Currently there are six subspecies of Artemisia tridentata recognized by the National Plant Data Center: basin (ssp. tridentata), Wyoming (ssp. wyomingensis Beetle & Young), mountain (ssp. vaseyana [Rydb.] Beetle), subalpine (ssp. spiciformis [Ousterhout] Kartesz & Gandhi), xeric (ssp. xericensis Winward ex R. Rosentreter & R. Kelsey) and Parish’s (ssp. parishii [Gray] Hall & Clements). Each is highly variable with multiple ecotypes, but can generally be separated using a number of morphological, geographical and topographical characters.
All chromosome number information was obtained from McArthur and Sanderson (1999) as updated in McArthur (2005). Appendix 1 contains a general summary of characteristics useful to separate subspecies. See McArthur and Stevens (2004) for a detailed review of the characters for the subspecies occurring in the Intermountain West.
Figure 2. Leafy stem of basin big sagebrush. Photo courtesy of the PLANTS database.
Basin big sagebrush usually occurs at the lowest elevational range of the species, being most abundant in the valley bottoms to mountain foothills. Plants typically have a single main trunk and may grow to a height of 4 m (13 ft) under proper conditions, making basin the largest subspecies. Basin big sagebrush plants are generally uneven-topped with loosely branching flowering stems distributed throughout the crown (see figure 1). Floral heads typically contain 3 to 6 small flowers per head. Leaves of the vegetative stems are narrowly cuneate averaging 2 cm (0.8 in) or more and can be as long as 5 cm (2 in) being many times longer than wide (see figure 2). Ultraviolet visible coumarins in leaf extracts are minimal; leaf UV color is none to light blue in water and a rusty red-brown color in alcohol. 2n = 18 or sometimes 36.
Figure 3. Wyoming big sagebrush.
Derek Tilley, USDA NRCS Idaho PMC
Wyoming big sagebrush overlaps in range and elevation with basin big sagebrush. Plants are considerably smaller than those of basin big sagebrush, usually less than 0.9 m (3 ft) tall, and have main stems branching from the ground (see figure 3). Flowering stems are not as widely branching as those of basin, but otherwise closely resemble that subspecies. Leaves are typically shorter, from 1 to 1.5 cm (0.4 to 0.6 in) long, and flabelliform. UV extract color in water is none to light blue and rusty in alcohol. 2n = 36.
The vegetative stems of mountain big sagebrush create a characteristic even topped crown with the panicles rising distinctly and relatively uniformly above the foliage (see figure 3). Plants are normally smaller than those of basin big sagebrush, averaging about 0.9 m (3 ft) tall. Inflorescences are narrow and spicate bearing flower heads containing 4 to 8 flowers per head. Leaves are characteristically wider than those of basin or Wyoming big sagebrush. In extracts, ultraviolet visible coumarins are abundant. Leaf extracts fluoresce blue in water and blue-cream in alcohol. 2n = 18 or sometimes 36.
Figure 4. Even topped mountain big sagebrush.
Derek Tilley, USDA NRCS Idaho PMC
Originally considered a xeric form of mountain big sagebrush, xeric big sagebrush shares similarities with both basin and mountain big sagebrush and may be the result of hybridization between the two subspecies. Xeric big sagebrush plants are large and have an uneven topped crown like those of basin big sagebrush, but in leaf UV color and cytological characters it resembles mountain big sagebrush. Ultraviolet visible coumarins are blue in water, blue-cream in alcohol. 2n = 36.
A new variation of big sagebrush being recognized by some is Bonneville big sagebrush. This as yet undescribed taxon may represent hybridization between Wyoming and mountain big sagebrush. It is reported to have the general growth form of Wyoming plants but bears the leaves and fluorescing characteristics of the mountain subspecies. It has been reported from the bench areas of Lake Bonneville and other ancient lakes of the Intermountain West in Utah and Nevada. Reports of Bonneville big sagebrush have also come from western Wyoming and western Colorado. Of particular importance is this sagebrush’s reported high palatability to wild ungulates and sage grouse.
Subalpine, or spicate big sagebrush, is believed to be a stabilized hybrid between mountain big sagebrush and silver sagebrush (Artemisia cana Pursh ssp. viscidula [Osterhout] Beetle). Plants are similar to those of mountain big sagebrush except that leaves and floral heads are larger, the floral heads having 10 to 18 flowers per head. Ultraviolet visible coumarins in leaf extracts fluoresce blue in water and blue-cream in alcohol. 2n = 18 or 36.
Parish’s big sagebrush is an uncommon taxon restricted to dry, sandy soils in the hills of southern California. It is nearest in appearance and relationship to basin big sagebrush, but differs from basin in having drooping flowering branches and the achenes are hairy. 2n = 36.
One additional taxon that should be mentioned is Lahontan sagebrush (Artemisia arbuscula ssp. longicaulis Winward and McArthur). It is thought to be a stable hybrid between low sagebrush (A. arbuscula) and Wyoming big sagebrush. It bears the flowers of low sagebrush but has the vegetative characteristics of its big sagebrush parent. This subspecies forms dominant communities in northwestern Nevada and adjacent portions of California and Oregon in shallow or clayey soils above and around the shoreline of the Pleistocene Lake Lahontan.
The following key should provide some assistance in separating the subspecies of big sagebrush.
1. plants larger, usually >0.9 m (3 ft) tall, with a
single main trunk; crown uneven with floral stems
2. achenes hairy; floral stems drooping; plants
endemic to sandy soils in southern
2. achenes glabrous; floral stems erect; plants
widely distributed throughout western U.S,
including southern California
3. plants occurring in valley bottoms and low
foothills, occupying deep fertile soils; leaves
narrowly cuneate, 2-5 cm (0.8-2.0 in) long,
UV leaf color in water=none, in alcohol=red
to brown ……...................…...ssp. tridentata
3. UV in water=blue, in alcohol=blue-cream;
plants restricted to well-drained basaltic soils in western Idaho….........ssp. xericensis
1. plants smaller, averaging 0.9 m (3 ft) or less, with
trunks branching at or near ground level; crowns
4. crowns uneven-topped, plants of low
valleys and foothills;
5. UV color in water=none, in alcohol=rust
5. UV color in water=blue, in alcohol=blue-
4. crowns even-topped, floral stems rising
uniformly above the vegetative stems; plants of
6. flowers 4 to 8; leaf tips lobed
6. flowers 10 to 18; leaf tips often pointed
Additional taxonomic information can be found in the Flora of North America, Volume 19 (FNA Editorial Committee 2006) and the Intermountain Flora, Volume 5 (Cronquist et al. 1994).
General: Although big sagebrush plants generally have a similar growth form, the species does have considerable morphological variation with several subspecies and ecotypes. Big sagebrush are evergreen shrubs ranging in size from less than 0.6 m (2 ft) tall to as large as 4 m (13 ft) tall. Branches are spreading, arising from numerous main stems in the lower growing subspecies or from one main trunk in the larger forms. Leaves are blue-gray to blue-green in color due to dense gray hairs. They are typically cuneate (wedge-shaped, triangular and gradually tapering to the base) or flabelliform (bell shaped) depending on subspecies, and have three lobes at the apex on the majority of the persistent foliage. Leaves vary in length from 0.5 to 5 cm (0.2 to 2.0 in), and can be 0.2 to 2.0 cm (0.08 to 0.8 in) wide. Leaves are spirally arranged with internodes short in young vegetative stems making the leaves very dense. Panicles overtop plants of mountain and spicate big sagebrush, or can grow throughout the crown in basin and Wyoming big sagebrush. Floral heads contain from three to 18 perfect (both male and female parts present) flowers per head. Achenes are typically glabrous but are hairy in the California endemic Parish’s big sagebrush. Big sagebrush plants are very aromatic with the smell being described as bitter pungent to pleasant, the odor varying by subspecies. Ploidy levels often differ among subspecies and may differ among populations.
A. tridentata ssp. parishii = Parish’s big sagebrush
A. tridentata ssp. spiciformis = subalpine or spicate big sagebrush
A. tridentata ssp. tridentata = basin big sagebrush
A. tridentata ssp. vaseyana = mountain big sagebrush
A. tridentata ssp. wyomingensis = Wyoming big sagebrush
A. tridentata ssp. xericensis = xeric or foothills big sagebrush
Regularity: Regularly occurring
Regularity: Regularly occurring
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
BLM PHYSIOGRAPHIC REGIONS :
5 Columbia Plateau
6 Upper Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
Occurrence in North America
Mountain big sagebrush occurs from southern British Columbia and Alberta south to California, northern Arizona and northern New Mexico, west into central Oregon and Washington, and east into Montana, Wyoming and Colorado [11,53,56,71,86,97]. Small populations of mountain big sagebrush have been reported as far east as the Dakotas and Nebraska [5,47,61].
Fossil records and records from early pioneers indicate that sagebrush was widespread and existed in nearly the same general distribution for the past several thousand years as it does in the present day. Densities of sagebrush communities, however, have been reduced historically due to range management practices. Big sagebrush presently covers a vast ecological range from British Columbia to Baja California eastward to the Dakotas. Mahalovich and McArthur (2004) provide distribution as well as seed and plant transfer guidelines for Artemisia subgenus Tridentatae. For current distribution for each subspecies, please consult the Plant Profile page for this species on the PLANTS Web site.
Global Range: Artemisia tridentata ssp. vaseyana ranges from British Columbia south to California; Calif., Colo., Idaho, Mont., Nev., N.Dak., Oreg., S.Dak., Utah, Wash., Wyo.
GENERAL BOTANICAL CHARACTERISTICS
Mountain big sagebrush is a long-lived (50+ years), woody, aromatic, native, evergreen shrub [7,11]. Shrubs often appear flat-topped from a distance because of the nearly equal height of flowering stalks . The fruit is a small, easily shattered cypsela that falls or is blown near the parent plant [111,151]. Root length of mature plants was measured to a depth of 6.5 feet (2 meters) in alluvial soils in Utah . Greenhouse-grown plants had roots 26.8 inches (68 cm) long at 6 months . Mountain big sagebrush roots are colonized by fungi that form symbiotic vesicular-arbuscular mycorrhizae [24,121]. Aboveground tissues host an unidentified, pathogenic snowmold fungus that decreases shrub cover and productivity [55,92].
Catalog Number: US 296840
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): G. R. Vasey
Year Collected: 1889
Locality: Washington, United States, North America
- Isotype: Rydberg, P. A. 1916. N. Amer. Fl. 34: 283.
Comments: Montane meadows, usually in rocky soils, sometimes in forested areas; 2000-2800 m. Subspecies vaseyana is the common sagebrush of mountain slopes and is the most abundant of all the subspecies of Artemisia tridentata.
In the Intermountain west, mountain big sagebrush usually occurs in the upper elevational range of the big sagebrush zone in montane valleys and on foothills, slopes and high ridges [5,6,11,71,148]. In northerly parts of its range, this species occurs in mountain valleys and on mountain slopes and ridges as high as 9,840 feet (3,000 m) . It has been reported as low as 2,600 feet (780 m) in Idaho. West and others  report that although mountain big sagebrush is the most common sagebrush in the Great Basin pinyon-juniper woodlands, only the wettest and coolest areas of the higher and larger mountain masses have mountain big sagebrush in their woodlands. Soils are moderately deep, well-drained, slightly acid to slightly alkaline and characterized by late-melting winter snow cover and summer moisture [6,11,19,20,71,124,144]. This shrub grows in full sun but tolerates shade, often occurring in association with mature conifers [96,144].
In a landscape-scale study in Wyoming, soils in topographic depressions occupied by mountain big sagebrush had higher organic matter, nutrients and microbial biomass than soils in more exposed (windblown) areas occupied by other vegetation, including basin and Wyoming big sagebrush. The effect was attributed to greater snow accumulation, leading to greater plant and litter biomass accumulation [19,20,21].
Elevations reported in the literature are as follows:
4,500 to 7,400 feet (1,370-2,255 m) in Arizona 
5,905 to 9,840 feet (1,800-3,000 m) in California [56,118]
7,760 to 8,480 feet (2,365-2,585 m) in Colorado 
2,560 to 8,990 feet ( 780-2,740 m) in Idaho [71,146]
3,770 to 7,810 feet (1,150-2,380 m) in Montana and British Columbia [3,68,78,97]
5,445 to 10,170 feet (1,660-3,100 m) in Nevada [82,118,121,124,154]
3,500 to 9,000 feet (1,066-2,740 m) in Oregon 
7,250 to 8,040 feet (2,210-2,450 m) in Wyoming[20,25,29]
4,690 to 8,990 feet (1,430-2,740 m) in Utah [26,82]
Key Plant Community Associations
Mountain big sagebrush occurs, often as a dominant in shrublands or codominant in savannah, over a range of habitats from montane parklands to warm desert fringes in western North America. This species is a common component of shrub patches in arid grasslands [60,70,89,108,127]. It occurs widely throughout Great Basin pinyon-juniper woodlands
dominated by true pinyon (Pinus edulis), singleleaf pinyon (P. monophylla), and Utah juniper (Juniperus osteosperma) . Mountain big sagebrush has been reported in association with numerous other tree species, including quaking aspen (Populus tremuloides)
[20,26,87,89], ponderosa pine (P. ponderosa) [53,60,100,108], lodgepole pine (P. contorta) [6,26], Douglas-fir (Pseudotsuga menziesii) [53,100], limber pine (P. flexilis) [6,53,100,101], subalpine fir (Abies lasiocarpa) , and whitebark pine (P. albicaulis) [6,90,122]. Mountain big sagebrush may also occur in association with white fir (A. concolor) and Engelmann spruce (Picea engelmannii) .
Common plant associates in Idaho and Montana include Wood's rose (Rosa woodsii), mountain snowberry (Symphoricarpos oreophilus), green rabbitbrush (Chrysothamnus viscidiflorus), antelope bitterbrush (Purshia tridentata), and Rocky Mountain juniper. Associated grasses and forbs include Kentucky bluegrass (Poa pratensis), bluebunch wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis), cheatgrass (Bromus tectorum), prairie
Junegrass (Koeleria macrantha) green needlegrass (Nassella viridula), needle-and-thread grass (Hesperostipa comata), Sandberg bluegrass (Poa secunda), and bottlebrush squirreltail (Elymus elymoides)
Common associated species reported for central and eastern Oregon and Washington are western juniper (J. occidentalis), ponderosa pine, Wyoming big sagebrush, gray low sagebrush (A. arbuscula ssp. arbuscula), antelope bitterbrush, wax currant (Ribes cereum), Idaho fescue, bottlebrush squirreltail, bluebunch wheatgrass, Sandberg bluegrass, Kentucky bluegrass, basin wildrye (Leymus cinereus), and cheatgrass [28,108,127,148].
In Wyoming sagebrush steppe communities, mountain big sagebrush is commonly associated with Idaho fescue, antelope bitterbrush, needle-and-thread grass, spike
fescue (Leucopoa kingii), sulphur eriogonum (Eriogonum umbellatum var. subalpinum) and silvery lupine (Lupinus argentius) [6,19,20].
Mountain big sagebrush is the most common sagebrush in the extensive Great Basin pinyon-juniper woodlands [123,144]. Associated species include true pinyon, singleleaf pinyon, ponderosa pine, Utah juniper, Rocky Mountain juniper (J. scopulorum), and Jeffrey pine (P. jeffreyi). Associated shrub species include Wyoming big sagebrush, basin big sagebrush, antelope bitterbrush, Gambel oak (Quercus gambelii), black sagebrush (A. nova), gray low sagebrush, and desert peach (Prunus andersonii). Associated genera include Chrysothamnus, Symphoricarpos, Cercocarpus, Ceanothus, Arctostaphylos, Physocarpus, Ribes, Rhus, and Purshia. Associated grasses are numerous, including Columbia needlegrass (Achnatherum nelsonii ssp. dorei), bottlebrush squirreltail, Sandberg bluegrass, bluebunch wheatgrass and cheatgrass [118,121,122,123,144,154].
Publications listing mountain big sagebrush as a dominant, codominant, or indicator species include the following:
Plant communities and habitat types in the Lava Beds National Monument,
Sagebrush-steppe habitat types in northern Colorado: a first
Grassland, shrubland, and forestland habitat types of the White
River-Arapaho National Forest 
Sagebrush-grass habitat types of southern Idaho 
Plant associations of Region Two: Potential plant communities of
Wyoming, South Dakota, Nebraska, Colorado, and Kansas 
Plant communities of the Similkameen Valley, British Columbia 
A preliminary classification of high-elevation sagebrush-grass
vegetation in northern and central Nevada 
Aspen community types on the Caribou and Targhee National Forests in
southeastern Idaho 
A preliminary classification and characterization of big sagebrush,
Artemisia tridentata Nutt., communities in central Montana 
Shrub-steppe habitat types of Middle Park, Colorado 
Big sagebrush (Artemisia tridentata vaseyana) and longleaf snowberry
(Symphoricarpos oreophilus) plant associations in northeastern Nevada 
Grassland and shrubland habitat types of the Shoshone National Forest 
Taxonomic and ecological relationships of the big sagebrush complex in
Sagebrush steppe 
Habitat: Rangeland Cover Types
This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):
More info for the term: cover
SRM (RANGELAND) COVER TYPES :
101 Bluebunch wheatgrass
102 Idaho fescue
104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
107 Western juniper/big sagebrush/bluebunch wheatgrass
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
209 Montane shrubland
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
317 Bitterbrush-bluebunch wheatgrass
318 Bitterbrush-Idaho fescue
319 Bitterbrush-rough fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
324 Threetip sagebrush-Idaho fescue
401 Basin big sagebrush
402 Mountain big sagebrush
403 Wyoming big sagebrush
404 Threetip sagebrush
405 Black sagebrush
406 Low sagebrush
408 Other sagebrush types
411 Aspen woodland
412 Juniper-pinyon woodland
413 Gambel oak
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
504 Juniper-pinyon woodland
509 Transition between oak-juniper woodland and mahogany-oak association
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the term: cover
SAF COVER TYPES :
208 Whitebark pine
210 Interior Douglas-fir
211 White fir
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
237 Interior ponderosa pine
238 Western juniper
247 Jeffrey pine
256 California mixed subalpine
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
More info for the term: shrub
KUCHLER PLANT ASSOCIATIONS  :
K005 Mixed conifer forest
K008 Lodgepole pine-subalpine forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K015 Western spruce-fir forest
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K020 Spruce-fir-Douglas-fir forest
K022 Great Basin pine forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodland
K026 Oregon oakwoods
K028 Mosaic of K002 and K026
K032 Transition between K031 and K037
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
K063 Foothills prairie
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES21 Ponderosa pine
FRES26 Lodgepole pine
FRES30 Desert shrub
FRES34 Chaparral-mountain shrub
FRES36 Mountain grasslands
The big sagebrush complex is adapted to a wide range of precipitation zones and soil conditions. Plants are well adapted to the arid plains, valleys, foothills and mountains of the West where annual precipitation ranges from as little as 200 to as much as 750 or more mm (8 to 30 in). It is often found growing in loamy to sandy loam soils, but plants are found on all 12 soil textural classes in five soil orders: Alfisols, Aridisols, Entisols, Inceptisols and Mollisols. Tolerance to alkalinity or acidity varies by subspecies. In general big sagebrush will grow in soils with a pH of 5.9 to 10.0 and with organic matter content of 0.62 to 4.14 percent.
Basin big sagebrush is commonly found at low to mid elevations from 600 to 2,100 m (1,900 to 6,900 ft) in valleys and mountain foothills, occupying sites with deep fertile loamy to sandy soil, 0.9 m (3 ft) or deeper. It is often the dominant shrub species of the plant community, but is also found in association with juniper, piñon pine and rabbitbrush communities. Basin big sagebrush has a deep penetrating root system that allows it to occupy deeper soils in areas receiving little precipitation. Plants are often found growing in valleys, plains, alluvial fans and in seasonal or perennial stream channels. Basin big sagebrush prefers soils which are non-alkaline, non-saline and non-calcareous. The deep root system does not allow plants to grow in soils with a soil depth limiting hardpan or caliche layer. Depending on soil infiltration and water storage capacity, plants will grow in areas receiving less than 200 to more than 400 mm (8 to 16 in) annual precipitation. This subspecies also does not tolerate soils saturated for more than a few weeks in a season.
Wyoming big sagebrush grows at low to intermediate elevations between basin and mountain big sagebrush, but also commonly overlaps in range with the other two subspecies. When found in proximity with basin big sagebrush, Wyoming sagebrush will occupy the shallower, better-drained soils. Like basin big sagebrush, Wyoming is typically found in large stands covering many acres. Plants are also found in juniper, rabbitbrush, bitterbrush and mountain mahogany communities. At lower precipitation areas it is sometimes intermixed with shadscale and other Atriplex species. Wyoming big sagebrush commonly occurs from 800 to 2,200 m (2600 to 7,200 ft) in elevation. Wyoming big sagebrush is the most drought tolerant of the big sagebrush subspecies and is commonly found growing on low valley slopes and foothills receiving between 200 and 300 mm (8 to 12 in) annual precipitation. It occupies loamy soils with high clay content and a depth of 25 to 75 cm (10 to 30 in). Soils may be quite rocky or gravelly, but in these cases plants will be smaller. Wyoming big sagebrush will be found growing in soils underlain by a caliche or silica layer if the available soil is deep enough. Plants are typically found in soils with a low water holding capacity where excess water may run off into channels more suitable to basin big sagebrush.
Mountain big sagebrush grows in mountain and mountain foothill plant communities such as rabbitbrush, piñon pine, juniper, mountain shrub, aspen, Douglas fir, ponderosa pine and spruce-fir habitats from 800 to 3,100 m (2,600 to 10,000 ft). Plants prefer moderately deep to deep, well-drained soils providing summer moisture. Mountain big sagebrush occurs at higher elevations and in higher annual precipitation zones than either Wyoming big sagebrush or basin big sagebrush. Soils are typically 45 to 90 centimeters (18 to 36 in) deep or more, and are most often loamy to gravelly but can contain greater amounts of clay. Plants commonly grow in areas receiving over 350 mm (14 in) annual precipitation, but may be found in lower elevations and precipitation zones under certain conditions such as snow drift accumulation areas and shaded north facing slopes.
Xeric big sagebrush is limited to basaltic and granitic soils of western and west central Idaho and is often associated with bluebunch wheatgrass. Plants grow in the foothills from 800 to 1,500 meters (2,600 to 4,900 ft). Precipitation ranges from 300 to 400 mm (12 to 16 in) annually.
Spicate big sagebrush grows at high elevation ridge lines and snow accumulation areas from 2,000 to 3,300 m (6,500 to 10,800 ft) in annual precipitation zones of over 750 mm (30 in). It is normally found near Douglas fir, spruce-fir, and aspen communities.
Figure 5. Adaptation of Intermountain big sagebrush subspecies based on elevational and moisture gradients (Mahalovich and McArthur, 2004).
Parish’s big sagebrush is adapted to the dry sandy soils of California’s Inner South Coast Ranges, South Coast, Western Transverse Ranges, White and Inyo Mountains and the desert mountains of the Mojave Desert.
Seed of big sagebrush are best adapted to germinate in habitats with ecological conditions approximating those of the seed collection site. Seed source and subspecies should always be seriously considered prior to seeding. It may be necessary to use seed from more than one subspecies in a given revegetation project to ensure adequate establishment in all habitats.
Seed should be sown in the late fall or early winter and allowed to naturally stratify. It should be noted that big sagebrush seed has special seed storage requirements (See “Seed and Plant Production” section). If stored in conditions with relative humidity above 30 percent, seeds lose vigor and germinability after two or three years. To ensure a greater chance of establishment success, check the viability of seed lots before planting.
Seed should be planted into a firm, weed-free seedbed at a depth of no more than 1/8 inch. Seed covered too deeply with soil will generally fail to establish. Best results come from surface broadcast seed that has been pressed into the soil to provide for good seed-soil contact. Seed can also be broadcast directly onto snow with good results. Pressing broadcast seed into the soil surface with a land imprinter has provided very good establishment success. Land imprinters create good contact between the seed and soil as well as provide microhabitats that optimize temperature and water requirements. Broadcast seeding has also yielded good results when followed by a cultipacker or drag chain.
Drill seeding can be successful, but strict attention must be paid to seeding depth. Optimal drilling depth is 0 to 1/8 inch.
Sagebrush seed lots range in purity from approximately 8 to 30 percent or greater pure seed. Seed lots with high purity levels (20 percent or greater) can be difficult to seed due to limitations of the seeding equipment. Because sagebrush seed is very small and is metered through seeding equipment with difficulty, seed can be diluted with rice hulls or another inert carrier to improve flow.
Post-fire aerial seeding of big sagebrush has been done with limited success. Studies suggest that best results come from aerial seeding followed by land imprinting, cultipacking or chaining, or after allowing native perennial grasses to establish for a season following fire. It is believed that native grasses would suppress exotic annual grass species while allowing the establishment of sagebrush. Further study of this option is indicated.
Big sagebrush is not recommended for pure seedings. Seed should be a small component of a seed mix. Drill seeding 0.025 lbs PLS per acre (approximately 1 viable seed/ft²) provides approximately 400 plants per acre for optimal wildlife habitat. For broadcast seeding increase to 0.05 to 0.075 lbs PLS (approximately 2-3 viable seeds/ft²). With adequate soil moisture seedlings develop quickly and compete well with other shrubs and most herbaceous plants. However, to enhance establishment, sagebrush should not be sown in the same drill row with more aggressive forbs and grasses.
Sagebrush seedlings require sufficient soil moisture to germinate and survive. Young plants do not do well in open, unprotected locations. Best establishment results occur in sites where soil moisture is at or near field capacity, or in areas where snow accumulates. Existing shrubs, downed trees and litter can create microhabitats which also provide very good germination conditions.
Containerized stock or bareroot seedlings can also be used with high establishment success (50% or greater). This method, however, is quite costly, and is rarely used except in small critical area plantings. Plants can be taken from nursery stock or field harvested wildings. Wildings should be collected and transplanted during dormancy in fall or very early spring when soil moisture conditions are best. For best cost efficiency, “mother plants” should be placed in key locations throughout the revegetation site to allow for natural seed dispersal and recruitment over time.
Fire Management Considerations
Prescribed fire can be an economically and ecologically sound method for meeting management objectives [11,17,18]. Low fine fuel loading is a common problem. Burning sagebrush shrubland may not result in intended increases in grass and forb production, but may instead result in unplanned and detrimental shifts in plant community composition. Concentrated large herbivore use should be expected and included in the planning process [17,40].
Fire does not result in substantial increases of herbaceous perennials on sites dominated by exotic annuals. The fuel load may be sufficient in such sites to sustain a fire, but the presence of annuals may prevent the establishment of perennial species. Annuals often increase following a fire, creating conditions where wildfires occur more frequently. Frequent fires prevent the reestablishment of shrubs and may reduce the existing perennial herb populations. Increasing the interval between fires allows time for perennials to establish, breaking the weed-perpetuating fire cycle .
In an Idaho prescribed burn conducted in winter, individual mountain and Wyoming big sagebrush plants burned easily when canopy fuel moisture was below 37%, air temperature was above freezing, relative humidity was below 45%, and skies were clear. In that study, only small areas burned because the canopy was not dense enough to carry fire. Where canopy cover was at least 50%, distance between plants was not greater than 50% of their average height, and effective wind speed was above 5 mph (8 km/hr), the fire carried successfully . Britton and others  developed a big sagebrush canopy cover-herbaceous fuel load curve representing proportions of big sagebrush cover and herbaceous fuels needed to produce a successful burn.
Several monographs provide detailed information about managing fire in sagebrush. One of the monographs  provides information specific to mountain big sagebrush. The other 3 discuss mountain big sagebrush, but recommendations are general in scope, extending to other species of sagebrush.
Managing Intermountain rangelands--sagebrush-grass ranges 
Fire response of shrubs of dry forest habitat types in Montana and Idaho 
Guidelines for prescribed burning in sagebrush-grass rangelands in the northern Great Basin 
Fuel and fire behavior prediction in big sagebrush 
Please refer to other FEIS reports for discussions of fire management considerations for important co-occurring species, including Wyoming and basin big sagebrush, bitterbrush subsp., bunchgrasses, and junipers. Related fire case studies for Wyoming big sagebrush and basin big sagebrush are available in the FEIS reports for those species.
Broad-scale Impacts of Plant Response to Fire
Early Response - Mountain big sagebrush regeneration from seed varies in the 1st postfire year. A high elevation (7,200 feet (2,200 m)) shrub-grass community in western Wyoming was burned in September, 1983, and evaluated 1 year later. The fire completely eliminated mountain big sagebrush cover on 50% of the site. Mean density of mountain big sagebrush seedlings on burned, east-slope plots was as high as 1,090 per acre (2,691/ha), compared to 97 seedlings per acre (240/ha) on paired, unburned plots. Measurements on west-facing slopes were impaired by sampling difficulties .
In contrast to the Wyoming study, Young and Evans  found no germination stimulating effect following wildfire in a stand of mountain big sagebrush in western Nevada. The August fire consumed all standing woody material. In September of the same year they collected 1000 soil samples from the interior of the burn and subjected them to a greenhouse germination test. No sagebrush germinated in any samples. At the end of the growing season following the fire, mountain big sagebrush seedlings in the field site were detected at a density of 4/acre (10/ha.).
Also in contrast to the Wyoming study, managers in California burned a high elevation meadow (8,202 feet (2,500 m)) to reduce shrub encroachment. The following spring only trace numbers of new mountain big sagebrush seedlings were present. Mature shrub species were replaced by an early seral grass-forb community .
Response Over Time - Mountain big sagebrush may return to preburn density and cover within 15-20 years following fire, but establishment after severe fires may proceed more slowly . On some sites mountain big sagebrush may recover slowly in the first years after fire. A southern Idaho sagebrush steppe site experimentally burned in August, 1936, was studied in subsequent decades [10,11,52]. The site was identified as a mountain big sagebrush habitat type, free of cheatgrass. The burned area was protected from grazing for a year following burning and grazed conservatively thereafter. To the advantage of desirable forage species, big sagebrush was practically eliminated, and reestablishment was slow during the first 9 years, but during the next 18 years big sagebrush cover increased greatly. Researchers' summary statements are excerpted here:
"Almost all important species of shrubs, grasses and forbs decreased in yield from 1948 to 1966 as the big sagebrush recovered its dominance after the burn...From observation, sagebrush in the vaseyana habitat type sometimes reinvades an area immediately following a burn; so control benefits do not always exist as long as they have on the 1936 burn. The length of time between control measures depends on grazing practices and the undefined weather variables that favor sagebrush seedling survival and establishment" .
Fraas and others  quantified the effects of prescribed fire on vegetation 8 years after burning in an antelope bitterbrush-mountain big sagebrush-bluebunch wheatgrass community in Montana. Mountain big sagebrush canopy cover and stem density in the burned plot remained low. Both parameters were significantly greater (P < 0.01) in the unburned plot, indicating a high fire-induced mortality coupled with lack of postburn seedling establishment.
The Research Project Summary
Vegetation response to restoration treatments in ponderosa pine-Douglas-fir forests of western Montana provides information on prescribed fire and postfire response of plant community species,
including mountain big sagebrush, that was not available when this species review was written.
Plant Response to Fire
Mountain big sagebrush plants top-killed by fire will not resprout [10,94]. Regeneration of mountain big sagebrush is from on-site or off-site seed. Depending on circumstances of the environment and seed source, mountain big sagebrush seeds may sprout profusely the spring after burning [27,103], or very sparsely [10,50,67]. These relationships are not well understood. Seedlings can grow rapidly and may reach reproductive maturity within 3 to 5 years . Where mountain big sagebrush is dominant and persistent (climax or long-term seral), fire often reduces its dominance and alters species composition for the first few years. If exotic species have not altered successional pathways, vegetation eventually reverts to its previous composition [1,11,17,88,94].
Immediate Effect of Fire
POSTFIRE REGENERATION STRATEGY :
Ground residual colonizer (on-site, initial community)
Initial off-site colonizer (off-site, initial community)
|Old burn line seperating mountain big sagebrush and bluebunch wheatgrass communities, Lassen County, California. Photo courtesy of the PRBO Conservation Science Shrubsteppe Monitoring Program.|
Fire regime: Presettlement fire return intervals in mountain big sagebrush communities varied from 15 to 25 years [22,155,157]. For example, mountain big sagebrush sites in southwestern Idaho show evidence of about 3 to 5 fires per century prior to 1910 . Very frequent fire suppresses mountain big sagebrush establishment, while long fire return intervals promote tree invasion into mountain big sagebrush communities. Arno and Gruell  considered average fire intervals of about 20 years sufficient to control mountain big sagebrush invasion in southwestern Montana grasslands. In the photo above, fire mortality has removed mountain big sagebrush from the foreground, creating a shrub-grassland mosaic.
Fire exclusion has led to invasion of mountain big sagebrush communities by western juniper [22,156,157]. Mountain big sagebrush can be a nurse plant for western juniper. On a southeastern Oregon site, less than 20% of western juniper seedlings established in the open; the rest were under mountain big sagebrush or low sagebrush plants . Sparse under presettlement fire frequencies of 15 to 25 years, western juniper has formed dense stands on former mountain big sagebrush communities in the Great Basin [22,156,157]. Miller and others  found that on southeastern Oregon and northeastern California sites, mountain big sagebrush cover declined to 80% of maximum potential as western juniper cover increased to 50% of maximum canopy cover. Herbaceous cover and species diversity declined, and bare ground cover increased, with increasing western juniper dominance. Burkhardt and Tisdale  concluded that fire frequencies of 30 to 40 years would control western juniper expansion onto mountain big sagebrush communities.
FIRE REGIMES for communities in which mountain big sagebrush occurs are summarized below. For further information about FIRE REGIMES and fire ecology of communities where mountain big sagebrush is found, see the 'Fire Ecology and Adaptations' section of the FEIS species summary for the plant community or ecosystem dominants.
|Community or Ecosystem||Dominant Species||Fire Return Interval Range in Years|
|sagebrush steppe||Artemisia tridentata/Pseudoroegneria spicata||20-70 |
|basin big sagebrush||A. t. var. tridentata||12-43 |
|mountain big sagebrush||A. t. var. vaseyana||15-40 [3,23,156]|
|Wyoming big sagebrush||A. t. var. wyomingensis||10-70 (40)** [128,149]|
|California montane chaparral||Ceanothus and/or Arctostaphylos subsp.||50-100 |
|curlleaf mountain-mahogany*||Cercocarpus ledifolius||13-1000 [4,110]|
|mountain-mahogany-Gambel oak scrub||C. l.-Quercus gambelii|
|western juniper||Juniperus occidentalis||20-70|
|Rocky Mountain juniper||J. scopulorum|
|Engelmann spruce-subalpine fir||Picea engelmannii-Abies lasiocarpa||35 to > 200|
|whitebark pine*||P. albicaulis||50-200 |
|Rocky Mountain lodgepole pine*||P. contorta var. latifolia||25-300+ [2,107]|
|Colorado pinyon||P. edulis||10-49|
|Jeffrey pine||P. jeffreyi||5-30|
|Pacific ponderosa pine*||P. ponderosa var. ponderosa||1-47|
|Rocky Mountain ponderosa pine*||P. p. var. scopulorum||2-10|
|Arizona pine||P. p. var. arizonica||2-10 |
|quaking aspen (west of the Great Plains)||Populus tremuloides||7-120 [16,48,79]|
|mountain grasslands||Pseudoroegneria spicata||3-40 (10)** |
|Rocky Mountain Douglas-fir*||Pseudotsuga menziesii var. glauca||25-100|
|oak-juniper woodland (Southwest)||Quercus-Juniperus subsp.||16]|
Fire adaptations: Mountain big sagebrush is readily killed by fire and requires at least 15 years to recover after fire . Postfire establishment is from seed. Data from 1 study suggest that germination is stimulated by fire. Champlin  reported that mountain big sagebrush seedling emergence under greenhouse conditions was greater in field-burned (in situ) soil samples than in unburned soil samples. By contrast, seedling emergence of Wyoming big sagebrush was reduced in burned soils. Possible explanatory mechanisms might be related to those explored by Blank and Young . They observed that smoke and compounds present in aqueous extracts of heated soils from beneath a sagebrush canopy increased the emergence of common associated plant species, though big sagebrush seeds were not among those tested.
There is other evidence that mountain big sagebrush seed germination and survival in the field may be quite low following fire. Please refer to the section titled Discussion and Qualification of Plant Response in the Fire Effects section of this report.
More info for the terms: association, climax, cover, density, fire suppression, shrub, succession
On a geologic time scale, the big sagebrush species have probably reached their maximum post-glacial spread .
According to Bunting  and references therein, most recent research indicates that big sagebrush is the climax species on its present-day range, and that invasion into other types is uncommon. Alterations of historic FIRE REGIMES have resulted in major successional changes in regions dominated by mountain big sagebrush and other sagebrush species, and the introduction of exotic annual grasses has modified the role of fire. In general, fire is less common, but in some cases it is more frequent.
In some areas, especially where fire suppression has been a factor, stands of mountain big sagebrush are being invaded by juniper woodlands [17,23,83], lodgepole pine  and Douglas-fir .
In the juniper woodlands of southern Idaho, western juniper has invaded large areas of mountain big sagebrush shrubland. Burkhardt and Tisdale [22,23] reviewed possible causes, including destruction of grassland via livestock grazing, increased seed dispersal by sheep, climate change and a reduction of the historic fire return interval. In field sites they examined seed dispersal mechanisms, fire history, and juniper seedling establishment, and concluded that succession of sagebrush-grass shrublands to juniper woodlands is directly related to cessation of periodic fires. In the same region, Hironoka and others  identified 10 climax habitat types dominated by mountain big sagebrush. Please see the Fire Ecology section of this report for more discussion of the Burkhardt and Tisdale study.
Beetle and Johnson  determined that most big sagebrush stands in Wyoming, including mountain big sagebrush, probably represent edaphic or topographic climax. Evidence indicates that stands were historically self-replacing after fire. In that area, mountain big sagebrush replaces pioneer grassland communities. Lodgepole pine, and occasionally Douglas-fir, were observed encroaching into established stands of mountain big sagebrush [6,7].
In Eastern Oregon and Washington, mountain big sagebrush forms climax shrub communities with snowberry, elk sedge, and Idaho fescue. Mountain big sagebrush climax shrublands occur in association with ponderosa pine and western juniper .
In southern British Columbia mountain big sagebrush sometimes dominates within openings in subalpine fir forests. These communities are characterized as edaphic climax .
Mountain big sagebrush is reported to have "a tendency" to increase in plant density or foliar cover following disturbance [57,146,147]. Beetle and Kendall  reported mountain big sagebrush has more potential for increasing in density than any other sagebrush species.
Please refer to the Fire Effects section of this report for information about short and long term responses of mountain big sagebrush to stand-replacing fires.
Mountain big sagebrush usually flowers in late summer and fall, but some strains may flower as early as July. Seed matures from September through October . Mature seeds fall or are blown from inflorescences during autumn and winter and emergence occurs in winter or spring [75,80,151]. Seeds are short-lived (less that 5 yr in warehouse) and probably do not form a persistent seed bank [82,151]. Average annual seed production in western Nevada was 29 pounds per 2.5 acres (1.3 kg/0.1 ha) over a 4 year period .
Recently harvested seeds are nondormant but require light for germination . Cold, moist conditions and exposure to light increase germination [75,76,82]. Germination response varies between populations of mountain big sagebrush growing in different habitats. Meyer and others [80,81,82] observed strong, significant correlations (P < 0.05) between percent germination and climate variables (light and cold). Seed collections from habitats with long, severe winters germinated slowly and incompletely, whereas seed collections from sites with shorter, milder winters germinated rapidly and completely.
Results of a western Nevada seed bank study showed the number of (greenhouse) germinable seeds of mountain big sagebrush decreased sharply as winter progressed and fell below detectable levels by June. Seeds did not persist in the soil seed bank. For 4 consecutive years there were no detectable seed reserves in the soil from June to November. Dispersal began in December and hundreds of newly dispersed mountain big sagebrush seeds were counted in seed traps near individual plants. Seedling emergence in the study plots began in February, but all seedlings died by June. No successful seedling establishment of mountain big sagebrush (nor basin big sagebrush) was observed in any of the permanently marked plots during the 4 years of the study .
To examine yearly variation in germinability, Harniss and McDonough  quantified percent germination in unstratified, laboratory-germinated seeds collected from the same 10 plants of mountain big sagebrush for 3 consecutive years. They detected no significant (P < 0.05) year-to-year difference in average germination, which ranged from 11% to 17%.
Mountain big sagebrush can reproduce vegetatively by layering [7,8,53,71]. It does not resprout when aboveground tissues are killed by fire or other means [10,11,94].
Growth Form (according to Raunkiær Life-form classification)
More info for the term: phanerophyte
RAUNKIAER  LIFE FORM:
Life History and Behavior
More info for the term: phenology
A study of sagebrush phenology in southern Idaho  showed marked differences in dates and rates of development among taxa. Mountain big sagebrush began growth approximately 2 weeks later and ripened seed at least 2 weeks earlier than basin and Wyoming big sagebrush. Blaisdell and others  reported that some strains of mountain big sagebrush start blooming as early as July, and that seed matures from September through October.
Generalized findings for mountain big sagebrush derived from the Idaho study are as follows :
|late June||early shoot development|
|early July||medium shoot development|
|mid-July||full shoot development|
|mid- to late July||flowerheads green|
|early August||flowerheads yellow|
|late September||seeds ripe|
Persistence: PERENNIAL, Long-lived, EVERGREEN
Flowering mid summber to late fall (FNA 2006).
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: T4 - Apparently Secure
Consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status (e.g. threatened or endangered species, state noxious status, and wetland indicator values).
Pests and potential problems
Perhaps the greatest danger to sagebrush stands comes from fire. Big sagebrush plants have no fire resistance and many acres are destroyed annually because of increased fire frequency resulting from infestations of exotic annual weeds such as cheatgrass and medusahead.
Another minor cause of sagebrush mortality is winter injury. This occurs when temperatures drop quickly below freezing before plants have entered dormancy, or when a warm spell promotes winter growth followed by a return to typical winter temperatures. Extended periods of winter and summer drought (normally more than 2 years) can also cause dehydration and death.
Big sagebrush is occasionally susceptible to limited outbreaks of the sagebrush defoliator moth, or webworm, (Aroga websteri). Although the moths can cause extensive damage, they too are subject to insect predators, and it is rare that entire stands will be lost.
Additionally, there are a number of other microbial and fungal pathogens known to attack big sagebrush. Although these may inflict serious damage locally, they have not been viewed as a great threat to sagebrush populations.
The ecology of mountain big sagebrush in the West has been altered by post-settlement increases or decreases in historical fire intervals and livestock grazing, widespread invasion by exotic annuals, and perhaps climate change [11,23,83,143]. Historical abundance of big sagebrush has been disputed. According to reviews [7,143] and a comparative examination of 20 historical photos from 3 states , big sagebrush was abundant and codominant with perennial bunchgrasses in pre-settlement times. Sagebrush species do not appear to have increased their range on a large scale, but reviewers agree that big sagebrush has increased in density in many places in response to excessive grazing and altered FIRE REGIMES. Regarding the sagebrush steppe ecosystem, West  makes the following remark: "Some of it has been so degraded by excessive livestock grazing and burning that its relationship to its origins is no longer easily recognizable."
Important management considerations in sagebrush ecosystems include wildlife use, livestock grazing and overgrazing, fire frequency and hazard, exotic plant invasion and conversion of the ecosystem to other uses. Blaisdell and others  provide an extensive review and guidelines for integrating multiple uses of the sagebrush grasslands, including determining range condition and trend, and controlling sagebrush.
Perryman and Olson  argue that sagebrush control decisions are typically based on characteristics such as canopy cover, but should instead be based on ecologically based community-successional criteria. To aid managers they used annual growth rings to develop a quantitative model of age-stem diameter relationships for the 3 subspecies of big sagebrush. They sampled 75-80 stem cross-sections within 9 stands in regionally dispersed locations across Wyoming. Using the model, managers should be able to quickly assess the age (and perhaps successional status) of big sagebrush stands based on the stem diameter of large individuals. Stand age could then be compared with fire frequency information to determine if control practices should be implemented.
Because mountain big sagebrush often co-occurs with Wyoming big sagebrush and basin big sagebrush, please refer also to the Management Considerations section in FEIS reports for those subspecies.
Cultivars, improved and selected materials (and area of origin)
‘Hobble Creek’ mountain big sagebrush was released by the Utah Agricultural Experiment Station, Utah State University and the USDA Forest Service Rocky Mountain Research Station in 1987. Seed was originally collected in 1968 by A. Perry Plummer at the Hobble Creek drainage east of Springville, UT. ‘Hobble Creek’ was chosen for its high vegetative production and for its high palatability to mule deer and wintering domestic sheep. It is adapted to sites with deep, well-drained soils receiving more than 350 mm (14 in) of annual precipitation and having a growing season of 90 days or longer. Soils should be no finer than a clay loam, containing 40% or less clay and have a pH between 6.6 and 8.6. Breeder seed is maintained at a breeder block at the USDA Forest Service Rocky Mountain Research Station, Shrub Sciences Laboratory, Provo, UT.
‘Gordon Creek’ Wyoming big sagebrush was originally collected near Helper, Carbon County, UT. It was released in 1992 by the USDA Forest Service Rocky Mountain Research Station to fill the need for a low precipitation ecotype of big sagebrush to improve winter diets of mule deer and sage grouse and for rangeland restoration. Gordon Creek was chosen for its high growth rate, nutrient levels and mule deer preference. It is widely adapted to dry regions of the west receiving 250 or more mm (10 in) mean annual precipitation. It prefers deep to shallow, well-drained soils with up to 55% clay content with a pH of 6.6 to 8.8.
Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”
The vast majority of big sagebrush seed used in revegetation is wildland collected material. Seed collection occurs in late fall to early winter (early October through the end of December) depending on the subspecies. Collections are commonly made by hand stripping, beating or clipping seed heads into containers or by using a reel type harvester. Seed can be cleaned with a hammermill, debearder, air-screen or gravity table with varying results. Most sagebrush seed lots used for rangeland seeding are only cleaned to a purity of 15 to 20 percent due to the small nature of the seeds (achenes). This practice requires less time for cleaning and also allows for easier seed flow and metering in seeding equipment. Pure seed yields approximately 1.7 to 2.5 million seeds per pound. The NRCS Plant Materials Center in Bridger, MT reported four hours collecting time and 5.5 hours cleaning yielded 200g (0.45 lb) cleaned material, or 21g (0.04 lb) per hour.
Sagebrush seed that has been dried to a minimum of 9 percent moisture content will remain viable for many years when stored under cool, dry conditions. Welch et al (1996) reported seed viabilities above 90% for seed stored at 10 ºC (50 ºF) and relative humidity (RH) of 20 percent after nine years of storage. Seed stored at higher RH levels are susceptible to germination or damage by insects or microorganisms.
Because sagebrush seed can readily be collected from wild stands, sagebrush is rarely grown in commercial production fields. However, in very droughty periods, very little sagebrush seed can be collected from wild stands. Increasing seed demands and decreasing sagebrush stands lost to weeds and fire are growing concerns. Recent studies suggest protecting wildland seed-producing stands for optimum harvesting. The greatest factor in seed production for sagebrush is protection against grazing animals. Surrounding plants with a wire fence has shown an increase in seed stalk number of as much as 3 to 5 times the amount of unprotected plants. Studies also show significantly higher seed yields from plants grown on reclaimed mine lands when compared with those on adjacent non-mined areas. The reason for this correlation is unclear, but it may be a result of increased available soil moisture due to lower competing plant frequencies on the mined lands.
Seed production varies greatly between years and between stands due to differences in climate, stand density and maturity, soil and genetics. It has been estimated that an average stand of big sagebrush could potentially produce 100 to 300 lbs PLS per acre annually. Seed production declines as plants and stands mature creating larger amounts of woody biomass. Greater seed yields can be achieved by thinning decadent stands to encourage new flower stalk production
For nursery plantings, pre-stratified seed can be planted in greenhouse conditions, or seed can be allowed to naturally stratify after being planted in containers outdoors. Keep soil medium slightly moist during germination. Greenhouse sprayers or misters are commonly used during daylight hours at a rate of 10 seconds every 15 minutes. Uniform germination occurs after two weeks of temperatures over 20º C (70º F). Seedlings are ready for field transplanting approximately 5 months after germination.
Historically, sagebrush communities have been poorly managed, mostly in attempts to reduce or eliminate sagebrush stands to increase forage production for livestock. Recently, however, the value of sagebrush to the western rangelands is being recognized, and practices are evolving to better manage healthy and productive sagebrush communities.
Contrary to long standing beliefs, studies show that complete sagebrush removal negatively affects biodiversity and has little long term affect on perennial grass production. Indeed, several studies indicate that forage production may actually decline when sagebrush is completely removed or controlled.
Overgrazing of the understory decreases plant biodiversity, especially the forb component of the plant community and increases the density of weeds. Annual weeds, such as cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae [L.] Nevski) often out-compete young sagebrush seedlings and create undesirable monocultures. Annual weed infestations also increase the frequency of wildfires which result in eliminating sagebrush stands therefore not allowing stand re-establishment.
Despite the many valuable benefits of sagebrush to rangelands, there may be cases when it is desirable to thin and rejuvenate sagebrush stands. In these instances it is not necessary to remove the entire stand, and control treatments in mosaic patterns are recommended. Several methods exist for partial removal of the shrubby over story.
Herbicide use is an effective means of thinning sagebrush stands. Contact your local agricultural extension specialist or county weed specialist to determine what works best in your area and how to use it safely.
Probably the simplest and most cost effective means of stand reduction is through prescribed burning. If there is sufficient fuel, a burn can completely eliminate a sagebrush community. For this reason niche burning is recommended when possible. In situations where cheatgrass is a dominant part of the understory, burning should take place when ripe cheatgrass seeds are still on the plants and will be consumed in the fire.
Methods of mechanical removal for sagebrush include anchor chaining, pipe harrowing, land imprinting offset disking and brush beating with brush hogs or mowers. Of these, chaining and land imprinting are the least expensive and do an excellent job of reducing sagebrush stands while still leaving enough plants for diversity and browsing. Brush beating does a good job, but it is expensive. Disking and harrowing also do a good job of shrub removal, but are more expensive and more destructive to under-story plant populations.
Relevance to Humans and Ecosystems
Value for rehabilitation of disturbed sites
Mountain big sagebrush is easily propagated from seed under greenhouse, nursery, and common garden conditions [37,53,69,106,150,152] and has been successfully seeded directly into field sites [26,30,65,106,111,152].
The temperature for drying seeds for storage should not exceed 140 degrees Fahrenheit (60oC). Humidity control is important for seed storage and should not exceed 32 to 40% [135,137]. Seed life in storage is about 5 years [111,137].
Mountain big sagebrush has also been successfully planted in field sites using nursery-grown bareroot and containerized stock [38,59,65]. After 3 years, percent survival of outplanted containerized seedlings in a Nevada study was as high as 80% in some plots . Mountain big sagebrush has been propagated by tissue culture with limited success .
Please refer to the General Botanical Characteristics section of this report for more information about mountain big sagebrush regeneration.
Cotts and others  included mountain big sagebrush in a detailed study of revegetation methods for abandoned roads in Grand Teton National Park. They tested 14 treatments. After 2 growing seasons, treatments that included the addition of topsoil (collected locally), followed either by natural colonization of mountain big sagebrush, or seeded with locally collected seed from the same year, had much greater percent plant cover (P=0.05) than various other treatments. The most successful treatment, producing 7.3% cover, was a combination of vegetation removal, substrate scarification, topsoil application, and phosphorus application. Application of locally collected seed alone, following vegetation removal, produced a cover of 0.3%. Application of commercial seed alone following vegetation removal produced only a trace of mountain big sagebrush cover. Sites treated with a combination of locally collected seed with topsoil increased plant cover compared to various treatments without topsoil. More notably, mountain big sagebrush was the most dominant species to naturally colonize nonseeded, topsoiled treatments.
There is evidence that mountain big sagebrush is not aided by the addition of supplemental water and/or fertilizer under field conditions. In a Wyoming study where researchers applied water and ammonium nitrate to transplants on a reclaimed strip mine (regraded with original topsoil), for 3 successive years, there was no significant increase (P=0.05) in aboveground biomass .
|upland game birds||-||good||good|
Importance to Livestock and Wildlife
Reliance on the big sagebrush ecosystem by many wild animals for both food and cover has been documented and reviewed extensively [11,57,77,91,96,98,111,129,137]. Wildlife researchers have argued that the importance of sagebrush as forage, and effects of foraging on sagebrush are not fully appreciated [130,131,140]. Big sagebrush is eaten by domestic sheep and cattle, but has long been considered to be of low palatability to domestic livestock, a competitor with more desirable species, and a physical impediment to grazing [11,33,111].
Other uses and values
Native peoples used big sagebrush leaves and branches for medicinal teas, and the leaves as a fumigant. Bark was woven into mats, bags and clothing .
The Hobble Creek cultivar of mountain big sagebrush is a highly preferred sagebrush that exceeds most other winter forage values in energy, protein, phosphorus, and carotene. Winter crude protein content of the cultivar is 10%-11% of dry matter, winter in vitro digestibility is 52.6% of dry matter, winter phosphorus level is 0.21%, and total winter monoterpenoid content is 2.09%. A study comparing mule deer preference for the Hobble Creek cultivar against antelope bitterbrush indicated that mean usage did not differ after the first 2 measurements, but was significantly higher (P < 0.05) for the 2 final measurements. The sagebrush cultivar was significantly more digestible than antelope bitterbrush, and significantly higher in crude protein and phosphorus [138,139,140].
Wambolt [130,131] studied elk and mule deer preference for the 3 big sagebrush subspecies and black sagebrush. The study was conducted annually for 10 years on 2 sites in Yellowstone National Park. Each year approximately 2,500 leaders on 244 plants were examined for browsing. The percentage mountain big sagebrush leaders utilized during a given winter was as high as 91%. In all cases, mountain big sagebrush was used more than the other 3 taxa, with an average of 56.1% use. In 16 of the 20 samplings, use of mountain big sagebrush was significantly (P < 0.05) greater than that of Wyoming big sagebrush, the second most preferred taxon, which had an average of 38.6% use. Differences in preference among taxa were smallest during severest winters when more elk were present on the site.
Welch and Wagstaff  noted that mountain big sagebrush is a highly preferred and nutritious winter forage for mule deer. They argued that "The perception that big sagebrush is largely unsuitable and unused is due to low palatability to cattle and its ability to quickly mask evidence of use." The "Hobble Creek" low elevation, USDA cultivar  of mountain big sagebrush is preferred by both wintering domestic sheep and mule deer. The cultivar has not been found to contain substances that negatively influence preference or suppress grass cell wall digestion in ruminants [138,139,140].
Forage/Wildlife: Big sagebrush is perhaps the most important shrub on western rangelands. Evergreen leaves and abundant seed production provide an excellent winter food source to numerous species of large mammals including mule deer, black-tailed deer, white-tailed deer, elk, pronghorn antelope, bighorn sheep and jack rabbits. Nearly 100 bird species depend on sagebrush ecosystems for their habitat needs. Additionally, there are several animal species having an obligate relationship with big sagebrush including sage grouse, sharp tailed grouse, pygmy rabbits, sage thrashers, sage sparrows and Brewer’s sparrow. Sagebrush also provide habitat and food for hosts of invertebrates which in turn support birds, reptiles and small mammals. In addition to the numerous species of animals that depend on sagebrush for food and cover, there are several plant species having close relationships with sagebrush as well.
Sagebrush plants maintain high levels of most nutrients including crude protein (see table 1). This high forage value makes it especially useful for wildlife, and in some areas livestock, winter grazing. Separate studies indicated that sagebrush made up 78% of the annual diet for antelope in Wyoming and 59% of the winter diet of deer and elk near Gardiner, Montana. Sagebrush also makes up close to 100% of the winter diet of sage grouse and over 60% of their total annual diet. Use of sagebrush by livestock is limited and variable.
Animal preference of sagebrush varies with subspecies, populations and even individual plants due to chemical variation found in the foliage. Deer and elk tend to prefer mountain big sagebrush followed by Wyoming big sagebrush and finally basin big sagebrush. Although many range managers believe that deer and other large mammals prefer to browse shrubby members of the Rosaceae such as mountain mahogany (Cercocarpus), bitterbrush (Purshia) and cliffrose (Cowania) over big sagebrush, studies show sagebrush significantly more readily browsed.
Sagebrush’s value as thermal or security cover is also very high for wildlife. This includes nesting cover and escape cover for sage grouse, sharp tailed grouse, pheasants, chukar and other upland birds.
Table 1. Nutritive values as percent dry matter and percent in-vitro dry matter digestibility (IVDMD).
(Adapted from Welch, 2005)
Revegetation/reclamation: Because of its wide range of adaptation and ease of establishment, big sagebrush can be a very important species for use in revegetation efforts. Seedlings are able to compete with grasses and forbs as well as other shrubs allowing it to be used as a component of a wide range of seed mixes. Seedlings are very easy to establish when planted correctly (see “Establishment” section) and can be drill seeded or broadcast with near equal levels of success. Because sagebrush plants spread readily by seed, it can be seeded at relatively low rates and allowed to spread by natural recruitment.
Big sagebrush plants provide many additional benefits to the plant community. The dense canopy protects understory herbaceous plants from grazing. Healthy sagebrush communities provide a multi- tiered ecosystem with high levels of biodiversity. Big sagebrush plants also have a two-part root system with a deep tap root and a shallow, diffuse root system. Numerous studies have shown sagebrush plants create “hydraulic lift” where deep soil moisture is brought to near the soil surface by the tap root system during the day and then released into the upper soil at night. This water is then available to the diffuse root system of big sagebrush as well as to the roots of other understory plants. Sagebrush plants also increase water retention by trapping and holding windblown snow.
Big sagebrush subspecies are often useful indicators of soil characteristics. Generally, a subspecies indicates the soils at a site, thus proper identification of big sagebrush at a subspecific level can provide useful information on soils and ecological site characteristics. In some areas, however, such as those with glacial deposits, a separation based on soil characteristics is considerably more complex.
Names and Taxonomy
The currently accepted scientific name of mountain big sagebrush is Artemisia tridentata ssp. vaseyana (Rydb.) Beetle (Asteraceae) [5,31,56].
There are 2 other widely distributed subspecies of big sagebrush (A. tridentata): basin big sagebrush (A. t. subsp. tridentata) and Wyoming big sagebrush (A. t. subsp. wyomingensis) [8,56,64]. There is substantial overlap in the distribution of big
sagebrush species, and the 3 major subspecies sometimes tightly co-occur . It is difficult to distinguish among them without chemical or molecular analysis [8,74,133,145]. Mountain big sagebrush contains chemical constituents that allow it to be distinguished from the other 2 major subspecies when subjected to an ultraviolet light test . Morphological characteristics, especially leaf and shrub shape, have been relied upon to distinguish among big sagebrush subspecies
[5,31,56]. Hybridization within
these 3 subspecies of big sagebrush has been confirmed [42,43,46,73,74,115].
In addition to the 3 major subspecies mentioned above, at least 2 other subspecies of big sagebrush with limited distributions are recognized: A.
t. subsp. parishii  and A. t. subsp. xericensis . Each is commonly known as big sagebrush. Snowfield
big sagebrush has been classified both within the big sagebrush complex (A. t. subsp. spiciformis) [45,64] and as a distinct species (A. spiciformis) .
In this report, the name "big sagebrush" is used when discussing the big sagebrush species complex. Infrataxa including mountain big sagebrush are referred to by the subspecific common names used above. Because the International Botanical Congress no longer recognizes varieties or forms of subspecies, forms and varieties within the vaseyana subspecies are treated here as A.
t. subsp. vaseyana. For more information about the species complex, please refer to the FEIS reports for other subspecies.
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