Desert wheatgrass and hybrids of desert and crested wheatgrass provide preferred cover and food for black-tailed jackrabbits in Nevada, Idaho, and Utah [29,35,47], and for mountain cottontails on the upper Snake River Plain in Idaho [54].
Seeding of historically sagebrush-dominated communities to desert wheatgrass may replace the shrub habitat necessary for many passerine birds [66,95].
Deer mice occupy moderately grazed desert wheatgrass range in Utah. Food in their caches on these sites was predominantly mature desert and crested wheatgrass seedheads. When grazing exceeded 50% use, the deer mouse population dropped by at least 20% [32].
Desert wheatgrass is a long-lived, perennial, exotic bunchgrass. Desert wheatgrass is taller and coarser than crested wheatgrass and is found more commonly throughout the western United States. Crested wheatgrass is smaller, leafier, has broader seedheads, and is found more often in the Northern Great Plains and in Canada [84]. Crested wheatgrass is a diploid species, while desert wheatgrass is a tetraploid [21].
Desert wheatgrass in older stands may form a sod [77].
The root system of desert wheatgrass has less spread but greater depth penetration than the roots of crested wheatgrass, making desert wheatgrass more suitable for arid environments [23].
Desert wheatgrass is an introduced species, originally from Russian and Siberian steppe habitats. It has been planted from Alaska south to California, throughout western Canada, east in the United States to Ohio, and south to Texas. It was first successfully established in the United States between 1907 and 1913 [22]. Desert wheatgrass and crested wheatgrass were considered distinct species upon their introduction to the United States in 1906, but since, the two species have often been referred to and treated as one [21]. Crested and desert wheatgrass became prevalent in the United States in the 1930s when they were used to seed abandoned cropland [83]. Desert wheatgrass is more commonly used than crested wheatgrass throughout the West and especially in the more arid regions of the Great Basin and Southwest. Desert and crested wheatgrass seedings have been established on 10 million acres (3.2 million ha) [4] and, by some accounts, as much as 26 million acres (10.4 million ha) in North America [61].
Desert wheatgrass is characterized as slightly damaged by prescribed fire [78], with a moderate to slow recovery period of 5 to over 10 years [92].
Desert wheatgrass may suppress pine reestablishment following wildfires in the southwestern United States, at least in part due to soil moisture competition [18].
In Wyoming, desert wheatgrass is best adapted to sites below 6,000 feet (1,829 m) [7]. In New Mexico, desert wheatgrass is common between 7,000 and 8,500 feet (2,134-2,591 m) [87].
Shown and others [85] found desert wheatgrass on 20 sites in New Mexico, Colorado, Idaho, Oregon, Utah, Wyoming, and Nevada to have highest yields at 12 inches (305 mm) mean precipitation. Only in sites with favorable temperatures and soil conditions did desert wheatgrass grow at annual precipitation as low as 8 inches (203 mm). Crested wheatgrass is more competitive on mesic sites than desert wheatgrass; desert wheatgrass competes better on more xeric sites [23]. Under arid conditions, desert wheatgrass produces large, widely spaced plants whose roots occupy the interstitial areas and prevent the establishment of competing plants (and invading weeds) [72].
Desert wheatgrass is most common on coarse or medium-textured soils, and can survive on extremely shallow soils. It does not establish well in crusted or fine-textured soils [85]. It prefers dry sites and is not saline tolerant [39,73].
Grazing had a significant (p less than 0.05) effect on colonization of desert wheatgrass by vesicular-arbuscular mycorrhizal fungi near Reno, Nevada. Colonization was 88% in a grazing excluded plot and only 63% in a heavily grazed stand [,9,10].
Desert wheatgrass is moderately shade intolerant [17].
42 Bur oak
68 Mesquite
209 Bristlecone pine
210 Interior Douglas-fir
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
233 Oregon white oak
236 Bur oak
237 Interior ponderosa pine
238 Western juniper
239 Pinyon-juniper
241 Western live oak
242 Mesquite
243 Sierra Nevada mixed conifer
FRES21 Ponderosa pine
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES42 Annual grasslands
101 Bluebunch wheatgrass
102 Idaho fescue
103 Green fescue
104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
106 Bluegrass scabland
107 Western juniper/big sagebrush/bluebunch wheatgrass
108 Alpine Idaho fescue
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
201 Blue oak woodland
206 Chamise chaparral
207 Scrub oak mixed chaparral
209 Montane shrubland
210 Bitterbrush
212 Blackbush
215 Valley grassland
301 Bluebunch wheatgrass-blue grama
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
304 Idaho fescue-bluebunch wheatgrass
305 Idaho fescue-Richardson needlegrass
306 Idaho fescue-slender wheatgrass
309 Idaho fescue-western wheatgrass
310 Needle-and-thread-blue grama
311 Rough fescue-bluebunch wheatgrass
312 Rough fescue-Idaho fescue
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
317 Bitterbrush-bluebunch wheatgrass
318 Bitterbrush-Idaho 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
404 Threetip sagebrush
405 Black sagebrush
406 Low sagebrush
407 Stiff sagebrush
408 Other sagebrush types
412 Juniper-pinyon woodland
413 Gambel oak
503 Arizona chaparral
504 Juniper-pinyon pine woodland
509 Transition between oak-juniper woodland and mahogany-oak association
601 Bluestem prairie
602 Bluestem-prairie sandreed
603 Prairie sandreed-needlegrass
604 Bluestem-grama prairie
605 Sandsage prairie
606 Wheatgrass-bluestem-needlegrass
607 Wheatgrass-needlegrass
608 Wheatgrass-grama-needlegrass
609 Wheatgrass-grama
610 Wheatgrass
611 Blue grama-buffalograss
612 Sagebrush-grass
613 Fescue grassland
614 Crested wheatgrass
703 Black grama-sideoats grama
704 Blue grama-western wheatgrass
705 Blue grama-galleta
707 Blue grama-sideoats grama-black grama
708 Bluestem-dropseed
709 Bluestem-grama
710 Bluestem prairie
711 Bluestem-sacahuista prairie
713 Grama-muhly-threeawn
714 Grama-bluestem
715 Grama-buffalograss
716 Grama-feathergrass
717 Little bluestem-Indiangrass-Texas wintergrass
718 Mesquite-grama
719 Mesquite-liveoak-seacoast bluestem
721 Sand bluestem-little bluestem (plains)
722 Sand sagebrush-mixed prairie
728 Mesquite-granjeno-acacia
733 Juniper-oak
734 Mesquite-oak
735 Sideoats grama-sumac-juniper
Desert wheatgrass burns quickly and is therefore less susceptible to fire damage than some bunchgrass species [19]. In especially thick bunchgrasses, the fire may stay longer in the
culm, resulting in heat transfer to the ground and the death of the plant. In desert wheatgrass, there is usually little heat transfer into the soil, so the tillers and root system are usually undamaged [18,86,96].
Desert wheatgrass and its close relative, crested 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 desert wheatgrass to increase range production. Desert wheatgrass has high yields and supplies green forage in both spring and fall making it an important early season food source [52]. Desert wheatgrass is resilient under grazing pressure [60].
Desert wheatgrass has been planted throughout North America in a variety of ecosystems; the appearance of the species within the following habitat types does not necessarily indicate that desert wheatgrass is particularly well adapted to those climatic conditions.
In the Great Basin of Nevada, desert wheatgrass thrives in native communities of big sagebrush (Artemisia tridentata), black sagebrush (A. nova), Indian ricegrass (Achnatherum hymenoides), bottlebrush squirreltail (Elymus elymoides), Sandberg bluegrass (Poa secunda), and bluebunch wheatgrass (Pseudoroegneria spicata) [23].
In Nevada, desert wheatgrass appears in the big sagebrush/desert wheatgrass community with green rabbitbrush (Chrysothamnus viscidiflorus), slenderbrush eriogonum (Eriogonum microthecum), cheatgrass (Bromus tectorum), prairie junegrass (Koeleria macrantha), bottlebrush squirreltail, blue grama (Bouteloua gracilis), Thurber needlegrass (Stipa thurberiana), tailcup lupine (Lupinus caudatus) and scarlet globemallow (Sphaeralcea coccinea) [11].
Also in Nevada, desert wheatgrass occurs in the Utah juniper (Juniperus osteosperma)/big sagebrush/desert wheatgrass community with green rabbitbrush, broom snakeweed (Gutierrezia sarothrae), rubber rabbitbrush (C. nauseosus), Stansbury cliffrose (Purshia mexicana var. stansburiana), slenderbrush eriogonum, and plains prickly-pear (Opuntia polyacantha). Minor members of the community are bottlebrush squirreltail and cheatgrass, and occasional Sandberg bluegrass, western wheatgrass (Pascopyrum smithii), Indian ricegrass, blue grama, bloomer fleabane (Erigeron bloomeri), longleaf phlox (Phlox longifolia), spreading phlox (P. diffusa), tailcup lupine, scarlet globemallow, hollyleaf clover (Trifolium gymnocarpon), and pale agoseris (Agoseris glauca) [11].
A vegetation typing in which desert wheatgrass is listed as a community dominant is given below.
Vegetation and soils of the Pine and Mathews Canyon watersheds [11]
Desert wheatgrass is a major host for black grass bugs (Labops hesperius) which can result in extensive defoliation. Burning and grazing appear to reduce the infestations [43].
Desert wheatgrass provides highly nutritional forage for livestock, especially in the early spring. As the growing season progresses, the nutritional valueÂin terms of phosphorous, nitrogen, crude protein, and digestibilityÂand palatability of desert wheatgrass decrease [3,48,65], and may drop below the nutritional requirements of cattle [36] and domestic sheep [69]. In Utah, winter crude protein values of desert wheatgrass were marginally deficient for grazing sheep [34].
Mule deer do not prefer desert wheatgrass to native shrub and grass species, but in captive deer feeding trials in the Great Basin, desert wheatgrass proved nutritious to mule deer. In vivo digestibility of a pure desert wheatgrass diet averaged 62% over a 20-day feeding trial in April. This figure is much higher than what is expected for available late winter and spring forages. Crude protein levels for fall, winter, green-up, and spring, were 23, 15, 23, and 30%, respectively. These levels are all good to excellent for the needs of mule deer, although deer may not be able to take advantage of the plant due to snow cover [90,91]. These levels are also higher than those cited by most authors [64].
In tractable elk feeding trials in the Great Basin, digestibility averaged 74% for the late vegetative stage and 53% for the late bloom stage [90].
Heinrichs and Carson [44] established the following nutritional values for desert wheatgrass in a trial in Saskatchewan, Canada:
Protein Nitrogen-free Ether
content(%) extract(%) extract(%)
early leaf 20.4 43.8 2.04
short blade 14.8 49.0 1.62
flower 6.6 54.6 1.19
mature seed 6.0 55.5 1.55
late fall 3.8 48.7 1.35
next spring 3.3 47.4 0.79
Crude Lignin Ash Ca P
fiber(%) (%) (%) (%) (%)
early leaf 25.0. 6.0 8.8 0.21 0.21
short blade 26.9 ---- 7.6 0.24 0.17
flower 32.3 11.4 5.3 0.19 0.11
mature seed 31.4 11.9 5.6 0.25 0.09
late fall 40.4 15.7 5.8 0.23 0.03
next spring 42.9 ---- 5.6 0.22 0.0
The probable dates when desert wheatgrass forage mineral content or ratio falls out of the range of the requirement for lactating cows in Idaho are as follows [75]:
Mineral Requirement Date
N 1.47% June 8
P 0.28% April 12
S 0.10% July 4
K 0.60% October 5
Zn 20 ppm March 30
Ca:P > 7:1 Never
N:S > 15:1 June 2
N:S < 10:1 July 19
AZ AR CA CO IA ID IL IN KS MO MT
NE NV NM ND OR SD TX UT WA WY
AB BC
Desert wheatgrass is highly palatable to livestock and wildlife, but it tends to become fibrous at maturity. Palatability and nutritional quality of the plant decline after June or so [34]. A frequently mentioned characteristic of desert wheatgrass is its tendency to form Âwolf or Âstag plants when ungrazed, which are plants thick with standing dead material. Wolf plants are unpalatable to livestock and decrease the forage potential of the stand [81].
Elk eat desert crested wheatgrass readily when its available [55,90].
Wildlife and livestock use of desert wheatgrass is outlined in the following table [15,36,58,67,83,76]:
AZ CA MT NV OR
Cattle ---- ---- high ---- high
Elk medium ---- ---- ---- ----
Mule deer medium low medium low ----
Pronghorn ---- ---- low low ----
Near Burns, Oregon, in a Great Basin shrub-steppe habitat, seasonal development of desert wheatgrass is as follows [3]:
Approximate date Phenology
mid-April early vegetative
late April mid
mid-May late
late May early boot
early June late boot
late June flowering
early July anthesis
late July seed formation
early August seed set
mid-August summer quiescence
In a study near Burns, Oregon, 80 to 90% of desert wheatgrass tillers present in the spring were produced the previous autumn. Desert wheatgrass leaves can photosynthesize at temperatures near 32° Fahrenheit (0ºC) and the new tillers may become active during the winter. Autumn defoliation by grazing reduces tiller production, but does not reduce biomass production the following year or necessarily otherwise detrimentally affect the plant [71].
Fire usually burns crested wheatgrass above ground but underground parts survive [62,96].
Few researchers have studied the effects of fire on desert wheatgrass stands. Kay [56] burned a sagebrush community that had been broadcast seeded to a mixture of desert wheatgrass, tall wheatgrass (Elytrigia elongata), and intermediate wheatgrass (E. intermedium) to study the effects of burning on forage species. The community also contained cheatgrass. The study site was 30 miles (50 km) east of Redding, California, on Blue Mountain, at 2,200 feet (700 m). It was burned in September of 1957. Desert wheatgrass was probably still in summer dormancy. The author classified the cheatgrass-fed fire as a Âhot grass fire. Wheatgrass frequency for the three seasons prior to burning was 64.5, 62.5, and 65.0 %, respectively. The grasses were ungrazed for the 3 years preceding the burn. In two measurements following the fire, in the following spring and fall, stocking rates of all wheatgrass species increased to 90%. The author concluded that the increase in stocking rate was primarily due to the rhizome production of intermediate wheatgrass. Desert wheatgrass did not appear to be as stimulated by the fall burn as intermediate wheatgrass.
Tussock graminoid
Desert wheatgrass is a long-lived, perennial, exotic bunchgrass. Desert wheatgrass is taller and coarser than crested wheatgrass and is found more commonly throughout the western United States. Crested wheatgrass is smaller, leafier, has broader seedheads, and is found more often in the Northern Great Plains and in Canada [84]. Crested wheatgrass is a diploid species, while desert wheatgrass is a tetraploid [21].
The root system of desert wheatgrass has less spread but greater depth penetration than the roots of crested wheatgrass, making desert wheatgrass more suitable for arid environments [23].
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
Desert wheatgrass seedlings establish easily and may outcompete other species with which they are planted, including native species [50,72,]. Because of this competitiveness, desert wheatgrass plantings may result in monocultural stands [63,68].
Cheatgrass can severely reduce the successful establishment of desert wheatgrass [49,57,80,97] due to early shading of the wheatgrass plants by the faster growing brome and to competition for soil moisture [26,27]. Cheatgrass roots appear to grow earlier and more quickly than those of desert wheatgrass, and to continue growing through the winter, allowing the plant to access and use soil moisture [40,41,42]. Cheatgrass competition appears to reduce root growth in desert wheatgrass and thereby lower long-term survival and competitiveness [1,30]. Francis and Pyke [30] suggest seeding desert wheatgrass at lower than recommended densities in cheatgrass areas to maximize desert wheatgrass.
Desert wheatgrass outcompetes the native bluebunch wheatgrass for water and soil nutrients, allowing it to replace bluebunch wheatgrass. Desert wheatgrass also outcompetes big sagebrush and cheatgrass [12,24]. The roots of desert wheatgrass grow quickly and densely into soil gaps, allowing the plant to take advantage of gaps in the vegetation cover and free spaces in the soil [24].
Desert wheatgrass remains productive for more than 30 years. Stand mortality is virtually unknown, except in cases of extreme drought during critical phenological stages [39]. Desert wheatgrass withstands drought by going dormant following rapid growth that utilizes all available soil moisture [31]. A drought occurred in the fourth year of a 6-year forage production study in eastern Montana. In the drought year, desert wheatgrass produced only 11% of the average production of the 3 preceding years. In the following years, however, production resumed the earlier higher levels [94].
In the arid shadscale (Atriplex spp.) zone of Utah and Nevada, stands of desert wheatgrass appear to be shorter lived than in the Great Plains, with an estimated 10-year life span [11].
The scientific name of desert wheatgrass is Agropyron desertorum (Fischer ex Link) Shultes (Poaceae). Wheatgrasses (Triticeae) including desert wheatgrass frequently hybridize and often produce fertile crosses [5,20,93]. There have been several revisions of the taxonomy of crested wheatgrass and its close Agropyron relatives [16,21,46], and A. desertorum is often called ÃÂcrested wheatgrass.ÃÂ Desert wheatgrass readily crosses with crested wheatgrass (A. cristatum) to produce fertile hybrids, the most common of which is called ÃÂHycrest.ÃÂ Some authorities do not consider crested and desert wheatgrass to be distinct species [45].
Desert wheatgrass has been used extensively to seed unused crop land and to revegetate burns, mines, road cuts and degraded areas [2,14,82,84]. Land managers have had some success preventing the spread of exotic weeds like halogeton (Halogeton glomeratus) and leafy spurge (Euphorbia esula) by seeding unused land with desert wheatgrass [73]. However, heavy grazing appears to neutralize this benefit [33].
Desert wheatgrass roots may extend past 6.6 feet (2 m) into the soil, contributing to desert wheatgrass ability to stabilize soils and reduce erosion [39].
