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SPECIES: Leymus ambiguus

INTRODUCTORY

AUTHORSHIP AND CITATION:
Anderson, Michelle D. 2004. Leymus ambiguus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.usda.gov /database/feis/plants/graminoid/leyamb/all.html [].

FEIS ABBREVIATION:
LEYAMB

SYNONYMS:
Elymus ambiguus Vasey & Scribn. [13,15,24]

NRCS PLANT CODE [38]:
LEAM

COMMON NAMES:
Colorado wildrye

TAXONOMY:
The currently accepted scientific name of Colorado wildrye is Leymus ambiguus (Vasey & Scribn.) D.R. Dewey (Poaceae) [10,23,41,42].

LIFE FORM:
Graminoid

FEDERAL LEGAL STATUS:
No special status

OTHER STATUS:
Colorado wildrye is rare in Nevada [24].
Special consideration status for Colorado wildrye was considered and rejected in Idaho [35].

DISTRIBUTION AND OCCURRENCE

SPECIES: Leymus ambiguus
GENERAL DISTRIBUTION:
Colorado wildrye grows primarily along the east slope of the Rocky Mountains, from Montana south through Wyoming, Colorado, and New Mexico [7,10,23]. It has also been reported in Idaho [35], Utah [23], and Nevada [24].

Plants database provides a distributional map of Colorado wildrye.

ECOSYSTEMS [18]:
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES23 Fir-spruce
FRES29 Sagebrush
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES38 Plains grasslands

STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES

CO ID MT NV NM UT WY

BLM PHYSIOGRAPHIC REGIONS [11]:
6 Upper Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau

KUCHLER [26] PLANT ASSOCIATIONS:
K011 Western ponderosa forest
K012 Douglas-fir forest
K015 Western spruce-fir forest
K018 Pine-Douglas-fir forest
K021 Southwestern spruce-fir forest
K023 Juniper-pinyon woodland
K032 Transition between K031 and K037
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe

SAF COVER TYPES [16]:
206 Engelmann spruce-subalpine fir
210 Interior Douglas-fir
220 Rocky Mountain juniper
237 Interior ponderosa pine
239 Pinyon-juniper

SRM (RANGELAND) COVER TYPES [34]:
301 Bluebunch wheatgrass-blue grama
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
304 Idaho fescue-bluebunch wheatgrass
309 Idaho fescue-western wheatgrass
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
401 Basin big sagebrush
403 Wyoming big sagebrush
405 Black sagebrush
406 Low sagebrush
409 Tall forb
412 Juniper-pinyon woodland
413 Gambel oak
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
417 Littleleaf mountain-mahogany
419 Bittercherry
420 Snowbrush
504 Juniper-pinyon pine woodland
509 Transition between oak-juniper woodland and mahogany-oak association

HABITAT TYPES AND PLANT COMMUNITIES:
In Colorado, Colorado wildrye may dominate montane grassland communities or codominate shrub communities with Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) [9]. Common associates in Rocky Mountain juniper (Juniperus scopulorum)-big sagebrush (A. tridentata) communities include wax currant (Ribes cereum), sulphur-flower buckwheat (Eriogonum umbellatum), varileaf phacelia (Phacelia heterophylla), and Indian ricegrass (Achnatherum hymenoides) [1,20].

The following classifications identify Colorado wildrye as a plant community dominant:

Colorado [9,22]

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Leymus ambiguus
GENERAL BOTANICAL CHARACTERISTICS:
The following description of Colorado wildrye provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [10,13,41,42]).

Colorado wildrye is a native, loosely caespitose perennial [10,13,21,23] that forms culms 12 to 43 inches (30-110 cm) tall [10,13].

Colorado wildrye leaves are mostly basal [10,13,21] and may be flat [10,41,42] or involute [13,15]. Leaves are 0.04 to 0.24 inch (1-6 mm) wide [13,15] and glabrous to sparsely pubescent [10]. Compared with the morphologically similar Salina wildrye (L. salinus), Colorado wildrye tends to be more lush in appearance due to its abundant vegetative growth and leafy culms [10].

Colorado wildrye spikes are erect and reach 3 to 7 inches (8-17 cm) long and 0.08 to 0.24 inch (2-6 mm) wide [10,13]. Spikelets may be paired or solitary at each node [10,13,41,42] and are 0.4 to 0.9 inch (10-23 mm) long [13]. Spikelets bear 2 to 10 flowers [10,13].

Colorado wildrye occasionally produces short rhizomes [10,21].

RAUNKIAER [32] LIFE FORM:
Hemicryptophyte

REGENERATION PROCESSES:
Colorado wildrye reproduces both by seed [28,36] and vegetative growth [10,21,28].

Breeding system: No information is available on this topic.

Pollination: No information is available on this topic.

Seed production: Limited data indicate Colorado wildrye exhibits "strong seed habits" [30], producing approximately 390 seeds per plant. There are approximately 6,875 seeds per pound (243 seeds/gram) [36].

Seed dispersal: No information is available on this topic.

Seed banking: No information is available on this topic.

Germination: No information is available on this topic.

Seedling establishment/growth: Initial seedling establishment of Colorado wildrye is generally high due to high germination rates and rapid seedling growth. Final establishment, however, is reportedly low, perhaps due to the xeric nature of most sites [30].

The growth of perennial range grasses can be described in 2 phases. The 1st phase is defined by the growth of vegetative shoots which is accelerated until the maximum growth rate is reached, after which the rate of growth declines. During this interval the inflorescence is differentiated from the apical meristem, thus initiating the 2nd growth period. The growth of the flower stalks is also accelerated, though the growth rate declines as the fruit ripens and the plant reaches maturity [28]. McCarty [28] found that growth of Colorado wildrye flower stalks progresses very slowly at first, with heads appearing in mid- to late June. As growth of the flower stalks accelerates, the dry weight of the plant is also greatly increased. Increases in dry weight slow in conjunction with flowering and the production of fruit. In general, increases in dry weight lag behind height growth. Adventitious root growth occurs in late July and lasts approximately 2 weeks, followed by secondary shoot growth [28].

Asexual regeneration: Colorado wildrye occasionally reproduces vegetatively from rhizomes [10,21,28].

SITE CHARACTERISTICS:
Colorado wildrye is found on steep, rocky mountainsides [10,20,41,42] and other dry slopes [13,15,20]. It is often more common near the base of slopes than at the crest or middle of slopes [12,13]. Colorado wildrye occurs on all aspects but grows best on south-facing slopes [20]. In Colorado where it is most prevalent, Colorado wildrye grows from 5,200 to 8,500 feet (1,585-2,590 m) [14]. Soils are usually shallow and coarse-textured [20], though Colorado wildrye can grow in light sand to heavy clay soil [21].

SUCCESSIONAL STATUS:
Self-perpetuating stands of Colorado wildrye are indicative of climax conditions on rocky, xeric grassland sites along the Colorado Front Range [22].

SEASONAL DEVELOPMENT:
Colorado wildrye growth ends in mid-September. Seeds are disseminated in early to mid-September [28].

FIRE ECOLOGY

SPECIES: Leymus ambiguus
FIRE ECOLOGY OR ADAPTATIONS:
Fire adaptations: Review of the available literature yielded no information pertaining specifically to the fire ecology or adaptations of Colorado wildrye. Further study is needed to clarify the relationship between fire and Colorado wildrye. Basin wildrye (L. cinereus) is a morphologically similar species, though it occurs on somewhat different sites and has a wider distribution. Information on fire ecology and adaptations of basin wildrye can be found in the FEIS species summary; it is unknown to what extent this information can be applied to Colorado wildrye.

Fire regimes: Fire return intervals for plant communities and ecosystems in which Colorado wildrye occurs are summarized below. Find further 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)
sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [29]
Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40**) [39,45]
plains grasslands Bouteloua spp. < 35 [29,44]
curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1,000 [6,33]
mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii < 35 to < 100
Rocky Mountain juniper Juniperus scopulorum < 35 [29]
wheatgrass plains grasslands Pascopyrum smithii < 5-47+ [29,31,44]
Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to > 200 [3]
pinyon-juniper Pinus-Juniperus spp. < 35 [29]
Colorado pinyon Pinus edulis 10-400+ [17,19,25,29]
interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [3,8,27]
mountain grasslands Pseudoroegneria spicata 3-40 (10**) [2,3]
Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [3,4,5]
oak-juniper woodland (Southwest) Quercus-Juniperus spp. < 35 to < 200 [29]
*fire return interval varies widely; trends in variation are noted in the species review
**mean

POSTFIRE REGENERATION STRATEGY [37]:
Rhizomatous herb, rhizome in soil
Tussock graminoid
Ground residual colonizer (on-site, initial community)
Initial off-site colonizer (off-site, initial community)

FIRE EFFECTS

SPECIES: Leymus ambiguus
IMMEDIATE FIRE EFFECT ON PLANT:
Little information is available regarding the effect of fire on Colorado wildrye, though it is presumably top-killed by fire. Colorado wildrye typically forms small, loosely caespitose bunches that grow in close aggregation [7,21]. This growth form suggests that Colorado wildrye may burn quickly, with little heat transferred downward into the crown. Typically, other bunchgrasses that are morphologically similar have basal buds at or just below the surface that are not subjected to prolonged heating and survive to resprout [44]. The occasionally rhizomatous nature of Colorado wildrye [10,21] also suggests some resistance to fire mortality.

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:
No additional information is available on this topic.

PLANT RESPONSE TO FIRE:
Available literature does not address Colorado wildrye's response to fire. More research is needed regarding both fire effects and Colorado wildrye response. More is known about basin wildrye, a morphologically similar bunchgrass; however, the degree to which this information can be applied to Colorado wildrye is unknown. Basin wildrye is adapted to well-drained lowland and upland sites in the Great Basin, while Colorado wildrye is generally found on steep, xeric sites. For more information regarding fire effects on basin wildrye, see the FEIS species summary.

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
No additional information is available on this topic.

FIRE MANAGEMENT CONSIDERATIONS:
No additional information is available on this topic.

MANAGEMENT CONSIDERATIONS

SPECIES: Leymus ambiguus
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Colorado wildrye has a low tolerance to grazing and generally rates low in palatability, except perhaps in early spring [30].

Palatability/nutritional value: McCarty [28] found that the starch and sugar content of Colorado wildrye roots and stem bases reaches a maximum immediately following current seasonal growth, declines slightly during the dormant period, and reaches minimum levels during the formative stages of shoot development. For initial growth of both roots and shoots, Colorado wildrye depends completely on stored carbohydrates for energy and building material. The manufacture of carbohydrates begins relatively quickly, but this carbohydrate is used as fast as it is manufactured. Carbohydrate storage only begins when growth rates decrease [28]. Carbohydrate reserves are therefore directly related to growth rates, decreasing during rapid growth and increasing during slow growth [28,43]; however, temperature and the availability of water and nutrients also affect the seasonal variation of carbohydrate reserves [43].

Cover value: No information is available on this topic.

VALUE FOR REHABILITATION OF DISTURBED SITES:
No information is available on this topic.

OTHER USES:
No information is available on this topic.

OTHER MANAGEMENT CONSIDERATIONS:
Field trials have demonstrated that Colorado wildrye has high survivability and forage production potential in the eastern Central Great Plains, perhaps indicating its usefulness in livestock production [40].

Leymus ambiguus: References

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