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Wildlife, Animals, and Plants
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BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Agropyron desertorum
| Desert Wheatgrass
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].
Hemicryptophyte
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].
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<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].
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].
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 (0ēC) 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].
Related categories for
SPECIES: Agropyron desertorum
| Desert Wheatgrass
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