This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [65,93,103,114,117,118,124,137,277,281]).
Bromus carinatus is a cool-season, perennial bunchgrass [87,103,114,117,148,178,231,255,262]. It is sometimes described as an annual [117,190,217,289] or a biennial [110,117,190]. It is a rapid-growing and short-lived species [48,49,93,108,178,239,262,265,289]. The lifespan of Bromus carinatus is approximately 3 to 10 years, although strong self-seeding habits may allow a stand to persist longer [227,231,272]. If seeding does not occur, Bromus carinatus is likely to be replaced by longer-lived species [178].
Bromus carinatus plants are tall and erect, growing from 1 to 4 feet (30-122 cm) or more [103,117,200,204,220,255,272,277]. The culms are coarse, stout, and solitary or tufted [112,170,180,190,220,255,265,272,277]. Leaf blades are coarse, flat (or rarely folded), broad, and hairy. They range from 6 to 16 inches (15-40 cm) long and 0.08 to 0.6 inch wide [93,103,117,120,272,277,281]. Plants produce "good leafy growth" [49]. The inflorescence is a large, open, erect, narrow to pyramidal panicle, 2 to 16 inches (5-40 cm) long with stiff, spreading, or ascending branches [93,103,112,114,117,124,180,190,272]. The panicle is likely to droop at fruiting under the weight of the fruits, which are caryopses [277]. Spikelets vary from 1 to 4 per branch and are distinctly flattened, 0.6 to 2.4 inch (15-60 mm) long, with 4 to 16 flowers bearing many large, heavy, bearded seeds [93,103,114,117,124,190,272,277,281]. Lemmas are hairy on the back with a terminal awn up to 0.25 inch (6 mm) long [262,265,272].
The fibrous root system is well-branched [49,108,120,262,272]. Descriptions of root depth in mountain brome range from shallow [272] to deeply penetrating [49,120]. In the Boise River Watershed, Idaho, mountain brome belongs to a group of grasses with roots that are concentrated in the upper 1.2 inches (3 cm) of soil, from which they spread laterally and downward. It is suggested that short-lived perennial species like mountain brome penetrate only the upper ~16 inches (40 cm) of soil, whereas longer-lived perennials produce many more roots that extend to a depth of ~63 inches (160 cm) [237]. Root bisects of mountain brome plants grown in field experiments showed a large percentage of the roots contained in the upper 8 inches (20 cm) of soil, but extending as far as 35 inches (90 cm) [15]. In a greenhouse study mountain brome plants produced 4 ounces (117 g) of roots and 3 ounces (83.5 g) of tops in a 4.5-month period. This was the highest-yielding grass of 6 included in the study, although the top-root ratio was smaller than that of longer-lived, slower developing species like smooth brome (Bromus inermis) and tall fescue (Schedonorus phoenix) [48].
Bromus carinatus is native from British Columbia to Alberta and south to California, Texas, and much of Mexico [114,117,137,190,277,281]. It is introduced in Illinois, Iowa, and Kansas [93,117]. Grass Manual on the Web provides a distributional map of Bromus carinatus.
California brome occurs throughout the general distribution of Bromus carinatus and also in Alaska [114,277]. It is nonnative in Europe [277]. Mountain brome also occurs throughout the general distribution of Bromus carinatus, and in south-central Saskatchewan [190] and South Dakota [117,137,281]. Mountain brome is introduced in Ontario, Maine, New York, New Hampshire, Massachusetts, and Connecticut [135].
STATES/PROVINCES (Bromus carinatus): (key to state/province abbreviations)Bromus carinatus occurs in the following vegetation types. Although Bromus carinatus is widespread, it is uncommon in some vegetation types and is not documented in every ecosystem or plant community in which it may occur. Although the list of vegetation types below is very broad, Bromus carinatus may occur in some types that are not listed below.
Fire adaptations: Grasses are generally well adapted to survive under a regime of frequent fire [125]. Some authors indicate, however, that California brome plants are unlikely to persist following a fire [292], and that California brome persists on burned sites mainly by postfire seedling establishment [272]. In a review of the literature, Maslovat [166] found no data on California brome adaptations to fire. Some information, however, can be deduced from various botanical and ecological characteristics of Bromus carinatus. The buds of California brome and other hemicryptophytes, for example, may be protected from heat-induced mortality by dense leaf bases [136]. California brome produces both self-pollinating and open-pollinating flowers [114]. Self-pollinating flowers are often found in areas susceptible to grazing and mowing [54] and may also be found in areas susceptible to fire and other stresses.
Seedling establishment after a fire is likely related to the amount of viable seed available in the seed bank or off site. Because there is conflicting information in the literature about seed banking in Bromus carinatus [51,52,166,196,270] (see Seed banking), the relationship between seed banking and regeneration after fire is unclear. One author reports that California brome seed was not present in soil samples collected from burned sites in Douglas-fir/pinegrass, quaking aspen/pinegrass, and subalpine fir/thinleaf huckleberry habitat types in Yellowstone National Park [51]. Seed from off-site sources may therefore be important in postfire recolonization. Such seeds are likely transported into a burned area by animals and/or wind. Both California brome and mountain brome produce abundant seed [108,170,180], "vigorous" seedlings [59,120,177,231,265], and grow in open, unshaded sites [111,242,292] and on bare soil [246]. All of these characteristics may increase the likelihood of establishment after a fire.
FIRE REGIMES: Bromus carinatus occurs in many different ecosystems and plant communities. It is apparently most prevalent in open-canopy forests, woodlands, shrublands, and grasslands. Fire plays an important role in many plant communities where Bromus carinatus is a dominant or common understory species. FIRE REGIMES in some of the most important communities are described briefly below:
Ponderosa pine forests: Ponderosa pine forests are generally maintained by frequent, nonlethal, understory fire at mean intervals ranging from 1 to 50 years. Historically, fire-maintained ponderosa pine forests were mostly park-like and open and were dominated by large, fire-resistant trees. The understory was comprised mainly of grasses and forbs that sprouted after each fire [9].
Douglas-fir forests: Interior Douglas-fir forests experience a highly variable, mixed-severity fire regime [9] ranging from low- to moderate-severity surface fires every 7 to 20 years to severe crown fires every 50 to 400 years [142]. These fires create heterogeneous forests with variable species composition, structure, and age classes [9].
Coulter pine-coast live oak forests: Wildfires are frequent in Coulter pine-coast live oak forests in the southern Coast Ranges of California where California brome is a dominant understory species. Since 1912, major fires (>10,000 acres (4,000 ha)) have burned on the average of once every 3 years [36].
Western oak woodlands: Oak woodlands are maintained by frequent return-interval (<35 years), understory fire [9]. Frequent, low-severity fires apparently maintained the structure and composition of open Garry oak communities on southern Vancouver Island and the Gulf Islands and prevented invasion by Douglas-fir and other woody species [100,144,166,264]. Fire is the primary natural disturbance agent in oak woodlands and grasslands in the Lower Middle Klamath River area in northern California, where California brome and several other perennial grasses form the primary ground cover. Fire burns the bunchgrasses thatch, creating space for colonization of forbs [218].
Pinyon-juniper woodlands: Fire intervals in pinyon-juniper woodlands vary greatly, but fire is important in eventually opening the canopy. Pinyon-juniper communities experience understory burns when fire is frequent, but typically have moderate- to long-interval, stand-replacing fires [176,256].
Aspen woodlands: Quaking aspen stands experience mixed-severity fires every 35 to 200 years [9]. Fuels are usually moister in quaking aspen stands than in surrounding forest. Crown fires in coniferous forests often drop to the surface in quaking aspen, or may extinguish after burning into quaking aspen a short distance [31,82]. Although individual stems are not particularly fire resistant, quaking aspen sobols and roots are very fire resistant, sending up new suckers to replace stems that die [38]. Following a fire, a new, even-aged quaking aspen stand can develop within a decade [69]. In quaking aspen/California brome communities in eastern Idaho and western Wyoming, quaking aspen depends on moderate-severity fire for successful regeneration [38]. Here, fire frequencies of 100 to 300 years appear to be appropriate for maintaining most seral quaking aspen stands [70].
Sagebrush: Historic fire return intervals in sagebrush (Artemisia sp.) ecosystems were variable, ranging from around 20 to 100 years. Fires were mostly mixed-severity [122,284,285]. Fire return intervals in mountain big sagebrush communities, where Bromus carinatus is often among the dominant species, range from 15 to 40 years [11,45,174].
Annual grasslands: Because they are dominated by nonnative annuals, annual grasslands have no "natural" fire regime. There are no data and few historic records of presettlement fire return intervals in pristine California prairie. Probable mean fire intervals (estimates of fire intervals that are derived from historical or very limited physical evidence) for California prairie are frequent: approximately every 1 to 2 years. Probable mean fire intervals for annual grasslands are every 20 to 30 years [253]. Heady and others [110] suggest that California coastal prairie species, including Bromus carinatus, probably evolved under a "relatively intense fire frequency regime."
The following table provides fire return intervals for plant communities and ecosystems where California brome and mountain brome are important. 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".
Community or ecosystem Dominant species Fire return interval range (years) grand fir Abies grandis 35-200 [9] California chaparral Adenostoma and/or Arctostaphylos spp. 192] silver sagebrush steppe Artemisia cana 5-45 [113,203,284] sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [192] basin big sagebrush Artemisia tridentata var. tridentata 12-43 [221] mountain big sagebrush Artemisia tridentata var. vaseyana 15-40 [11,45,174] Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (men = 40) [267,288] coastal sagebrush Artemisia californica 192] desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 10 to <100 [172,192] plains grasslands Bouteloua spp. 192,284] blue grama-needle-and-thread grass-western wheatgrass Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii 192,215,284] cheatgrass Bromus tectorum 195,279] California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [192] curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1,000 [13,224] mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii <35 to <100 [192] California steppe Festuca-Danthonia spp. 192,253] western juniper Juniperus occidentalis 20-70 Rocky Mountain juniper Juniperus scopulorum <35 [192] western larch Larix occidentalis 25-350 [10,24,67] wheatgrass plains grasslands Pascopyrum smithii <5-47+ [192,203,284] Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to >200 [9] pinyon-juniper Pinus-Juniperus spp. <35 [192] Rocky Mountain bristlecone pine P. aristata 9-55 [72,73] whitebark pine* Pinus albicaulis 50-200 [1,7] Mexican pinyon Pinus cembroides 20-70 [176,256] Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [23,24,257] Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 [9] Colorado pinyon Pinus edulis 10-400+ [85,95,138,192] Jeffrey pine Pinus jeffreyi 5-30 western white pine* Pinus monticola 50-200 Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [9] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [9,16,150] Arizona pine Pinus ponderosa var. arizonica 2-15 [16,58,228] quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [9,98,173] mountain grasslands Pseudoroegneria spicata 3-40 (x=10) [8,9] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [9,11,12] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [9,181,213] California mixed evergreen Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii <35 California oakwoods Quercus spp. <35 [9] coast live oak Quercus agrifolia 2-75 [97] oak-juniper woodland (Southwest) Quercus-Juniperus spp. <35 to <200 [192] coast live oak Quercus agrifolia 2-75 [97] canyon live oak Quercus chrysolepis <35 to 200 blue oak-foothills pine Quercus douglasii-P. sabiniana <35 Oregon white oak Quercus garryana <35 [9] California black oak Quercus kelloggii 5-30 [192] bur oak Quercus macrocarpa <10 [269] interior live oak Quercus wislizenii <35 [9] redwood Sequoia sempervirens 5-200 [9,84,254] western redcedar-western hemlock Thuja plicata-Tsuga heterophylla >200 mountain hemlock* Tsuga mertensiana 35 to >200 [9] *fire return interval varies widely; trends in variation are noted in the species reviewPostfire revegetation: In central Oregon, California brome is 1 of several plants that naturally revegetates disturbed sites where bare mineral soil is exposed, including logged and burned areas [22]. When seeded on disturbed sites, both California brome and mountain brome establish quickly and later yield to longer-lived species [120,132,199]. California brome became an understory dominant after seeding in a burned Douglas-fir/pinegrass forest in central Idaho, for example [244], and mountain brome became well established after fall seeding in an area that was selectively cut and burned under prescription in north-central Washington [273]. In the mountain brush zone of central Utah, it was 1 of 9 grasses that established readily after seeding in a burned area. It produced relatively high yields for ~4 years but was later suppressed by smooth brome. The authors conclude that short-lived, self-reseeding bunchgrasses are useful in mixtures with slower developing grasses to ensure rapid establishment of grass cover following seeding [89]. Mountain brome produced a "good" stand within the 1st year after seeding on a burned, 2nd-growth ponderosa pine site in northern Idaho. Within 15 years the longer-lived native vegetation had returned, and mountain brome and other seeded species were difficult to find [234].
Prescribed burning: Successful prescribed burning may be difficult in the snowfield big sagebrush/California brome habitat type in southern Idaho. Fire spread is limited by the wide spacing of shrubs, the gentle terrain, and the mesic nature of the habitat [116].
Time of year was found to be a reliable indicator of moisture content of herbaceous vegetation, including California brome, in the understory of quaking aspen forests on the Bridger-Teton National Forest in Wyoming. During both a wet (1981) and dry (1982) summer, California brome, blue wildrye, and slender wheatgrass cured at slow but steady rates beginning early in the growing season, primarily because seed stalks cured early even though leaves remained lush. The moisture content of grasses in a closed-canopy quaking aspen stand averaged 41% higher than in the adjacent open stand. In quaking aspen forests where herbaceous vegetation is the primary fine fuel, at least 50% curing is needed to sustain fire spread. Information on moisture content throughout the season and degree of curing can therefore be used to plan timing of prescribed burns [40].
Other: The mountain big sagebrush-mesic west potential vegetation type in the Interior Columbia River Basin (which corresponds with Johnson and Simon's [131] mountain big sagebrush-mountain snowberry/California brome habitat type) has been slightly to severely altered due to "improper" livestock management and fire exclusion. This vegetation type, however, is also 1 of the most resilient types in the Columbia River Basin, responding readily to changes in livestock and fire management [43].Bromus carinatus is found on open ground, disturbed sites, and in meadows, shrublands, open forest, and woodlands throughout its range [93,114,117,117,137,216,220,261]. Site characteristics vary by variety and by region. California brome grows in sagebrush (Artemisia spp.), mountain brush, quaking aspen, spruce-fir, moist grassland, and subalpine meadow communities throughout the Intermountain West [193,198,277]. In California it grows in open shrubland, woodland, coniferous forest, dunes, and meadows [114,217] as well as on more fertile sites, such as under oak canopies [227]. In south-central Oregon it is found in nonforested openings on stream terraces and floodplains [86], and in the South Umpqua River drainage of Oregon, it is more common on cold, moist sites than on warm, dry, and cool sites [175]. It grows in open woods, quaking aspen woodlands, shrublands, meadows, and "waste places" in Colorado [112], and on dry, open ground in coastal sage scrub and creosotebush (Larrea tridentata) scrub in Baja California [281].
Mountain brome grows on open slopes, grass balds, shrublands, dry to moist meadows, open ponderosa pine, lodgepole pine (Pinus contorta), and quaking aspen forests in the montane and subalpine zones of the Rocky Mountains and western Great Plains [103,190]. In Alaska, it grows in "waste places," roadsides, and yards [124]. In Arizona, it grows along roadsides, in moist meadows, and on moist sites in Douglas-fir or ponderosa pine forests [126,137]. It grows on grassy slopes and rocky, open areas in Baja California [281] and on coastal prairie terraces along the northern California coast [110].
Elevation: Bromus carinatus occurs between sea level and 11,000 feet (3,400 m) throughout its range [59,109,112,114,137,137,182,219,277,286]. The results of a study in Ephraim Canyon, central Utah, suggest that California brome production increases with increasing altitude, an effect that may be related to greater precipitation and insolation at higher elevations [78]. In California, however, stands were more scattered and plant height was reduced at high elevations [220]. Elevation ranges by state/region are as follows:
California brome State Elevation Arizona 2,198-9,000 feet [137,280] California sea level-10,000 feet [114,220,262] Colorado 5,000-10,000 feet [112] Utah 5,500-10,100 feet [37,61,277]Mountain brome State/region Elevation Arizona/New Mexico 5,500-9,500 feet [83,137] California (northeastern Sierra Nevada and White Mountains) 6,000-11,000 feet [59,286] Oregon (Wallowa National Forest) 6,500-8,500 feet [219] South Dakota (Black Hills) 6,500-7,500 feet [109] Rocky Mountains ≤10,000 feet [182,219,272,274]
Soils: Bromus carinatus is adapted to a wide variety of soil types including sands, silts, and clays [178,231,255,261,266]. California brome is most productive in moderately moist, well-developed, deep, medium-textured soils [178,255]. It can also grow in poorly drained soils [255] and in dry, shallow, and infertile soils on disturbed sites [178]. In the Intermountain West, it grows well on somewhat poorly drained clay to sandy loam soils in the 5.5 to 7.5 pH range, but is not suited to long-term cover on shallow soils without irrigation or fertilization [108]. In Oregon, it is found on well-drained sites, including stream terraces and floodplains where soils are generally derived from deep alluvial deposits of pumice or basic scoria [86]. In a mountain brush/California brome community on the Humboldt National Forest in Nevada, the mean summer soil temperature was 55 °F (13 °C) and the mean annual soil temperature was 44 °F (7 °C) [129].
Mountain brome thrives on moderately deep, fertile, moist, medium to fine-textured soils and is moderately "vigorous" on thin, infertile, coarser, fairly dry soils, especially in open communities and disturbed sites [231,272]. It tolerates soils in the pH range of 5.5 to 8.0 [236].
Salinity tolerance: Bromus carinatus is moderately tolerant of saline soils [178,197,231,250,266,272].
Moisture requirements: California brome is adapted to sites that receive mean annual precipitation of 18 inches (46 cm) or more [108]. It is only moderately drought resistant and is therefore limited to more moist sites [152,170,265]. It is moderately tolerant of flooding [197,250] but is intolerant of long periods of flooding or high water tables [178].
Mountain brome grows best in areas with 15 to 30 inches (38-76 cm) of annual precipitation [109,231,236]. It is intolerant of high water tables and early spring flooding [272]. For optimum production, the water table should not be closer than 36 inches (91 cm) [231]. Seeds, seedlings, and mature plants can tolerate only 14 days of spring flooding [231]. Drought tolerance is low to moderate [231,266,272]. In drought conditions simulated in greenhouse experiments, mountain brome lost 49.1% of its total water content before permanent wilting occurred, indicating a moderate ability to withstand drought without permanent injury. During a 6-month period of simulated severe drought, the underground parts of mountain brome remained dormant, and plants produced new shoots when water was added to the soil. After a second 6-month drought period, however, plants did not produce new shoots [15]. Root bisects of plants grown in field experiments showed a large percentage of the roots contained in the upper 8 inches (20 cm) of soil, but extending as far as 35 inches (90 cm), suggesting that the roots can extend to sufficient depths to enable the plant to withstand drought [15].
Mountain brome has been referred to as a "snow increaser," appearing to grow well on sites with late-melting snow [275]. On an Idaho fescue grassland northeast of Bozeman, Montana, mountain brome was more abundant on sites with deep and therefore late-melting snow than on earlier-melting sites [274]. In the Limestone District of the Black Hills, South Dakota, mountain brome is a dominant plant in upland meadow communities where the snowpack remains in place into late spring, providing ample soil moisture [109].
Temperature: California brome is adapted to sites where the minimum winter temperature is above -40 °F (-40 °C). It has only fair heat tolerance [108].
SRM (RANGELAND) COVER TYPES (Bromus carinatus) [232]:
102 Idaho fescue
103 Green fescue
108 Alpine Idaho fescue
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
208 Ceanothus mixed chaparral
209 Montane shrubland
213 Alpine grassland
214 Coastal prairie
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
304 Idaho fescue-bluebunch wheatgrass
305 Idaho fescue-Richardson needlegrass
307 Idaho fescue-threadleaf sedge
309 Idaho fescue-western wheatgrass
310 Needle-and-thread-blue grama
311 Rough fescue-bluebunch wheatgrass
316 Big sagebrush-rough fescue
319 Bitterbrush-rough fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
324 Threetip sagebrush-Idaho fescue
401 Basin big sagebrush
402 Mountain big sagebrush
403 Wyoming big sagebrush
405 Black sagebrush
408 Other sagebrush types
409 Tall forb
410 Alpine rangeland
411 Aspen woodland
412 Juniper-pinyon woodland
413 Gambel oak
415 Curlleaf mountain-mahogany
420 Snowbrush
422 Riparian
503 Arizona chaparral
509 Transition between oak-juniper woodland and mahogany-oak association
606 Wheatgrass-bluestem-needlegrass
607 Wheatgrass-needlegrass
608 Wheatgrass-grama-needlegrass
610 Wheatgrass
612 Sagebrush-grass
613 Fescue grassland
733 Juniper-oak
California brome vegetation classifications:
In addition to those listed above for Bromus carinatus, California brome
also occurs in the following vegetation types:
Mountain brome vegetation classifications:
In addition to those listed above for Bromus carinatus, mountain brome
also occurs in the following vegetation types:
Bromus carinatus is 1 of the best forage grasses on western rangelands [112,262], particularly in open habitats, mountainous summer rangeland, and, due to its shade tolerance relative to many other grasses, some forest and woodland habitats [126,265]. A deep, fibrous, spreading root system makes it fairly resistant to grazing and drought, and the large, leafy plants yield abundant forage [49,120,262,265]. Use of California brome and mountain brome has been documented for horses, cattle, domestic sheep, bears, deer, elk, pronghorn, small mammals, birds, and invertebrates as follows:
Livestock: California brome is 1 of the most important forage grasses in the quaking aspen zone of Colorado and Wyoming between 8,000 and 10,500 feet (2,400-3,200 m) elevation, where it produces 11.7% of the forage [60]. In the quaking aspen-subalpine fir zone of central Utah, it forms dense stands and is a key forage plant used to estimate degree and intensity of grazing [170]. California brome is an excellent grass for hay or pasture [236]. It produces moderate amounts of high-quality forage and receives considerable use in spring and early summer prior to seed dispersal [108]. It is tolerant of grazing, although excessive use weakens the stands [255]. The forage is ranked "excellent" for cattle and horses and "good" for domestic sheep [255]. California brome was among the 5 species most utilized by cattle in the Biosphere Reserve of La Michilia in Durango, Mexico [81]. Horses and domestic sheep eat California brome seed heads [262].
Mountain brome accounted for 7% of vegetative cover and 3% of cattle diet in the quaking aspen-willow (Salix spp.) vegetation type on the Helena National Forest in west-central Montana [94]. Horses and cattle graze the flowering stems of mountain brome [180]. Domestic sheep graze mountain brome only when it is fairly succulent [180]. Along with other native perennial grasses and shrubs, mountain brome can be a valuable source of intermittent livestock forage in forest openings created by thinning, fire, wind, or insect outbreaks in the western Sierra Nevada, California [44]. In a study conducted in Douglas-fir/ninebark habitat in northeast Oregon, mountain brome frequency was 9% in plots grazed only by cattle, 14% in plots grazed only by big game, and 18% in plots grazed by both. In the plots where no big game grazing was allowed, mountain brome was reduced by shrubs [146]. Gruell and others [99] state that in western Montana, grassland management should focus on such "productive and palatable species" as mountain brome, bluebunch wheatgrass, and western needlegrass (Achnatherum occidentale).
Bear: California brome is a known grizzly bear food [282].
Deer: California brome was ranked "low" in importance as a food for Columbian black-tailed deer on southern Vancouver Island, British Columbia. It was eaten "casually" in April and May or under stress in early winter when palatability is low. Under natural conditions, Columbian black-tailed deer generally consume very small quantities of graminoids [64]. California mule deer on the Los Padres National Forest ate ripe mountain brome seed heads [214]. Mountain brome comprised 1 to 10% of the mule deer diet in a 2nd-growth giant sequoia forest in Tulare County, California, that had been cleared and burned to create an open, park-like condition [153]. Deer in Arizona make "little use" of grasses including mountain brome in the understory of open quaking aspen stands, and are more likely to browse young quaking aspen or other woody species [126].
Elk: California brome is considered excellent forage for elk [255]. Several authors report that elk mainly consume it in summer [154,178,255], although in 1 study, Rocky Mountain elk utilized California brome only during September on the Sapphire Range of western Montana. California brome comprised 3% of the total elk September diet. The preference index value (average utilization divided by the average cover for that species) was 1. Values ≥1 indicate a forage preference by elk for that species. Graminoids generally became the preferred forage class in fall, when frost lowered the palatability of succulent vegetation [165].
The percentage of California brome in elk diets was generally low in montane meadow and fire-created grassland habitats on Bandelier National Monument, New Mexico [283]:
Montane meadows
2 September 1991-
La Mesa fire grasslands
5 November 1991-Elk consumed mountain brome at a higher rate than browse species on clearcut quaking aspen stands near Farmington, Utah [55]. In the coastal redwood belt in northwestern California, mountain brome comprised 0.3% cover, and Roosevelt elk used it 0.8% of the total forage minutes recorded. This translated to an index value of 2.7, the 7th highest of 28 species documented. Therefore, while mountain brome was not a leading forage species, it was consumed at a moderately high rate relative to its abundance in the study area [106].
Pronghorn: Einarsen [75] noted that pronghorn ate mountain brome in spring.
Small mammals and birds: California brome seedheads and seeds provide food for many birds and small mammals [178,255]. California quail use bunchgrass-dominated habitats, including oak woodlands and grasslands in the Klamath Basin of northern California where California brome, blue wildrye, and California fescue are understory dominants [218]. In central Oregon, California brome is an important food for northern and Mazama pocket gophers on disturbed sites in early stages of succession [22]. In at least 1 case, California brome increased on areas of northern pocket gopher activity [76]. Over 2 years, Mazama pocket gopher preference for California brome on the Winema National Forest in Klamath County, Oregon, was highest in September, 2nd highest in November, and lowest in July. The authors of the study suggest that the high moisture content of California brome may help explain this feeding pattern. Tietjen and others [259] found that grasses with high moisture content, such as California brome, provide a better diet compared to diets of only nonsucculent grasses. Columbia ground squirrels inhabiting subalpine forest openings in central Idaho ate California brome leaves and fruits on sites subject to either medium- or heavy-intensity domestic sheep grazing. The relative preference index for California brome was 0.25 in the medially grazed site and 3.09 in the heavily grazed site. The latter was among the highest relative preference index ratings for all plants measured in the study [149].
Songbirds and rodents eat mountain brome seeds [272]. Canada geese pluck young plants [272], and seeds have been found in the crops of chukar [105].
Invertebrates: California brome is a host plant of the umber skipper along the Coast Ranges and the foothills of the Sierra Nevada in California. It is reportedly used by both adults and larvae. Adult females have been observed laying eggs singly on the undersides of the leaf blades [17].
Palatability/nutritional value: The palatability of California brome ranges from good to excellent for livestock and big game [37,170,184,197,220,230,250,255], particularly during late spring and early summer [220,265]. The foliage becomes harsh, fibrous, and less palatable at maturity [220,255,262], although if grazed early in the season it produces additional foliage that is palatable into late fall [220]. Some protection from late-season grazing may be necessary, however, since early spring growth depends on carbohydrates stored in the roots and stem bases during the previous fall. Deferred and rotation grazing may be employed to ensure that plants are not grazed continuously during 1 season or at the same time of the season in consecutive years [220].
The palatability of California brome is "excellent" for deer and elk in grassland and shrubland habitats of western Montana [184]. Palatability is "good" for pronghorn [75]. California brome seedheads are palatable and nutritious [112]. Sheep "relish the nutritious seed heads" and lambs "fatten rapidly and economically when well-filled seed heads are abundant" [220]. In a native upland prairie in the Coast Ranges of Oregon, vertebrate predation was an important mortality factor for California brome seeds. In a 1-year study, 21.2% of the seeds planted were lost to vertebrate predation, presumably because California brome has large seeds that are easy to see, easy to handle, and have greater nutrient content than small seeds [52].
California brome was 1 of 8 grasses included in a palatability test in the mountain brush zone near Ogden, Utah. California brome was rated highly palatable relative to the other grasses tested. Mean cattle utilization was [127]:
Date 25 May 3 June 11 June 23 June Days after the initiation of grazing 4 13 21 33 Average utilization estimate to nearest 5% 40% 60% 70% 80%California brome is highly nutritious to livestock [170], although phosphorus and protein content are both somewhat lower than most mountain grasses at the same growth stages [265]. Crude protein content varied from 13% in mid-June to 3% in mid-September on Utah rangeland [265]. Average percent dry matter and chemical composition of California brome plants collected between 8 July and 27 September was compared between big sagebrush and quaking aspen sites on the Cache National Forest, Utah [56]:
Site Dry matter Ether extract Protein Cellulose Lignin Other carbohydrates P Ca Crude fiber sagebrush 61.2 2.07 4.68 46.06 8.59 33.79 .174 0.34 41.76 aspen 51.1 1.84 5.12 46.63 9.57 31.91 .214 0.38 44.13Average percent dry matter and chemical composition of California brome collected from quaking aspen and big sagebrush sites on summer range on the Cache National Forest, Utah, varied between early July and late September as follows [56]:
Date Dry matter Ether extract Protein Cellulose Lignin Other carbohydrates P Ca Crude fiber 8 July 36.40 2.44 8.23 43.09 7.49 33.07 .289 0.31 38.62 31 July 49.90 1.52 5.45 42.72 9.26 35.66 .214 0.35 39.02 28 Aug. 63.08 1.92 3.33 49.49 9.65 30.99 .134 0.36 46.88 27 Sept. 78.20 1.82 3.23 49.88 9.73 30.71 .144 0.44 47.52On the Wasatch Plateau in central Utah, carbohydrate content of California brome herbage was highest immediately after snow melt and lowest during flowerstalk formation. It rose again near the end of the snow-free period. Of the carbohydrates stored in the roots during the fall, ~75% was consumed by physiological activity during the winter and by early spring growth of herbage and adventitious roots (accounting for about 10% of the total annual herbage growth of the plant). The other 25% was not used unless the plant was clipped or grazed. Stored carbohydrates were lowest soon after snow melt, indicating that normal annual growth takes place with carbohydrates produced by photosynthesis [170].
Palatability of California brome in several western states has been rated as follows [71]:
CO MT UT WY cattle good good good fair-good domestic sheep good good fair-good good horses good good fair-good good pronghorn ----- poor poor-good poor elk ----- poor good good mule deer ----- poor fair-good fair white-tailed deer ----- poor ----- fair small mammals ----- poor good good small nongame birds ----- poor fair-good fair upland game birds ----- ----- fair fair waterfowl ----- ----- poor poorPalatability of mountain brome is intermediate to high for cattle and other livestock in western forests and rangelands [30,126,148,180,183,231,277]. Daily gains of 1.58 lbs were obtained for beef cattle grazing on a 'Bromar' mountain brome-sweetclover (Melilotus spp.) mixture [101]. Mountain brome palatability is low during the winter months and high during the green growth period [180,231,266]. This seasonal palatability could lead to overuse in mixtures or pure stands if not carefully managed [231]. The seeds are highly palatable to livestock in the fall. [272]. It is an "important and desirable range grass" in Montana, where palatability ratings (the average degree to which a plant is eaten by livestock under natural conditions and under good range management) range from 50% for domestic sheep and goats to 80% for cattle and horses [209]. Mountain brome palatability is ranked moderate to good for elk in the spring and summer and fair to moderate for deer in the spring [231,272].
Mountain brome is generally high in crude protein and digestible carbohydrates and makes good quality hay [101,231]. On a Canadian rangeland, dry matter yield and crude protein content increased until approximately the early seed stage (Fulkerson and others 1967, cited in [96]). In a Montana study, the 3-year crude protein average was 4.56%, which was the lowest average obtained for any grass in the study [271]. The average winter crude protein content is 2.6% [231]. On a ponderosa pine plantation in south-central Oregon, crude protein content dropped below the minimum level determined necessary for cattle (9.3%) after week 8. Digestible energy and plant moisture dropped below the minimum levels (2.34 kcal/g and 50%, respectively) after week 12. When these critical levels are reached for forage plants, browse damage to ponderosa pine seedlings in the plantation is more likely [90].
Cover value: In northern California grasslands, tall perennial bunchgrasses including California brome provide bedding material, cover, and protection from predators. "Fawning" occurs in this habitat type in the Lower Middle Klamath River watershed of northern California where California brome, California fescue, and blue wild rye are dominant species (Terrill, personal communication cited in [218]). The degree to which California brome provides cover for small mammals and birds has been rated as follows [71]:
MT UT WY Small mammals fair good good Small nongame birds fair good good Upland game birds good fair-good fair Waterfowl ----- poor poorMountain brome provides cover for voles. Both montane vole and meadow vole abundance was positively correlated with grassland areas dominated by mountain brome, orchardgrass (Dactylis glomerata), and Kentucky bluegrass in southwest Montana [119].
California brome
―
California brome is documented in several plant communities besides
those listed above. In California, it grows in Coulter pine-coast
live oak (Pinus coulteri-Quercus agrifolia) forest in the southern
Coast Ranges [36], in dune scrub communities at Point Reyes National
Seashore [19], and in Torrey pine (P. torreyana) woodland on Santa Rosa
Island [53]. It is a common understory species in the
singleleaf pinyon-Utah juniper (P. monophylla-Juniperus osteosperma)
association in the northern Hualapais Mountains of Arizona [47], and is an
important grass in native upland prairie in the Oregon Coast
Range foothills, codominating with Roemer's fescue (Festuca roemeri)
and blue wildrye (Elymus glaucus) [52].
California brome is listed as a dominant species in the
following vegetation classifications:
United States ―
California:
coastal prairie [110]
Douglas-fir/ninebark (Pseudotsuga menziesii/Physocarpus malvaceus)/California brome habitat type in central Idaho [242]
grand fir/mountain maple (Abies grandis/Acer glabrum)/California brome habitat type in central Idaho [243]
Douglas-fir/pinegrass (Calamagrostis rubescens)/California brome habitat type in central Idaho [244]
Douglas-fir/white spiraea (Spiraea betulifolia)/California brome habitat type in central Idaho [245]
snowfield big sagebrush (Artemisia tridentata ssp. spiciformis)/California brome habitat type
in southern Idaho, elevation 7,000-9,500 feet (2,100-2,900 m) [116]
parsnipflower buckwheat (Eriogonum heracleoides)-California brome community in southeast Idaho
(a seral community within the mountain big sagebrush-mountain snowberry/Idaho
fescue (Artemisia tridentata ssp. vaseyana-Symphoricarpos oreophilus/Festuca idahoensis) habitat type)
one-flower helianthella (Helianthella uniflora)-California brome community in southeast Idaho (a seral
community within the mountain big sagebrush-mountain snowberry/Idaho fescue habitat type)
pioneer violet (Viola glabella)-California brome community in southeast Idaho (a seral community within the mountain big
sagebrush-mountain snowberry/Idaho fescue habitat type)
timber milkvetch (Astragalus miser)-California brome community in southeast Idaho (a seral community within the
mountain big sagebrush-mountain snowberry/Idaho fescue habitat type) [223]
Douglas-fir/mountain maple/California brome community type (ponderosa pine (Pinus
ponderosa) phase) in central Idaho [241]
quaking aspen (Populus tremuloides)/California brome community type in eastern Idaho and western Wyoming,
west of the crest of the Wind River Mountains [38]
mountain big sagebrush-mountain snowberry/California brome community type on Humboldt National Forest, Nevada [128]
California brome subassociation within the low sagebrush (Artemisia arbuscula) association, Utah juniper series in the Lahontan Basin of
western Nevada
California brome subassociation within the longflower snowberry (Symphoricarpos longiflorus)
association, singleleaf pinyon series in the southeastern Great Basin of Nevada and Utah
California brome subassociation within the western serviceberry (Amelanchier alnifolia)
association, singleleaf pinyon series in the central Great Basin of Nevada [278]
mountain big sagebrush/Idaho fescue-California brome association in the Great Basin
mountain big sagebrush/Great Basin wildrye (Elymus cinereus)-California brome
association in the northern Great Basin [179]
mountain big sagebrush-snowberry/California brome shrubland
mountain big sagebrush/California brome shrubland
mountain big sagebrush/Idaho fescue/California brome shrubland
quaking aspen/California brome forest [186]
ponderosa pine/big sagebrush (Artemisia tridentata)/California brome ecosystem in
central Oregon between 6,000-7,200 feet (1,800-2,200 m) elevation [68]
quaking aspen/big sagebrush/California brome ecosystem in central Oregon between
6,000-7,100 feet (1,800-2,160 m) elevation [68]
mountain big sagebrush-mountain snowberry/California brome community type on the Wallowa-Whitman National Forest, Oregon [131]
Oregon white oak (Quercus garryana)/California brome
community in southwest Oregon below 3,000 feet (1,000 m) elevation [211]
quaking aspen/California brome community type [185]
quaking aspen/mountain snowberry/California brome community type [185]
quaking aspen/western serviceberry/mountain snowberry/California brome community type [185]
Kentucky bluegrass-Sandberg bluegrass-inland bluegrass-Richardson's
needlegrass-slender wheatgrass-California brome-nodding brome (Poa pratensis-P.
secunda-P. nemoralis ssp. interior-Achnatherum
richardsonii-Elymus trachycaulus-Bromus carinatus- B. anomalus)
grassland ecosystem in the Prince Rupert Forest Region [201]
Mountain brome
―
Mountain brome is also documented in several
plant communities besides those listed for above. It occurs in mixed-conifer
forest with giant sequoia (Sequoiadendron
giganteum) in the Sierra Nevada of California [2,32,141]. In western Texas
it grows in Colorado pinyon-gray
oak (Pinus edulis-Quercus grisea) woodland [115].
Mountain brome is a dominant grass in a big sagebrush-silver
sagebrush (Artemisia cana) community on the
Gallatin National Forest in Montana [188], in a tall larkspur (Delphinium
exaltatum)-slender wheatgrass-mountain
brome community on the Manti LaSal National Forest in Utah [205],
and in a mesophytic upland meadow community in the Black Hills
of South Dakota [109].
Mountain brome is listed as a dominant
species in the following vegetation classifications:
Utah snowberry (Symphoricarpos oreophilus var. utahensis)-big
sagebrush/mountain brome mountain brush community of the Transverse Ranges [290]
coastal prairie [110]
mountain big sagebrush/mountain brome-Idaho fescue community in the Sawtooth, White Cloud, Boulder, and
Pioneer Mountains between 7,000 and 9,000 feet (2,100-2,700 m) elevation [222]
subalpine fir-Engelmann spruce (Picea engelmannii) forest subtype of Montana grasslands
(dominant trees are subalpine fir (Abies lasiocarpa), Engelmann spruce and/or whitebark pine (Pinus
albicaulis) [191]
snowfield big sagebrush/mountain brome-Idaho fescue habitat type in the Ruby-East Humboldt Mountains [157]
quaking aspen/mountain snowberry association [208]
Response to grazing:
Bromus carinatus' response to grazing appears to be related to grazing
severity. California brome
decreases under heavy, continuous grazing pressure [230,242,255]. It was scarce
on heavily grazed rangeland on the Wasatch Plateau,
Utah, except in places that were protected from grazing (e.g., steep slopes,
shrub thickets) [77]. The density of 7 palatable native grass
species, including California brome, was
5 times greater in Red Butte Canyon, Utah, a relatively undisturbed area,
than in Emigration Canyon, a heavily grazed area, suggesting the tendency for
overgrazing to deplete populations of palatable native grasses [62].
Reducing grazing pressure during the reproductive stages
may help to maintain California brome populations [255].
On the other hand, California brome is tolerant of, and may even
increase under, light to moderate grazing pressure [78]. On the Umatilla National Forest in
northeastern Oregon, California brome developed more cover in an experimentally
grazed area than in a protected area [212]. In southwestern
Utah, California brome was more abundant in a domestic sheep-grazed pasture (10.1% cover)
than in the control area (<1% cover) [37]. In
Garry oak meadows in southwestern British Columbia, California brome cover did
not change significantly after mowing
[160]. Grazing and clipping treatments have stimulated new growth and caused
repetition of certain growth stages (e.g., production of flower
stalks) [170,262].
In central Oregon, California brome increased with grazing in mixed conifer/pinegrass and
ponderosa pine-lodgepole pine/shrub/Idaho fescue communities [268].
California brome responds favorably to decreased grazing
pressure. In central Utah, California brome comprised 4% cover in a domestic
sheep corral that had been free from grazing for ~20 years, but was absent from
an area outside the corral that had been grazed continuously since the late
1800s [143]. In the Wallowa Mountains in northeast
Oregon, California brome has increased since livestock grazing ceased at the
turn of the 21st century [130]. When grazing was reduced on depleted quaking aspen range
in Ephraim Canyon, central Utah, California brome and other plants were observed
increasing 1st under the aspen canopy and then spreading into openings
within the quaking aspen stands. This may be because severe grazing makes
regeneration in openings difficult for moisture-loving species due to loss of
litter, drying effects of sun and wind, accelerated erosion of
topsoil, and loss of shade from tall herbs [78].
Response of California brome to grazing may depend on the season. On the Wasatch Plateau
in central Utah, McCarty and Price found the
effects of clipping on carbohydrate storage in California brome varied depending
on when clipping occurred. Plants clipped early in
the growing season and plants clipped late in the growing season had the highest
content of stored carbohydrates (~90% of those stored in unclipped plants). In
plants clipped at intermediate stages, carbohydrate content was lower (~67% of
those stored in unclipped plants), flower stalks were shorter, seed did not
mature, and many of the plants died at the end of the growing season. When
plants are clipped early in the season, the regular growth cycle can then be
completed and the quantity of carbohydrates stored is nearly normal. If plants
are clipped late in the season when herbage growth is complete, carbohydrates
stores are not greatly depleted, and regrowth does not occur.
The authors therefore suggest that early
grazing, when plants are 4 to 6 inches (10-20 cm) high, and grazing near the end of the growing
season would permit greater carbohydrate storage and ensure maximum viability in the plants. They also recognize,
however, that restriction of grazing periods may not be practical considering
the impacts of early grazing on wet soil, the lack of sufficient forage early in
the season, and reduced palatability of late-season forage. High mountain ranges with California brome,
therefore, should be used moderately, incorporating grazing rotations and
providing for less severe grazing during the reproductive period and the
beginning of the fall storage period [170].
Mountain brome also appears to decrease under heavy grazing pressure [148,184].
In a greenhouse experiment testing the response of 6 grass
species to clipping, root and top production decreased significantly for all
species, including mountain brome, under a 30-day clipping schedule. None
of the species withstood a 15-day clipping schedule [48].
There is some evidence, on the other hand, that mountain brome
increases under light to moderate grazing [260]. In an exclosure
experiment on dry mountain meadows near Elk City, Idaho, mountain brome was more abundant outside the exclosure than
inside, suggesting that it was favored by light cattle grazing [156].
On the Wallowa National Forest in northeast Oregon, mountain brome increased
after grazing in early September in 2 out of 3 quadrats [219].
In study conducted on the Gallatin Game Preserve in Montana, mountain brome
showed increases in herbage production, flower stalk numbers, and flower stalk height
after 2 years of clipping. The author attributed the increase to
reduced competition from forbs. Herbage and flower stalk production began
to decrease after 3 years of clipping, although production remained higher on
clipped plots than on control plots for all 3 study years. Mountain brome was
harmed most by clipping just before seed ripening in late August and during the
bloom stage in late
July. The author stated that grasslands at higher
elevations in the northern Rocky Mountains are sensitive to grazing because
plant growth is limited to short periods during the summer, which is when these
areas are accessible to grazing animals [182].
Rangeland seeding:
Bromus carinatus is suitable for seeding in a variety of habitat types on
rangelands throughout the western United States [3,107,158,178,180,200,204,240,266]. For information
on rangeland seeding methods, seed mixtures, cultivars, and harvest methods
pertaining to California brome, see [6,34,39,108,123,151,169,198,247,262,265]. For similar information
pertaining to mountain brome, see [59,101,101,120,158,231,239,261,266,271].
In general, Bromus carinatus grows actively during mild winters, develops rapidly and flowers in spring and summer, becomes relatively dormant in the summer, sets seed in summer or fall, and resumes growth in the fall [49,57,108,120,133,148,231,255]. This general phenology pattern varies by region. In Colorado, for example, California brome grows principally in the summer months [112]. In California, seeds ripen in May and June at low elevations and by late August at high elevations [220]. In central Utah, annual herbage growth begins under the snow 45 to 89 days before the snow melts. Root growth alternates with herbage growth in 3 main periods: 1) immediately before snow melt, 2) at the end of seasonal shoot growth, and 3) at the end of the snow-free period in the fall. [170]. Seasonal fluctuations in precipitation and temperature cause fluctuations in the growth rate [170]. In mountain brome, the seeds at the tips of the inflorescences mature earlier than those at the base [167].
It often takes 2 years for California brome to establish, mature, and flower [133], although it can flower the 1st growing season [114,178,277]. Flowering times reported for California brome and mountain brome vary by region:
California brome: Date Location May-early August Intermountain region [178] June-early July Wasatch Mountains, Utah [4] June-early August Vancouver Island, BC [159] August-October Arizona [137]
Costello and Price [61] provide more detailed phenological data for California brome on the Wasatch Plateau in central Utah. The following dates are 9-year averages:
Elevation (ft) Plant 6 inches tall Flower stalks evident Flower heads showing Flowers in bloom Seeds ripe Seeds disseminated 8,850 11 June 7 June 27 June 14 July 12 August 8 September 9,000 16 June 19 June 7 July 25 July 26 August 17 September 10,100 30 June 22 June 10 July 27 July 5 September 28 SeptemberThe actual dates of each growth stage were variable across the 9-year study period [61]:
Growth Stage Date Range Flower stalks or buds evident 23 April-15 June Flower heads showing 9 June-6 July Flowers in bloom 24 June-21 July Seeds ripe 8 August-20 September Seeds disseminated 9 September-11 OctoberThe postfire response rating for California brome is medium (the plant will regain its prefire frequency or cover in 5-10 years) [202]. The effect of wildfire on California brome depends on the amount of viable seed available and the severity of the fire [246]. California brome is a pioneer species in numerous community types following fire. It was 1 of 42 species that appeared in most pioneer communities following severe fire across an elevational gradient from grasslands to subalpine fir forests in Yellowstone National Park in 1988, suggesting that it is a successful postfire pioneer in the northern Rocky Mountains [5]. It was a dominant plant following burning and salvage logging in a ponderosa pine/antelope bitterbrush (Purshia tridentata)/needlegrass (Achnatherum sp.) community on the Winema National Forest, Oregon [46]. It was present in the 1st year following a severe fire in ponderosa pine-Douglas-fir forest on the Entiat Experimental Forest in north-central Washington [258], and in the first 2 years following a 1959 fire in a Colorado pinyon-Utah juniper woodland in Mesa Verde National Park, Colorado [79]. It was also present in a pioneer mixed-conifer forest community on southern Vancouver Island that had been logged and burned in 1938 [64].
California brome increased after fire in some cases. It was absent, for example, from unburned plots and present in moderately and severely burned plots following the Waterfalls Canyon Fire in Grand Teton National Park, Wyoming [74]. In a mixed-conifer forest in northern Idaho, 2 prescribed underburns were conducted following shelterwood cutting. A moist burn was conducted in June 1989, and a dry (hotter) burn was conducted in September 1989. California brome cover increased following the moist burn and on control plots, and did not change following the dry burn. Percent cover 1 year before logging and 1 year after burning was as follows [233]:
Treatment Prefire Postfire Control (no burn) 0.7 1.4 Moist burn 0.4 1.6 Dry burn 0.3 0.3California brome cover did not change significantly (p<0.05) following several disturbance treatments (burning, mowing and selective removals of exotic species) in Garry oak meadows of southwestern British Columbia, suggesting that it was either slow to respond or tolerant of the disturbances [160]. In another study, California brome cover was the same in untreated and burned plots 2 and 4 years after burning in pure quaking aspen and mixed quaking aspen-conifer forests on the Caribou National Forest, Idaho, and the Bridger-Teton National Forest, Wyoming. In the pure quaking aspen forests, cover was 6% to 25% in both untreated and burned plots. In the mixed quaking aspen-conifer forests, California brome cover was 5% or less in both untreated and burned plots [41].
In at least 1 study, California brome decreased after burning. A spring burn was conducted on elk winter-spring range on the Clearwater National Forest, Idaho. California brome was reduced by fire and had not returned to prefire density by the 4th growing season. The frequency (%) of California brome in control and burned areas was low on all sites, however [155].
Treatment Prefire Postfire year 1 Postfire year 2 Postfire year 4 Control 0 1 1 1 Prescribed burning 3 1 1 0Mountain brome has been shown to both increase and decrease after fire. Mountain brome may be more abundant in early successional postfire communities and decline over time. Although it was not dominant in the prefire community, it assumed dominance, along with Kentucky bluegrass and dandelion (Taraxacum officinale), 1 year following a fall prescribed burn in a mountain big sagebrush/Kentucky bluegrass community on the Helena National Forest, Montana. By 2 years postfire, mountain brome was no longer dominant [226]. Mountain brome is also present in the understory of seral quaking aspen stands in Arizona that are maintained by severe fires [126].
Mountain brome increased slightly in plots cleared and burned to create an open, park-like condition in 2nd growth giant sequoia forest in Tulare County, California. The number of plants per acre before treatment and in the first 3 years after treatment were as follows [153]:
Pretreatment Posttreatment year 1 Posttreatment year 2 Posttreatment year 3 920 930 980 940Mountain brome frequency decreased on cut-and-burn plots in a giant sequoia forest in Kings Canyon National Park, California [141]. Mountain brome cover also decreased significantly (P=0.05) in the 12 weeks following a low-severity prescribed fire in a mountain big sagebrush community on the Gallatin National Forest, Montana. It was a dominant grass before burning. Average basal cover in the 1st postfire growing season was 55% on burned plots and 72% on unburned plots [188].
In a mixed-conifer forest in central El Dorado County, California, mountain brome became more abundant after forest stands were opened by thinning, fire, insect attack, or wind [44]. Mountain brome is often associated with Lemmon's needlegrass (Achnatherum lemmonii), California needlegrass (A. occidentale ssp. californicum), blue wildrye, and other native perennials that assume dominance following an initial 2 to 3 year influx of annual grasses and other early successional herbaceous species. This herbaceous stage is succeeded by a shrub stage during which deerbrush (Ceanothus integerrimus), whitethorn ceanothus (C. cordulatus), manzanitas (Arctostaphylos spp.), and Sierra mountain-misery (Chamaebatia foliolosa) are dominant [44]. In Teton County, Wyoming, mountain brome made up 5% of the total vegetation in mature lodgepole pine stands and 10% in stands opened by fire and on sunny sites within nearly mature stands [28].
Bromus carinatus is nonrhizomatous [246]. It regenerates by self seeding and vegetative spread [49,89,178,202,231,255]. Bunchgrasses like Bromus carinatus typically spread laterally by tillers from buds near the root crown. Continuation of this process for many years results in a large clump [18]. New plants grow readily from seed as the old plants die [180].
Pollination: Bromus carinatus is generally self pollinating [101,162].
Breeding system: In California brome, both chasmogamous and cleistogamous florets are commonly found on the same plant [114]. Open pollination facilitated by wind is most common when growing conditions are optimum [104], whereas self-pollination is often a response to stressful conditions such as overgrazing, repeated mowing [54], and fire [166]. In California brome, both types of florets may appear on the same panicle if there is an abrupt change in environmental conditions at an early stage in panicle development [104].
Seed production: Bromus carinatus produces abundant seed [101,108,170,220] unless it is severely overgrazed [180]. California brome plants may not produce seed for the first 2 to 3 years [65].
Seed dispersal: Bromus carinatus seeds are dispersed by wind [246] and, because they are awned, also presumably by animals when awns attach to hair or feathers. Mountain brome seeds are prone to shattering when ripe or during harvesting [167].
Seed banking: There is conflicting information about seed banking in California brome. Numerous authors state that California brome seed is not stored in the soil. In a greenhouse study, for example, only 1 California brome seedling emerged from the litter out of 28 soil samples taken from mixed-conifer forest in the Blue Mountains, Oregon, suggesting that California brome stores little or no seed in the soil [252]. California brome was found only in the aboveground vegetation in subalpine fir/pinegrass and Idaho fescue-bearded wheatgrass (Elymus caninus) habitats in the Gallatin Valley, Montana [51]. In a Garry oak (Quercus garryana) ecosystem in southeastern British Columbia, California brome did not form a seed bank but germinated readily when fall rains began [166]. In a field experiment in native upland prairie in the Coast Range foothills 5 miles (8 km) northwest of Corvallis, Oregon, California brome did not form a "persistent" seed bank [52].
There is, however, evidence of seed banking in California brome in several other studies. California brome was present in soil samples taken from unburned Douglas-fir/pinegrass, quaking aspen/pinegrass, and subalpine fir/thinleaf huckleberry (Vaccinium membranaceum) habitat types in Yellowstone National Park [51]. In a greenhouse experiment, it germinated from soil collected at 1 out of 4 Sonoran Desert locations [270]. In a native bunchgrass prairie restoration project in San Francisco, California brome was among several native plants that regenerated naturally on the restored sites. While known from other prairie locations, California brome had not been known to flower on the test site for at least 15 years, suggesting there is a bank of seeds ready to emerge if interference is reduced [196].
No information is available on seed banking in mountain brome. Further research is needed on seed banking in Bromus carinatus.
Germination: Bromus carinatus seed germinates quickly [52,166,231,239]. California brome germinates well on both bare soil and from beneath the soil surface [26,246]. Germination rates are high, often exceeding 85% [178,248]. Optimum germination for California brome in a greenhouse occurred at alternating temperatures of 86 °F (30 °C) for 6 hours and 68 °F (20 °C) for 18 hours [198]. The germination rate dropped considerably at greenhouse temperatures, which fluctuated between 50 °F and 104 °F (10 °C and 40 °C), approximating outside conditions in early spring. These results suggest that California brome germinates more slowly in the early spring months under natural conditions, and may therefore be at a disadvantage relative to other early-growing species. Percent germination for California brome is shown below [198].
Treatment % Germination Days required for germination Alternating temperature (86 °F for 6 hrs; 68 °F for 18 hrs) 85 10 Constant temperature (86 °F) 85 13 Room temperature (70 °F) 83 13 Greenhouse temperature (mean 57 °F) 46 21In another greenhouse experiment, the optimum temperature regime for California brome germination was a daily minimum of 59 °F (15 °C) for 16 hours of darkness and a daily maximum of 77 °F (25 °C) for 8 hours of light [189]:
Observation days
Percentage of seeds germinated under optimum temperature regime (59-77 °F) 7 10 14 94 21 97 28 97 35 97Mountain brome seeds require ~14 days from the date of seeding for germination [231,272]. In the San Gabriel Mountains of California, temperatures representative of the 4 seasons were simulated in a greenhouse. Mountain brome germinated best at day/night temperatures of 62/39 °F (17/4 °C) [14]. In another study, the optimum temperature range for germination in the presence of light was 68 °F to 86 °F (20-30 °C) [231].
Germination rates have been reported in the literature as follows:
Germination rateLocation
85% Montana [231] 48% Oregon [219] 89% southwestern U.S. [151]In greenhouse tests, mountain brome seeds collected in the milk stage germinated at the same rate as mature seeds throughout a 58-month storage period [167]. Premilk stage seeds had the lowest viability over time of all stages of seed development (milk, dough, and mature), decreasing from 91% viability at 4 months to 50% viability at 58 months [167]. The seeds have been stored for 3 to 15 years in warehouse storage without significant loss of viability [101,133,167,231].
Seedling establishment/growth: Bromus carinatus seedlings establish easily and grow quickly [59,101,120,177,231,239,265,272]. California brome seedlings establish well in seeded subalpine meadows, upper-elevation quaking aspen openings, quaking aspen and coniferous forests, and silver sagebrush and big sagebrush sites in the Intermountain West [250]. Lantz (Lantz 1997, cited in [52]) found that seedling mortality decreased in plots with vegetation removal, suggesting that interference may be an important factor in the survival or mortality of California brome seedlings.
Plants with heavy seeds like California brome can send up shoots from greater depths compared to plants with lighter seeds. In a greenhouse study, California brome responded as well when planted 1.5 inches (3.8 cm) deep as at 0.25 inch (0.6 cm) deep, while emergence of shoots of other, lighter-seeded species was greatly reduced [198].
Shoot growth over a 28-day period under greenhouse conditions was as follows [198]:
Days after planting
Total shoot length (cm) 14 3 17 4 21 5 28 7California brome produces roots at a rapid rate immediately after germination and can successfully establish initial stands on dry sites, although they may later succumb to drought [198]. In a greenhouse study, California brome roots developed much faster over a 28-day period than several other grasses studied [198]:
Days after planting
Total root length (cm) Number of roots 14 11 2 17 36 26 21 88 40 28 164 61Mountain brome seedlings develop a large root mass rapidly [236], and plants reach full development the year after planting [239]. Frischknecht (Frischknecht 1951, cited in [145]) found mountain brome and slender wheatgrass were the most winter hardy in the seedling stage of all grasses tested.
Asexual regeneration: California brome and mountain brome regenerate vegetatively by tillers from buds near the root crown [18,49,231].
BLM PHYSIOGRAPHIC REGIONS (Bromus carinatus) [29]:
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
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
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
Bromus carinatus occurs in the following vegetation types.
Although Bromus carinatus is widespread, it is uncommon in some
vegetation types and is not documented in every ecosystem or plant community in
which it may occur. Although the list of vegetation types below is very
broad, Bromus carinatus may occur in some types that are not listed below.
Bromus carinatus is a short-lived, pioneer species [164] but occurs in late seral stages as well. California brome is described as both shade-intolerant [242,292] and moderately shade tolerant [178]. It is common in both early and late seral communities [178]. It is an early seral species in Douglas-fir habitat types in east- and west-central Idaho [246]. It is a pioneer, early seral, and late-seral species in subalpine meadows, wet/semiwet meadows, silver sagebrush, big sagebrush, subalpine big sagebrush, quaking aspen, and coniferous forests in the Intermountain West [250]. It comprised 12% cover in an early successional community in the Wenaha-Tucannon Wilderness of northeastern Oregon following severe insect defoliation that resulted in 75% overstory removal with little ground disturbance [292]. California brome was 1 of 7 grasses that were seeded onto a burned area near Kilgore, Idaho, and established concurrently with big sagebrush seedlings. California brome cover increased for the first 4 years after seeding, but then yields decreased to 0 after 8 years due to interference from big sagebrush. The author concludes that due to their earlier maturity, California brome and the other seeded grasses suppress big sagebrush seedlings initially, but later decline when big sagebrush gains dominance [34].
Mountain brome is moderately shade tolerant [126], and thrives on sites which are partially shaded [231] including moderately dense quaking aspen stands [272] and open mixed-conifer forest [287]. It also grows in open, unshaded sites [111] but was absent from heavily shaded sites in the Wallowa Mountains of northeastern Oregon [287]. Mountain brome occurs in big sagebrush and lodgepole pine communities in Teton County, Wyoming. Both communities are successional communities in the Engelmann spruce-subalpine fir habitat type [28]. In the lodgepole pine communities, it made up 5% of the total vegetation composition in mature stands, and 10% in stands opened by fire and sunny sites in nearly mature stands [28].
The scientific name of this grass is Bromus carinatus Hook. & Arn. (Poaceae)
[93,114,118,135,137]. There are 2 varieties [20,21]:
Bromus carinatus var. carinatus, California brome
Bromus carinatus var. marginatus (Nees) C.L. Hitchc. ex Scoggar, mountain brome
Seaside brome (B. maritimus) and Great Basin brome (B. polyanthus)
were formerly considered synonyms of Bromus carinatus
but are now considered separate species [20].
In this review, "Bromus carinatus" refers to the species as a whole.
"California brome" refers to Bromus carinatus var. carinatus and
"mountain brome" refers to Bromus carinatus var. marginatus.
California brome is an excellent native bunchgrass for seeding alone or in mixtures in disturbed areas in the western United States including depleted rangelands, burned areas, roadways, mined lands, and degraded riparian zones [63,132,197,199,249,250]. As an early successional, rapid-growing grass with a deep, well-branched root system, it establishes quickly and provides erosion control [108,132,161,178,204,249] before eventually yielding to longer-lived species [132]. It is cold-tolerant and therefore suitable for seeding at higher elevations [108,249]. It establishes well from transplants [199]. California brome may also naturally revegetate disturbed sites in the early stages of succession [22], although seeds are often scarce in the seed bank [52].
California brome was one of 9 grasses that established readily after seeding in a burned area in the mountain brush zone of central Utah. It produced relatively high yields for ~4 years, but was later suppressed by smooth brome, a nonnative that was also seeded in. The authors conclude that these short-lived, self-reseeding bunchgrasses are useful in mixtures with slower-developing grasses like smooth brome to ensure rapid establishment of grass cover following seeding [89]. However, native grass mixtures are generally recommended over mixes with nonnative species such as smooth brome [42]. California brome was among the most flexible and successful seeded grasses used in a native vegetation restoration project at Berkeley North Waterfront Park, California. Regular watering and mowing allowed planted native grasses to establish despite presence of nonnative herbs [134]. Restoration of California brome and other native grasses and elimination of nonnative grasses appears to be important to overall valley oak (Quercus lobata) regeneration in the California valley oak ecosystem [66].
California brome seeds have been successfully germinated and established on production fields at the Upper Colorado Environmental Plant Center and shipped to Grand Teton National Park for use in restoration projects [225]. In test plots seeded with a native seed mixture in Grand Teton National Park, California brome responded most favorably to a combination of topsoil application to 6 inches (15 cm), phosphorus application, ripping, and mulching prior to seeding [63].
California brome did not perform well in restoration after the 1993 Old Topanga Fire in Los Angeles County. It was the only native component in the seed mix used, but it never exceeded a few plants/1,000 m² on the reseeded area. None of the postfire studies conducted in the Santa Monica Mountains prior to this fire reported finding California brome, suggesting this was a poor choice for inclusion in the seed mixture [139,140]. In a field experiment in native upland prairie in the Oregon Coast Ranges, 51.6% and 67.5% of California brome seeds planted in each of 2 years died of undetermined causes. Factors not directly tested could include nonfungal diseases, growth interference, and lack of dormancy mechanisms, which makes California brome seeds more vulnerable to adverse abiotic conditions [52].
Mountain brome is 1 of the most valuable grasses where native vegetative cover is needed immediately for revegetation and erosion control on road cuts, fill slopes, burned and logged areas, and other disturbed sites [42,59,101,120,204,231,234,238]. It performs particularly well on moist sites [102,277]. It grows rapidly, has vigorous seedlings, and has a well-branched and deeply-penetrating root system [120,231]. By producing a great number of roots directly below the soil surface, it binds the soil where erosion is most active [237]. Total root volume can double when it is used in a seed mixture with alfalfa (Medicago sativa) or sweetclover, offering greater soil protection than legumes alone [101,120]. The 'Bromar' cultivar is adapted to streambanks, semiwet meadows, subalpine conifer forests, quaking aspen, and upper mountain brush communities in the Intermountain West. It is used to stabilize logging, mining, roadway, and other disturbances [178,266].
The use of successional native plant species is essential to achieve ecological restoration of severely disturbed lands [42]. Because it is quick-growing but short-lived, mountain brome can help to suppress weedy plants in the short term, and then allow longer-lived species to take hold as it dies out [59,231,276]. It produced a good stand, for example, within the 1st year after seeding on a burned 2nd-growth ponderosa pine site in northern Idaho. Within 15 years the longer-lived native vegetation had returned, and mountain brome and other seeded species were difficult to find [234].
Mountain brome is also used to restore forage production on degraded forest and rangeland [59,231,235,273] and to revegetate mined sites in the western United States [207,210]. On an abandoned mine site near Steamboat Springs, Colorado, it produced "fair" and "good" stands in 3 years and was among 9 species that consistently had the best stand ratings [171]. It was 1 of 3 plants classified as "highly resistant" to allelopathic chemicals secreted by spotted knapweed (Centaurea maculosa) roots under laboratory conditions, suggesting that it may be useful for revegetation of grasslands infested with spotted knapweed [194]. In a study of the effects of frost heaving on reseeded grasses in a burned chamise brushland in Lake County, California, 67% of mountain brome seedlings were frost heaved on the north-facing slope, while only 9% of seedlings on the south-facing slope were heaved. The authors suggest that mulching can minimize frost heaving in recently reseeded areas [33].
Mountain brome colonizes naturally on disturbed sites in Yellowstone and Glacier National Parks, and is included in seed mixtures used for restoration of sites disturbed by road construction, visitor impact, and facility maintenance. It has been included in seed mixtures for Idaho fescue grassland and western redcedar-western hemlock forest in Glacier National Park, and for lodgepole pine forest in Yellowstone National Park [163]. The seeds of mountain brome and other short-lived, pioneer species are relatively easy to collect. The average collection rate in Yellowstone National Park was 269 g/person-hour [164]. Seeds are commercially available [263].
Bromus carinatus is a species of brome grass known by the common names California brome and mountain brome.
It is native to western North America from Alaska to northern Mexico, where it can be found in many types of habitat. It is known in parts of the American midwest and eastern North America as an introduced species.
Bromus carinatus is a perennial bunchgrass growing in clumps 0.5 to 1.5 meters tall, with many narrow leaves up to 40 centimeters long. The inflorescence is a spreading or drooping array of flat spikelets longer than they are wide.
The grass is wind-pollinated but is also sometimes cleistogamous, so that the flowers pollinate themselves, especially under stressful conditions. It also reproduces vegetatively via tillers.
This species is highly variable. It can be easily confused with B. catharticus and B. stamineus.
This grass is used for control of erosion and revegetation of damaged land, as well as a highly palatable forage for livestock; however, it has the capacity to become a noxious weed in agricultural settings.[2]
Bromus carinatus is a species of brome grass known by the common names California brome and mountain brome.
