Ungulates, birds, and rodents use antelope bitterbrush for cover [26,79,107,178]. Mule deer preferred antelope bitterbrush habitat during winter in central Washington, maybe because of height and large crown of antelope bitterbrush [48]. Pronghorn prefer shrubs up to two feet tall (0.6 cm), so tall, decadent, fire-excluded stands of antelope bitterbrush are not good pronghorn habitat [245]. Sage grouse use short (12-inch (30.5 cm)) antelope bitterbrush for cover in Idaho [135,152], Oregon [188], and Wyoming [136]. Antelope bitterbrush and other shrubs provide important cover for Lewis' woodpeckers [138].
Antelope bitterbrush is a native, deciduous shrub [30]. The fruit is an achene, 0.13 to 0.5 inch (3-13 mm) long. Antelope bitterbrush has two common ecotypes, both present throughout its range: multiple-stemmed, decumbent plants, and single-stemmed, columnar plants [30,44,169,191]. Plants may reach 12 to15 feet (3.6-4.5 m) in height, but usually grow to 3 or 4 feet (0.9-1.2 m) [20]. The decumbent form is more prevalent at higher elevations. Antelope bitterbrush is long lived. Nord [176] reported a 115-year-old plant that was 10 inches (25 cm) high and spread over 7 square feet (1.8 m2). At a lower elevation, Nord found a 128-year-old plant that was 12 feet (3.6 m) high and 20 feet (6 m) across.
Antelope bitterbrush has a long taproot or taproots [19, 58] that reach up to 15 to 18 feet (4.5-5.4 m) in length [158,176], and few shallow roots [12].
Antelope bitterbrush sometimes has nitrogen-fixing root nodules, a result of a symbiotic association with Frankia spp. actinomycetes [2,46,151,169,192,195,238]. Degree of nodulation depends on site conditions including soil moisture content and salinity, presence of inoculants, and available nitrogen [171,192,193]. Presence of nodules, even in high numbers, does not necessarily indicate that significant amounts of nitrogen are being added to the soil [130,131,195]. Trappe [132] claims antelope bitterbrush has vesicular-arbuscular mycorrhizae, not nodule-forming actinorrhizae.
Antelope bitterbrush occurs from British Columbia east of the Cascade Range through Washington and Oregon; in the Klamath, North Coast, Cascade, and Sierra Nevada ranges of California; southeast into western Montana and throughout the Rocky Mountains; in the Great Basin; and in Arizona and New Mexico [30,36,102,169]. It is distributed over approximately 340 million acres [99].
Antelope bitterbrush is highly susceptible to fire kill [187]. Some ecotypes sprout following fire, either from dormant buds encircling an aboveground root crown, from calluses of meristematic tissue beneath the bark, or from dormant buds on a belowground lignotuber [75,78]. Very young and very old plants (younger than 5 or older than 40-60 years) do not sprout well [29,154].
Antelope bitterbrush occurs in plant communities with a variety of FIRE REGIMES. Pre-settlement fires in the ponderosa pine/antelope bitterbrush habitat type were probably less frequent than in other ponderosa pine types due to lower fuel loading [35,60,68]. Driver and Winston [78] estimate a mean fire interval of 7 to 10 years in a ponderosa pine/bitterbrush/pinegrass habitat in north-central Washington. In a pinyon woodland in the San Bernardino Mountains of California, antelope bitterbrush sprouted and became an early dominant following several wildfires. According to the authors, the fire regime in this pinyon-juniper woodland is predominantly long-interval canopy fires, and vegetation recovers slowly after fire [233]. Fuel loading in sagebrush-bitterbrush and juniper/bitterbrush communities tends to be light except in decadent stands, where extremely dry and windy conditions may result in severe fire [191]. Of four shrub communities east of the Cascade Range in Oregon and California-antelope bitterbrush, big sagebrush, snowbrush ceanothus, and greenleaf manzanita-fuel load was lowest in antelope bitterbrush [155]. The range of fire intervals reported for some species that dominate communities where antelope bitterbrush occurs are listed below. To learn more about the FIRE REGIMES in those communities, refer to the FEIS summary for that species, under "FIRE ECOLOGY OR ADAPTATIONS." Community dominant Fire interval range (yrs) interior ponderosa pine 2-42 Pinus ponderosa var. scopulorum Mexican pinyon 20-70 Pinus cembroides Rocky Mountain Douglas-fir 40-140 Pseudotsuga menziesii var. glauca curlleaf mountain-mahogany 13-1350 Cercocarpus ledifolius Rocky Mountain lodgepole pine 25-300+ Pinus contorta var. latifolia
In ponderosa pine/antelope bitterbrush communities, antelope bitterbrush is more prevalent in communities where fire has been suppressed for decades than in communities that have occasionally burned [191]. However, when fire is completely excluded from ponderosa pine for a long time, antelope bitterbrush becomes decadent [10,144]. Its density declines because dying plants are not replaced [43,44,200]. Frequent Indian-set fires probably favored grasses over antelope bitterbrush on most sites. On dry or stony sites, however, fires would not have carried as well, and antelope bitterbrush probably dominated such sites [8]. According to Driver and Winston [78], frequent, low-intensity wildfire in ponderosa pine communities of north-central Washington encouraged sprouting and maintained antelope bitterbrush as a community dominant.
Following prescribed burns to restore pre-settlement condition of ponderosa pine at Lick Creek in western Montana, antelope bitterbrush mortality was 25% during the harvest phase of treatment and increased to 40% after the prescribed burning that followed. Plants surviving the treatments had greater live biomass and palatability than unburned plants [9]. Also in western Montana, burn treatments in a ponderosa pine community resulted in antelope bitterbrush mortality of 72%. Following spring fire, only two antelope bitterbrush seedlings were found on study plots. Browsing was heavy on these sites and may have reduced available seeds. Twelve percent of burned plants sprouted the first year after fire. Annual growth rate of antelope bitterbrush was greater on burned plots compared to unburned plots for the first 2 years after fire [18].
Blaisdell [28] found some antelope bitterbrush sprouting following prescribed burns in Idaho, but total production of antelope bitterbrush was far below prefire levels. Sprouting bitterbrush dominated big sagebrush 9 years after fire, since it outgrew big sagebrush regeneration from seed. Twelve years after the burn, antelope bitterbrush production was still lower on burned plots compared to unburned plots.
In western juniper-antelope bitterbrush associations, antelope bitterbrush appears more vigorous where fire has killed junipers [44,191]. Antelope bitterbrush has a low (6%) sprouting success rate, low seedling establishment, and short lifespan in western juniper communities [42]. In these communities, regular but not too frequent fires are required to clear out older, decadent antelope bitterbrush and western juniper; to establish new antelope bitterbrush seedlings; and/or to encourage sprouting [42,108].
In dry Douglas-fir habitat types, antelope bitterbrush requires fire to reduce competition from conifer seedlings [35]. Prescribed fire in mesic forest communities maintains a subclimax community type and therefore encourages antelope bitterbrush establishment [44].
Antelope bitterbrush recovery from fire often takes too long for fire to be a useful tool in managing antelope bitterbrush [15,49,170,181]. Gruell [108] claims a fire frequency of 5 to 20 years would result in sparse distribution and low density of antelope bitterbrush. Driver and Winston [78] found fire recovery in the Craters of the Moon National Monument to take 15 to 20 years. Barrington and others [14] claim antelope bitterbrush density remains lower than prefire density for over 30 years in ponderosa pine communities on the eastern slope of the Cascade Range in Washington. Wright [242] reported that antelope bitterbrush was not fully recovered 27 years after a fire in a ponderosa pine community on the Warm Springs Reservation, Oregon. In contrast, Davis and others [68] found that antelope bitterbrush established quickly in a burned ponderosa pine/antelope bitterbrush habitat type on the Lolo National Forest, Montana.
Rodent-cached seeds are an important source of antelope bitterbrush regeneration after fire [44,225]. Rodent caches near or in a burned area may suffer less from seed predation following a fire because of reduced cover for rodents [56].
In British Columbia, Demarchi and Lofts [73] evaluated the nutritional content of antelope bitterbrush following fire. They concluded that there was a 3-year increase in nitrogen; a 2-year increase in calcium; a 1-year increase in phosphorus, potassium, and zinc; a decrease in copper; and no change in manganese.
Antelope bitterbrush is found on all slopes and aspects, usually on well-drained, permeable soils, from 3,100 to 10,000 feet (900-3,000 m) elevation. Average annual precipitation varies from 12 to 36 inches (300-910 mm) and usually falls as winter snow [205]. In Montana west of the Continental Divide, the antelope bitterbrush-bluebunch wheatgrass association occurs from 3,500 to 5,500 feet (1,000-1,650 m) elevation, generally on southern and eastern slopes. Annual precipitation ranges from 10 to 15 inches (250-380 mm) [109,205]. In Utah, antelope bitterbrush is common on dry rolling hills with northern exposures. In the basin big sagebrush cover type, antelope bitterbrush is found on deep, permeable soils below 7,000 feet (2,100 m) elevation [179].
Antelope bitterbrush survives on rocky and arid sites due to its long taproot or taproots [19, 58] and nitrogen-fixing capacity [12,192,205]. In Idaho, Murray [170] found more plants established on lava outcroppings than in swales with deeper soils. Antelope bitterbrush occurs on substrates with minimal root restriction. It is common on coarse-textured soils and on finer-textured soils with high stone content [77]. Antelope bitterbrush is found on slightly acid soils in California [175] but on basic soils in Utah [186]. It does not tolerate saline soils [176]. Seedlings have high tolerance for extremely high surface soil temperatures [91]. In eastern Oregon and western Nevada, antelope bitterbrush is important on upland sites. It is most frequent on highly calcareous, fine-textured sedimentary soils but also occurs on loamy sand and silty loam soils [7]. In Craters of the Moon National Monument, antelope bitterbrush dominates on old cinder cones, lava flows, and other substrates of volcanic origin [14].
210 Interior Douglas-fir
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
237 Interior ponderosa pine
238 Western juniper
239 Pinyon-juniper
247 Jeffrey pine
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES23 Fir-spruce
FRES29 Sagebrush
FRES30 Desert shrub
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K015 Western spruce-fir forest
K016 Eastern ponderosa pine forest
K017 Black Hills pine forest
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K020 Spruce-fir-Douglas-fir forest
K021 Southwestern spruce-fir forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodlands
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K040 Saltbush-greasewood
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
107 Western juniper/big sagebrush/bluebunch wheatgrass
109 Ponderosa pine shrubland
210 Bitterbrush
212 Blackbush
317 Bitterbrush-bluebunch wheatgrass
318 Bitterbrush-Idaho fescue
319 Bitterbrush-rough fescue
401 Basin big sagebrush
402 Mountain big sagebrush
406 Low sagebrush
413 Gambel oak
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
421 Chokecherry-serviceberry-rose
504 Juniper-pinyon pine woodland
509 Transition between oak-juniper woodland and mahogany-oak association
Antelope bitterbrush is very susceptible to fire kill. It is considered a weak sprouter and is often killed by summer or fall fire [27,35,51,52,173,176]. Antelope bitterbrush in some areas may sprout after light-severity spring fire [1,29,35,44,20]. Scholten [201] reports 70 and 91% of plants killed, respectively, in two separate Idaho wildfires, with 26% sprouting after the first fire and only 2% after the second fire.
Antelope bitterbrush is important browse for wildlife and livestock [3,15,30,56,106,169,176,228]. Pronghorn [110,174,207,215,245], mule deer [110,147,223,226,237,239], elk [121], bighorn sheep, and moose utilize antelope bitterbrush extensively [5,169,227]. Mule deer use of antelope bitterbrush peaks in September, when antelope bitterbrush may compose 91 percent of the diet [11]. Winter use is greatest during periods of deep snow [201]. In northwestern Nevada and northeastern California, antelope bitterbrush is a critical winter food for mule deer. Domestic livestock and mule deer may compete for antelope bitterbrush in late summer, fall, and/or winter [56]. Cattle prefer antelope bitterbrush from mid-May through June and again in September and October [201]. Antelope bitterbrush seed is a large part of the diets of rodents [229], especially deer mice and kangaroo rats [85,88,110,114,176].
Antelope bitterbrush supports several insect populations [92,99,100,105], some of which eat the seeds or cotyledons [86, 99, 159]. Especially important are Pogonomyrmex ants, which stash seeds and are important to natural regeneration [61,85], and tent caterpillars, which often cause antelope bitterbrush die-back [126,145,176,198].
Antelope bitterbrush appears in several mesic habitat types. Plant communities with antelope bitterbrush include range types such as antelope bitterbrush-bluebunch wheatgrass (Pseudoroegneria spicata), antelope bitterbrush-Idaho fescue (Festuca idahoensis), other steppe vegetation, and tree-dominated types such as ponderosa pine (Pinus ponderosa) forest and juniper (Juniperus spp.) woodland [191].
In Utah, antelope bitterbrush appears in warm, dry Douglas-fir (Pseudotsuga menziesii) habitat types, pinyon (Pinus spp.)-juniper "breaks," ponderosa pine, sagebrush (Artemisia spp.), and fir-spruce (Abies-Picea spp.) communities [35,40].
In Colorado, antelope bitterbrush occurs in the Rocky Mountain juniper (Juniperus scopulorum)/antelope bitterbrush habitat type and on warm, dry sites with ponderosa pine, Douglas-fir, thickspike wheatgrass (Elymus lanceolatus), plains prickly-pear (Opuntia polyacantha), and Ross sedge (Carex rossii) [116].
Plant species associated with bitterbrush are given below.
At Craters of the Moon National Monument, Idaho, antelope bitterbrush appears with wheatgrass (Triticeae), cheatgrass (Bromus tectorum), Indian ricegrass (Achnatherum hymenoides) and basin wildrye (Leymus cinereus) [14].
In lodgepole pine (Pinus contorta)/antelope bitterbrush forest in Oregon, antelope bitterbrush occurs with rubber rabbitbrush (Chrysothamnus nauseosus), mountain big sagebrush (Artemisia tridentata ssp. vaseyana), wax currant (Ribes cereum), and bluebunch wheatgrass [80].
In the Great Basin, antelope bitterbrush codominates in the sagebrush-grass zone along with little horsebrush (Tetradymia glabrata), green ephedra (Ephedra viridis), desert gooseberry (Ribes velutinum), and rabbitbrush (Chrysothamnus spp.). Forbs include northwestern Indian paintbrush (Castilleja angustifolia), Beckwith violet (Viola beckwithii), Nevada biscuitroot (Lomatium nevadense), and Anderson larkspur (Delphinium andersonii). Grasses include bluegrass (Poa spp.), needlegrass (Stipa spp.), wildrye (Elymus spp.), wheatgrass [189], Indian ricegrass, and dropseed (Sporobolus spp.) [22].
In the Wyoming mountain shrub community, antelope bitterbrush appears with big sagebrush, bluebunch wheatgrass, spike fescue (Leucopoa kingii), Ross sedge, and needle-and-thread grass (Stipa comata) [58].
References describing antelope bitterbrush as a community dominant or co-dominant are:
Forest vegetation of northern Idaho and adjacent Washington, and its bearing on concepts of vegetation classification [63]
Steppe vegetation of Washington [64]
Western juniper communities on rangelands of the Pacific Northwest [71]
Vegetation-soil units in the central Oregon juniper zone [77]
The vegetation of the Wasatch Mountains, Utah and Idaho [98]
Plant communities of the Blue Mountains in eastern Oregon and southeastern Washington [111]
Sagebrush-grass habitat types of southern Idaho [120]
Plant associations of south Chiloquin and Klamath Ranger Districts-Winema National Forest [124]
Plant associations of the Wallowa-Snake Province: Wallowa-Whitman National Forest [129]
Forest vegetation of the Gunnison and parts of the Uncompahgre National Forests: a preliminary habitat type classification [139]
Forest habitat types of Montana [183]
Forest habitat types of central Idaho [210]
Plant associations (habitat types) of the forests and woodlands of Arizona and New Mexico [212]
Coniferous forest habitat types of central and southern Utah [252]
Antelope bitterbrush is moderately browse tolerant [30,47,101,160,169]. Zacek and others [253] describe antelope bitterbrush a community "decreaser" under browsing pressure. Domestic sheep may be particularly damaging to antelope bitterbrush since they prefer young and small plants [176]. Almost 40 years after two years of heavy domestic sheep grazing in Oregon, no young antelope bitterbrush were present on grazed sites [76]. However, some authors claim that browsing helps maintain an antelope bitterbrush community's seral stage and therefore increases shrub vigor [183, 222]. In an 8-year study in southwestern Colorado, mortality was higher in unclipped and 80% clipped antelope bitterbrush compared to intermediate treatments of 20, 40, and 60% clipped antelope bitterbrush [203]. Monsen [164] found livestock browsing decreased the number of antelope bitterbrush that established or survived over 32 years in south-central Idaho. Kindschy [133] found that cattle grazing of grasses opened an area in southeastern Oregon and aided antelope bitterbrush establishment, whereas fewer plants established in ungrazed areas.
Antelope bitterbrush varies for many traits including sprouting, cold and elevation tolerance, nitrogen fixing, seed dormancy, palatability, nutritional content, drought resistance, form, and size. Because of this variation, it is important that the ecotype selected as a seed source matches the intended environment [66,192,162,163,210,241].
Antelope bitterbrush seedlings apparently have little resistance to damping off, particularly in greenhouse environments [100,172,202].
Total digestible nutrient levels of bitterbrush range from 39.7 to 54.8%, slightly less than the probable requirements for wintering sheep and mule deer and less than the values for big sagebrush and juniper species [201]. Dry-matter in vitro digestibility averages 25.4% [41]. Crude protein can reach 14% or higher in the leaves in early summer [11,17,25,118,205,206], but is around 7.9% in winter [67]. Winter protein content is generally below requirements of mule and white-tailed deer [11,15,201,227,231,234]. Twigs have lowest carbohydrate values in June and July and highest in November [102]. Antelope bitterbrush contains calcium, phosphorus, carotene, and fat [118,201,205]. It is an important source of carotene for rodents [85,169]. Winter phosphorus content is 0.13%, short of the 0.24% requirement for mule deer [201].
In natural and thinned Oregon ponderosa pine stands, the nutritional quality of antelope bitterbrush was as follows [69]:
Nutrient group Nutritional content in Nutritional content under
natural stands (%) thinned saplings (%)
N-free extract 50.31 47
crude protein 9.76 9.4
crude fat 5.8 4.9
crude fiber 21.64 27
ash 4.2 3
Digestible content (%) of antelope bitterbrush for mule deer was
as follows [105]:
State Crude protein Crude fat Crude fiber N-free extract
Colorado 8.7 7.5 22.8 57.7
California 9.4 4.9 ---- ----
Utah 7.4 5.4 30.6 53.6
Antelope bitterbrush is palatable to all types of livestock and wildlife. It is often critical browse for mule deer in winter [16,109,146,148,180,205,227].
The palatability of antelope bitterbrush has been rated as follows [110,113,143,196,219]:
CA ID MT NV
domestic sheep good poor-fair ---- good
mule deer very good very good very good very good
elk ---- fair-good very good ----
moose ---- ---- ---- ----
mountain sheep ---- ---- moderate ----
pronghorn very good very good very good very good
cattle good good good good
UT WY
domestic sheep good ----
mule deer very good very good
elk ---- very good
moose ---- very good
mountain sheep ---- ----
pronghorn very good very good
cattle good good
Reports conflict on antelope bitterbrush's ability to sprout in response to fire [13,14,28,36,37,50,53,60,111,118,125,139,169,200,208,227,242]. Geographic and ecotypic variation is considerable. Sprouting is common in eastern Idaho, occasional in Utah, and rare in Oregon, California, and Nevada [244]. In an eastern Idaho study, 50% of burned plants and 72% of top-clipped plants sprouted. However, 33 and 21%, respectively, of those sprouts died within a few years, so sprouting may not result in good long-term survivorship rates [29]. Postfire mortality is higher in central and southeastern Idaho than in southwestern Idaho and Nevada [184]. Britton and Wright [38] claim antelope bitterbrush above 7,500 feet (2,250 m) elevation is resistant to fire due to low fuels loads.
Sprouting ability is affected by fire severity and season; plant genetics, carbohydrate stores, and age; competition; soil moisture and type; and air temperature [51,154,191]. Decumbent plants seem to sprout better [14,35,37,44,52] than columnar forms [18,96]. Columnar forms sprout either from the root crown and/or from aboveground calluses of meristematic tissue, whereas decumbent forms sprout from the root crown and from points where branches layer [44]. Columnar types sprout best when fire severity is low and postfire soil moisture is high [19].
In Idaho and Montana, Bunting and others [44] found decumbent antelope bitterbrush sprouted more frequently than columnar forms. Sprouting frequencies on spring- and fall-burned sites averaged 55 and 42%, respectively. Greatest sprouting potential was found in plants in mountain shrub and conifer (Douglas-fir or ponderosa pine) communities (60% for shrub and 49% for conifer, respectively), where plants were mostly decumbent. Decumbent antelope bitterbrush also dominated mountain big sagebrush communities, but sprouting was lower in that group, possibly due to more xeric conditions. Predominantly columnar antelope bitterbrush in basin big sagebrush and juniper (western or Utah) communities sprouted the least. Seedling success paralleled sprouting success, except that average density of antelope bitterbrush seedlings in the conifer type was much higher than average density of antelope bitterbrush sprouts. Lowest seedling density was found in the juniper communities, possibly due to seed predation by rodents.
Season of burning and environmental conditions impact antelope bitterbrush ability to survive fire and sprout. Driscoll [75] measured postfire sprouting ability of antelope bitterbrush in several Oregon burns. Sprouting success ranged from 1 to 80%. Sprouting success was less after a July fire than after a September fire. In Nevada, an August burn defoliated plants, but due to high moisture content of stemwood, plant crowns did not burn. At the same site in October, a repeat fire consumed stemwood up to 0.25 inch (0.6 cm) in diameter and all plants were killed [187,190]. Murray [170] found that postfire yields of antelope bitterbrush were less after a spring fire than a fall fire, and speculated that sprouting after a spring fire would be greater than after summer fire. When soils are moist at the time of the burn, the root crown incurs less damage. Additionally, sprouting is more likely if fires are followed by rain [36,176,242]. Clark and others [52] found mortality was higher on watered fall-burned plots than on spring-burned plots.
More plants sprouted following a light August burn than a light July burn in southern Idaho, which the authors attributed to greater carbohydrate storage in the roots in August. Most moderately and heavily burned plants were killed [225].
High fuel consumption increases antelope bitterbrush mortality and therefore favors seedling establishment [36,44]. A low intensity, high frequency fire regime favors sprouting, whereas higher intensity, less frequent fires favors seedling regeneration [78]. Driver [77], who found high sprouting rates on his study plots in Washington, suggests that successfully sprouting columnar ecotypes may have been selected on habitats with high fire frequencies. According to Agee [1], nonsprouting antelope bitterbrush is now widespread in ponderosa pine ecosystems due to fire exclusion.
Soil texture affects the thermal transfer properties of soil and therefore the ability of antelope bitterbrush to sprout from undamaged underground buds [177]. Fire is more damaging to antelope bitterbrush on fine-textured calcareous soils than on coarse-textured, well-drained soils [37]. In several Oregon burns, Driscoll [75] found plants on northerly slopes with loose, coarse-textured, nonstony soils without pumice sprout best. Plants on fine-textured, stony soil sprouted poorly.
Cheatgrass invasion has increased the amount of fine fuels in big sagebrush-antelope bitterbrush grasslands, and antelope bitterbrush is not adapted to the more frequent, high severity fires resulting from increased fuel loads. Cheatgrass may outcompete antelope bitterbrush after fire [227]. Murray [170] found prescribed burned plots in Idaho had less than half the average yields of antelope bitterbrush compared to unburned plots. He concludes that vigorous competition from grasses may have decreased seedling establishment of antelope bitterbrush.
Antelope bitterbrush seeds germinate and grow on mineral soil exposed by fire [35,108]. In the Black Hills of South Dakota, antelope bitterbrush survival was measured 10 years after planting on a burned site and in an unburned, open stand of ponderosa pine [74]. Establishment from seed and containerized seedlings was higher on burned plots: Percent survival on: Seeded Planted from containerized seedlings Burned 22.0 20.0 Unburned 8.3 11.0
Tall shrub, adventitious bud/root crown
Small shrub, adventitious bud/root crown
Initial off-site colonizer (off-site, initial community)
FIRE REGIMES: 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".
Regeneration is by seed, stem layering, and sprouting [20,30,169,205]. Sprouting ability of antelope bitterbrush varies. Reports of sprouting in the literature mostly relate to fire and are discussed in "PLANT RESPONSE TO FIRE" below.
Antelope bitterbrush reaches seed-bearing age in 8 to 10 years, depending on local site conditions [105]. Flowers are pollinated by insects [21,30,] except where plants are crowded and wind pollination is possible [182]. Antelope bitterbrush is highly self-incompatible [30].
Achenes fall beneath parent plants when mature and dry [105]. The papery cover prevents seed germination until the cover rots away, which usually occurs over winter [85]. Seeds are dormant and require cool-moist stratification or damage to the seedcoat by mechanical scarification, chemical treatment, or soaking in aerated water for 1 to 2 weeks to break dormancy [33,84,163,250,246]. Four to six weeks of chilling at 36 degrees Fahrenheit (2 degrees C) is sufficient to germinate antelope bitterbrush seeds [163,248]. Seeds may enter a second dormancy if chilling requirements are not met [162,163,246,251]. Stevens and Jorgensen [212] found that 74% of antelope bitterbrush germinated after 25 years of storage. There is no available information regarding antelope bitterbrush persistence in seedbanks. Natural seedling establishment occurs only in years with normal to above-normal spring precipitation [84,133]. Artificial seeding processes that do not bury the seed are rarely successful because conditions needed for germination do not usually exist for long on the soil surface.
Rodent caches are often crucial to natural regeneration of antelope bitterbrush [55,83,85,126,199,201,204,229,236,248]. Rodents and ants may stash the entire crop of seed. Accumulation of litter and duff in forested antelope bitterbrush habitats discourages rodent caching and therefore decreases seedling regeneration [85]. Rodents return in spring to eat the sprouting cotyledons, which are a rich source of carotene. Uneaten seeds are a key source of new plants [85,169]. Rodent and insect herbivory are significant causes of establishment failure, however [85,161]. Clements and Young [55] found rodents preferred antelope bitterbrush cotyledons to millet (Panicum millaceum) seed, which is usually a preferred food. Rodent herbivory reduced ability of antelope bitterbrush seedlings to reach true leaf stage by 47 to 87% in test plots.
Ferguson and Medin [94] estimate that on an undisturbed Idaho range site dominated by antelope bitterbrush, only two antelope bitterbrush plants established per year due to competition from cheatgrass. They suggest, however, that antelope bitterbrush is likely to persist if it completes its first growing season without competition [123].
Decumbent antelope bitterbrush may layer. Layering is more prevalent above 7,000 feet (2,100 m) in California, where more than 30% of bitterbrush plants were found to layer. Only 12% did so below 7,000 feet. Layering is more common on fine-textured than coarse-textured soils [176].
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
Antelope bitterbrush is shade intolerant [14,154,159,208]. It is an early colonizer on disturbed sites [14,192], perhaps aided by its nitrogen-fixing capacity. In areas where antelope bitterbrush dominates and natural regeneration is not occurring, old, decadent antelope bitterbrush may be the climax community [218]. Biomass productivity in antelope bitterbrush declines after 70 years [14]. Stands without disturbance become senescent and decadent [56].
Antelope bitterbrush is generally replaced by western juniper where their ranges overlap [43]. In Colorado, antelope bitterbrush is much more prevalent in seral rather than climax Colorado pinyon-Utah juniper (Pinus edulis-Juniperus osteosperma) communities [81].
Hayward [115] identified antelope bitterbrush as a xerosere species in mountain shrublands.
Leopold [150] claims antelope bitterbrush is a seral species that would be replaced by bunchgrasses in eastern California if overgrazing by livestock and wildlife had not disrupted the natural succession.
The scientific name of antelope bitterbrush is Purshia tridentata (Pursh) DC (Rosaceae) [185]. Antelope bitterbrush hybridizes readily with Stansbury cliffrose (P. mexicana var. stansburiana) and desert bitterbrush (P. glandulosa) [62,156,214].
Antelope bitterbrush has been used extensively in land reclamation [30,44,93,95,100,165,168,202]. It is a pioneer species on some harsh sites. Antelope bitterbrush enhances succession by retaining soil and depositing organic material [12,36,104,166,169,176], and, in some habitats and with some ecotypes, by fixing nitrogen [89]. Antelope bitterbrush is important for watershed erosion control in central Washington [218].
Direct seeding of antelope bitterbrush has had mixed results [134]. Establishing antelope bitterbrush from planted seeds is difficult and requires optimum seedbed preparations including good weed control [83]. Seedling survival can be very low [91,127,194], particularly when antelope bitterbrush competes with cheatgrass [55,122,184,251]. Antelope bitterbrush is responsive to seeding in pinyon-juniper communities but is less successful in big sagebrush and mountain brush types [165]. Scholten [201] planted antelope bitterbrush in Idaho using several methods, with success ranging from 0 to 7% with direct seeding and from 19 to 69% with greenhouse seedlings. Everett and others [87] reported 79% antelope bitterbrush seedling survival 3 years after planting on an untreated acid spoil site in California. They concluded that antelope bitterbrush is a good choice for revegetating similar sites. Propagation from stem cuttings may prove more useful for rehabilitation projects [134]. Everett [86] successfully used containerized plants to revegetate arid roadcuts in Nevada. Survival rates on north and south slopes averaged 70%. Knapp [137] found natural antelope bitterbrush establishment on abandoned mining town sites was poor. He attributed the limited establishment to the weight of antelope bitterbrush seeds, which are too heavy to be easily transported or windblown to disturbed areas, and to the lack of favorable soil conditions. His study did not directly evaluate either of these factors.
Purshia tridentata, with the common name bitterbrush,[1][2][3] is a shrub in the genus Purshia of the family Rosaceae. It is native to mountainous areas of western North America.[3]
Common names include antelope bitterbrush,[3][2] antelope bush,[2] buckbrush, quinine brush, and less commonly deerbrush, blackbrush, and greasewood.[4] Some of these names are shared with other species.
Purshia tridentata is a deciduous shrub growing to a height of 1–5 metres (3+1⁄2–16+1⁄2 feet). It has many branches and slender green,[5] three- to five-lobed leaves 5–20 millimetres long. It is a nitrogen-fixing plant.[6]
The flowers are pale yellow,[5] with five petals 6–8 mm long, and darker yellow anthers. The fruit is a cluster of dry, slender, leathery achenes 0.6–2 centimetres long.
The yellow flowers have five petals and darker yellow anthers.
Purshia tridentata var. glandulosa on dry slope
There are two named varieties of the species:
The plant is found from southeastern British Columbia in the north, east to Montana and Wyoming, south to New Mexico, and west in California.[3] It grows on arid mountainsides and slopes, as well as rocky or drained soils with somewhat more moisture than the sagebrush steppe.[5] It is often associated with Balsamorhiza as well as Wyethia species, and in southern areas hybridizes with Purshia stansburyana.[5]
In California it occurs between 700–3,400 m (2,300–11,200 ft) above sea level, including in the Peninsular Ranges, Transverse Ranges, and Sierra Nevada, and southern Cascade Range.[2][9] Further north it occurs at lower elevations, such as at 320–1,065 m (1,050–3,494 ft) in British Columbia.[10]
The shrub is an important forage plant for many game animals, including deer,[5] especially during the winter.[11]
{{citation}}: CS1 maint: uses authors parameter (link) Purshia tridentata, with the common name bitterbrush, is a shrub in the genus Purshia of the family Rosaceae. It is native to mountainous areas of western North America.
Common names include antelope bitterbrush, antelope bush, buckbrush, quinine brush, and less commonly deerbrush, blackbrush, and greasewood. Some of these names are shared with other species.
