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Wright [208] compared bottlebrush squirreltail response to burning and
clipping near Boise, Idaho. Heat was applied by propane burner for 20 to 30 seconds to raise soil
surface temperature to 400 or 800 degrees Fahrenheit. The 800 degree Fahrenheit treatment killed 25%
of bottlebrush squirreltail plants during July and August. No other treatment caused mortality.
Burning and clipping during all seasons reduced yields 1 year after treatment. Burning reduced
yield most during May. Average herbage weight (in grams) per bottlebrush squirreltail plants
in relation to season and treatment at 1 postfire year is summarized below:
Although frequency of bottlebrush squirreltail was too low for statistical analysis,
Champlin [42] reported no damage to bottlebrush squirreltail basal cover and height 2 postfire years after a
spring fire in a big sagebrush community of northern California. Bottlebrush squirreltail vigor increased the
1st and 2nd postfire growing season in central Oregon, following a spring fire within
a sagebrush-bitterbrush/bunchgrass plant community [1].
Summer:
Bottlebrush squirreltail increased following an August wildfire in a big sagebrush
community with an understory dominated by cheatgrass and Lyall's milkvetch (Astragalus
lyallii) [95]. Significantly (p<0.01) greater biomass was achieved 1 postfire
year after a 19 July prescribed fire in Oregon. At time of burn, bottlebrush
squirreltail had entered summer quiescence with no green shoot material evident. Mean
shoot biomass of burned plants was greater per unit crown area, compared to
control. Burned plants also averaged 49% higher root
biomass per unit crown area, producing a shoot:root biomass ratio of 1.73 compared to
control plots at 0.43 shoot:root biomass. Burning also increased the proportion of reproductive
culms; 74.8% of all shoots of burned plants produced reproductive culms compared to 14.3% for unburned plants
[220].
Bottlebrush squirreltail showed a negative postfire response to summer (July) wildfire
within a sagebrush rangeland in Utah, for the 2nd and 3rd postfire years compared to
control [202].
Bottlebrush squirreltail decreased in abundance 1 postfire year after a summer
(July) prescribed fire and after a lightning fire within a mountain mahogany-big sagebrush community [187].
Fall:
Bottlebrush squirreltail maintained previous levels of production (kg/ha) 1 postfire
year after an October fire in an aspen-bunchgrass community of northern Arizona.
Although total vegetative production remained constant, percent cover and density
of bottlebrush squirreltail were significantly higher. The October fire resulted in a
large bottlebrush squirreltail population consisting of small individuals whose
combined vegetative biomass equaled or exceeded preburn levels. Associated
dominants, Arizona fescue and mountain muhly, decreased [86].
For further information on bottlebrush squirreltail response to fire, see Fire Case Studies,
Lyon's Research Paper
(Lyon 1971),
and the following Research Project Summaries:
Humphrey and Schupp [103] compared bottlebrush squirreltail seedling emergence within burned and unburned cheatgrass dominated areas of the Great Basin, Utah. Greater seedling emergence (April) occurred on seeded burned areas compared to unseeded, within loamy fine sand (85% sand) sites. On a dune site with sandy soil (95% sand), seedling emergence occurred in March with no significant difference between burned and unburned sites. However, a significantly greater proportion of bottlebrush squirreltail seedlings survived on burned dune areas compared to unburned.
Seeding:
Aerially applied seed mixture of mutton grass, prairie Junegrass, Indian ricegrass, slender wheatgrass (Elymus trachycaulus) and bottlebrush squirreltail aided in the reestablishment of bottlebrush squirreltail after a summer (August) wildfire within Mesa Verde National Park, Colorado [74]. Bottlebrush squirreltail was an important component 1, 2, [76] and 3 postfire years [75] in seeded areas, whereas no bottlebrush squirreltail was observed in unseeded areas [74].
Postfire recovery of bottlebrush squirreltail occurred after a summer (June 1956) wildfire in Arizona chaparral, aerially seeded with weeping lovegrass (Eragrostis curvula) and crested wheatgrass. Results shown that percent frequency of bottlebrush squirreltail within 9.6 foot (2.9 m) square plots increased steadily for 4 years postfire [157]:
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 uninfested plants. Results are summarized below
:
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]:
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).
Bottlebrush squirreltail collection site description Days to flower 7,410 feet (2,260 m), silt loam, ponderosa pine 205.5 4,990 feet (1,520 m), stony clay loam, ponderosa pine 201.2 7,200 feet (2,200 m), loam, pinyon-juniper 193.8 7,810 feet (2,380 m), clay loam, ponderosa pine 192.5 9,780 feet (2,980 m), gravelly loam, spruce-fir 172.5 9,320 feet (2,840 m), gravelly sandy loam, mountain grassland 166.8 4,530 feet (1,380 m), loamy fine sand, short grass 165.8 4,720 feet (1,440 m), cobble clay, pinyon-juniper 162.2 4,990 feet (1,520 m), stony clay loam, ponderosa pine 159.5 5,510 feet (1,680 m), silty clay loam, sagebrush-greasewood 158.0 4,530 feet (1,380 m), stony loam, oak savannah 153.5
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]:
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:
Elymus elymoides is a species of wild rye known by the common name squirreltail. This grass is native to most of North America west of the Mississippi River and occurs in a number of ecosystems, from the alpine zone to desert sage scrub to valley grassland.
Elymus elymoides is a perennial bunch grass growing to around 0.5 metres (20 in) in height. Its erect solid stems have flat or rolled leaf blades. The inflorescence is up to 15 centimetres (5.9 in) long and somewhat stiff and erect, with spikelets one or two centimeters long not counting the awn, which may be 9 centimeters long and sticks straight out at maturity, making the inflorescence look like a bottlebrush (see main image), and aiding wind dispersal of the seeds. In contrast, the early-season spike is compact and reddish, as in the images at left.[2]
This grass is considered very good forage for sheep. It is best for grazing during the winter, when it is small and green. It becomes less palatable to livestock when its awns grow long and sharp at maturity.
The genus Elymus is a part of the Poaceae, the grass family, which is the most economically important plant family to modern human civilization. Evolving 55 million years ago, members of the Poaceae produce wheat, rice, and barley cereal grains. Elymus elymoides (also known as squirreltail) is a specific type of wild rye that experiences competitive forces when introduced to invasive species, such as cheat grass (Bromus tectorum). E. elymoides experiences a decrease in fitness when growing concurrently with B. tectorum, leading to natural selection acting negatively on E. elymoides. This is perhaps best seen in the Great Basin, as the dry environment makes water a limiting resource, resulting in competition over it. B. tectorum's advantages may be due to its ability to re-engineer that particular ecosystem's scarce water supply.[3] B. tectorum affects Elymus multisetus similarly, indicating that the trait causing decreased fitness is shared among the entire genus Elymus.[4]
Competition also occurs between E. elymoides and the invasive crested wheatgrass (Agropyron cristatum). When introduced, crested wheatgrass negatively affects mature E. elymoides, despite being able to effectively compete at the seedling stage. If crested wheatgrass is used in rehabilitation or restoration of a site, then co-planting a native bunch grass, such as E. elymoides, may be helpful in preventing a crested wheatgrass monoculture. Because E. elymoides populations decline when introduced to certain populations, squirreltail may benefit more from a monoculture setting.[5] This characteristic is supported by another species, Elymus nutas. However, although it is successful as a monoculture food source, it results in a reduction of carbon transfer and decreased soil health when grown alone.[6] To preserve a prosperous Elymus elymoides food source, one must take into consideration its effects on the soil when grown alone, and its responses to competitive forces if grown with other plants.
Subspecies include:
Elymus elymoides is a species of wild rye known by the common name squirreltail. This grass is native to most of North America west of the Mississippi River and occurs in a number of ecosystems, from the alpine zone to desert sage scrub to valley grassland.
Elymus elymoides early-season spike close
