Physiographic features

This site is found at elevations between 3700 and 5700 feet, and occurs mostly on hummocky sand dunes on top of structural benches and plateaus. Slopes are typically between 2 and 15 percent, but may be as high as 30 percent in some areas. This site is not influenced by a heightened water table, flooding or ponding.

Table 2. Representative physiographic features

Climatic features

The climate of this site is characterized by hot summers and cold winters. Average annual precipitation is 6 to 9.5 inches. On the average June is the driest month and August, September, and October are the wettest months. Approximately 40-45 percent of the annual precipitation occurs as rain from July through October.

The average freeze-free period is 177 to 201 days and frost free period is 152 to 176 days. Precipitation is extremely variable from month to month and from year to year. Much of the summer precipitation occurs as monsoonal thunderstorms. In average years, plants begin growth around February 20 and end growth around October 30.

Table 3. Representative climatic features

Influencing water features

Due to its landscape position, this site is not typically influenced by streams or wetlands.

Soil features

The characteristic soils in this site are deep sands that formed in aeolian deposits derived mainly from sandstone parent materials. Typically there are no rock framgments on the surface or throughout the profile. Soils are torripsamments with a water holding capacity is 2 to 3.1 inches. They are subject to blowing and drifting when dry and bare. Much of this site is stabilized sand dunes.

Soil moisture regime is typic aridic and the soil temperature regime is mesic.

This site occurs most commonly on the Sheppard soil. It also occurs on the following soils and soil survey areas:

UT623-Mido, Sandbench
UT631-Sheppard, Trail
UT633-Sheppard
UT638-Sheppard
UT642-Denazar, Sheppard
UT643-Sheppard
UT686-Peekaboo, Sheppard
UT689-Denazar, Sheppard

Table 4. Representative soil features

Animal community

--Livestock and Wildlife Grazing--

This site provides fair/good grazing for livestock and wildlife during fall, winter, and spring due to accessibility; however this site may have sparse vegetation cover. This site also may lack natural perennial water sources, which can influence the suitability for livestock and wildlife grazing. The suitability for re-seeding or restoring this site is poor due to severe wind erosion, extreme temperatures and variability in time and amount of precipitation, and thus care should be taken to maintain the natural plant communities. This site may occur in pronghorn antelope and desert bighorn sheep ranges; yet in many places the populations will be small and have little grazing impact on the site.

The plant community is primarily grasses, including Indian ricegrass, sand dropseed, and sandhill muhly. These grasses, if in abundance, provide desirable grazing conditions for all classes of livestock and wildlife. The presence of shrubs, including sand sagebrush, fourwing saltbush, and mormontea provide good winter browse for cattle, sheep, goats, bighorn sheep, and pronghorn antelope. Forb composition and annual production depends primarily on precipitation amounts and thus is challenging to use in livestock grazing management decisions. However, forb composition should be monitored for species diversity, as well as poisonous or injurious plant communities which may be detrimental to livestock if grazed. Before making specific grazing management recommendations, an onsite evaluation must be made.

--References--

Relative Forage Preference of Plants for Grazing Use by Season: Plants commonly found in Major Land Resource Area D35 --The Colorado Plateau. 2007

Stubbendieck, J., S. L. Hatch, and C. H. Butterfield. 1997. North American range plants. Lincoln, NE: University of Nebraska Press. 501p.

USDA, Forest Service. 2007. Fire effects information: plant species life form. Available at http://www.fs.fed.us/database/feis/plants/index.html. Accessed 7 August 2007.

Hydrological functions

The soil is in hydrologic group a. The hydrologic curve numbers are 39 to 68 depending on the watershed condition

Recreational uses

Recreation activities are hiking and hunting.

Wood products

None

Other information

--Poisonous/Toxic Plant Communities--

Toxic plants associated with this site include sand sagebrush, wavy leaf (shinnery) oak, and broom snakeweed. Sand sagebrush is toxic to horses, but not to other livestock and wildlife ruminants. This plant contains sesquiterpene lactones and monoterpenes, where toxic concentrations are greatest in the late fall and winter. Horses develop neurological signs and exhibit abnormal behavior, such as ataxia and the tendency to fall down, after eating sand sagebrush for several days. Wavy leaf oak is thought to contain tannins that can be detrimental to cattle, sheep, and occasionally horses if grazed as more than 50% of the diet. Oak is highly toxic during the budding stage, leafing stage, and when acorns are available. Symptoms include lack of appetite, weakness, excessive thirst, edema, reluctance to follow the herd, and emaciation. Broom snakeweed contains steroids, terpenoids, saponins, and flavones that can cause abortions or reproductive failure in sheep and cattle, however cattle are most susceptible. These toxins are most abundant during active growth and leafing stage. Cattle and sheep will generally only graze broom snakeweed when other forage is unavailable, typically in winter when toxicity levels are at their lowest.

Potentially toxic plants associated with this site include four-wing saltbush, and buckwheat species, which may accumulate selenium, but only when growing on selenium enriched soils. These plants, when consumed will cause alkali disease or chronic selenosis, which affects all classes of livestock (excluding goats). Typically animals consuming 5-50 ppm selenium will develop chronic selenosis and animals consuming greater than 50 ppm selenium will develop acute selenosis. Clinical signs include lameness, soughing of the hoof, hair loss, blindness, and aimless wondering. Horses tend to develop what is called a “bob” tail or “roached” main due to breakage of the long hairs.

Russian thistle is an invasive toxic plant, causing nitrate and to a lesser extent oxalate poisoning, which affects all classes of livestock. The buildup of nitrates in these plants is highly dependent upon environmental factors, such as after a rain storm during a drought, cool/cloudy days, and soils high in nitrogen and low in sulfur and phosphorus, all which cause increased nitrate accumulation. Nitrate collects in the stems and can persist throughout the growing season. Clinical signs of nitrate poisoning include drowsiness, weakness, muscular tremors, increased heart and respiratory rates, staggering gait, and death. Conversely, oxalate poisoning causes kidney failure; clinical signs include muscle tremors, tetany, weakness, and depression. Poisoning generally occurs when livestock consume and are not accustomed to grazing oxalate-containing plants. Animals with prior exposure to oxalates have increased numbers of oxalate-degrading rumen microflora and thus are able to degrade the toxin before clinical poisoning can occur.

--Invasive Plant Communities--

Generally, as ecological conditions deteriorate and perennial vegetation decreases due to disturbance (fire, over grazing, drought, off road vehicle overuse, erosion, etc.) annual forbs and grasses will invade the site. Of particular concern in semi-arid environments are cheatgrass, Russian thistle, kochia, halogeton, and annual mustards. The presence of these species will depend on soil properties and moisture availability; however, these invaders are highly adaptive and can flourish in many locations. Once established, complete removal is difficult but suppression may possible.

Cheatgrass and Russian thistle are common invaders to this site, especially in lower areas that concentrate nutrients and moisture. The severe wind erosion associated with the site may inhibit invasive annual establishment; however if growing conditions are conducive to invaders and the disturbance is not removed, these plants can create dense mono cultures that can alter the nutrient cycling, erosion rates and the fire regime of the area.

--Fire Ecology--

The ability for an ecological site to carry fire depends primarily on the present fuel load and plant moisture content. Due to sparse vegetative cover, fire does not carry well through this site. When the site is degraded by the presence of invasive annuals, the ability for fire to carry through the site may be increased and the increased fire interval may be sufficient to suppress the native plant community reestablishment. Sand sagebrush is top killed by fire and will readily resprout after a fire. Not much is known about the fire regimes of sand sagebrush dominated plants and thus fire regimes are based upon adjacent vegetation stands.

--References--

Knight, A. P. and R. G. Walter. 2001. A guide to plant poisoning of animals in North America. Jackson, WY: Teton NewMedia. 367p.

USDA, Forest Service. 2007. Fire effects information: plant species life form. Available at http://www.fs.fed.us/database/feis/plants/index.html. Accessed 7 August 2007.

Other references

Modal Soil: Sheppard FS, LFS, S — mixed, mesic Typic Torripsamments

Type Location: Goosenecks, Junction of 276 and 95

Contributors

George Cook