• IMPORTANCE TO LIVESTOCK AND WILDLIFE
• PALATABILITY
• NUTRITIONAL VALUE
• COVER VALUE
• VALUE FOR REHABILITATION OF DISTURBED SITES
• OTHER USES AND VALUES
• MANAGEMENT CONSIDERATIONS

IMPORTANCE TO LIVESTOCK AND WILDLIFE:

Crested wheatgrass and its close relative, desert wheatgrass, have been planted in millions of acres in the arid and semi-arid West to benefit livestock and wildlife. Native shrub habitats have been replanted with crested wheatgrass to increase range production. Crested wheatgrass has high yields and supplies green forage in both spring and fall [67,85], and can be important to livestock and wildlife when other preferred food sources are unavailable [112].

PALATABILITY:

Crested wheatgrass is highly palatable and a nutritious spring forage. It can be especially useful to ranchers in the Intermountain West, where spring forage shortages are common [13,60,67]. Crested wheatgrass can be grazed 2 or 3 weeks earlier than native grasses in Utah, Montana, and the Great Basin, and 3 to 4 weeks earlier in Colorado [57, 63,66,83]. Crested wheatgrass tends to become fibrous at maturity, and therefore palatability and nutritional quality of the plant decline after June or so [46,76,86]. Crested wheatgrass provides little summer grazing [10]. In some habitat types with sufficient soil moisture, crested wheatgrass continues to grow in fall after summer dormancy [85].

Reports conflict on the importance of crested wheatgrass to wild ungulates. In Oregon and Nevada, mule deer appear to prefer native grasses and cheatgrass (Bromus tectorum) to crested wheatgrass. Grass contributes less to the diets of pronghorn than to deer, and crested wheatgrass is minimally used by pronghorn in the Great Basin and Intermountain West [112].

Wildlife use of crested wheatgrass is detailed in the following table [8,9,13,16,19,39,56,64,65,68,69,71,73,73,79,83,86,104,116]:

               Alberta  Montana    Idaho       Oregon   Utah
Cattle         ----     high       high        high     high
Domestic sheep high     ----       ----        ----     high
Elk            high     spring use spring use  ----     spring use
Mule Deer      low-none low        medium      medium   low-none
Bighorn sheep  high     medium     ----        ----     ----
Pronghorn      ----     low-none   low         low-none low-none
Moose          medium   ----       ----        ----     ----
Small mammals  -----    ----       low-none    ----     ----

time                             Percentage of diet  
late fall (Nov.)                 51.1 (30.3)
early winter (Dec.)               1.9  (2.0)
mid-winter (Jan.-Feb.)            2.5  (0.8)
late winter (1-20 March)         37.9 (16.9)
early spring (21 March-10 April) 89.7  (5.3)
mid-spring (11-30 April)         57.2 (17.6)

NUTRITIONAL VALUE:

Green crested wheatgrass can be a valuable addition to the browse-dominated diets of wild ungulates in winter [9,112]. In Central Oregon, crested wheatgrass consistently contained more than 20% crude protein during the winter and early spring, leading Urness [113] to conclude that it provided better forage value than native grass species for white-tailed deer.

At certain times during the year, crested wheatgrass lacks highly digestible protein [27]. In Alberta, crested wheatgrass was deficient in crude protein for pregnant ewes [83]. By mid-June, the nutritional value of crested wheatgrass can be too low for lactating cattle. By the end of the summer, crested wheatgrass has low total protein values and lacks adequate phosphorus for cattle [8].

Deer mice occupy moderately grazed crested wheatgrass range in Utah. Food in their caches on these sites was predominantly mature desert and crested wheatgrass seedheads. When livestock grazing exceeded 50% use, the deer mice population dropped by at least 20% [44].

Nutritional content (%) of crested wheatgrass in Alberta, Canada, was [85]:

Stage of    Sample Crude   Crude Ether   N-free  Total Ca    P
maturity    date   protein fiber extract extract ash

preflower   5/10   22.7    19.9    2.7     45.8   8.85  0.42 0.27
heading     6/8    13.9    29.2    1.6     48.0   7.45  0.29 0.24
flowering   6/29   11.7    33.1    1.8     46.3   7.12  0.32 0.19
seed ripe   7/30    8.5    32.5    1.9     51.1   5.92  0.33 0.14
seed shed  10/21    4.5    34.7    1.9     52.1   6.85  0.30 0.05

COVER VALUE:

Seeding of historically sagebrush-dominated communities with crested wheatgrass may replace the shrub habitat necessary for many passerine birds [116]. In southeastern Idaho, Reynolds [100] found fewer nesting species and fewer individual birds on crested wheatgrass plantations than in the native sagebrush habitat. However, grassland bird species may respond favorably to seeded stands of crested wheatgrass that replace brush habitats, except when the area is heavily grazed. In Nevada, ground-nesting bird species comprised 91% of nesting birds in an established crested wheatgrass stand, whereas an unconverted sagebrush habitat with 21% shrub cover supported only 30% ground nesters [87].

In southeastern Idaho, deer mice, montane voles, Ord's kangaroo rats, and Townsend's ground squirrels all frequently use the crested wheatgrass habitat type for food and cover [72]. However, another study in southeastern Idaho reported fewer deer mice, least chipmunks, and northern grasshopper mice in crested wheatgrass stands than in the original sagebrush community. Numbers of western harvest mice were higher in ungrazed crested wheatgrass than in the native sagebrush community but were not increased in the domestic sheep-grazed crested wheatgrass treatment. The authors concluded that conversion to crested wheatgrass and grazing decreased small mammal density and had synergistic negative effects on the mice [101].

VALUE FOR REHABILITATION OF DISTURBED SITES:

Crested wheatgrass has been used extensively to seed unused cropland and to revegetate burns and degraded areas, including mine spoils [3,6,31,99,105,109].

If crested wheatgrass is used to reclaim disturbed sites, a grass monoculture may prohibit the return of predisturbance animal and plant diversity [92,117]. Dusek [37] reviewed a mining reclamation site in southeastern Montana that was seeded with crested wheatgrass. Crested wheatgrass established easily, but the resulting community lacked diversity and sufficient forage quality to support mule deer. As a result, Dusek concluded that managers should not use ease of establishment as the primary characteristic for choosing revegetation species [37].

Crested wheatgrass has lower belowground productivity than native bunchgrass species. Over time, this difference can result in higher soil bulk densities, less organic material in the soil, and poorer nutrient relations in crested wheatgrass than in native grass habitats [36,78].

Crested wheatgrass is used for erosion control [2,22,23]. However, wide row spacing, recommended to increase plant productivity, may persist for years following establishment of the stand. These gaps leave the areas between rows susceptible to erosion, especially if the competitiveness of crested wheatgrass prohibits the establishment of other plants [36,75,78].

Land managers have had some success preventing the spread of exotic weeds like halogeton (Halogeton glomeratus) by seeding unused land with crested wheatgrass [2]. However, heavy grazing appears to neutralize this benefit [45]. Crested wheatgrass' ability to prevent the spread of weeds may also depend on climatic conditions. In northwestern Utah, Cook [29] studied grass seedling competition with halogeton. He concluded that crested wheatgrass is better adapted to low rainfall habitats and competes better with halogeton than do native tall (Elytrigia elongata) and intermediate (E. intermedia) wheatgrasses. Near Cache Creek, British Columbia, established crested wheatgrass stands inhibited the spread of diffuse knapweed (Centaurea diffusa) on arid study plots that received 8 inches (20 cm) annual precipitation. In areas of the study plots with higher soil moisture and in more mesic climatic areas, crested wheatgrass did not exclude diffuse knapweed as successfully, leading the authors to conclude that soil moisture competition during key growth stages caused knapweed failure [15].

Popovich and Pyke [96] concluded that seeding a wildfire-burned area in south-central Idaho to crested wheatgrass did not significantly reduce reproduction potential of Picabo milkvetch (Astragalus oniciformis), a sensitive plant endemic to the north-central Snake River Plain.

OTHER USES AND VALUES:

No entry

MANAGEMENT CONSIDERATIONS:

The seeds of crested wheatgrass are relatively large and easy to process and plant, and its seedlings can withstand drought and cold conditions [6,67,105]. Crested wheatgrass is resilient under grazing pressure [67,89,76,102], easy to establish [63], and may compete successfully against exotic weeds.

Cheatgrass competition appears to reduce root growth in crested wheatgrass and thereby to lower long-term survival and competitiveness, most likely due to competition for water [1,42,55,62,71,103,104]. In a laboratory study, Hycrest wheatgrass grown with cheatgrass at planting ratios of 1:1 and 1:4 suffered reductions in leaf area of 46 and 76%, respectively. Researchers concluded, however, that crested wheatgrass competed more successfully with cheatgrass than did bluebunch wheatgrass (Pseudoroegneria spicata) [1]. Francis and Pyke [42] suggest that by seeding crested wheatgrass at lower than recommended densities in cheatgrass areas, crested wheatgrass is favored because greater spacing reduces within-species competition.

Light to moderate grazing (up to 70% utilization) invigorates a crested wheatgrass stand and extends its life [19,110]. Heavy grazing of crested wheatgrass stands may speed up the re-invasion of sagebrush or of weeds such as Russian thistle (Salsola kali). Above 88% use, production decreases, plants die, and stand quality suffers [19].

When crested wheatgrass is planted as part of a seed mix, it may outcompete and crowd out the other species in the mix, including native species [24,83]. Seeding a disturbed site with crested wheatgrass may prohibit the establishment of other species. Crested wheatgrass contributes heavily to the seedbank, and crested wheatgrass seeds may take advantage of openings in the canopy [83].

Crested wheatgrass seed shatters easily. Timing of seed harvest is crucial. Seed harvested too early, before the seed has matured, is far less likely to germinate. Seedling emergence declined in the field from 46% for mature seeds, to 33, 10, and 3% for dough, milk, and premilk stages, respectively. In cold storage (0 to 19° Fahrenheit (-18 to -7°C)), seed viability remained at 80 to 90% after 20 years [67].

Casterline [25] suggests the following conditions to germinate crested wheatgrass seeds:

pre-chill days to break dormancy:  47oF for 7 days
days needed to break dormancy:  at least 5
temperature needed for germination:  41-86oF
days allowed for germination test:  14
total days to break dormancy and test germination:  21   

Related categories for SPECIES: Agropyron cristatum | Crested Wheatgrass