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Wildlife, Animals, and Plants
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VALUE AND USE
SPECIES: Elymus elymoides
| Bottlebrush Squirreltail
Bottlebrush squirreltail is a dietary component of several wildlife species.
It is a minor component of bison and cattle
summer diets within sagebrush rangelands of southern Utah [195].
Although of little importance, bottlebrush squirreltail may provide forage for mule deer [122,124].
Pronghorn of western Utah feed upon bottlebrush squirreltail [16]. Townsend's ground squirrels [211],
Nuttall's cottontails [111,127], and black-tailed
jackrabbits [5,72,112,127] all feed upon bottlebrush squirreltail.
In southeastern Oregon salt desert-shrub ranges, bottlebrush squirreltail is an
important component of domestic livestock seasonal diets. Winter months show greatest use
[83,140].
Bottlebrush squirreltail is a very palatable winter forage for domestic sheep of
Intermountain ranges. Domestic sheep relish the green foliage [104]. Overall, bottlebrush
squirreltail is considered moderately palatable to livestock.
When present, the long sharp awns of bottlebrush squirreltail greatly reduce
its palatability [150]. Mature awns may penetrate flesh around the mouth of grazing
animals, producing inflammation [51,115]. Eye and ear injury may also occur [51].
Clary [44] compared chemical constituents (%) of bottlebrush squirreltail within
open and timbered ponderosa pine
overstories in Arizona.
Greater digestibility and significantly (p<0.05) higher crude protein
were found in open versus timbered overstories:
|
Open |
Timbered |
| Crude protein (%) |
16.0 |
9.7 |
| Phosphorus (%) |
0.25 |
0.26 |
| Ash (%) |
12.3 |
13.7 |
| Digestibility (%) |
66.7 |
61.0 |
Bottlebrush
squirreltail nutrient levels fluctuate throughout the growing season. Levels
of S, P, and K usually drop
from March to October. Amounts of Mg and Ca stay relatively the same with
high points in spring, late summer, and early fall [152]. Overall,
bottlebrush squirreltail is a poor source of phosphorus, carotene, and digestible
protein, but a good source of energy [48]. The
average chemical composition (%) of bottlebrush squirreltail in Great Basin desert ranges
is summarized below [47]:
|
Composition (%) |
| Ether Extract |
2.6 |
| Total protein |
4.5 |
| Ash |
17.1 |
| Lignin |
8.7 |
| Cellulose |
37.5 |
| Other Carbohydrates |
29.6 |
| Phosphorus |
0.07 |
| Gross energy |
1730 (kcal/lb) |
| Carotene |
0.5 (mg/lb) |
The degree of environmental protection provided by bottlebrush squirreltail for wildlife species is as follows
[58]:
| |
Utah |
Wyoming |
| Pronghorn |
Poor |
Poor |
| Elk |
Poor |
Poor |
| Mule deer |
Poor |
Poor |
| White-tailed deer |
---- |
Poor |
| Small mammals |
Good |
Good |
| Small nongame birds |
Fair |
Good |
| Upland game birds |
Fair |
Fair |
| Waterfowl |
Poor |
Fair |
Bottlebrush squirreltail is tolerant of disturbance [133]. The Bureau of Land Management,
U.S. Department of the Interior, identifies bottlebrush
squirreltail as a high priority species for restoring native plant diversity in the Great
Basin and the Columbia River
Plateau [90]. Bottlebrush squirreltail naturally colonizes disturbed sites
in Yellowstone National Park and is a component of seed mixtures used
for restoration of
lodgepole pine communities [129]. Brown and Amacher [34] recommend
bottlebrush squirreltail for use in restoration of disturbed arid to semi-arid,
desert shrub and pinyon-juniper
systems. Bottlebrush squirreltail is well adapted for seeding of Wyoming, black and low sagebrush communities
of the Intermountain West, receiving 9 to 13 inches (229-330 mm) annual precipitation. Bottlebrush squirreltail
grows well under rabbitbrush canopies in south-central Idaho rangelands [149].
Bottlebrush squirreltail
inhabits xeric sandy soils (73.9% sand, 16.8% silt, 9.2% clay,
1.3% organic matter) of a 50-year-old abandoned tailings pond from a Pb-Zn-processing mill [41], and is
recommended for seed mixtures used to reclaim strip mines in southeastern Montana [64].
The
large ecological amplitude of bottlebrush squirreltail lends to ecotypic
differentiation. Phenological differences in growth rate, root:shoot ratios, leaf area, and overall plant size
exist between subspecies of bottlebrush squirreltail. Differences are directly related to
subspecies distribution
[100]. Bottlebrush squirreltail seed source
should be considered when implementing revegetation projects. Arredondo and others [9] observed
a higher root length-to-leaf area ratio in plants grown from seed
collected from different environments. Differences in phenology between
individuals of different habitats are common (see: SEASONAL DEVELOPMENT
within the Botanical and Ecological Characteristics section for further information).
Bottlebrush squirreltail seed is available commercially [103,104,134].
The United States Department of Agriculture (USDA), Utah Division of Wildlife Resources,
in conjunction with the Intermountain Research Station, Forest Service, USDA,
established bottlebrush squirreltail seed quality standards. Seed quality standards
as of 1990 are summarized below [181]:
| Seed unit1 |
Acceptable purity (%)2 |
Acceptable viability (%)2 |
| spikelet with or without awns |
90 |
85 |
1 Reproductive structure marketed as seed.
2 Purity (%) and germination (%) expected using seed quality testing rules in seeds of commercial quality.
Germinability of primed bottlebrush squirreltail seed significantly (p<0.05)
decreases when dried and stored [89].
Competition with invasive weeds:
The
persistence of bottlebrush squirreltail in areas invaded by exotic weeds is well recognized. Bottlebrush
squirreltail persists in areas infested with cheatgrass [9,18,99,100,103,188],
medusahead (Taeniatherum caput-medusae) [9,96,169,213,216], and Japanese brome (Bromus japonicus) [166].
Bottlebrush squirreltail naturally invades rangelands
dominated by cheatgrass and medusahead [9]. However, mechanisms behind
bottlebrush squirreltail's ability to occupy weed-infested areas are
not completely understood. Several studies have evaluated the persistence
of bottlebrush squirreltail within cheatgrass infested ranges. Beckstead [18] found recently harvested bottlebrush
squirreltail seeds from mountain brush and meadow sites to possess lower levels of
dormancy than cheatgrass at higher temperatures, 68/86 degrees Fahrenheit (20/30 C), whereas the opposite was
true of lower temperatures, 41/59 degrees Fahrenheit (5/15 C).
Bottlebrush squirreltail at lower elevations (4,100 feet (1,250 m)) have a greater
probability of autumn germination than cheatgrass [2].
Established bottlebrush squirreltail plants generally
initiate growth before the rosettes of cheatgrass in desert rangelands of Nevada
[188].
Beckstead [18] suggests fall seeding of bottlebrush squirreltail into cheatgrass
infested rangelands.
Early spring growth and ability to grow at low temperatures contribute to the
persistence of bottlebrush squirreltail among cheatgrass dominated ranges [100]. Bottlebrush
squirreltail seedlings have the ability to grow roots at low soil
temperatures, allowing for soil penetration similar to medusahead and cheatgrass in the
northern regions of
the Great Basin. Root development at low temperatures promotes bottlebrush squirreltail
seedling establishment
and effective competition with medusahead [96].
Bottlebrush
squirreltail has potential to outcompete medusahead. Management goals often concentrate
on protecting bottlebrush squirreltail seedlings from livestock and
rabbits, along with maintaining a natural supply
of seed [169]. Hironaka and Sindelar [98] evaluated bottlebrush squirreltail growth under
greenhouse conditions,
when closely associated with medusahead. Bottlebrush squirreltail plants (10 plants)
were observed in combination
with 0, 4, 12, 36, 108, and 324 medusahead/foot2.
Bottlebrush squirreltail growth was not affected by medusahead until 5 weeks old, grown under densities of 108 and 324
medusahead/foot2. Although stunted, no
bottlebrush squirreltail mortality was seen at all densities tested, whereas a large
amount of medusahead mortality
was observed in the 324 medusahead/foot2 level. Bottlebrush squirreltail
acquired greater
root carbohydrate reserves than medusahead under competitive conditions.
Under proper management, Hironaka [96] suggests a successional
sequence of cheatgrass to medusahead to bottlebrush squirreltail dominated sites for northern Great Basin areas receiving greater than 11 inches
(279 mm) precipitation.
Rome and Eddelman [166] compared bottlebrush squirreltail seedling growth in competition
with Japanese brome at densities of 0,
50, 100, 200, 400 Japanese brome/m2. Observations were
made in Missoula, Montana at 23, 42, 56, 82, and 97 days following an 8
April seeding of bottlebrush squirreltail and Japanese brome. Bottlebrush squirreltail averaged
85% survival in areas without Japanese brome, compared to an average of 66% survival from areas
with 100 to 400 Japanese brome/m2 (p<0.05).
Overall, bottlebrush squirreltail under competition with Japanese brome showed the
greatest competitive ability at 100 Japanese brome/m2.
Martlette and Anderson [131] observed poor bottlebrush squirreltail seed dispersal into
adjacent crested wheatgrass (Agropyron cristatum) stands. Plant cover acted as a barrier restricting the
dispersal capabilities of bottlebrush squirreltail.
Under greenhouse conditions, Schlatterer and Tisdale [172] found sagebrush leaf litter
to significantly (p<0.05)
decrease bottlebrush squirreltail germination compared to moss and rabbitbrush
(Chrysothamnus spp.) litter. The average number of bottlebrush squirreltail seeds (20 seeds/pot)
germinating under different litter treatments is summarized below:
| Big sagebrush |
Moss |
Rabbitbrush |
No litter |
| 11.25 |
18.75 |
18.25 |
18.25 |
Bottlebrush squirreltail will readily establish in pinyon-juniper tree litter
when a fermentation layer is not present [69].
Robertson [165] observed seeded bottlebrush squirreltail within a big sagebrush habitat
at 5,200 feet (1,585 m) in northern Nevada to be short lived, persisting for 5 years.
Bottlebrush squirreltail persisted for 30 years following direct seeding within a
big sagebrush/bluebunch wheatgrass
site in south-central Idaho [148].
No entry
The addition of nitrogen to disturbed sagebrush communities in Colorado [141] and mountain meadows of Nevada [62]
had no positive effect on
bottlebrush squirreltail establishment.
Bottlebrush squirreltail decreased after the addition of nutrients in the form of stabilized sewage
sludge [78].
Bottlebrush squirreltail reproductive potential is adversely affected by jointworm larvae.
Spears and Barr [179]
found culm length, seed weight, germination (%),
and germination rate all significantly lower (p<0.01) on bottlebrush squirreltail
infested with jointworms compared to noninfested plants. Results are summarized below
:
| Variable |
Infested |
Uninfested |
| Culm length (cm) |
30.0 |
33.7 |
| Leaf length (cm) |
22.0 |
23.1 |
| # of spikelets |
5 |
9 |
| Seed weight (mg 25 seeds) |
108.2 |
162.5 |
| Germination (%) |
20.0 |
66.0 |
| Growth rate (Seedlings day -1 100 seeds -1) |
2.8 |
7.8 |
Rangelands:
Bottlebrush squirreltail is a valuable winter range plant in the Great Basin [48], with
leaves remaining green and succulent through the winter.
Bottlebrush squirreltail's total available root carbohydrate reserves are lowest in early spring
(approximately 3rd leaf stage), and at the beginning of fall regrowth. Total available carbohydrates are highest after
anthesis [50].
By the 4th leaf stage, bottlebrush squirreltail has replaced the carbohydrate
reserves found in roots at the beginning of the growing season [20]. Wright [206]
found bottlebrush squirreltail most tolerant to herbage removal at
time of seed maturity, declining slightly after maturity before fall regrowth.
In eastern Oregon, bottlebrush squirreltail is resistant to late season defoliation [31]
Bottlebrush squirreltail generally increases in abundance when moderately grazed
or protected on the foothills of intermountain winter ranges [104].
Moderate trampling by livestock in big sagebrush rangelands of central Nevada enhanced
bottlebrush squirreltail seedling emergence compared to untrampled conditions. Heavy trampling
destroys germination sites and significantly
(p<0.05) reduces germination, whereas moderate trampling may
enhance germination [63].
Bottlebrush squirreltail is tolerant of grazing in big sagebrush rangelands of
southeastern Idaho [4].
In sagebrush rangelands of western Utah, Cook and Child [46] found winter harvesting
to have a minor effect on crown cover, whereas early spring (April 1, May 1) harvest greatly
reduced bottlebrush squirreltail cover.
Bottlebrush squirreltail vegetative vigor was evaluated over 25 years within a sagebrush rangeland
of southeastern Oregon excluded from grazing. Vigor of bottlebrush squirreltail increased
significantly over the 25 year period, with the 1st decade showing slower growth than the
2nd. The average annual precipitation over the 25 years equaled 8.3 inches (210 mm) with 40%
falling during April, May, and June. Winters were cold with snow cover from December to March.
Summers were hot, occasionally exceeding 100 degrees Fahrenheit (38 °C) [3].
Bottlebrush squirreltail is commonly found in heavily grazed and browsed
(cattle and deer) aspen stands of big sagebrush steppe in Wyoming [36].
McPherson and Wright [144] observed significantly (p<0.01) greater coverage of bottlebrush
squirreltail on ungrazed versus grazed Pinchot juniper rangelands in western Texas.
Within the ponderosa pine bunchgrass ranges of the central Rocky Mountains, bottlebrush squirreltail
production is greatest under light and moderate grazing regimes [52].
Bottlebrush squirreltail is tolerant of heavy grazing in the ponderosa pine zone of the Coconino Plateau, Arizona, since its long, sharp
awns are usually present to discourage grazing [8].
On shortgrass ranges of the central plains bottlebrush squirreltail is very tolerant of light
to moderate grazing [118].
Silviculture:
Climax western juniper stands are of mixed age, consisting of 1st year seedlings to trees
several hundred years old. Seral stands are composed of predominately younger aged trees.
In central
Oregon, Vaitkus and Eddleman [194] observed significantly greater (p<0.05) bottlebrush squirreltail
production when associated with large (older) trees compared to small trees. Production of bottlebrush
squirreltail was also significantly greater (p<0.05)
under juniper canopies compared to intercanopy zones. McPherson and others [143]
observed significantly greater (p<0.01) bottlebrush squirreltail
under Pinchot juniper canopies and at canopy edges compared to areas
beyond canopy, within grazed and relict grasslands
of western Texas. Evaluations by Tueller and Platou [190] lend
supporting evidence (see: SUCCESSION within the Botanical and Ecological Characteristics section).
Bottlebrush squirreltail does not reduce ponderosa pine seedling growth. Two-year-old pine
seedlings that were planted the 1st postfire spring, after a June wildfire in northern Arizona,
were not affected in height or diameter by competition with bottlebrush squirreltail [66].
In Arizona ponderosa pine forests, seedlings
normally gain dominance over bottlebrush squirreltail within 5 years [8].
Bottlebrush squirreltail drastically increased 4 years after a clear-cut within
a lodgepole pine forest of northeastern Utah at 8,800 feet (2,700 m). Bottlebrush
squirreltail
showed the largest increase in vegetative production out of all grasses present [10]:
|
1976 (kg/ha) |
1980 (kg/ha) |
| Ross' sedge |
56.8 |
42.0 |
| elk sedge |
2.1 |
4.4 |
| Poa spp. |
10.2 |
40.7 |
| bottlebrush squirreltail |
3.3 |
47.7 |
| 5 others |
0.0 |
13.9 |
Bottlebrush squirreltail was an early colonizer after the clear-cut of a
ponderosa pine forest in north-central California [138].
Bottlebrush squirreltail populations were greatest 11 to 25 years after clearcuts
of a red fir forest in the Sierra Nevada, California [73].
Everett and Sharow [70] found bottlebrush squirreltail seed production was less
under singleleaf pinyon (Pinus monophylla)-Utah juniper
woodland canopies than in clearcut areas (1 and 2 postharvest years).
Related categories for
SPECIES: Elymus elymoides
| Bottlebrush Squirreltail
|
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