Physiographic features

This site is typically found in alluvial valley bottoms on alluvial fans and stream terraces at elevations between 5000 and 6300 feet. Flooding is very rare and extremely brief and most commonly occurs in July and August. Slopes range from 1 to 8% and runoff is low.

Table 2. Representative physiographic features

Climatic features

The climate of this site is dry with hot summers and cool winters. Average annual precipitation ranges from 7 to 9 inches. About half of the precipitation occurs as convective thunderstorms from July to October, while June is typically the driest month during the growing season. Plant growth typically begins around March 1st and ends around Octover 30th. Large fluctuations in daily temperatures are common, and precipitation can vary greatly from month to month and from year to year.

Modeled climate data (PRISM) was used to develop this section due to the remote location of this site (distance from established climate stations).

Table 3. Representative climatic features

Influencing water features

Ephemeral washes usually cross this site. Rubber rabbitbrush and/or greasewood are productive and often dominate near washes, but riparian obligate species are uncommon. When riparian obligate species are present, the wash is associated with an intermitent stream ecological site. Site R035XY030UT--Colorado Plateau Riparian Complex Discontinuous (Valley Type VIII - B5C Stream Type)--has been documented to cross this alkali sacaton site in the South Desert of Capitol Reef National Park (Polk Creek).

Soil features

The soils of this site are very deep sandy loams. They may be slightly to strongly saline, bordering on sodic. They formed in alluvial valley bottoms derived from sandstone, shale and/or eolian deposites. Rock fragments are not common on the soil surface or in the profile, but can comprise up to 20% of the soil volume. These soils are well drained with moderate to rapid permeability. Water holding capacity ranges from 2.4 inches (in coarser soils) to 6.4 inches (in finer soils) of water in the upper 40 inches of soil. The soil moisture regime is aridic and the soil temperature regime is mesic.

This site has been correlated to soils in the following soil surveys:

UT685 - Capitol Reef National Park - Fruitland, Peachspring, Monue, Begay, Mido, and Sheppard;

Table 4. Representative soil features

Animal community

--Livestock and Wildlife Grazing--
This site provides good/fair grazing conditions for livestock and wildlife during fall, winter, and spring due to accessibility and available nutritious forage. This site often lacks natural perennial water sources, which can influence the suitability for livestock and wildlife grazing. Care should be taken to maintain the native perennial grasses and shrubs due to the poor suitability for re-seeding or restoring this site. Reseeding and/or restoration are difficult due to the extreme temperatures, variability in time and amount of precipitation, and sodic soils. This site may occur in mule deer, desert bighorn sheep, and elk habitat; however in many places the populations will be small and have little grazing impact on the site.

The plant community is primarily grasses, including alkali sacaton, Indian ricegrass, galleta, and blue grama. These grasses provide good grazing conditions for all classes of livestock and wildlife. Dominant shrubs, including shadscale, greasewood, winterfat, and fourwing saltbush, provide good winter browse for cattle, sheep, goats, bighorn sheep, mule deer, and elk. 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--
1. Relative Forage Preference of Plants for Grazing Use by Season: Plants commonly found in Major Land Resource Area D35 --The Colorado Plateau. 2007
2. Stubbendieck, J., S. L. Hatch, and C. H. Butterfield. 1997. North American range plants. Lincoln, NE: University of Nebraska Press. 501p.
3. 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.

Wildlife-
This ecological site provides food and very limited cover for wildlife. Wildlife using this site includes coyote, bobcat, jackrabbit, snake, hawk, mule deer, coyote, and desert bighorn.

Recreational uses

Recreational uses are hiking, hunting, and horseback riding. This site often has scenic
vistas associated with it.

Wood products

None

Other information

--Poisonous/Toxic Plant Communities--
Toxic plants associated with this site include broom and threadleaf snakeweed, greasewood, and lupine. Snakeweeds 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 typically only graze broom snakeweed when other forage is unavailable and generally in winter when toxicity levels are at their lowest. Greasewood contains sodium oxalate, which is toxic to cattle and sheep that have not accustomed to eating oxalate-containing plants. Oxalates accumulate in the greasewood leaves and are toxic only when consumed as 1.5 to 5.0 percent of the animal’s body weight over a short period of time. Oxalate poisoning causes kidney failure; clinical signs include muscle tremors, tetany, weakness, and depression. Lupine toxicity depends primarily on species—many lupines are nontoxic. The toxic compounds, quinolizidine and piperlizidine alkaloids, are found in all part of the plants, during all phases. Lupine poisoning is associated with 2 syndromes: 1) crooked calf disease and 2) neurological disease. Crooked calf disease is characterized by calves being born with skeletal deformities and caused by cows consuming toxic levels of lupines between 40 and 70 days gestation. The neurological diseases is marked by include muscle tremors, labored breathing, coma, and death and is caused by animals grazing lupines at anytime.
Potentially toxic plants associated with this site include four-wing saltbush, some buckwheat species, and basin big sagebrush. Four-wing saltbush and some buckwheat species 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. Basin big sagebrush contains sesquiterpene lactones and monoterpenes which have been suspected of being toxic to sheep. An experimental dosage of ¾ lbs of big sagebrush fed to sheep for three days was found to be lethal.

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 the non-native annual invaders including 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 be possible. Due to the steep slopes associate with this site, the chance for disturbance is rare and thus possibility for invasion decreases. However, cheatgrass and Russian thistle are expected to invade when given the opportunity.

--Fire Ecology--
The ability for an ecological site to carry fire depends primarily on the present fuel load and plant moisture content—sites with small fuel loads will burn more slowly and less intensely than sites with large fuel loads. Many semi-desert plant communities in the Colorado Plateau may have evolved without the influence of fire. However a year of exceptionally heavy winter rains can generate fuels by producing heavy stands of annual forbs and grasses. When fires do occur, the effect on the plant community may be extreme due to the harsh environment and slow rate of recovery.

The occurrence of fire in alkali sacaton ecological sites is rare and fire intervals are most likely influenced by adjacent plant communities. Factors contributing to fire frequency in these areas include water table, flooding frequency, and annual forb/grass invasion. Alkali sacaton is tolerant of fire but, top killing is frequent, and the plants can be killed by severe fires. Recovery time of alkali sacaton following fire has been reported as 2-4 years and summer fires have the most effect on this plant.

--References--
1. Knight, A. P. and R. G. Walter. 2001. A guide to plant poisoning of animals in North America. Jackson, WY: Teton NewMedia. 367p.
2. 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

Johnson, Kathleen A. 2000. Sporobolus airoides. In: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2012, August 30].

Contributors

Jamin Johanson