, L. Engelking, D. Faber-Langendoen, M. Gallyoun, K. Goodin, D. H. Grossman, S. Landaal, K. Metzler, K. D. Patterson, M. Pyne, M. Reid, L. Sneddon, and A. S. Weakley. 1998. International classification of ecological communities: terrestrial vegetation of the United States. Volume II. The National Vegetation Classification System: list of types. The Nature Conservancy, Arlington, Virginia, USA.

Fisher, H., and B. Moseley. 1997. Soil field notes and geology for some riparian sites, July 1997 site visits. Unpublished notes on file at Lower Snake River District, BLM, Boise, ID.

Hironaka, M., M. A. Fosberg, and A. H. Winward. 1983. Sagebrush-grass habitat types of southern Idaho. Forestry, Wildlife, and Range Experiment Station Bulletin Number 15, University of Idaho, Moscow. 44 pp.

Kittel, G., E. VanWie, M. Damm, R. Rondeau, S. Kettler, A. McMullen, and J. Sanderson. 1999. A classification of riparian wetland plant associations of Colorado: A users guide to the classification project. Colorado NaturalHeritage Program, Colorado State University, Fort Collins. 71 pp plus appendices.

Moseley, R. K. 1998. Riparian and wetland community inventory of 14 reference areas in southwestern Idaho. Conservation Data Center, Idaho Department of Fish and Game, Bureau of Land Management Technical Bulletin No. 98-5. 52 pp. plus appendices.

U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. 2000. Fire Effects Information System, [Online]. Available: http://www.fs.fed.us/database/feis/

Weixelman, D. A., D. C. Zamudio, and K. A. Zamudio. 1996. Central Nevada Riparian Field Guide. USDA Forest Service R4-ECOL-96-01. Intermountain Region, Ogden, UT. 90 pp. plus appendices.

Author/Date(Update): R. K. Moseley/1998-01-05(1998-12-01)