Distinguishing black sagebrush: Black sagebrush closely resembles and often grows near low sagebrush and subspecies of big sagebrush [81,107,191,263]. Distinguishing among these taxa may be difficult, especially where hybridization occurs. Because sagebrush species are important rangeland shrubs that differ in ability to provide habitat and food for animals (see Management Considerations), McArthur and Plummer [171] noted that "range managers will benefit from learning as much as they can about variation in sagebrush". It is difficult to identify the Tridentatae based on any one morphological character, but black sagebrush and other sagebrushes can be distinguished when morphological features are compared together [171]. For keys for identifying black sagebrush and similar sagebrush taxa based on gross morphology, see these sources: [13,38,64,81,107,139,160,222,286,306]. Visible with a hand lens, black sagebrush's leaf trichomes are distinctive and can also help distinguish it from other Tridentata taxa; see Kelsey [141,142] for details. Chemical analyses may be required to verify morphological observations; Rosentreter [222] reviews chemical techniques used for black sagebrush identification. Other sources provide identification keys based on chromatography [38] and ultraviolet light [222,246] tests that can be conducted in the field. The following description covers characteristics that may be relevant to fire ecology and is not meant for identification.
Form and architecture: Black sagebrush is an evergreen, aromatic shrub. It is low-growing and decumbent, so it is grouped with the dwarf sagebrushes [16,222]. Black sagebrush crowns are typically irregular, spreading, and U-shaped [222,319], although heavily browsed plants become rounded [230]. Habit is occasionally upright [16]. Black sagebrush has a taproot [79] and wide-spreading lateral roots. Roots can be deep on favorable sites [79,125], but shallow soils prevent deep root development on most sites where black sagebrush is dominant (see Soils). Black sagebrush tends to have a larger number of fibrous roots than big sagebrush [248]. Above ground, vegetative growth typically reaches 4 to 10 inches (10-30 cm), with inflorescences rising about equally high above branches [64,107,160,298]. Within black sagebrush stands, individual shrubs tend to reach similar heights, giving the stands a "hedged" appearance [81]. Branches are woody [145] and short, spreading loosely [81,298] from a short trunk [107]. Vegetative branches are typically numerous [13]. Lowest branches may arise from the base of the root crown [138]. Mature bark is shreddy [13,205,290].
Leaves: Black sagebrush leaves are darker than leaves of associated sagebrush (Artemisia spp.); hence, the common name "black sagebrush" [298]. There are 3 different leaf types: ephemeral, unlobed flowerstalk leaves; ephemeral, lobed stem leaves; and persistent, lobed stem leaves [13,38]. Ephemeral stem leaves are larger than persistent stem leaves and are irregularly lobed [71,222]. Persistent leaves are bell-shaped [222], shallowly to deeply 3- to 5-lobed, and small, mostly 0.2 to 0.8 inch (0.5-2 cm) long [138,298]. Persistent stem leaves are considered characteristic of sagebrush species, so they are nearly always those used in keys for identifying sagebrush taxa [71].
Reproductive structures: The black sagebrush inflorescence is a long, narrow panicle [13]. There are typically 3 to 5 flowers/flowerhead [64,138,174]; the small, few-flowered heads are characteristic of this species [138,160]. Ray flowers are lacking; all are perfect disc flowers [107,135,165,174,209]. The fruit is an achene [64] about 1 to 2 mm long [107]. Seeds have a thin, waxy seed coat [19]. Black sagebrush seeds are the largest of the Tridentatae, but with about 2,000 seeds/g [176], they are still small.
Morphs: The 2 black sagebrush morphs are distinguishable by leaf color: one morph has gray leaves and the other green [13,16,222]. Chemical differences between the morphs have important implications for rangeland management (see Palatability). Black sagebrush morphs may occur in pure stands or together [13]. Studies are needed to determine the geographic ranges of these morphs [222].
Stand and age class structure: Black sagebrush communities are typically open, with crown cover usually less than 15% [302]. In black sagebrush communities in the Buckskin Mountains of western Nevada, black sagebrush density averaged 2.2 plants/m² and frequency was 100% [319]. See Fuels for more information on plant densities in black sagebrush communities.
Limited information was available on black sagebrush's age class structure as of 2009. The Buckskin Mountains study [319] divided black sagebrush into 5 age classes: seedling, young, mature, patriarch, senescent, and dead plants. Seedlings were very rare, with only 1 seedling found on 1,000 square feet (100 m²). Within stands, about 6% of the black sagebrush were young plants (woody but not yet seed-producing); there were as many dead as young plants. Plants were mostly mature (seed-producing but <40 years old), ranging from 0.7 to 2.0 feet (0.2-0.6 m) tall and 0.7 to 1.6 feet (0.2-0.5 m) in crown diameter. For mature plants, about 10% of the canopy was dead. Plants older than about 40 years gained biomass but did not grow taller due to decay of the main stem. Patriarch plants (≥40 years with the main stem mostly intact) had about 30% aboveground dead material, with relatively fewer leaves and more branch spread than plants in younger age classes. Senescent black sagebrushes had ≥50% dead material; their ages could not be estimated due to stem decay. Comparing stand structure of black sagebrush communities with that of lower-elevation basin big sagebrush communities, Young and Palmquist [319] found that within each community, mean biomass of the 2 sagebrushes was similar. Although basin big sagebrush was taller and wider, black sagebrush was about twice as dense [319].
Passey and Hugie [206] estimated the maximum age of black sagebrushes in southern Idaho, northern Utah, and northeastern Nevada at 47 years.
Physiology: Black sagebrush is highly drought tolerant [185]; it is more likely to endure drought than most sagebrush taxa [236]. It is slightly salt tolerant (reviews by [145,302]) and flood intolerant [230]. Laboratory studies suggest its ability to photosynthesize is restricted to a narrow temperature range [300] (see Elevation).
Black sagebrush is native to and widely distributed in the western United States. It has the broadest geographical spread of all the dwarf sagebrushes [236], and its range is second only to basin big sagebrush among all North American sagebrush (Artemisia spp.) taxa [222]. Black sagebrush occurs from central Idaho, west-central Montana, and southwestern Wyoming south to southeastern California, northern Arizona, and northern New Mexico [64,81,137,139,191,236]. It dominates about 43,300 square miles (112,100 km²) of rangeland in the western United States, the majority of which is in Nevada and Utah. Beetle [13] provides a breakdown of the acreage by state. In its farthest reach to the northeast, black sagebrush grows on foothills and in mountain valleys rimming the Northern Great Plains [133], with its distribution extending as far as 100 miles (200 km) east of the Continental Divide (review by [57]). Black sagebrush cover types occupy about 5.1% of the Great Basin [308] and about 0.5% of the Columbia and Wyoming basins. Surveys in the Columbia and Wyoming basins showed most black sagebrush (67%) and low sagebrush (A. arbuscula)-black sagebrush (76.5%) shrublands were in undesignated public lands (those with permanent protection from conversion of natural land cover but subject to extractive use) [250]. Flora of North America provides a distributional map of black sagebrush.
Expert opinion and historical evidence from pioneer journals support the idea that distribution of sagebrush species has not greatly shifted since European settlement. Sagebrushes dominate the Columbian and Great basins today, and most pristine plant communities in the Columbian and Great basins were historically dominated by sagebrushes (review by [156]).
Black sagebrush communities: Frequent prescribed fires are not recommended in black sagebrush communities [39,274]. Vallentine [274] recommended protecting black sagebrush communities from fire due to black sagebrush's high forage value. Large-scale fires can greatly reduce availability of this palatable species [39], although small, patchy fires can provide openings that allow for black sagebrush establishment from the soil seed bank or upwind seed sources [204]. Fuel loads are generally low and fires rare in many black sagebrush communities (see Fuels and FIRE REGIMES), so prescribed fires are not needed to maintain sparsely-vegetated black sagebrush communities. Greenstripping may slow wildfire's spread and reduce its size in productive black sagebrush communities [204]. See Green [94] for information on greenstripping.
Occasional prescribed fire may be a valuable management tool on productive sagebrush (Artemisia spp.) sites or sagebrush sites where conifers are invading [310]. Because it is a natural component of these ecosystems, fire may disruption sagebrush ecosystems less than other stand-replacing events [36]. In general, lower productivity and the low growth form of black sagebrush and other dwarf sagebrushes make it more difficult to conduct prescribed burning in dwarf sagebrush communities compared to communities dominated by tall, upright sagebrush species such as big sagebrush. Black sagebrush-dominated communities may serve as natural fuelbreaks on some sites; however, the same sites may carry fire in years of above-average precipitation [39]. Irregular edges and islands of unburned and burned black sagebrush are optimal wildlife habitat [273]. A mosaic of different age classes provides optimal habitat for most wildlife species that prefer or are obligates in sagebrush ecosystems. Benefits of prescribed burning in sagebrush ecosystems may include the following (review by [39]):
Pinyon-juniper: Even though black sagebrush is fire-sensitive, periodic fire or other disturbance may be needed to promote black sagebrush and reduce conifers in pinyon-juniper communities or black sagebrush communities invaded by conifers [145]. Periodic fire that reduces pinyon and/or juniper density also increases habitat quality for sage-grouse [92].
Postfire invasion by nonnative annuals may be more likely in black sagebrush communities with pinyons and/or junipers than in upland or more xeric sites. Goodrich [91] writes that the "potential for cheatgrass invasion greatly complicates management of black sagebrush communities within the pinyon-juniper belt in many areas". In areas where cheatgrass, pinyons, and/or junipers are spreading into black sagebrush communities simultaneously, Kitchen and McArthur [145] recommend nonfire or combination restoration treatments. Combination treatments may include conifer thinning, herbicides, or mechanical treatments (such as chaining or harrowing) in conjunction with prescribed fire. The authors review the use of these alternative treatments in sagebrush ecosystems. To minimize cheatgrass invasion, they recommend against burning areas that lack a healthy understory of perennial grasses. They suggest that restoration fires be small and patchy to perpetuate a mosaic of seral stages and facilitate dispersal of black sagebrush seed onto burned areas. Grazing deferment for 2 years before fire may be necessary to build up the fuel load. The authors do not recommend prescribed fire in black sagebrush stands of southern Utah, where black sagebrush is nearing its southernmost geographical range, due to black sagebrush's slow postfire recovery time and the risk of invasion by nonnative annual grasses [145].
Postfire restoration: Natural recovery of a burned sagebrush (Artemisia spp.) area is the most desirable alternative. Postfire seeding or transplanting can interfere with recovery of on-site native vegetation [242]. Postfire seedings may slow invasion of nonnative species on degraded sites, although success of seeding can vary among sites and years. Grazing deferment is recommended for 1 or 2 postfire growing seasons ([145], review by [204]).
Restoring or rehabilitating degraded black sagebrush communities after fire is challenging; as with other types of restoration, unpredictable postfire weather and invasive species can make postfire restoration a long-term project. A Utah project illustrates some problems that arise with postfire rehabilitation in black sagebrush communities. Seeding had mixed results on the US Army Dugway Proving Ground postfire rehabilitation project; results were confounded by postfire weather, nonnative grazing, and establishment of nonnative annuals. A year after a 1998 wildfire, plots in a black sagebrush/shadscale community were drilled and seeded with a mix of native and nonnative forbs, grasses, and shrubs to minimize postfire invasion of cheatgrass. Cheatgrass cover was "minimal" before the wildfire, although it occurred in patches beneath shrubs. The wildfire eliminated all black sagebrush plants from the site, and black sagebrush was not among the shrubs drill-seeded after fire. When drilled and undrilled plots were compared in postfire years 1 to 3, density of seeded shrub seedlings was visibly greater on drilled, seeded plots than on undrilled, seeded plots. If black sagebrush seedlings were present after fire, it was not noted in the study. Cheatgrass density was lower on unburned than burned plots (P<0.05). On burned plots, cheatgrass density was lower on drilled than undrilled plots; however, these differences were significant (P<0.01) for only 1 year (2000), when summer precipitation was more than 2 times above normal. Cover of nonnative, invasive forbs was significantly higher on drilled and seeded compared to undrilled and seeded or unburned control plots (P=0.03). The authors speculated that this was because drill farrows provided protected microsites for nonnative forb establishment. The combination of the wildfire and drill-seeding reduced biological soil crusts 93% compared to unburned plots. Feral horses on the site preferentially grazed seeded species, and their hoofprints served as catchment and establishment sites for cheatgrass seeds. Although an adjacent black greasewood (Sarcobatus vermiculatus) community was also drilled and seeded, feral horses did not use the black greasewood site. The authors concluded that the impact of "soil-disruptive methods on biological soil crusts should be considered prior to implementation" of restoration projects. Although their results were mixed, they thought that "even moderate success from drill seeding could suppress postfire establishment of cheatgrass in the long run". They called for more research on techniques that might help restore Great Basin shrublands [130].
A review [204] recommends against seeding burned sagebrush communities to crested wheatgrass except on severely degraded sites that would otherwise be vulnerable to cheatgrass or medusahead invasion. See Value for Rehabilitation of Disturbed Sites for further information on restoring disturbed black sagebrush communitiesThere are no records of historic fire frequencies or FIRE REGIMES for black sagebrush communities [120]. Black sagebrush communities tend to occupy unproductive sites that have little fuel build-up, so fire was probably historically rare on many black sagebrush-dominated landscapes [35,121,219,319]. Winward [307] stated that "fire is not a major ecological component of these (black and other dwarf sagebrush) types". There were likely long intervals between fires in black sagebrush communities [310]. When fires did occur, they were probably mostly patchy [175,310] and of mixed severity, although stand-replacement fires may have occurred rarely. Estimates of fire-return intervals for xeric, low-productivity sagebrush communities of the Great Basin range from 35 to over 100 years [37,219]. Many authors estimate historical mean fire-return intervals of 100 to 200 years or more for low-productivity black sagebrush communities [145,153,188,219,317]. For the Buckskin Mountains of western Nevada, Young and Palmquist [319] suggested that fires in black sagebrush communities were rare and small in extent. Black sagebrush communities there occur on the most arid, highest-elevation (5,640-5,840 feet (1,720-1,780 m)) shrubland sites. These black sagebrush communities lacked sufficient herbaceous fuels to carry fires for most of the 20th century [319].
Historically, fire reduced sagebrush density in both sagebrush and pinyon-juniper ecosystems [120]. In areas where juniper and black sagebrush communities are adjacent, periodic fires may have helped prevent juniper encroachment into black sagebrush communities [145]. In order for black sagebrush to remain dominant, fire-free intervals need to be long enough to permit black sagebrush stands to mature, yet short enough to prevent displacement by conifers [186]. Historically, intervals of 150 to 250 years between stand-replacement fires were likely for black sagebrush habitat types otherwise subject to conifer encroachment [152]. Expansion or contraction of pinyons and junipers into black sagebrush and other sagebrush communities is largely regulated by a combination of climate, fire frequency [310], and bark beetle infestations [51], with the conifers expanding into sagebrush communities during times of wet weather and infrequent fire (review by [310]) and contracting during bark beetle infestations [51] and frequent fires (review by [310]). Fire-return intervals of >30 years tend to maintain or increase conifer densities, while fire-return intervals of 10 to 30 years help maintain sagebrush dominance (review by [310]). Infrequent fire likely maintains the western juniper-black sagebrush and other western juniper-dwarf sagebrush communities as savannas in the interior Columbia Basin [40]. Tausch and Hood [256] give descriptions of black sagebrush and other sagebrush communities susceptible to juniper and/or pinyon invasion.
Effects of invasive nonnatives on Cheatgrass and other nonnative annual grasses may alter FIRE REGIMES from historic frequency in black sagebrush communities [130]. When it produces abundant, continuous fine fuels, cheatgrass can shorten fire-return intervals and result in larger, more continuous fires. Cheatgrass dies early in the growing season on dry sites, and early curing can result in earlier fire seasons than occurred historically [145]. Degraded black sagebrush communities with even minimal amounts of cheatgrass may be vulnerable to cheatgrass dominance after fire (review by [130]). In black sagebrush communities of the Buckskin Mountains, wildfires have become "occasional", and probably larger in extent, since cheatgrass invasion [319]. Across 4 years in the Buckskin Mountains, either cheatgrass or bottlebrush squirreltail dominated the herbaceous layer, depending upon climate. Cheatgrass was dominant in a dry year (x=6.89 inches (175 mm) annual ppt) and bottlebrush squirreltail in a relatively wet year (x=10.0 inches (255 mm) annual ppt). Over 4 years, cheatgrass was more frequent (44%) than bottlebrush squirreltail (39%) [319]. Cheatgrass population expansion frequently occurs in conjunction with expansion of pinyons and/or junipers into black sagebrush communities, compounding fuel load increases [145]. Livestock grazing may increase cheatgrass density [5]. See FEIS's review of cheatgrass for further information on the fire ecology of cheatgrass.
Medusahead (Taeniatherum caput-medusae) is invasive in some black sagebrush communities on fine-textured soils, altering FIRE REGIMES on those sites from historic patterns. Like cheatgrass, it has increased the fine fuel load above historical levels, resulting in stand-replacement fires that are more frequent than those of the past [50]. On sites in northeastern California and northwestern Nevada, increased fuel loads from medusahead invasion in black sagebrush and other dwarf sagebrush communities have introduced fire to ecosystems that had rarely burned since European settlement. Based on fire scars on western junipers in these communities, these dwarf-sagebrush communities burned occasionally prior to settlement, but livestock grazing during the settlement period reduced the fuel load such that fires did not carry [50].
Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
FIRE ADAPTATIONS AND PLANT RESPONSE TO FIRE:
Fire adaptations: Black sagebrush plants have no morphological adaptations for surviving fire [307,310].
Plant response to fire: Black sagebrush establishes from seed after fire [197,272,310,321]. Since it cannot sprout after fire [64,272], its postfire recovery can be slow [287]. Black sagebrush recovery is quickest if fire follows a good seed-crop year [321] and/or browsing pressure is light in early postfire years [148]. Repeated fire on pristine black sagebrush/bunchgrass communities of eastern Oregon and Washington may reduce black sagebrush cover (also see Fuels) [62]. Because black sagebrush may take "several years" to establish and produce seed after fire, repeated, frequent fires can eliminate it from a site [204].
Black sagebrush establishes from wind-dispersed ([321], review by [31]) and other off-site seed [31,91], soil-stored seed (review by [197]), and seed from on-site parent plants that fire missed [30,31]. Since black sagebrush has a transient soil seed bank, the ability of black sagebrush to establish after fire is mostly dependent on the amount of seed deposited in the seed bank the year before the fire [197]. There is limited information on how long black sagebrush takes to regain prefire cover. In general, sagebrushes require 15 to 60 years to regain prefire cover (review by [140]). Since black sagebrush tends to dominate the harshest sites in sagebrush ecosystems, its recovery time is likely slower than that of most sagebrushes. Although present before fire, black sagebrush did not occur on any of 19 study plots 1 [83] or 2 [84] years after the Chapin 5 Wildfire in Mesa Verde National Park, Colorado. On montane black sagebrush communities on Tavaputs Plateau, black sagebrush regained prefire cover about 20 years after fire [91]. Nineteen years after a stand-replacement wildfire in a big sagebrush community the Gardiner Basin of Wyoming, recovery of black sagebrush, basin, Wyoming, and mountain big sagebrushes was "minimal", while abundance of rabbitbrush (Chrysothamnus spp.) taxa was "much greater". The authors attributed the difference to rabbitbrushes's ability to sprout [287]. Data for black sagebrush recovery alone were not available.
Higgins and others [108] review fire effects on and postfire responses of plant species that occur frequently in black sagebrush communities. Young [321] provides a review of fire effects on forage grasses and forbs that are common in sagebrush ecosystems.
While long-term maintenance of the black sagebrush understory in pinyon-juniper communities may require periodic fire to reduce the conifers [91], black sagebrush's postfire recovery will likely be slow. In a chronosequence fire study of Utah juniper-singleleaf pinyon communities in west-central Utah, black sagebrush was the most abundant shrub on 71-year-old burns, showing greater density and cover than associated big sagebrush, rubber rabbitbrush, and bitterbrush (Purshia tridentata). It began declining on burns older than 71 years. Black sagebrush was significantly more abundant on old burns (>70 years, P=0.05) than younger burns, where it occurred in only trace amounts [7].
Black sagebrush abundance on old Utah juniper-singleleaf pinyon burns [7] Burn age (years) Density (plants/100 ft²) Cover (%) Frequency (%) 71 6.2 7.3 30.0 86 2.4 2.1 17.2 100+ 0.7 0.7 4.7Many black sagebrush communities without infestations of nonnative annual grasses lack sufficient fuels for frequent reburns. Portions of the Jarbidge Resource Area of south-central Idaho were burned by wildfires in the early 1960s, then reburned in a 1971 wildfire. Incidence of reburn on black sagebrush sites receiving 12 or more inches (305 mm) of annual precipitation was low. Based on species frequencies and relative plant masses in postfire years 10 to 13 (after the 1971 fire), black sagebrush-dominated communities were judged to have a lower-than-average likelihood of reburning due to discontinuous fine fuels and a longer green period than other shrub communities. They were in "better ecological condition" than more xeric communities, with little cheatgrass invasion. Sagebrush (Artemisia spp.) frequency in black sagebrush communities averaged 35% in postfire years 10 to 13. Black sagebrushes in zones receiving 10 to 16 inches (250-400 mm) of annual precipitation had greater fire survival and/or postfire reseeding. The author speculated that except in extreme fire conditions, black sagebrush communities act as fuelbreaks in the Jarbidge Resource Area [30].
In areas with high numbers of sagebrush-feeding ungulates, browsing pressure may damage or kill black sagebrushes that a patchy fire missed. After the 1988 wildfire in the Gardiner Basin of the Gallatin National Forest, Wyoming, postfire elk and mule deer browsing killed 35% of remaining mountain big sagebrush. Fifty-nine percent of surviving mountain big sagebrush had high percentages of dead crown material due to browsing damage [284,285]. Although this study focused on big sagebrush, black sagebrush also occurs in the area. The generally high palatability of black sagebrush likely puts black sagebrush at risk for postfire browsing mortality and damage in areas with large populations of browsing ungulates.
Hybrids: Black sagebrush × silver sagebrush hybrids may sprout after fire. Genetics studies suggest black sagebrush is most closely related to silver sagebrush [149,150,177,275], which sprouts, and big sagebrush, which does not [310]. Studies on the sprouting ability of silver sagebrush, black sagebrush, and other silver sagebrush × dwarf sagebrush hybrid combinations were lacking to date (2009), but such studies might provide insight into the genetic basis for sprouting in woody sagebrushes and ultimately produce woody sagebrush plants that can better survive on sites where nonnative annual grasses have altered FIRE REGIMES. Sprouting, drought-tolerant sagebrush hybrids may be useful in rehabilitating sagebrush rangelands that have converted to annual grasslands dominated by nonnative annual grasses [166].
Stand structure in black sagebrush communities varies from very open to moderately dense. Potential fire spread depends greatly on stand structure; some black sagebrush communities function as fuelbreaks, while others are susceptible to rapid fire spread.
Black sagebrush shrublands: Pristine black sagebrush habitat types typically have low productivity (review by [187]), with scattered shrubs and a sparse understory. Consequently, fuel loads are usually low [22,24,145], with insufficient fine fuels to carry fire [121,175,272,310]. Some black sagebrush communities may serve as fuelbreaks [30,321]. Tisdale and Hironaka [262] described black sagebrush stands as "virtually fireproof" due to sparse vegetation.
In the Intermountain region, total plant cover in black sagebrush communities averages <30% [187]. In a review, Bunting and others [39] reported a mean of 12% black sagebrush cover in black sagebrush habitats of Oregon and a range of 7% to 29% cover in black sagebrush habitat types of Idaho. Understory production tends to decrease as black sagebrush stands mature [176]. A black sagebrush community near Eureka, Nevada, had 13% cover of black sagebrush and trace cover of other plant species; nonliving ground cover (52%) was mostly desert pavement [24]. On the Stratton Sagebrush Hydrology Study Area, black sagebrush communities had >50% bare ground cover; associated species were cushion plants and grasses [43]. On the Owl Creek Range of Wyoming, mean black sagebrush cover in black sagebrush-dominated communities ranged from 7% on black sagebrush-big sagebrush communities to 24% in nearly pure to pure black sagebrush stands. Cover of other vegetation was 13.1% for herbaceous species and 0.9% for shrubs other than the sagebrushes. Areas beneath and near the sagebrushes were usually bare [79]. In Yellowstone National Park near Gardiner, Wyoming, basin, mountain, and Wyoming big sagebrush habitat types experienced stand replacement after a 1974 wildfire. However, the black sagebrush habitat type occurred on limestone outcrops with "strongly calcareous" soils; the black sagebrush habitat was sparsely vegetated and "very little" of it burned [247].
Some pristine black sagebrush/bunchgrass communities of eastern Oregon and Washington are productive enough to carry fire in some years. Productive sites generally have bluebunch wheatgrass and/or Idaho fescue in the understory as well as the grass dominant, Sandberg bluegrass [62]. In common garden experiments in central Utah, productivity of black sagebrush stands was correlated with a 3-way interaction of annual precipitation, depth to the soil's caliche layer, and percent rock in soil (R²=0.65). Productivity increased with increasing precipitation and depth to the caliche layer and decreased with increasing rock content in soil. Black sagebrush stands were the least productive among black sagebrush, black sagebrush-big sagebrush, and big sagebrush stands [248].
Some sites with black sagebrush are dense and productive. A mesic site in northern Nevada had >60% black sagebrush cover [221]. Studies of black sagebrush communities in southern Idaho, northern Utah, and northeastern Nevada found overall plant production ranged from 110 to 322 pounds/acre, and black sagebrush density ranged from 164 to 480 plants/1,000 feet², depending on soil type [206]. On the Desert Experiment Range of Utah, mean productivity of black sagebrush over 5 years was 9.9 lb black sagebrush/acre. The site was dominated by shadscale; black sagebrush was the 3rd most productive plant in the community. Total plant productivity averaged 98.7 lb black sagebrush/acre [8].
Models: Dean and others [69] provide equations for predicting aboveground biomass of black sagebrush and other dominant shrubs of west-central, central, and east-central Nevada [69]. Young and Palmquist [319] provide equations to predict annual accumulations of black sagebrush woody biomass, other aboveground growth, and leaf weight.
Woodlands: Woodland habitat types where black sagebrush is a dominant understory shrub typically have unproductive or open overstories. In the Boulder and Escalante mountains of south-central Utah, interior ponderosa pine/black sagebrush habitat types have the lowest timber production among the ponderosa pine series for those areas. Stand structure is open, and conifer regeneration is generally poor [322].
Understory production in woodlands with black sagebrush is variable. Utah juniper/black sagebrush/bluebunch wheatgrass communities of southeastern Idaho were described as very open (15 trees/acre), with "abundant" low shrubs and grasses in the understory [224]. Some pinyon-juniper/black sagebrush communities in mid- to late succession may have dense understories and/or dense conifer overstories. At these successional stages, cover of the shade-intolerant black sagebrush is likely sparse. In east-central Nevada, closed-canopy singleleaf pinyon-Utah juniper/black sagebrush stands had 0.1% black sagebrush cover, 30% conifer cover, and 50% litter cover. Open stands had 17% black sagebrush cover, 1.5% conifer cover, and 24% litter cover [23]. Utah juniper-Colorado pinyon/black sagebrush/bluebunch wheatgrass communities of Moffat County, Colorado, were moderately dense (400-500 trees/ha). Black sagebrush cover was 8% to 10%, with black sagebrush plants "nearly hidden" by dense bluebunch wheatgrass (20% cover). Black sagebrush/bluebunch wheatgrass communities in the same area had 8% to 20% black sagebrush cover and 15% to 30% bluebunch wheatgrass cover [5].
Effect of nonnatives on In years with favorable spring moisture, cheatgrass may produce large quantities of continuous fine fuels. Cheatgrass cover may vary across years, however, and can sometimes be sparse. For example, a black sagebrush/cheatgrass community near Elko, Nevada, had 20% black sagebrush cover and 0.4% cheatgrass cover. Ground cover was 44% litter, 28% lichen soil crust, 13% pavement, 12.5% bare ground, and 2.5% rock [21].
Old black sagebrush plants may facilitate cheatgrass establishment, thereby increasing fuel loads. In the Buckskin Mountains, depth and cover of litter beneath black sagebrush plants increased with black sagebrush age, with deep litter apparently facilitating cheatgrass establishment. Ground under black sagebrush seedlings lacked litter. For mature black sagebrushes, litter ranged from 0.4 to 0.6 inch (1-1.5 cm) deep, and black sagebrush had from 40% to 60% cover. Patriarch and senescent plants had 0.8- to 7-inch-deep (2-3 cm) litter and 80% cover (see Stand and age class structure for age class definitions). Patriarch and senescent black sagebrushes supported more grasses beneath their canopies than younger age classes. Grasses on black sagebrush mounds were mostly either "dense" cheatgrass or bottlebrush squirreltail [319]. See Grasslands and Invasives for more information on succession and management in black sagebrush communities infested with nonnative annuals.
Most black sagebrush seeds go dormant and overwinter in the soil seed bank, although some may be immediately germinable. Stratified seeds showed 80% to 90% germination in the greenhouse [19]. Laboratory tests have had mixed success trying to germinate fresh black sagebrush seed. In some cases, different seedlots gave different results [184], suggesting a genetic component to seed dormancy. Meyer and others [184] reported "near full" germination of most fresh black sagebrush seedlots in the laboratory, but 2 collections showed dormancy. Other laboratory studies found fresh black sagebrush seeds had low germinability and required cold stratification to germinate [19,183].
Seeds may germinate over a broad temperature range, although all but shallowly buried seed may show poor germination. Since black sagebrush seeds disperse in late fall, it is likely that cold temperatures inhibit germination until spring. Beetle [13] speculates that in the field, duration of high temperatures during the day is probably more important to black sagebrush germination than fluctuating temperatures. Restoration studies [232,280,291] and another field study [13] suggest black sagebrush establishes best from seeds on or near the soil surface. Laboratory studies show black sagebrush seed germinates better in light than in dark [183,184,232]. Germination rates may be 3 or more times greater in light than in dark. In the laboratory, Meyer and others [183,184] reported mean germination rates of 92% with light and 21% with dark. A mean of 48 days was required for the seedlot to reach 50% germination at 30 °Fahrenheit (1 °C) in light [183].
Black sagebrush growth rate varies from slow [67] to rapid [255], depending on site and year. Because black sagebrush grows in shallow soils, growth is likely contingent upon high soil moisture levels just before [105] and during (review by [262]) the growing season. This may not apply to all sites, however. A northwestern Utah study found no significant correlations between black sagebrush production and amount of spring precipitation or spring temperatures. Among 7 associated cold-desert shrubs, black sagebrush was the only shrub lacking those correlations [78]. Black sagebrush may have an intrinsically slower growth rate than associated sagebrushes. Productivity rates of black sagebrush, basin big sagebrush, mountain big sagebrush (Artemisia tridentata subsp. vaseyana), and Wyoming big sagebrush were compared in a common garden in Ephraim, Utah. Black sagebrush gained least annual stem growth and stem and leaf biomass of the 4 taxa [67]. Release from interference of grasses may result in a black sagebrush growth spurt [13].
In the Buckskin Mountains, mean biomass accumulation of black sagebrush was 13.2 g/m²/year [319]. On shale-oil restoration sites in Utah, container stock showed 64% mean survivorship; surviving plants averaged 7 inches (0.2 m) in height and 2 feet (0.6 m) in canopy diameter at 5 years of age [77]. On the Owl Creek Range of Wyoming, black sagebrushes on sites subject to snowdrift accumulation, such as depressions and benches, showed more aerial crown development than black sagebrushes on adjacent sites. Black sagebrush on adjacent sites showed sprawling, low growth [79].
See Young and Palmquist [319] for black sagebrush growth models.
Soils supporting black sagebrush communities are typically shallow [15,64,107], rocky [64,107], and xeric. They are often poorly developed, overlying bedrock or caliche [230,236]. On the Humboldt National Forest of northeastern Nevada, black sagebrush dominates on minimally developed Aridisols and Entisols [127]. In east-central Nevada, soils with black sagebrush are typically frigid [25]. See Jensen [129] for a classification of sagebrush communities on the Humboldt National Forest based on soil characteristics.
Soil type is important in determining productivity [206] and fuel loads in black sagebrush communities. See Fuels for more information.
Depth: Although black sagebrush is most common in shallow soils, it also grows in deeper soils. In Nevada, black sagebrush generally occurs on soils where rooting depth is restricted to the upper 18 inches (46 cm) or less [230]. Soils where black sagebrush dominates tend to be shallower ([15], review by [145]) than soils where big sagebrush dominates (review by [145]). An Albany County, Wyoming, study found black sagebrush occurred on the shallowest soils of 4 sagebrush species [258]. On the Modoc Plateau of northeastern California, black sagebrush occurred on young, shallow alluvial fans, with the oldest, deepest lakebed soils occupied by big sagebrush [2]. In the White Mountains of California, black sagebrush replaced big sagebrush as a dominant only on shallow, gravelly, calcareous soils [260]. Soils are typically deep, however, where black sagebrush codominates with big sagebrush [11]. Studies in Idaho, Utah, and Nevada found black sagebrush occurred on moderately deep gravels as well as shallow soils [206].
Nutrients: Burke and others [43] suggested that there may be a soil-nutrient gradient among black sagebrush and big sagebrush vegetation types, with black sagebrush on the low-fertility end of the gradient. Soils where black sagebrush dominates tend to have lower soil organic matter, nitrogen, and phosphorus levels than soils supporting big sagebrush communities ([162,230], review by [91]). On the Stratton Sagebrush Hydrology Study Area of Wyoming, soils of black sagebrush communities had lower mean soil nitrogen and phosphorus levels at shallow depths compared to Wyoming or mountain big sagebrush communities [41]. On the Humboldt National Forest, sagebrush-dominated communities tended to sort out on a soil fertility gradient, with black sagebrush dominating sites with lowest soil organic matter, nitrogen, and exchangeable calcium levels. Black sagebrush-dominated communities also had significantly drier, shallower soils than other sagebrush communities (P<0.05 for all variables) [127,128]. Unlike other sagebrush taxa, black sagebrush dominance was poorly correlated to soil subgroups [127].
In the Buckskin Mountains, soil nitrate levels beneath black sagebrush plants increased with black sagebrush age, and nitrate levels under black sagebrush plants dropped significantly after plant death (P≤0.1). Litter accumulation resulted in mounding beneath black sagebrushes; nitrates accumulated at mound edges [315,319].
pH and parent materials: Black sagebrush is common on neutral [258] to basic [91,258], calcareous soils. Soil pH on sites with black sagebrush ranges from slightly acidic to alkaline across black sagebrush's range [125,280]. In the Columbia River Basin, black sagebrush generally occurs on calcareous soils that are aridic, frigid, shallow, and gravelly [111]. Black sagebrush may be restricted to limestone-derived or other calcareous soils on most dry sites [111], although it is not limited to calcareous soils on all sites [168,300]. Black sagebrush is apparently limited to limestone-derived soils in southern Idaho [111]. On Limestone Ridge in Moffat County, Colorado, black sagebrush-bluebunch wheatgrass communities occur exclusively on soils derived from calcareous parent materials. Mean pH of these soils is 7.94, while Utah juniper-Colorado pinyon/black sagebrush communities in the same area have a mean soil pH of 7.85. [5]. On the Shoshone National Forest, black sagebrush is an indicator species of "very shallow, stony soils that are calcareous to the surface" [118], although black sagebrush has also been found on granitic soils there [268]. In southern Utah, black sagebrush grows on soils derived from dolomite and volcanic materials [11]. In the White Mountains of California, West [300] found black sagebrush was restricted to dolomite soils, while low sagebrush and big sagebrush grew on other parent materials. Black sagebrush grew well on other soils in the laboratory [300], suggesting that poor competitive ability limits black sagebrush to dolomite soils in the White Mountains.
Black sagebrush tolerates slightly saline soil [218]. Within salt-desert shrub communities, it grows on the "least salty, comparatively mesic sites" [302].
Texture: Black sagebrush grows in soils of all textures [212,258]. It is most common on sandy or gravelly loams [176] and on clays [205,286,315]. Studies in Utah, Idaho, and Nevada found black sagebrush occurred on silty loams [206]. Black sagebrush-dominated communities in northeastern Nevada occur on loamy-skeletal soils [21]. Soils supporting black sagebrush communities in west-central Nevada are very fine and clayey-skeletal [25]. Soils where black sagebrush dominates tend to have a higher percentage of rock than soils where big sagebrush dominates (review by [145]).
Soil texture and depth may be critical in determining where black sagebrush is dominant. In the Buckskin Mountains of west-central Nevada, Young and Clements [315] found ecotones between big sagebrush and black sagebrush communities were "extremely abrupt and distinct, with no intermixing of the two types". They attributed this to different soils; across sites, plant community composition changed rapidly with relative soil development or erosion. Within an alluvial fan complex, black sagebrush occurred on undeveloped, stony clay soils; black sagebrush and a dwarfed form of green rabbitbrush were the only woody species growing on those soils. Big sagebrush communities occurred in areas with an erosional fill of fine sand, and their plant species composition was more diverse [315]. On the east slopes of the Sierra Nevada and Cascade Range, boundaries between black sagebrush and other vegetation types are usually abrupt. Black sagebrush types occur mostly on shallow soils overlying bedrock, claypan, or a cemented layer of iron oxide that is 2 to 30 inches (5-76 cm) deep [58]. Duchesnicola black sagebrush is limited to red clay uplands of the Uinta Basin, Utah [167,298].
Moisture: Black sagebrush tolerates and is most common on xeric soils [110,236] but also grows on mesic soils [302]. Within the rooting zone, soils supporting black sagebrush communities are usually dry for most of the growing season (review by [145]). Soils where black sagebrush dominates tend to have a lower water-holding capacity than soils where big sagebrush dominates ([162,230], review by [91]). Wyoming big sagebrush rangeland types often transition to black sagebrush types on their xeric edges [263]. On the Snake River Plain of southern Idaho, black sagebrush series are confined to the driest portions of the sagebrush ecosystem, on limestone-derived, calcareous soils [110,261]. A study of plant-water relationships of shrub and graminoid plant communities of the Ruby Valley of Nevada found that black sagebrush-dominated sites were more xeric than all but saltbush (Atriplex spp.) and green rabbitbrush (Chrysothamnus viscidiflorus) sites. The black sagebrush sites had the highest ratio of plant-water potential (estimate of energy expended by a plant to draw soil moisture) to evapotranspiration of 14 plant communities studied (r= -0.92) [185]. A similar study in eastern Idaho found sagebrush communities were arranged along a mesic-to-xeric moisture gradient from threetip sagebrush (Artemisia tripartita) to low sagebrush, big sagebrush, and—on the most xeric sites—black sagebrush [110]. Soil parent materials or texture may affect black sagebrush's ability to tolerate low soil moisture. In the White Mountains, black sagebrush seedlings survived drought better on limestone- than on sandstone-derived soils [300].
Topography: Black sagebrush grows on flat to steep sites [93,122,230,323] on all aspects [258,300]. Some black sagebrush-dominated communities may be relatively inaccessible due to steepness of slope [53]. Black sagebrush is common on alluvial fans [260,268,315]. On the Desert Experimental Range, black sagebrush occurs on rough, broken topography [48]. In the northern Bonneville Basin, Utah, black sagebrush grows on rounded knolls above the barren playa of the Pleistocene-epoch Lake Bonneville [93]. It is reported on mesas, rocky ridges, slopes, and plains in Arizona [103] and New Mexico [160]. At Chaco Culture National Historic Park, where black sagebrush is near its southernmost geographical limit, black sagebrush-dominated communities occur on mesa tops of sheetwash alluvium [82].
Black sagebrush is common on windy ridges [43] that are often swept free of snow in winter [98,195]. On the Stratton Sagebrush Hydrology Study Area, black sagebrush and black sagebrush-Wyoming big sagebrush communities both occurred on windy ridges, but pure black sagebrush stands were more prevalent on these exposed sites. Black sagebrush, Wyoming big sagebrush, and mountain big sagebrush vegetation types were correlated with topographic position, with the big sagebrush types occupying gentler slopes that held more snow than slopes supporting black sagebrush-dominated types (P=0.04, R²=66.7) [42].
Although black sagebrush may occur on all aspects [5,22], it is most common on warm, south and west slopes [190,237]. At high elevations, it is mostly confined to south slopes [67]. The black sagebrush/cheatgrass community type of Crane Spring Watershed in Nevada occurs on south-facing slopes of 10% to 25% around 5,400 feet (1,600 m) elevation [21]. On the Rock Spring Watershed, the type occurs on all aspects on slopes of 3% to 33% at 6,200 to 6,900 feet (1,900-2,100 m) [22].
Elevation: Black sagebrush has a wide elevational range [91]. Across its distribution, it occurs from 4,600 to 11,000 feet (1,400-3,400 m) ([11,64,81,138,169,192], review by [47]), although poor competitive ability may restrict its elevational range on many sites. Along elevational gradients, black sagebrush communities often occur between lower-elevation basin big sagebrush or salt-desert sites and higher-elevation low sagebrush [191,301], Wyoming big sagebrush, mountain big sagebrush, or pinyon-juniper [190,254] sites. On the Nevada Test Site, the ecotones of shadscale and higher-elevation black sagebrush communities lay at about 4,900 feet (1,500 m). At about 5,900 feet (1,800 m), dominance switches from black sagebrush to singleleaf pinyon and Utah juniper [10]. In Colorado, black sagebrush communities occur between lower-elevation basin big sagebrush and higher-elevation mountain big sagebrush communities [293]. Black sagebrush reaches its highest known elevational range in California and Nevada:
Elevational ranges of black sagebrush across its geographic distribution Area Range (feet) Arizona 6,000-8,000 [139] California 5,000-11,000 [192] White Mts. 7,000-9,500 [191] Colorado 7,000-8,200 [70,103] Nevada 5,000-11,000 [11,138] New Mexico 7,000-8,000 [160] Utah 4,600-8,500 [298] south-central Utah 8,000-9,000 [322] southern Utah 4,920-7,870 [298] Great Basin 5,000-8,000;In part, black sagebrush's physiology restricts it to certain elevational zones. A study in the White Mountains of California found peak photosynthesis rates for black sagebrush occurred at 68 °F (20 °C) [300,301]. West [300] described black sagebrush's ability to photosynthesize at other temperatures as "essentially nil". Although it occurs at lower and higher elevations, inefficient photosynthesis at lower and higher elevations and poor competitive ability on low-elevation, fertile soils tend to concentrate black sagebrush on limestone-derived soils in the singleleaf pinyon-Utah juniper zone (6,600-8,200 feet (2,000-2,500 m)), where daytime temperatures favor black sagebrush photosynthesis [300,301].
Climate: Black sagebrush is largely restricted to semiarid, cold-desert climates with cool to cold winter temperatures. Most precipitation is in winter and spring (reviews by [91,145]). Across black sagebrush's range, mean annual precipitation ranges from 7.1 to 12.6 inches (180-320 mm) [176]. Across cold desert regions, mean annual precipitation may be as low as 5.9 to 7.1 inches (150-180 mm) [302]. In the Columbia River Basin, mean annual precipitation in areas where black sagebrush grows ranges from 8 to 10 inches (200-300 mm) [111]. The frost-free period of sagebrush ecosystems averages 120 days but may be as short as 80 days in high-elevation sagebrush sites [90], where black sagebrush is most likely to dominate (see Habitat Types and Plant Communities).
Black sagebrush provides important fall and winter forage and habitat for wildlife; it is used less in spring and summer [253]. Black sagebrush forage and habitats are especially important to mule deer [3,50,98,136,200], pronghorn [8,48,144,172,304], and sage-grouse (Centrocercus spp.) [12,34]. Among wildlife species, pronghorn and sage-grouse may be best adapted to diets high in black sagebrush and other sagebrush species [273].
Black sagebrush is also a valuable browse plant for livestock [56,136]. It is particularly valued on rangelands stocked with domestic sheep [55,95,123,124]. On a salt-desert winter rangeland in Utah, domestic sheep browsed black sagebrush more than expected (43% utilization, 8% of total diet) based on its availability (3.5% cover) [95]. Black sagebrush is generally less palatable to cattle than to domestic sheep and wild ungulates [169]. Cattle use of black sagebrush is greatest in fall and winter [230], with only trace amounts consumed in summer [277].
Ungulates may underutilize black sagebrush if more palatable shrubs are available. On the Kaibab National Forest, Arizona, cattle, domestic sheep, and mule deer used black sagebrush lightly (x=20% for each ungulate spp.), while Ceanothus species and bigtooth maple (Acer grandidtatum) were utilized heavily (≥50%) [136].
Habitat:
Wild ungulates: Mule deer and pronghorn often use black sagebrush habitats extensively. Mule deer use may be especially heavy in early decades after fire. A fire chronosequence study in Nevada showed mule deer used burned singleleaf pinyon-Utah juniper communities with black sagebrush-dominated or big sagebrush-black sagebrush-dominated understories as summer rangeland habitat. Burned plots were studied 17, 24, 45, and 155 years after fire (the oldest burn may have burned twice). Mule deer use of the area was significantly higher in 17- and 24-year-old burns compared to unburned sites (P≤0.05). Use on 45- and 155-year-old burns was similar to that of sites showing no evidence of fire [241].
Sagebrush (Artemisia spp.) habitats are key components of pronghorn winter rangelands [311], and black sagebrush is especially important to pronghorn. A review identified black sagebrush as the most important source of winter browse for pronghorn in Utah [1]. Pronghorn in southeastern Oregon use black sagebrush rangelands preferentially over big sagebrush rangelands, possibly because their movement is more restricted where the taller big sagebrushes dominate [311]. Kindschy and others [143] report that "the best winter (pronghorn) ranges" are dominated by black sagebrush or a combination of black sagebrush and salt-desert species. On the Desert Experimental Range, pronghorn winter distribution was significantly associated with black sagebrush dominance (P=0.01). Pronghorn used black sagebrush communities 2 or 3 times more than expected based the area occupied by black sagebrush communities [48].
Black sagebrush and other sagebrush communities are less attractive to elk and moose. In a southwestern Wyoming comparing winter habitat use by wild ungulates, elk and moose used a Wyoming big sagebrush community with black sagebrush less than expected, while mule deer used it more than expected (almost exclusively) based on availability [200].
Birds: As of 2009, little was published on use of black sagebrush habitats by birds in general. In Wyoming big sagebrush habitats, sage thrashers prefer areas with "large amounts" of black sagebrush and other dwarf shrubs over areas with taller shrubs [181]. Medin and others [180,181] provide information on passerine use of sagebrush habitats in east-central Nevada.
Sage-grouse are known obligates in black sagebrush and other sagebrush habitats [12,34]. They use black sagebrush for food and cover [34]. Generally, black sagebrush's short stature and the low number of forbs in black sagebrush communities make black sagebrush habitats less favorable than big sagebrush habitats for sage-grouse [91]. However, some black sagebrush sites are preferred winter sage-grouse grounds. Greater sage-grouse on the Snake River Plains of Idaho use black sagebrush-big sagebrush communities as winter range [65]. In Nevada, greater sage-grouse select wind-swept ridges with short, scattered black sagebrush plants as winter feeding areas [98]. In the Gunnison Basin of Colorado, Gunnison sage-grouse used black sagebrush stands—which occurred on flats—as winter range and forage in a low snow year, when black sagebrush branches were not covered with snow. They used the big sagebrush stands—which were taller—on southwest slopes in a high snow year because some big sagebrush branches projected above snow [122]. See the FEIS review of sage-grouse for further details on sage-grouse use of black sagebrush and other sagebrush communities.
Rodents: A study in northeastern Nevada showed deer mice, Great Basin pocket mice, and Ord's kangaroo rats made moderate to heavy use of gray low sagebrush (A. arbuscula subsp. arbuscula)-black sagebrush rangelands on dry ridgetops in late spring and summer. Most rodents preferred more productive sites with loamy soils [163].
A study on cold desert-warm desert ecotones of the Nevada Test Site showed rodents preferred cold-desert communities over transition and warm-desert communities. Black sagebrush communities were among 10 cold-desert communities included in the study [102]. Rodent use of specific plant communities within cold and warm deserts was not determined.
Predators: Black sagebrush communities also support predators. For example, greater sage-grouse were the primary avian prey of golden eagles in a mixed big sagebrush-black sagebrush shrubland in southeastern Wyoming [159].
Invertebrates: Although black sagebrush is wind pollinated, insects may seek out the flowers of other plant species in black sagebrush communities for pollen. A study in the Wasatch Mountains of Idaho and Utah found black sagebrush communities had the 2nd-highest count of insect pollinator species among 25 plant communities [203].
Sagebrush obligates: Among animals that use black sagebrush habitats, some are either sagebrush obligates or prefer sagebrush to other habitats. See these sources: [204,309] for lists and other information on these animals.
Several protected birds and mammals are dependent on sagebrush ecosystems. However, except for sage-grouse (see Birds) and pronghorn (see Wild ungulates), research to date (2009) has rarely focused on potential dependency of protected animals on particular sagebrush taxa. Legally protected sagebrush obligates that may depend on black sagebrush for food and/or cover include the Gunnison sage-grouse, greater sage-grouse, Columbian sharp-tailed grouse, Brewer's sparrow, sage sparrow, sage thrasher, pronghorn, and pygmy rabbit [147,204]. Wisdom and others [308] provide guidelines for assessing habitat quality of black sagebrush and other sagebrush ecosystems in the western United States for protected species.
Palatability: Black sagebrush provides generally palatable, nutritious browse for wildlife and most classes of livestock [16,117]. Sampson and Jesperson [226] rate black sagebrush as palatable to pronghorn, mule deer, domestic sheep, and domestic goats and unpalatable to cattle and horses. Overall black sagebrush palatability has been rated as moderate [276]. Beetle [14] rated black sagebrush "somewhat less palatable" than Wyoming big sagebrush. McArthur and Stevens [174] caution that the results of ungulate preference tests may not apply to every area and that there are infraspecific differences in black sagebrush palatability. Utilization of black sagebrush may be higher if other forage species are also available [304]. In a cafeteria study, tame mule deer (n=4) preferred big sagebrush to black sagebrush. In the field, mule deer generally utilize black sagebrush mostly in winter, when other forage is scarce [98]. Black sagebrush can be an important emergency food for wintering mule deer [193].
Pronghorn utilize black sagebrush heavily [8,239]. On the Desert Experiment Range, pronghorn preferred black sagebrush to any other plant species on the rangeland. Although it was the 3rd most common plant, it comprised the majority (68%) of their summer diet [8]. Black sagebrush comprised from 14% to 98% (x=65%) of the diet of 48- to 137-day-old pronghorn fawns from November through March. Fawns utilized black sagebrush more than all other forage species combined. Researchers found "little difference" in plant species that juveniles and adults selected for forage; black sagebrush was also the most important late fall and winter forage species of adult pronghorns [239].
Ranchers appreciate black sagebrush as high-quality forage for domestic sheep, cattle, and domestic goats [191]. Black sagebrush is best as livestock feed when it grows with other palatable forage (review by [98]). It is especially valuable as domestic sheep food [81]. Domestic sheep generally browse sagebrush species lightly from spring through fall. Utilization increases in winter or when domestic sheep are fed a protein supplement (review by [88]). The domestic sheep industry that emerged in the Great Basin in the early 1900s was largely based on wintering domestic sheep in back sagebrush communities; black sagebrush was regarded as "hot" feed that allowed domestic sheep to survive harsh, cold-desert winters [191].
Black sagebrush morphs: There are genetic and/or geographic differences in black sagebrush's palatability [233,246,251]. Although overall black sagebrush palatability is rated as moderate [276], black sagebrush palatability varies across sites and between black sagebrush morphs. Laboratory and field tests show that depending on the morph, black sagebrush shows 2 different responses to long-wave ultraviolet light. Gray-leaf types fluoresce to bluish-white due to the presence of coumarin, a chemical substance that is highly palatable to ungulates and sage-grouse. Green-leaf types do not fluoresce, are low in coumarin, and low in palatability [222]. Experiments in Nevada show palatable black sagebrush morphs can be identified in the field [246]. See Distinguishing black sagebrush and Stevens and McArthur [246] for further details on identifying black sagebrush morphs.
Mule deer food choices among black sagebrush and big sagebrush taxa vary with location [297]. A study near Yellowstone National Park, Wyoming, found mule deer preferred black sagebrush least (8% utilization) among black, basin, Wyoming, and mountain sagebrushes [210,288]. Mountain big sagebrush had highest (52%) utilization. Black sagebrush had the highest concentrations of nonvolatile terpenoids among the 4 sagebrush taxa [210]. Nutritional content of the 4 sagebrushes was not analyzed. Other studies in [251] and near [283] Yellowstone National Park found mule deer preferred Wyoming big sagebrush and mountain big sagebrush over black sagebrush and basin big sagebrush, although black sagebrush tested as the most digestible taxa in the laboratory [251].
Wildlife use of black sagebrush browse likely depends on the balance of distasteful volatile and nonvolatile oils and palatable substances including coumarin and nutrients. Terpenoid oils in black sagebrush browse may lower black sagebrush's digestibility and palatability and discourage browsers. High concentrations of volatile terpenes can kill rumen bacteria and interfere with ungulate digestion [194]. Concentrations of black sagebrush's volatile and nonvolatile terpenes may vary by site and season ([210,229,251,297,305], review by [193]). In a common garden experiment near Helper, Utah, mule deer utilization of current-year black sagebrush growth ranged from 0.0% to 82.7% in black sagebrush accessions from 7 sites in Utah. Although digestibility of the most palatable accession was relatively low, the accession had moderate monoterpene and high protein and phosphorus content relative to other accessions [18,296]. It also showed fastest stem leader growth [18], implying that the accession was well-adapted to browsing. There was no significant relationship between monoterpene content of black sagebrush browse and mule deer preference [17].
Nutritional value: Black sagebrush is generally highly digestible and high in protein (reviews by [270,294]), phosphorus (review by [294]), and carotene (review by [294]). These publications provide analyses of the nutritional content of black sagebrush: [55,56,56,104,157,295,296].
Black sagebrush and horsebrush (Tetradymia app.) can be a deadly combination to domestic sheep [131,191,231]. Domestic sheep feeding on black sagebrush followed by horsebrush can become severely photosensitive and ewes may abort. Feeding trials using domestic sheep showed sequential injection of black sagebrush and gray horsebrush produced a synergistic effect; levels of some blood toxins were greatly elevated compared to toxin levels of domestic sheep that consumed only one of the shrubs [131].
Cover value: Black sagebrush provides fair to good cover for small animals [242], sometimes giving shelter on harsh sites where few other plant species can grow [242].
Black sagebrush is too short to provide good cover for ungulates. A study in southeastern Idaho found elk preferred Wyoming big sagebrush to black sagebrush for bedding cover [252]. Although mule deer rely heavily on black sagebrush for food, they do not use it for cover. Even mule deer fawns cannot hide beneath black sagebrush shrubs [201].
Sage-grouse usually use black sagebrush communities less than surrounding communities for cover. With total plant ground cover in black sagebrush communities averaging <30% in the Intermountain region, some black sagebrush communities do not meet sage-grouse's cover needs [187]. In big sagebrush-black sagebrush communities, sage-grouse hens may prefer to nest under big sagebrush. On the Sheep Experiment Station in southeastern Idaho, for example, greater sage-grouse hens nested beneath big sagebrush and other sagebrushes in preference to black sagebrush. Black sagebrush dominated on rocky and windswept areas, while other sagebrush taxa were most common on gentler sites [119]. However, sage-grouse prefer some wind-swept areas as wintering grounds (reviews by [44,220]). On the Inyo National Forest, California, greater sage-grouse use black sagebrush communities "heavily" for nesting cover and food [227]. Hens may prefer black sagebrush communities in areas where snow lingers under larger shrubs longer than it stays under black sagebrush. On such sites, sage-grouse hens use black sagebrush communities as prenesting, nesting, and brood-rearing sites; broodless hens and males use such black sagebrush communities for foraging [61]. Among black sagebrush communities, hens generally prefer communities with tall bunchgrasses for nesting; they prefer black sagebrush communities with forbs, especially legumes, for prenesting and brood rearing [61].
Besides being the most widely distributed species in cold-desert, dwarf-shrub plant communities, black sagebrush is also the most
common overstory dominant. Black sagebrush-dominated communities are most common in Nevada and Utah, although black sagebrush dominates some plant communities in all states in which it occurs. Black sagebrush is also a common component of nearby plant communities. At low elevations, black sagebrush communities often form ecotones with the salt-desert shrublands lying below them, and they often merge with pinyon-juniper (Pinus-Juniperus spp.) woodlands at their upper limits. Black sagebrush is associated with these lower- and upper-elevation communities ([175,310], review by [145]). Pinyons and junipers cooccur with black sagebrush at around 6,000 feet (2,000 m) at the Nevada Test Site [11]. In Utah, black sagebrush is an associated species in horsebrush (Tetradymia spp.),
greasewood (Sarcobatus spp.), shadscale, other sagebrush, mountain brush, and pinyon-juniper (Pinus-Juniperus spp.) communities [298]. Black sagebrush has similar zonation in Nevada [138]. In the White Mountains of California, black sagebrush spans 4 major vegetation zones that range from the desert floor to mountain peaks: the shadscale (Atriplex confertifolia) salt-desert, sagebrush (Artemisia spp.) shrubland, singleleaf pinyon-Utah juniper (P. monophylla-J. osteosperma) woodland, subalpine Great Basin bristlecone pine-limber pine (P. aristida-P. flexilis) woodland, and alpine zones [191].
Black sagebrush communities:
Black sagebrush habitat types typically form wide, often continuous bands along elevational zones that separate black sagebrush
from other communities. Low-elevation black sagebrush communities commonly form nearly pure to pure shrub stands, with a
sparse herbaceous understory (review by [145]). On a latitudinal gradient, black sagebrush vegetation types reach their
northern limit in southeastern
Idaho [111]. Black sagebrush is not typically dominant near its southern limits. However, a black sagebrush-snake broomweed-Greene's
rabbitbrush (Gutierrezia sarothrae-Chrysothamnus greenei) vegetation type occurs at Chaco Culture
National Historic Park, New Mexico [82], and a few other black sagebrush types are also described for northern New Mexico.
Left: A black sagebrush-needle-and-thread grass community in southern Utah. USDA, Forest Service photo.
Density of this productive community contrasts with that of the sparsely-vegetated black sagebrush community in the Inyo Mountains.
Rangeland:
Response to browsing:
Black sagebrush evolved under browsing pressure from native animals and is likely to tolerate light to moderate winter livestock use [3,267,286,304], but it cannot withstand sustained heavy browsing [46,59,100,315]. In Millard and White Pine counties, Nevada, mean black sagebrush cover was significantly less on sites with domestic sheep or domestic sheep and cattle compared to sites without livestock (2.0% and 4.5% with and without livestock, respectively, P<0.1). Black sagebrush cover declined most on xeric, low-elevation black sagebrush sites, while black sagebrush cover on relatively moist, high-elevation black sagebrush sites did not significantly decline with grazing. It was not clear whether black sagebrush decline on low-elevation sites was due to drier climate, greater livestock use, differences in plant palatability, or a combination of these factors [47]. A study in the Pine Valley of western Utah showed a significant increase in sagebrush cover (black sagebrush, basin big sagebrush,
and black sagebrush × basin big sagebrush hybrids) over 53 years of mostly moderate livestock grazing. Black sagebrush cover increased significantly, from 1.7% to 4.0%, during that time (P<0.05) [312]. Since black sagebrush is more palatable
to domestic sheep than to cattle, black sagebrush may increase under cattle grazing and decrease under sheep grazing [205].
Black sagebrush can withstand moderate wildlife use. Black sagebrush seedling establishment was similar on grazed and ungrazed plots on the Fountain Green Wildlife management area (see Seedling establishment).
Mule deer numbers were "low", and black-tailed jackrabbit numbers were "high" in grazed plots [243]; relative utilization of black sagebrush by each animal was not assessed. In the Duck Creek Basin of east-central Nevada, black sagebrush was less productive on sites protected from wildlife and livestock grazing for 10 years (x=39.0 kg black sagebrush/ha) compared to grazed sites (x=99.4 kg black sagebrush/ha) [267].
Productivity in black sagebrush communities generally ranges from low to medium [135]. See Fuels
for quantitative data on productivity and density of black sagebrush communities. Young and Clements [316] aptly describe rangeland productivity and utilization of black sagebrush communities in Nevada: "You can argue whether black sagebrush/bunchgrass communities represent the higher potential salt desert communities or the lower potential sagebrush/bunchgrass environments, but nonetheless, black sagebrush is a major browse species on winter ranges".
Black sagebrush declines with long-term overuse. Long-term overgrazing by domestic sheep may convert black sagebrush-dominated communities to communities dominated by unpalatable shrubs such as Greene's rabbitbrush or broom snakeweed [145]. For domestic sheep ranges of the Great Basin and southwestern Wyoming, a 1954 Farmer's Bulletin recommended no more than 70% utilization of annual black sagebrush growth to maintain good condition [123]. Heavy domestic sheep grazing "virtually removed" black sagebrush from Cedar Valley, Utah (Bowns 1987 personal observation cited in [134]). A black sagebrush-dominated rangeland in eastern Nevada was subjected to mostly domestic sheep and some cattle grazing, with permanent plots established on grazed and ungrazed sites. After 42 to 50 years of use, black sagebrush cover was significantly greater on ungrazed than grazed sites (2.8% vs. 1.7% cover, P<0.01), and overall shrub cover was greater on ungrazed plots (P<0.05). Shadscale, Greene's rabbitbrush, and broom snakeweed were more abundant than black sagebrush on grazed plots [46]. In the Antelope Valley of Nevada, combined productivity of black sagebrush and big sagebrush was much greater on domestic sheep rangelands grazed every other year compared to those grazed every year (36 vs. 2 lbs/acre, respectively) [116]. On the Ashley National Forest, black sagebrush crown cover near the upper edge of the pinyon-juniper zone increased with decreased utilization; it was 11% on sites with heavy deer and elk use, 15% to 18% on mule deer winter ranges, and 27% to 28% on sites with low ungulate use and/or where livestock were excluded [91].
Overgrazing can change the species composition in black sagebrush communities. On the Shoshone National Forest and other rangelands in southeastern Wyoming, shadscale has invaded overgrazed black sagebrush stands (Baker personal communication in [52]).
Control:
Controlling black sagebrush is not recommended because it rarely spreads and it provides valuable wildlife forage [14,16,120,156]. Beetle and Johnson [14,16] state there is "no reason to control black sagebrush". Humphrey [120] recommended against black sagebrush control in northern Arizona because it provides good forage and apparently does not interfere greatly with growth of herbaceous forage. Because black sagebrush typically dominates on unproductive sites (see Site Characteristics),
controlling black sagebrush is unlikely to boost production of other forage in black sagebrush-dominated communities [207]. Other Tridentatae—particularly big sagebrush—were targeted for control from the 1960s through the 1980s to help establish nonnative crested wheatgrass as a forage plant (for example, [74,235]), but black sagebrush often escaped that management practice. In the Crowley Lake area of the Inyo National Forest, California, black sagebrush communities have been protected from sagebrush control due to their high value as greater sage-grouse habitat, although big and silver sagebrush in adjacent sagebrush communities have been targeted for reduction on greater sage-grouse and cattle rangelands [227].
Invasives:
It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities [158,234] (for example, avoiding road building in wildlands [269])
and by monitoring several times each year [132]. Managing to maintain the integrity of the native plant community and mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invaders [113]. Besides cheatgrass, there are many other nonnative species that are, or have the potential to be, invasive in sagebrush ecosystems. Rice and others [216] and Knick and others [147] discuss these sagebrush-ecosystem invasives in reviews.
Black sagebrush is used in native landscaping.
Native Americans used a decoction of black sagebrush stems, leaves, and twigs to treat bronchitis; vapors from the crushed leaves were inhaled to treat nasal congestion [253].
Black sagebrush is considered a warm-season shrub [151]. Seeds typically overwinter and germinate the spring after production [125,176,183]. Beetle [13] reported that black sagebrush seeds disperse too late in fall to germinate. Overwintering seeds germinate as early as April on some sites. Vegetative growth may also start in April [13]. Ephemeral leaves are shed during summer drought [222], while persistent leaves remain on the branches through winter [64,222]. Black sagebrush's flowering time in the Intermountain West is later than that of associated sagebrush species [64]. Black sagebrush flowers from midsummer to midfall across its range [13,19,81].
Depending on location, fruit ripens from late summer [115] to November [19]. Seeds are first shed in October, with dispersal continuing through winter [13,176]. Flowerstalks persist until the following year [13,16,222]. Black sagebrush continues photosynthesizing through winter [236]. In northern Utah, root carbohydrate concentrations fluctuated erratically but showed a general increase from stages of early stem growth in March to floral bud development in August. Root carbohydrates declined sharply in September [60].
On sites across western Wyoming, black sagebrush showed less variation in timing of its phenology than big sagebrush and associated bunchgrasses. Over 3 years, black sagebrush phenological development was [146]:
Ranges and means of black sagebrush phenological events in Wyoming [146] Event Dates Vegetative growth starts 15-30 May; x=20 May Full bloom 15-20 Sept.; x=15 Sept. Seed disseminates 25 Oct.-5 Nov.; x=5 Nov.Most black sagebrush seedlings establish near parent plants. On oil-shale reclamation sites in Utah, black sagebrush seedlings were found under or near black sagebrush nursery stock transplanted 4 years earlier [179]. Seedlings emerge quickly; in the laboratory, cotyledons are fully exposed within 4 days [13]. Deep litter reduces establishment of black sagebrush seedlings and is likely to favor grass seedlings, while a thin litter layer or soil disturbance such as rodent digging is likely to favor black sagebrush establishment [13]. In early development, black sagebrush seedlings grow microscopic hypocotyl hairs that apparently help seedlings attach to and their radicles penetrate the substrate. A laboratory study found early seedling development was similar on fine sand, coarse sand, and filter paper. Hypocotyls and radicles emerged 25 hours after the achene broke open [318].
In the Buckskin Mountains, the black sagebrush seedlings on study plots established only between soil mounds, which supported parent plants. Soil nitrate levels were lower between mounds (with seedlings) than on mounds (with parents). Although the lower-elevation basin big sagebrush community showed episodic basin big sagebrush seedling establishment that might have occurred after fires and/or during periods of favorable climate, black sagebrush did not show similar episodic recruitment. The authors suggested that black sagebrush may rely on infrequent, steady establishment, but they noted that it is difficult to infer patterns in black sagebrush recruitment without further information [319].
Limited research suggests that black sagebrush seedlings may establish well on some sites and in some years, especially after disturbances such as chaining or fire that remove interfering vegetation. McArthur and Stevens [174] called black sagebrush an "aggressive natural spreader from seed". Once established, seedlings usually persist even under adverse conditions [176]. Black sagebrush showed good establishment following chaining of a Colorado pinyon-Utah juniper community on the Fountain Green Wildlife Management Area, Utah [243]:
Black sagebrush density in lagomorph-ungulate exclosures after chaining in central Utah [243] Postchaining year 2 11 22 Plants/300 feet² 1 2,754 3,306In this study, black sagebrush seedling establishment rates were similar on exclosure plots and plots accessible to black-tailed jackrabbits, mule deer, or both [243]. Black sagebrush also showed good establishment after chaining in a Colorado pinyon-Utah juniper community in central Utah. Total shrub density increased from 9,570 plants/ha before chaining to 11,880 plants/ha 2 years after chaining. Black sagebrush seedlings were the most numerous of the 4 shrub species that increased after chaining [68], with average densities of 320 mature black sagebrush/ha before and 470 seedlings black sagebrush/ha 3 years after chaining [66].
See Plant response to fire for information on black sagebrush postfire seedling establishment.
Black sagebrush occurs in all stages of succession in shrublands [209,291]. It is highly light tolerant and shade intolerant [291] and commonly establishes on disturbed sites [148]. In areas where black sagebrush is heavily browsed by ungulates, it may be replaced successionally by shrubs that are not so heavily utilized (review by [91]). Black sagebrush persists in some woodlands but is shaded out if canopies close. Since black sagebrush does not sprout, it usually regains cover slowly after fire or other disturbances that remove shrubs [62].
Black sagebrush communities: Beetle [13] stated that black sagebrush has "topographic and edaphic climax status" where it dominates. Black sagebrush and other sagebrush-dominated communities are likely late-seral or "climax" types in most of the Great Basin ([106], reviews by [33,91]). Pioneers on the Oregon Trail described pristine, sagebrush-dominated shrublands in these areas, with grasslands mostly confined to valley bottoms and moist sites [33]. See Plant response to fire for information on postfire succession in black sagebrush communities.
Montane black sagebrush communities—generally those above the pinyon-juniper zone—are usually stable. In the Uinta Mountains region of the Ashley National Forest, Utah, black sagebrush cover was greatly reduced after 2,4-D application. However, black sagebrush cover on sprayed sites was similar to that of unsprayed sites 20 years after herbicide treatment [91]. Montane black sagebrush communities are generally more resistant to invasion by cheatgrass or other nonnative grasses than lower-elevation communities [91,221]. On the Travputs Plateau region of the Ashley National Forest, black sagebrush displaced crested wheatgrass (Agropyron cristatum) and other nonnative grasses within 20 years after nonnative grasses were seeded in. The sites were protected from cattle and lagomorph grazing [91].
In montane black sagebrush shrublands, black sagebrush is sometimes displaced successionally by Rocky Mountain Douglas-fir or other conifers [310]. It is sometimes a nurse plant for junipers, and without fire or other disturbance, black sagebrush may be replaced by junipers in some black sagebrush habitat types. Increasing conifer densities in black sagebrush communities are thought to be due to past fire exclusion, past overgrazing, climate change, or a combination of these factors. As succession proceeds, the conifers eventually shade out black sagebrush in the absence of fire or other stand-replacing disturbance [23]. In the late 1970s, Young and others [169] reported that "large areas" in Nevada that were formerly dominated by black sagebrush had become dominated by Utah juniper and singleleaf pinyon [169]. Utah juniper has encroached upon black sagebrush/bluebunch wheatgrass communities in the Bighorn Basin of Wyoming. Prior to 1890, Utah juniper was apparently restricted to limestone and skeletal soils there. The author attributed successional replacement of black sagebrush with Utah juniper to fire exclusion and livestock grazing. Cattle had removed many of the grasses that historically fueled fires in the black sagebrush community. Periodic fires tended to kill Utah juniper seedlings and increase black sagebrush cover [292]. See Fuels and FIRE REGIMES for more information on expansion of pinyons and junipers into black sagebrush communities due to fire exclusion.
In the Wasatch Mountains of southern Idaho and northern Utah, black sagebrush is followed successionally by tiny trumpet (Collomia linearis) and Douglas's knotweed (Polygonum douglasii), native forbs that, in large numbers, are undesirable on rangelands [215].
Pinyon-juniper communities: Black sagebrush is often seral in pinyon-juniper communities, with successional replacement by the conifers ([91,241], unpublished report by [257]). In west-central Utah, black sagebrush was a midsuccessional species after fire in a Utah juniper-singleleaf pinyon woodland. These conifers replaced black sagebrush and big sagebrush successionally around 75 years after fire [7] (see Plant response to fire for more information on this study). Black sagebrush biomass declined with increasing tree biomass (r²=0.85) in a Utah juniper-singleleaf pinyon/black sagebrush community in the Needle Range of central Utah. Black sagebrush cover averaged 80% across seral stages (unpublished report by [257]).
Black sagebrush understory cover remains stable or increases on some pinyon-juniper sites without stand-replacing events such as fire. In a chronosequence study in Nevada, black sagebrush dominated the understories of 17-, 24-, 45- and 115-year-old burns in singleleaf pinyon-Utah juniper woodlands [241]. In the Pine Valley of western Utah, black sagebrush cover increased significantly over 53 years—from 0.8% to 2.9% (P<0.01)—in a singleleaf pinyon-Utah juniper/black sagebrush community. Overall, cover of shrub and native perennial grass species tended to remain stable or increase (P<0.01), while cover of singleleaf pinyon (P<0.01) and Utah juniper (P<0.05) decreased. Mostly light livestock grazing occurred over that period; otherwise, study plots were undisturbed [313].
Grasslands: In northern desert-grassland ecosystems, black sagebrush may be an edaphic climax species on some sites with shallow, limey soils [87]. Drought generally favors black sagebrush over grasses on more favorable sites. In nondrought years, shade from grasses may result in black sagebrush seedling death [13].
Sagebrush communities on relatively mesic sites are generally more susceptible to cheatgrass infestation than xeric black sagebrush sites, but cheatgrass may invade black sagebrush communities on some sites and in wet years. On burned areas in the Nevada Test Site, cheatgrass was more frequent on deep soils associated with big sagebrush than shallow soils associated with black sagebrush [9]. In black sagebrush communities, cheatgrass is most invasive at midelevations [314]. With the introduction of cheatgrass, a few communities where black sagebrush was dominant have undergone a type conversion to annual grassland communities [91]. Loss of black sagebrush can degrade ecosystem function by reducing availability of palatable black sagebrush browse (see IMPORTANCE TO LIVESTOCK AND WILDLIFE), reducing litter and soil accumulation, altering nutrient cycling, and increasing soil erosion [80]; increases in cheatgrass may alter historic FIRE REGIMES (see Effects of invasive nonnatives on FIRE REGIMES). These alterations may push succession on new trajectories. Cheatgrass is most invasive on disturbed sites [9]; however, it may also invade undisturbed sites. An inventory of a big sagebrush-black sagebrush community above the Flaming Gorge Reservoir in Utah showed cheatgrass was the most frequent plant species in the community, with frequencies of 67% for cheatgrass, 5% for big sagebrush, and 4% for black sagebrush. The area was on a steep, south-facing slope that was inaccessible to livestock, little used by humans, and had not experienced fire for at least 50 years [92]. Cheatgrass will likely persist in cold-desert ecosystems where it has replaced black sagebrush stands [91]. Potential for black sagebrush recovery may be low on many cheatgrass-invaded sites [91], so it is unlikely that black sagebrush will regain its position as climax dominant on some invaded sites where it was formerly dominant. See the FEIS review of cheatgrass for more information on how cheatgrass may impact succession and other ecosystem processes in cold-desert and other ecosystems.
Grazing: Livestock grazing may alter successional trajectories in the Great Basin [303]. Due to black sagebrush's generally high palatability, succession in overgrazed black sagebrush communities is likely to proceed to unpalatable species. A long-term study of black sagebrush communities on the Desert Experimental Range showed season of grazing affected plant succession more than grazing intensity, although both were important. Over 53 years, spring grazing by domestic sheep resulted in greater increases in annuals, especially nonnative cheatgrass, halogeton (Halogeton glomeratus), and Russian-thistle (Salsola iberica), than fall grazing. Ungrazed plots had few to no nonnative annuals. High-intensity grazing in early spring (42 sheep days/ha from March-April) increased nonnative annuals the most. Fall grazing resulted in greatest shrub cover compared to spring-grazed and ungrazed plots [303]. In eastern Oregon, black sagebrush/bluebunch wheatgrass rangelands in poor condition due to overgrazing may be composed of mostly black sagebrush and bare ground [306]. Rangeland conditions in black sagebrush and other dwarf sagebrush, cold-desert communities declined—sometimes severely—with unrestricted livestock grazing in the early 1900s. Sagebrush communities may recover with complete livestock removal. They may recover, but at a slower rate, when livestock are managed to protect palatable plant species (for example, by limiting livestock numbers, using deferred or rotational grazing, and limiting spring and summer grazing). Permanent plots across central and northern Nevada and western Utah, established in the 1930s when public grazing was first controlled, showed significant increases in the number of black sagebrush and other palatable shrubs (P<0.1) and of palatable bunchgrasses (P<0.01) by the 1980s. Plots were subject to up to 30 years of continuous grazing after they were established. When livestock grazing was stopped, the successional trend was toward increasing dominance by black sagebrush and other palatable shrubs. Overall, palatable plant species increased relative to unpalatable species [49]. See Management Considerations for more information on grazing in black sagebrush communities.The scientific name of black sagebrush is Artemisia nova A. Nelson (Asteraceae) [13,64,81,107,137,139,298]. It is placed in Tridentatae [145,173,225], a North American subgenus of Artemisia [169,173]. There are 2 distinct races or morphs of black sagebrush (review by [222]), which are discussed in General Botanical Characteristics and Palatability.
Hybrids:
Black sagebrush hybridizes readily with big sagebrush (A. tridentata) and other Tridentatae sagebrushes [13,89,138,149,298]
and with Bigelow sagebrush (A. bigelovii, which some treatments exclude from Tridentatae) [169]. Among Tridentatae, black sagebrush cooccurs most often with and is closely related to basin big sagebrush (A. tridentata. subsp. tridentata) [310], so black sagebrush × basin big sagebrush is the most common black sagebrush cross [242]. Black sagebrush hybrids often
form narrow bands between the black sagebrush zone and the adjacent zone of the other Tridentatae parent [298]. See these publications: [150,164,173] for lists of Tridentatae taxa with which black sagebrush may hybridize, and these sources: [150,173] for an explanation of phylogenetic relationships within Artemisia.
Black sagebrush is used for postfire restoration [80], erosion control [169,170,212], wildlife plantings [213,232,238], rangeland plantings [16,76,125,170,213], and mining reclamation [16,76,178,218]. It may grow on harsh sites to which few other shrubs are adapted [213].
Many sagebrush types may not require postfire seeding because the native plants recover on their own. As with burned sagebrush sites [242], natural recovery of other disturbed sagebrush areas is the most desirable alternative. Seeding or transplanting can interfere with recovery of on-site native vegetation [242]. However, natural recovery may not be possible on mined or other severely disturbed sites. Horton [117] advised that sites with infestations of invasive nonnative species or some sites that support nonsprouting species (such as black sagebrush) may be "extremely slow" to recover by natural regeneration alone. However, black sagebrush shows good natural seed regeneration on many disturbed sites [16].
Artificial regeneration is established from seeds or nursery stock [213,232]. Seeds are commercially available, and nursery stock can be started from wild cuttings [16,76]. Stevens [244] rated expected establishment success for bareroot, wild, or container-grow black sagebrush stock as "high". In the Big Horn Basin of Wyoming, black sagebrush showed good establishment from direct seeding after prescribed fire to control junipers (Juniperus sp.). Fall seeding resulted in more black sagebrush establishment than spring seeding [80]. Black sagebrush can be direct seeded onto rangelands in good condition. On rangelands invaded by cheatgrass, medusahead, or other nonnative annual grasses, the native perennial grass understory may need to be restored before black sagebrush and other sagebrushes can establish [183]. On shale-oil reclamation sites in Utah, transplanted black sagebrush stock showed 55% mean survival; about average among 9 transplanted shrub species [179]. On other shale-oil restoration sites in Utah, black sagebrush container stock showed 64% mean survivorship; surviving plants averaged 7 inches (20 cm) in height and 2 inches (5 cm) in canopy diameter after 3 to 4 years [77]. Kitchen and McArthur [145] review restoration planting techniques that have been successful in black sagebrush communities. See the following sources for information on black sagebrush seed collection [232,280,291], propagation [232,280], and outplanting [232,280,291] information. Monsen and Stevens [189,247] provide information on selecting species for and conducting postfire restoration plantings in black sagebrush communities.
As of 2009, programs for restoring degraded black sagebrush and other sagebrush ecosystems were still in development. Restoring sagebrush ecosystems is difficult, expensive, and will likely require decades to centuries. Restoration may not be possible on sites where a type conversion to annual grassland has occurred because political and economic support may be lacking or ecosystem functions (for example, fire and/or nutrient cycles) may be altered beyond a returnable threshold (review by [147]).
An unpredictable climate makes restoration projects in the Great Basin risky. Success of plantings on black sagebrush types may be especially unpredictable due to variable but usually low precipitation, which can result in death of new plants [109]. Survivorship of transplanted black sagebrush seedlings may be low with drought, and other, seeded native species may show poor establishment on xeric black sagebrush sites [274]. Black sagebrush showed 48% mean survivorship the first 3 years following transplanting of nursery-grown black sagebrush and other shrub seedlings on exclosures near Provo, Utah. However, survivorship of black sagebrush and other shrubs declined rapidly when seedlings were hit with above-average precipitation followed by drought. The site supported a winterfat-sickle saltbush (Krascheninnikovia lanata-Atriplex falcata) community on "slightly saline" soils. Precipitation rose above normal when black sagebrush seedlings were 6 years old, and above-average precipitation continued for a record-breaking 3 years (1982-1984). This extremely wet period was followed by 5 years of below-normal precipitation and increased black sagebrush mortality. Black sagebrush did not recover from its decline; black sagebrush mortality was 100% by posttransplant year 12 (1989) [208]. Die-off of black sagebrush transplants followed a region-wide trend of shrub die-off during the extreme wet-to-dry climate fluctuation [161,196,208]. The authors attributed the die-off to a high water table and subsequent build-up of pathogenic fungi, extreme swings in wet and dry weather, and a peak in grasshopper numbers and subsequent heavy grasshopper browsing [208].
Survivorship of transplanted black sagebrush seedlings by age and yearly mean annual precipitation [208] Seedling age (Year) 1 (1977) 2 (1978) 3 (1979) 4 (1980) 5 (1981) 6 (1982) 7 (1983) 8 (1984) 12 (1989) Survivorship (%) 52 50 43 34 14 7 7 ---* 0 Annual precipitation (inches)** --- --- --- --- 9 13 14 12 7 *No data.See Postfire restoration for more information restoring black sagebrush communities.
Black sagebrush in particular and shrubs in general can be under-used in postfire and other restoration projects. Although federal regulations dictate using native species when available (see Richards and others [217] for a review of these laws), lack of native propagule sources and poor performance often result in nonnative plantings outnumbering native plantings. Postfire plantings are often aimed at short-term watershed protection rather than maintaining long-term ecosystem function and diversity. A 1998 survey of postfire and mine rehabilitation projects in Nevada found black sagebrush was used on 0% of burned sites (n=50) and 9% of mined sites (n=32). All shrubs used on burned or mined sites were native, but both native and nonnative herbs were used. Wyoming big sagebrush was the only substantially outplanted shrub on burned sites (8%). Among shrubs, forbs, and grasses, nonnative crested wheatgrass (Agropyron cristatum, 38% of sites) and Siberian wheatgrass (A. fragile, 36%) were the 2 most heavily planted species on burned sites [217].
Black sagebrush does not sprout [13,27,138,169]. Typically, it does not layer [13,27,138], although McArthur and others [169] noted layering of black sagebrush in Washington County, Utah.
Silver sagebrush × black sagebrush hybrids may sprout. The 2 sagebrushes are closely related; among Tridentatae, some cladistic treatments place black sagebrush directly between silver sagebrush [177], which sprouts, and big sagebrush, which does not. Sprouting is thought to be a heritable trait in crosses between nonsprouting and sprouting sagebrushes [166]. See FEIS's review of silver sagebrush for more information on sprouting in silver sagebrush hybrids.
Artemisia nova is a North American species of sagebrush, known by the common name black sagebrush. It is "one of the most common shrubs in the western United States".[2][3]
The native range of Artemisia nova is from the Mojave Desert mountains in southern California and in the Great Basin of Nevada and Utah, north to Oregon, Idaho and Montana, east to Wyoming and Colorado, and south to Arizona and northwestern New Mexico.[2][4]
It grows in forest, woodland, and grassland habitats, often on calcareous soils.[2]
Identification is sometimes difficult, because this species is similar in appearance to Little sagebrush, Artemisia arbuscula, and it easily hybridizes with Big sagebrush, Artemisia tridentata, when it grows in the same area, leading to intermediate forms.[5]
Also, Artemisia nova has two main morphological forms, a darker, easily recognized form, and a less common light gray-green colored variant which closely resembles other sagebrush species.[5][3]
In general, Artemisia nova is a small, erect shrub producing upright stems branched off a central trunklike base. It is usually no taller than 20 to 30 centimeters but it has been known to exceed 70 centimeters in height.[2][3]
The aromatic leaves are green, short, narrow, and sometimes toothed at the tip. This species can sometimes be distinguished from its similar-looking relatives by glandular hairs on its leaves.[2][5][3]
The inflorescence bears clusters of flower heads lined with shiny, oily, yellow-green phyllaries with transparent tips. The fruit is a tiny achene up to a millimeter long.[3]
The plant reproduces from seed except in very rare occasions when it reproduces vegetatively by layering.[5][3]
Artemisia nova is a North American species of sagebrush, known by the common name black sagebrush. It is "one of the most common shrubs in the western United States".
