Natural Resources
Conservation Service
Ecological site R028AY218UT
Semidesert Silt Loam (Winterfat)
Last updated: 6/12/2025
Accessed: 10/19/2025
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 028A–Ancient Lake Bonneville
MLRA 28A occurs in Utah (82 percent), Nevada (16 percent), and Idaho (2 percent). It encompasses approximately 36,775 square miles (95,246 square kilometers). A large area west and southwest of Great Salt Lake is a salty playa. This area is the farthest eastern extent of the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. It is an area of nearly level basins between widely separated mountain ranges trending north to south. The basins are bordered by long, gently sloping alluvial fans. The mountains are uplifted fault blocks with steep side slopes. Most of the valleys are closed basins containing sinks or playa lakes. Elevation ranges from 3,950 to 6,560 feet (1,204 to 2000 meters) in the basins and from 6,560 to 11,150 feet (1996 to 3398 meters) in the mountains. Much of the MLRA has alluvial valley fill and playa lakebed deposits at the surface from pluvial Lake Bonneville, which dominated this MLRA 13,000 years ago. A level line of remnant lake terraces on some mountain slopes indicates the former extent of this glacial lake. The Great Salt Lake is what remains of the pluvial lake.
Mountains in the interior of this MLRA consist of tilted blocks of marine sediments from Cambrian to Mississippian age with scattered outcrops of Tertiary continental sediments and volcanic rocks. The average annual precipitation is 5 to 12 inches (13 to 30 cm) in the valleys and ranges up to 49 inches (124 cm) in the mountains. Most of the rainfall in the southern LRU occurs as high-intensity, convective thunderstorms during the growing season (April through September). The driest period is from midsummer to early autumn in the northern LRU. Precipitation in winter typically occurs as snow. The average annual temperature is 39 to 53 °F (4 to 12 °C). The freeze-free period averages 165 days and ranges from 110 to 215 days, decreasing in length with increasing elevation. The dominant soil orders in this MLRA are Aridisols, Entisols, and Mollisols. Soils are dominantly in the mesic or frigid soil temperature regime, aridic or xeric soil moisture regime, and mixed mineralogy. The soils are generally well drained, loamy or loamy-skeletal, and very deep.
LRU notes
The Basin and Range South LRU has mountain ranges that are about 40 percent sedimentary/metasedimentary (limestone/quartzite dominant) and about 40 percent Tertiary volcanics. The basin floors are generally higher in the southern LRU than in the north LRU between 4,900 and 6,100 feet (1,493 to 1,859 meters) in elevation. The Basin and Range South LRU also exhibits patterns of summers with a greater relative amount of precipitation in July and August coming from convective storms (ustic trending pattern). Pinyon and juniper ecological sites have a great percentage of pinyon pine (Pinus edulis or monophylla) than Utah juniper (Juniperus osteosperma), with pinyon pine up to 50 percent of the tree composition in the semidesert zones and more than 50 percent in upland zones. Warm season grasses, such as James’ galleta (Pleuraphis jamesii) or blue grama (Bouteloua gracilis), are present within the plant community, and can make up a large portion of the subdominant grass composition. Bristlecone pine (Pinus longaeva) and cliffrose (Purshia sp.) are also present and dominant on some ecological sites in the southern LRU, while they are sparse or absent in the northern LRU.
Classification relationships
MLRA: 28A Great Salt Lake Area LRU: Basin and Range South Ecological Zone: Semidesert Ecological Site Semidesert Silt Loam (Winterfat)
EPA Ecoregions: North American Deserts Cold Deserts Central Basin and Range Shadscale-Dominated Saline Basins Sagebrush Basins and Slopes, Woodland- and Shrub-Covered Low Mountains
Ecological site concept
The Semidesert Silt Loam (Winterfat) site is typically located on alluvial flats or fans. The dominant plant community is winterfat (Krascheninnikovia lanata) and Indian ricegrass (Achnatherum hymenoides).
This site occurs across the LRU boundary (southern portion of the Basin and Range north), however because of the location of the site, it was determined to keep the entire site in the south LRU until further evaluation of the plant community across the MRLA.
Associated sites
| R028AY220UT |
Semidesert Loam (Wyoming Big Sagebrush) May be found adjacent to the site, upslope on coarser texture soils. |
|---|---|
| R028AY202UT |
Semidesert Alkali Loam (Black Greasewood) North This site may be found on the same landform adjacent to the Silt Loam site, however the Alkali Loam site should have significant increases of alkalinity in the soil profile in comparison to the Silt Loam site. |
Similar sites
| R028AY030NV |
SILTY 8-10 P.Z. This site is a similar site that has been developed in Nevada. Information from this site was used to develop the state and transition model for site 218. |
|---|---|
| R028AY224UT |
Semidesert Sandy Loam (Winterfat) This site is also dominated by winterfat, however the Sandy Loam site is on a slightly different landscape position and has a coarser textured soil. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Krascheninnikovia lanata |
| Herbaceous |
(1) Achnatherum hymenoides |
Physiographic features
The Semidesert Silt Loam (Winterfat) site occurs on alluvial flats, alluvial fans, flood plains, and low lying valley bottoms. Slopes range from 0 to 15 percent but are mostly 2 percent or less. Elevations range from 5000 to 5490 feet although this site can be found up to 6200 feet.
Table 2. Representative physiographic features
| Landforms |
(1)
Alluvial flat
(2) Alluvial fan (3) Flood plain |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 5,000 – 5,490 ft |
| Slope | 2% |
| Aspect | Aspect is not a significant factor |
Climatic features
The climate is dry subhumid and semiarid. It is characterized by cold, snowy winters and warm summers. The average annual precipitation is about 11 inches. The most reliable sources of moisture for plant growth are the snow that accumulates over the winter, and spring rains. Summer thunderstorms are intermittent and sporadic in nature, although this moisture in the summer allows warm season grasses to establish.
Table 3. Representative climatic features
| Frost-free period (characteristic range) | 88-89 days |
|---|---|
| Freeze-free period (characteristic range) | 128-129 days |
| Precipitation total (characteristic range) | 11 in |
| Frost-free period (actual range) | 87-90 days |
| Freeze-free period (actual range) | 128-129 days |
| Precipitation total (actual range) | 11 in |
| Frost-free period (average) | 89 days |
| Freeze-free period (average) | 129 days |
| Precipitation total (average) | 11 in |
Figure 1. Monthly precipitation range
Figure 2. Monthly minimum temperature range
Figure 3. Monthly maximum temperature range
Figure 4. Monthly average minimum and maximum temperature
Figure 5. Annual precipitation pattern
Figure 6. Annual average temperature pattern
Climate stations used
-
(1) SALINA [USC00427557], Salina, UT
-
(2) MILFORD MUNI AP [USW00023176], Milford, UT
Influencing water features
The Semidesert Silt Loam (Winterfat) site receives some run-off water from adjacent sites.
Soil features
The characteristic soils are deep and well drained. They formed in alluvium derived mainly from sandstone, shale, limestone, and igneous and lacustrine parent materials. The surface horizon typically has a silt loam or loam texture about 4 inches thick. The soils are usually rock free but may occasionally contain up to 24% coarse fragments.
Soils are strongly to moderately to very strongly alkaline. They are also strongly calcareous.
This site has been used in the following soil surveys and has been correlated to the following components:
UT627 - Sanpete Valley Area: Naser, Xeric Haplogypsids
UT626 - Beaver County, Utah Western Part: Bandag
UT628 - Beaver County Area: Genola, Naser, Xeric Haplogypsids
UT629 - Loa-Marysvale Area, Utah, Parts of Piute, Wayne and Garfield Counties: Genola
UT634 - Iron-Washington Area, Utah, parts of Iron, Kane, and Washington Counties: Ashdown, Bandag, Wales
Typical Profile (Bandag):
A - 0 to 2 inches; loam; strongly effervescent; carbonates disseminated; moderately alkaline.
A2 - 2 to 5 inches; loam; strongly effervescent; very slightly saline; strongly alkaline.
A3 - 5 to 10 inches; loam; strongly effervescent; carbonates disseminated; moderately alkaline.
C1 - 10 to 23 inches; silt loam; strongly effervescent; carbonates disseminated; moderately alkaline.
C2 - 23 to 34 inches; loam; strongly effervescent; carbonates disseminated; moderately alkaline.
C3 - 34 to 60 inches; sandy clay; strongly effervescent; carbonates disseminated; moderately alkaline.
Table 4. Representative soil features
| Parent material |
(1)
Alluvium
–
sandstone and shale
(2) Limestone (3) Igneous and sedimentary rock |
|---|---|
| Surface texture |
(1) Silty clay loam (2) Loam |
| Drainage class | Well drained |
| Permeability class | Slow to moderate |
| Soil depth | 60 in |
| Surface fragment cover <=3" | 5% |
| Surface fragment cover >3" | Not specified |
| Available water capacity (0-40in) |
2.2 – 5.5 in |
| Calcium carbonate equivalent (0-40in) |
5 – 40% |
| Electrical conductivity (0-40in) |
2 mmhos/cm |
| Sodium adsorption ratio (0-40in) |
5 |
| Soil reaction (1:1 water) (0-40in) |
7.4 – 9 |
| Subsurface fragment volume <=3" (Depth not specified) |
24% |
| Subsurface fragment volume >3" (Depth not specified) |
Not specified |
Ecological dynamics
The Semidesert Silt Loam (Winterfat) site is found in the southern portion of the Great Salt Lake Area of the Basin and Range Ecological Provence. It developed under the natural ecological conditions found there, including the normal influences of native wildlife herbivory, fire, and climate. Vegetation is composed primarily of winterfat and Indian ricegrass. Other common shrubs include bud sagebrush, four-wing saltbush, and both smooth and spiny horsebrush species. Other important herbaceous species include James' galleta, bottlebrush squirreltail, and western wheatgrass. Green molly is an important sub-shrub and scarlet globemallow is the most common forb. On average years, plant growth begins around March 15th and ends when available moisture is gone which is typically about June 15th. Some fall regrowth is expected following fall rains.
The Semidesert Silt Loam (Winterfat) ecological site has been grazed by domestic livestock since they were first introduced into the area around 1860. This livestock introduction, including the use of fencing, and the development of reliable water sources, has influenced the disturbance regime historically associated with this ecological site. This site often serves as wintering pastures for horses and cattle.
Improperly managed livestock grazing (continuous season long grazing, heavy stocking rates, repeated early spring grazing, etc.) can cause this site to depart from the reference plant community. During periods of continuous winter grazing by horses or cattle, winterfat, and palatable perennial grasses will decrease allowing less palatable species including sand dropseed, purple threeawn, and shadscale to increase, and at times, dominate the site.
A significant portion of this site has been converted to irrigated cropland with alfalfa being the most commonly grown crop.
As vegetative communities respond to changes in management or natural influences that move them from one state to another, a return to previous states may not be possible. The amount of energy needed to affect these vegetative shifts depends on present biotic and abiotic features and the desired results.
The following state and transition model diagram depicts some of the most commonly occurring plant communities. These communities may not represent every possibility, but they are the most prevalent and repeatable. As more data are collected, some of these plant communities may be revised or removed, and new ones may be added. This model was developed using range data collected for publication of the Sanpete Valley Area (UT627) and the Iron/Washington Area (UT634) Soil Surveys. Both ocular and measured data was collected and utilized. Range data collected by the NRCS since 1983 was also used. The state and transition model from R028AY030NV was also used to develop the STM for this site.
State and transition model
Figure 7. STM Diagram R028AB218UT
More interactive model formats are also available.
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More interactive model formats are also available.
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Click on state and transition labels to scroll to the respective text
Ecosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 1
Reference State
The Reference State describes the various biotic communities that are expected to be found on this ecological site under natural conditions. The Reference State is dominated by a shrub layer composed mainly of winterfat and bud sagebrush. Four-wing saltbush, shadscale, and spiny horsebrush are other common shrub species. Indian ricegrass is the dominant herbaceous species with James' galleta, bottlebrush squirreltail, and western wheatgrass commonly occurring. Other native grasses, forbs, and shrubs will often produce a significant portion of the vegetative composition in the plant community. The Reference State is self-sustaining and resistant to change due to a natural resilience to its natural disturbances. The primary natural disturbance mechanisms are wildlife population densities which can affect the shrub layer composition, weather fluctuations, and fire period. Indicators: These communities are dominated by winterfat, bud sagebrush, and Indian ricegrass. The density of the shrub canopy helps determine the amount and composition of the other native species present in the community. Feedbacks: Natural fluctuations in weather patterns that allow for a self-sustaining shrub and native grass community. Prolonged drought, an increase in fire frequency, or other disturbances may allow for the establishment of invasive species. At-risk Community Phase: All communities are at risk when native plants are stressed and conditions are created that may allow invasive plants to establish. Trigger: The establishment of invasive plant species.
Community 1.1
Winterfat, Bud Sagebrush-Indian ricegrass
Figure 8. Community Phase 1.1
This community phase is dominated by a shrub layer of winterfat with lesser amounts of bud sagebrush. Four-wing saltbush, shadscale, and spiny horsebrush are also commonly present. Indian ricegrass is the dominant herbaceous species with James' galleta, bottlebrush squirreltail, and western wheatgrass commonly occurring. A variety of other perennial grasses, shrubs, and forbs may also be present and cover is quite variable. Bare ground is also variable (30 to 60 percent). Air dry composition of this site is approximately 30 percent grasses, 5 percent forbs, and 65 percent shrubs. Bare ground is variable (30 to 60 percent) depending on biological crust cover, which is also variable (1 to 20 percent), and surface rock fragments (0 to 15 percent). Biological crusts can vary from sites dominated by light cyanobacteria in the plant interspaces, with occasional moss and lichen pinnacles under shrub canopies, to those dominated by lichen and moss pinnacles as well as cyanobacteria in the site interspaces.
Figure 9. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Shrub/Vine | 120 | 300 | 390 |
| Grass/Grasslike | 60 | 150 | 180 |
| Forb | 20 | 50 | 80 |
| Total | 200 | 500 | 650 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 15-35% |
| Grass/grasslike foliar cover | 10-20% |
| Forb foliar cover | 2-5% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0% |
Table 7. Canopy structure (% cover)
| Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.5 | – | – | – | – |
| >0.5 <= 1 | – | – | – | 1-10% |
| >1 <= 2 | – | 30-40% | 15-25% | – |
| >2 <= 4.5 | – | – | – | – |
| >4.5 <= 13 | – | – | – | – |
| >13 <= 40 | – | – | – | – |
| >40 <= 80 | – | – | – | – |
| >80 <= 120 | – | – | – | – |
| >120 | – | – | – | – |
Figure 10. Plant community growth curve (percent production by month). UT1391, PNC. Excellent Condition.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 0 | 5 | 25 | 50 | 10 | 0 | 0 | 5 | 5 | 0 | 0 |
Community 1.2
Perennial bunchgrasses/winterfat
Figure 11. Community Phase 1.2
This community phase is characterized by a much reduced shrub layer. Shrubs present often include bud sagebrush and shadscale with lesser amounts of winterfat and four-wing saltbush. A mixture of other shrubs including smooth and spiny horsebrush, green molly, and green rabbitbrush may also be present. Indian ricegrass and other more palatable grasses are reduced in the herbaceous layer. James' galleta, sand dropseed, and western wheatgrass are often the most common grasses. A limited amount of other perennial grasses, shrubs, and forbs may also be present and cover is quite variable. Bare ground is also variable (30 to 60 percent). Air dry composition of this site is approximately 60 percent grasses, 5 percent forbs, and 35 percent shrubs. Bare ground is variable (30 to 60 percent) depending on biological crust cover, which is also variable (1 to 20 percent), and surface rock fragments (0 to 15 percent). Biological crusts can vary from sites dominated by light cyanobacteria in the plant interspaces, with occasional moss and lichen pinnacles under shrub canopies, to those dominated by lichen and moss pinnacles as well as cyanobacteria in the site interspaces.
Figure 12. Annual production by plant type (representative values) or group (midpoint values)
Table 8. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Shrub/Vine | 120 | 300 | 390 |
| Grass/Grasslike | 60 | 150 | 180 |
| Forb | 20 | 50 | 80 |
| Total | 200 | 500 | 650 |
Table 9. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 15-35% |
| Grass/grasslike foliar cover | 10-20% |
| Forb foliar cover | 2-5% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0% |
Table 10. Canopy structure (% cover)
| Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.5 | – | – | – | – |
| >0.5 <= 1 | – | – | – | 1-10% |
| >1 <= 2 | – | 30-40% | 15-25% | – |
| >2 <= 4.5 | – | – | – | – |
| >4.5 <= 13 | – | – | – | – |
| >13 <= 40 | – | – | – | – |
| >40 <= 80 | – | – | – | – |
| >80 <= 120 | – | – | – | – |
| >120 | – | – | – | – |
Figure 13. Plant community growth curve (percent production by month). UT1391, PNC. Excellent Condition.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 0 | 5 | 25 | 50 | 10 | 0 | 0 | 5 | 5 | 0 | 0 |
Pathway 1.1a
Community 1.1 to 1.2
This community pathway occurs when any combination of long-term drought, significant periods without fire and/or improper livestock grazing allows non-palatable shrubs such as shadscale and green rabbitbrush to significantly increase. These events can also cause herbaceous understory vegetation to be reduced and eventually, nearly eliminated from the site. Drought alone, however, can reduce native perennial grass production.
Pathway 1.2a
Community 1.2 to 1.1
This community pathway occurs when weather patterns return to within normal ranges and some level of fire reduces shadscale and other less palatable shrubs, allowing winterfat and four-wing saltbush to recover. Green rabbitbrush will likely remain higher than normal in the community until herbaceous species recover, increase in production and flourish on the site. Proper livestock grazing during these periods can facilitate this process.
State 2
Current Potential State
The Current Potential State is similar to the Reference Sate except that non-native species are now present. This state describes the plant communities that may or have become established on this ecological site under various successional sequences and disturbance conditions. This state typically has a well developed shrub layer with winterfat often dominating. Four-wing saltbush, bud sagebrush, and shadscale are other common shrub species. Indian ricegrass is typically the most dominant herbaceous species with James' galleta, western wheatgrass, and other perennial grasses and forbs. Sand dropseed and purple threeawn may be increasing where conditions permit. Cheatgrass, Halogeton, Russian thistle, various mustard species, and other non-native species are present on the site and under certain circumstances and may visually dominate the sites aspect. The primary disturbance mechanisms are the shrub layer density, the amount of invasive species present, weather fluctuations, and fire. The Current Potential State is still self-sustaining but may be losing its resistance to change due to the impact of disturbances with less resilience following those disturbances. Current Potential State: Plant communities influenced by shrub canopy density, long term weather fluctuations, and periodic fire. Invasive species are present in various amounts. Indicators: A community dominated by winterfat, four-wing saltbush, and Indian ricegrass. The health and density of the shrub canopy determines the amount and composition of the other native and introduced grasses and forbs that may be present. Feedbacks: Natural fluctuations in weather patterns that allow for a self sustaining shrub and native grass community. Prolonged drought, more frequent fires, and/or other disturbances that may allow for the increase of invasive species. At-risk Community Phase: All communities are at risk when native plants are stressed and nutrients become available for invasive plants to increase. Trigger: A reduction of perennial grass and forb species combined with an increase of invasive plant species.
Community 2.1
Winterfat/Indian ricegrass/invasive annuals
This community phase is dominated by a shrub layer of winterfat with lesser amounts of bud sagebrush. Four-wing saltbush, shadscale, and smooth and spiny horsebrush may also be present. Indian ricegrass is the most common herbaceous species with bottlebrush squirreltail and western wheatgrass also occurring. Sand dropseed and purple threeawn may be increasing where conditions permit. Non-native species are now present in the all plant communities and are expected to remain a permanent part of these communities. Cheatgrass, Russian thistle and Halogeton are the most common invasive species. A variety of perennial and annual grasses, various shrubs, and forbs are also be present and cover is quite variable. Bare ground is also variable (30 to 60 percent). Air dry composition of this site is approximately 45 percent grasses, 10 percent forbs, and 45 percent shrubs. Bare ground is variable (30 to 60 percent) depending on biological crust cover, which is also variable (1 to 20 percent) and surface rock fragments (0 to 15 percent). Biological crusts can vary from sites dominated by light cyanobacteria in the plant interspaces, with occasional moss and lichen pinnacles under shrub canopies, to those dominated by lichen and moss pinnacles as well as cyanobacteria in the site interspaces.
Figure 14. Annual production by plant type (representative values) or group (midpoint values)
Figure 15. Plant community growth curve (percent production by month). UT1391, PNC. Excellent Condition.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 0 | 5 | 25 | 50 | 10 | 0 | 0 | 5 | 5 | 0 | 0 |
Community 2.2
Winterfat-Indian ricegrass/invasive annuals
This community phase is characterized by a much reduced shrub layer. Shrubs present often include bud sagebrush and shadscale with lesser amounts of winterfat and four-wing saltbush. A mixture of other shrubs including smooth and spiny horsebrush, green molly, and green rabbitbrush may also be present. Indian ricegrass and other more palatable grasses are reduced in the herbaceous layer. James' galleta, sand dropseed, and western wheatgrass are often the most common grasses. Invasive annual grasses and forbs are present, but do not dominate the plant community. A limited amount of other perennial grasses, shrubs, and forbs may also be present and cover is quite variable. Bare ground is also variable (30 to 60 percent).
Figure 16. Annual production by plant type (representative values) or group (midpoint values)
Figure 17. Plant community growth curve (percent production by month). UT1391, PNC. Excellent Condition.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 0 | 5 | 25 | 50 | 10 | 0 | 0 | 5 | 5 | 0 | 0 |
Pathway 2.1a
Community 2.1 to 2.2
This community pathway occurs when any combination of long-term drought, significant periods without fire and/or improper livestock grazing over long periods of time allow non-palatable shrubs such as black greasewood, shadscale, and green rabbitbrush to dominate the site. These events can also cause herbaceous understory vegetation to be reduced, and eventually, nearly eliminated from the site. Drought alone, however, can reduce native perennial grass production. Abandoned cropland that was disked can result in nearly pure stands of black greasewood.
Pathway 2.2a
Community 2.2 to 2.1
This community pathway occurs when weather patterns return to within normal ranges and some level of fire reduces shadscale and other less palatable shrubs, allowing winterfat and four-wing saltbush to recover. Green rabbitbrush will likely remain higher than normal in the community until herbaceous species recover, increase in production and flourish on the site. Proper livestock grazing during these periods can facilitate this process.
State 3
Shrub State
The Shrub State consists of one community phase. The site has crossed a biotic threshold and site processes are being controlled by shrubs. Bare ground has increased.
Community 3.1
Rabbitbrush/Winterfat/non-native annuals
Figure 18. Community Phase 3.1
Perennial bunchgrasses are reduced and the site is dominated by shrubs and non-native annual grasses/forbs.
State 4
Annual State
The Annual State consists of one community phase. The community is characterized by the dominance of non-native annual species. Rabbitbrush and other sprouting shrubs may dominated the overstory
Community 4.1
Invasive annuals/rabbitbrush
This community is dominated by non-native annual species, such as Halogeton and/or cheatgrass with rabbitbrush in the overstory. Winterfat and other shrubs may be present, but do not contribute to site function. Bare ground may increase, especially during drought years. Wind erosion and high soil temperatures may drive site function.
Transition T1A
State 1 to 2
This transitional pathway occurs when any combination of improper livestock grazing, prolonged drought, or other disturbance causes the perennial herbaceous community to become significantly reduced allowing non-native species such as cheatgrass, Halogeton, Russian thistle and other invasive weeds to become established. Broom snakeweed may also increase during this time. Once invasive species occupy the site, a threshold has been crossed. Cheatgrass, however, has been known to become established in healthy communities on this site.
Transition T2A
State 2 to 3
Inappropriate grazing management, with the presence of non-native species
Transition T2B
State 2 to 4
Catastrophic fire and/or multiple fires, inappropriate grazing management and/or soil disturbing treatments.
Transition T3A
State 3 to 4
Catastrophic fire and/or multiple fires, inappropriate grazing management, and/or soil disturbing treatments.
Additional community tables
Table 11. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Primary Grasses | 100–160 | ||||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 80–120 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 40–60 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 40–60 | – | ||
| James' galleta | PLJA | Pleuraphis jamesii | 40–60 | – | ||
| 4 | Secondary Grasses | 40–80 | ||||
| Grass, perennial | 2GP | Grass, perennial | 20–30 | – | ||
| meadow foxtail | ALPR3 | Alopecurus pratensis | 20–30 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 20–30 | – | ||
| blue grama | BOGR2 | Bouteloua gracilis | 20–30 | – | ||
| saltgrass | DISP | Distichlis spicata | 20–30 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 20–30 | – | ||
| alkali sacaton | SPAI | Sporobolus airoides | 20–30 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 20–30 | – | ||
|
Forb
|
||||||
| 2 | Primary Forbs | 40–80 | ||||
| Forb, annual | 2FA | Forb, annual | 20–30 | – | ||
| Forb, perennial | 2FP | Forb, perennial | 20–30 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 20–30 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 20–30 | – | ||
| woolly locoweed | ASMO7 | Astragalus mollissimus | 20–30 | – | ||
| sego lily | CANU3 | Calochortus nuttallii | 20–30 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 20–30 | – | ||
| largeflower hawksbeard | CROC | Crepis occidentalis | 20–30 | – | ||
| povertyweed | IVAX | Iva axillaris | 20–30 | – | ||
| hoary tansyaster | MACA2 | Machaeranthera canescens | 20–30 | – | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 20–30 | – | ||
| silverleaf phacelia | PHHA | Phacelia hastata | 20–30 | – | ||
| longleaf phlox | PHLO2 | Phlox longifolia | 20–30 | – | ||
| woolly plantain | PLPA2 | Plantago patagonica | 20–30 | – | ||
| old-man-in-the-Spring | SEVU | Senecio vulgaris | 20–30 | – | ||
| scarlet globemallow | SPCO | Sphaeralcea coccinea | 20–30 | – | ||
| Pursh seepweed | SUCA2 | Suaeda calceoliformis | 20–30 | – | ||
| yellow salsify | TRDU | Tragopogon dubius | 20–30 | – | ||
| salsify | TRPO | Tragopogon porrifolius | 20–30 | – | ||
|
Shrub/Vine
|
||||||
| 3 | Primary Shrubs | 160–240 | ||||
| winterfat | KRLA2 | Krascheninnikovia lanata | 100–160 | – | ||
| bud sagebrush | PIDE4 | Picrothamnus desertorum | 40–60 | – | ||
| fourwing saltbush | ATCA2 | Atriplex canescens | 40–60 | – | ||
| 5 | Secondary Shrubs | 60–90 | ||||
| shortspine horsebrush | TESP2 | Tetradymia spinosa | 30–60 | – | ||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 20–30 | – | ||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 20–30 | – | ||
| shadscale saltbush | ATCO | Atriplex confertifolia | 20–30 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 20–30 | – | ||
| Nevada jointfir | EPNE | Ephedra nevadensis | 20–30 | – | ||
| mormon tea | EPVI | Ephedra viridis | 20–30 | – | ||
| rubber rabbitbrush | ERNA10 | Ericameria nauseosa | 20–30 | – | ||
| spiny hopsage | GRSP | Grayia spinosa | 20–30 | – | ||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 20–30 | – | ||
Table 12. Community 1.2 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Primary Grasses | 80–120 | ||||
| James' galleta | PLJA | Pleuraphis jamesii | 80–120 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 60–90 | – | ||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 40–60 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 20–40 | – | ||
| 4 | Secondary Grasses | 40–80 | ||||
| Grass, perennial | 2GP | Grass, perennial | 20–30 | – | ||
| meadow foxtail | ALPR3 | Alopecurus pratensis | 20–30 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 20–30 | – | ||
| blue grama | BOGR2 | Bouteloua gracilis | 20–30 | – | ||
| saltgrass | DISP | Distichlis spicata | 20–30 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 20–30 | – | ||
| alkali sacaton | SPAI | Sporobolus airoides | 20–30 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 20–30 | – | ||
|
Forb
|
||||||
| 2 | Primary Forbs | 40–80 | ||||
| Forb, annual | 2FA | Forb, annual | 20–30 | – | ||
| Forb, perennial | 2FP | Forb, perennial | 20–30 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 20–30 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 20–30 | – | ||
| woolly locoweed | ASMO7 | Astragalus mollissimus | 20–30 | – | ||
| sego lily | CANU3 | Calochortus nuttallii | 20–30 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 20–30 | – | ||
| largeflower hawksbeard | CROC | Crepis occidentalis | 20–30 | – | ||
| povertyweed | IVAX | Iva axillaris | 20–30 | – | ||
| hoary tansyaster | MACA2 | Machaeranthera canescens | 20–30 | – | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 20–30 | – | ||
| silverleaf phacelia | PHHA | Phacelia hastata | 20–30 | – | ||
| longleaf phlox | PHLO2 | Phlox longifolia | 20–30 | – | ||
| woolly plantain | PLPA2 | Plantago patagonica | 20–30 | – | ||
| old-man-in-the-Spring | SEVU | Senecio vulgaris | 20–30 | – | ||
| scarlet globemallow | SPCO | Sphaeralcea coccinea | 20–30 | – | ||
| Pursh seepweed | SUCA2 | Suaeda calceoliformis | 20–30 | – | ||
| yellow salsify | TRDU | Tragopogon dubius | 20–30 | – | ||
| salsify | TRPO | Tragopogon porrifolius | 20–30 | – | ||
|
Shrub/Vine
|
||||||
| 3 | Primary Shrubs | 200–320 | ||||
| shadscale saltbush | ATCO | Atriplex confertifolia | 100–140 | – | ||
| winterfat | KRLA2 | Krascheninnikovia lanata | 60–80 | – | ||
| bud sagebrush | PIDE4 | Picrothamnus desertorum | 40–60 | – | ||
| fourwing saltbush | ATCA2 | Atriplex canescens | 40–60 | – | ||
| 5 | Secondary Shrubs | 60–90 | ||||
| shortspine horsebrush | TESP2 | Tetradymia spinosa | 30–60 | – | ||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 20–30 | – | ||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 20–30 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 20–30 | – | ||
| Nevada jointfir | EPNE | Ephedra nevadensis | 20–30 | – | ||
| mormon tea | EPVI | Ephedra viridis | 20–30 | – | ||
| rubber rabbitbrush | ERNA10 | Ericameria nauseosa | 20–30 | – | ||
| spiny hopsage | GRSP | Grayia spinosa | 20–30 | – | ||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 20–30 | – | ||
Table 13. Community 2.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Primary Grasses | 100–120 | ||||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 60–80 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 40–60 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 40–60 | – | ||
| James' galleta | PLJA | Pleuraphis jamesii | 40–60 | – | ||
| 4 | Secondary Grasses | 100–120 | ||||
| bulbous bluegrass | POBU | Poa bulbosa | 30–60 | – | ||
| cheatgrass | BRTE | Bromus tectorum | 30–60 | – | ||
| saltgrass | DISP | Distichlis spicata | 20–30 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 20–30 | – | ||
| alkali sacaton | SPAI | Sporobolus airoides | 20–30 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 20–30 | – | ||
| Grass, perennial | 2GP | Grass, perennial | 20–30 | – | ||
| meadow foxtail | ALPR3 | Alopecurus pratensis | 20–30 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 20–30 | – | ||
| blue grama | BOGR2 | Bouteloua gracilis | 20–30 | – | ||
|
Forb
|
||||||
| 2 | Primary Forbs | 40–80 | ||||
| Forb, annual | 2FA | Forb, annual | 20–30 | – | ||
| Forb, perennial | 2FP | Forb, perennial | 20–30 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 20–30 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 20–30 | – | ||
| woolly locoweed | ASMO7 | Astragalus mollissimus | 20–30 | – | ||
| sego lily | CANU3 | Calochortus nuttallii | 20–30 | – | ||
| lambsquarters | CHAL7 | Chenopodium album | 20–30 | – | ||
| crossflower | CHTE2 | Chorispora tenella | 20–30 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 20–30 | – | ||
| largeflower hawksbeard | CROC | Crepis occidentalis | 20–30 | – | ||
| western tansymustard | DEPI | Descurainia pinnata | 20–30 | – | ||
| herb sophia | DESO2 | Descurainia sophia | 20–30 | – | ||
| common sunflower | HEAN3 | Helianthus annuus | 20–30 | – | ||
| povertyweed | IVAX | Iva axillaris | 20–30 | – | ||
| prickly lettuce | LASE | Lactuca serriola | 20–30 | – | ||
| hoary tansyaster | MACA2 | Machaeranthera canescens | 20–30 | – | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 20–30 | – | ||
| silverleaf phacelia | PHHA | Phacelia hastata | 20–30 | – | ||
| longleaf phlox | PHLO2 | Phlox longifolia | 20–30 | – | ||
| woolly plantain | PLPA2 | Plantago patagonica | 20–30 | – | ||
| Russian thistle | SAKA | Salsola kali | 20–30 | – | ||
| old-man-in-the-Spring | SEVU | Senecio vulgaris | 20–30 | – | ||
| tall tumblemustard | SIAL2 | Sisymbrium altissimum | 20–30 | – | ||
| scarlet globemallow | SPCO | Sphaeralcea coccinea | 20–30 | – | ||
| Pursh seepweed | SUCA2 | Suaeda calceoliformis | 20–30 | – | ||
| yellow salsify | TRDU | Tragopogon dubius | 20–30 | – | ||
| salsify | TRPO | Tragopogon porrifolius | 20–30 | – | ||
|
Shrub/Vine
|
||||||
| 3 | Primary Shrubs | 160–240 | ||||
| winterfat | KRLA2 | Krascheninnikovia lanata | 100–160 | – | ||
| bud sagebrush | PIDE4 | Picrothamnus desertorum | 40–60 | – | ||
| fourwing saltbush | ATCA2 | Atriplex canescens | 40–60 | – | ||
| 5 | Secondary Shrubs | 60–90 | ||||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 40–60 | – | ||
| shortspine horsebrush | TESP2 | Tetradymia spinosa | 30–60 | – | ||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 20–30 | – | ||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 20–30 | – | ||
| shadscale saltbush | ATCO | Atriplex confertifolia | 20–30 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 20–30 | – | ||
| Nevada jointfir | EPNE | Ephedra nevadensis | 20–30 | – | ||
| mormon tea | EPVI | Ephedra viridis | 20–30 | – | ||
| rubber rabbitbrush | ERNA10 | Ericameria nauseosa | 20–30 | – | ||
| spiny hopsage | GRSP | Grayia spinosa | 20–30 | – | ||
Table 14. Community 2.2 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Primary Grasses | 100–120 | ||||
| cheatgrass | BRTE | Bromus tectorum | 60–160 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 40–60 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 40–60 | – | ||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 40–60 | – | ||
| 4 | Secondary Grasses | 100–120 | ||||
| bulbous bluegrass | POBU | Poa bulbosa | 30–60 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 20–30 | – | ||
| alkali sacaton | SPAI | Sporobolus airoides | 20–30 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 20–30 | – | ||
| Grass, perennial | 2GP | Grass, perennial | 20–30 | – | ||
| meadow foxtail | ALPR3 | Alopecurus pratensis | 20–30 | – | ||
| purple threeawn | ARPU9 | Aristida purpurea | 20–30 | – | ||
| blue grama | BOGR2 | Bouteloua gracilis | 20–30 | – | ||
| saltgrass | DISP | Distichlis spicata | 20–30 | – | ||
| James' galleta | PLJA | Pleuraphis jamesii | 20–30 | – | ||
|
Forb
|
||||||
| 2 | Primary Forbs | 40–80 | ||||
| Forb, annual | 2FA | Forb, annual | 20–30 | – | ||
| Forb, perennial | 2FP | Forb, perennial | 20–30 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 20–30 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 20–30 | – | ||
| woolly locoweed | ASMO7 | Astragalus mollissimus | 20–30 | – | ||
| sego lily | CANU3 | Calochortus nuttallii | 20–30 | – | ||
| lambsquarters | CHAL7 | Chenopodium album | 20–30 | – | ||
| crossflower | CHTE2 | Chorispora tenella | 20–30 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 20–30 | – | ||
| largeflower hawksbeard | CROC | Crepis occidentalis | 20–30 | – | ||
| western tansymustard | DEPI | Descurainia pinnata | 20–30 | – | ||
| herb sophia | DESO2 | Descurainia sophia | 20–30 | – | ||
| common sunflower | HEAN3 | Helianthus annuus | 20–30 | – | ||
| povertyweed | IVAX | Iva axillaris | 20–30 | – | ||
| prickly lettuce | LASE | Lactuca serriola | 20–30 | – | ||
| hoary tansyaster | MACA2 | Machaeranthera canescens | 20–30 | – | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 20–30 | – | ||
| silverleaf phacelia | PHHA | Phacelia hastata | 20–30 | – | ||
| longleaf phlox | PHLO2 | Phlox longifolia | 20–30 | – | ||
| woolly plantain | PLPA2 | Plantago patagonica | 20–30 | – | ||
| Russian thistle | SAKA | Salsola kali | 20–30 | – | ||
| old-man-in-the-Spring | SEVU | Senecio vulgaris | 20–30 | – | ||
| tall tumblemustard | SIAL2 | Sisymbrium altissimum | 20–30 | – | ||
| scarlet globemallow | SPCO | Sphaeralcea coccinea | 20–30 | – | ||
| Pursh seepweed | SUCA2 | Suaeda calceoliformis | 20–30 | – | ||
| yellow salsify | TRDU | Tragopogon dubius | 20–30 | – | ||
| salsify | TRPO | Tragopogon porrifolius | 20–30 | – | ||
|
Shrub/Vine
|
||||||
| 3 | Primary Shrubs | 160–240 | ||||
| fourwing saltbush | ATCA2 | Atriplex canescens | 40–60 | – | ||
| winterfat | KRLA2 | Krascheninnikovia lanata | 40–60 | – | ||
| bud sagebrush | PIDE4 | Picrothamnus desertorum | 40–60 | – | ||
| 5 | Secondary Shrubs | 60–90 | ||||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 100–140 | – | ||
| shortspine horsebrush | TESP2 | Tetradymia spinosa | 30–60 | – | ||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 20–30 | – | ||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 20–30 | – | ||
| shadscale saltbush | ATCO | Atriplex confertifolia | 20–30 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 20–30 | – | ||
| Nevada jointfir | EPNE | Ephedra nevadensis | 20–30 | – | ||
| mormon tea | EPVI | Ephedra viridis | 20–30 | – | ||
| rubber rabbitbrush | ERNA10 | Ericameria nauseosa | 20–30 | – | ||
| spiny hopsage | GRSP | Grayia spinosa | 20–30 | – | ||
Interpretations
Animal community
--Wildlife Interpretation--
The Semidesert Silt Loam (Winterfat) ecological site is limited in acreage and has only minor importance for wildlife habitat alone. Where it occurs associated with other Semidesert sites, however, they together produced significant amounts of nutritious forage that was and still is utilized by native herbivores including Rocky Mountain elk, mule deer, and pronghorn antelope who live here along with their associated predators. Although much of this site is presently different from the Reference State, it is still very important as wildlife habitat. Other wildlife commonly observed using this site include mountain lions, rabbits, coyotes, badgers, and red fox.
The Semidesert Silt Loam (Winterfat) site also provides habitat for raptors and other bird species including golden eagles, red-tailed hawks, ferruginous hawks, and several species of owls. Ringneck pheasant, sage grouse, chukars, and California quail are also commonly found.
--Grazing Interpretations--
This site provides fairly good spring, fall, and winter grazing conditions for domestic livestock due to its accessibility and its supply of nutritious forage. The plant community is a combination of palatable shrubs and grasses, with the majority of forage being attributed to winterfat and Indian ricegrass. Improper livestock grazing can cause these species to decrease while annual forbs, shadscale, and rabbitbrush species increase.
When this site is stressed, cheatgrass, Halogeton, and Russian thistle are likely to invade.
Hydrological functions
The soils associated with this ecological site are generally in Hydrologic Soil Groups C and D (NRCS National Engineering Handbook). Runoff curves range from 80 to 89. These soils are saturated quickly due to high infiltration rates and fine textures; once soils are saturated, run off potential varies from moderate to high. Hydrological groups are used in equations that estimate runoff from rainfall. These estimates are needed for solving hydrologic problems that arise in planning watershed-protection and flood-prevention projects and for designing structures for the use, control and disposal of water. Heavy grazing can alter the hydrology by decreasing plant cover and increasing bare ground. Fire can also affect hydrology, but its affect is variable. Fire intensity, fuel type, soil, climate, and topography can each have different influences. Fires can increase areas of bare ground and hydrophobic layers that reduce infiltration and increase runoff (National Range and Pasture Handbook, 2003).
Recreational uses
Recreation activities include aesthetic value and good opportunities for hiking, horseback riding, hunting, and off-road vehicle use. Due to the high erosion potential after a surface disturbance, care should be taken when planning recreational activities. Camp sites are usually limited due to lack of sheltering trees or rock outcrop.
Wood products
None
Other products
None.
Other information
--Poisonous and Toxic Plant Communities--
Toxic plants possibly associated with this site include woolly locoweed, broom snakeweed, and Russian thistle.
Woolly locoweed is toxic to all classes of livestock and wildlife. Locoweed is palatable and has similar nutrient value to alfalfa, which may cause animals to consume it even when other forage is available. Locoweed contains swainsonine (indolizdine alkaloid) and is poisonous at all stages of growth. Poisoning will become evident after 2- to 3 weeks of continuous grazing and is associated with 4 major symptoms: 1) neurological damage, 2) emaciation, 3) reproductive failure and abortion, and 4) congestive heart failure linked with “high mountain disease”.
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 generally will only graze broom snakeweed when other forage is unavailable, typically in winter when toxicity levels are at their lowest (Knight and Walter, 2001).
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, during periods with cool/cloudy days, and when growing on soils high in nitrogen and low in sulfur and phosphorus. 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, drought, off road vehicle overuse, erosion, etc.) annual forbs and grasses may invade the site. Of particular concern in semi-arid environments are annual invaders including cheatgrass, Russian thistle, alyssum, 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. Very few invaded site have been observed to date and so documentation is very limited.
--Fire Ecology--
The ability for an ecological site to carry fire depends primarily on its' 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. Most research agrees that historic fire return intervals are approximately 80 to 100 years, indicating that fire may have not played an important role in short term community dynamics. Fires are more common when plants are stressed or dead due to drought. Fire tolerant shrubs will recover quickly following fire. Shadscale and other fire sensitive species must reestablish either by seeds dispersed from adjacent unburned patches or by unburned seeds found at the burn site. Continuous (every 20 to 40 years) burning of these ecological sites can result in herbaceous dominated communities, due to the relatively fast recovery of grasses and forbs when compared to shrubs. If invasive annual grasses are allowed to establish, fires may become more frequent, inhibiting the site’s ability to recover.
Supporting information
Type locality
| Location 1: Iron County, UT | |
|---|---|
| Township/Range/Section | T34S R13W S26 |
| General legal description | Four Miles North of Iron Springs, Utah; SW ¼ of the NE ¼, Section 26, Township 34S, Range 13W |
Other references
Baily, R.G. 1995. Description of the ecoregions of the United Sates. Available http://www.fs.fed.us/land/ecosysmgmt/ecoreg1_home.html. Accessed February 27, 2008.
Belnap, J. and S.L. Phillips. 2001. Soil biota in an ungrazed grassland: response to annual grass (Bromus tectorum) invasion. Ecological Applications. 11:1261-1275
Chapin, S.F., B.H. Walker, R.J. Hobbs, D.U. Hooper, J.H. Lawton, O.E. Sala, and D. Tilman. 1997. Biotic control over the functioning of ecosystems. Science. 277:500-504
Cox R.D. and V.J. Anderson. 2004. Increasing native diversity of cheatgrass-dominated rangeland through assisted succession. Journal of Range Management. 57:203-210,
Howard, Janet L. 2003. Atriplex canescens. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/. Accessed on February 25, 2008.
Knight, A.P. and R.G. Walter. 2001. A guide to plant poisoning of animals in North America. Teton NewMedia. Jackson, WY.
National Engineering Handbook. US Department of Agriculture, Natural Resources Conservation Service. Available: http://www.info.usda.gov/CED/Default.cfm#National%20Engineering%20Handbook. Accessed February 25, 2008.
NRCS Grazing Lands Technology Institute. 2003. National Range and Pasture Handbook. Fort Worth, TX, USA: US Department of Agriculture, Natural Resources Conservation Service, 190-VI-NRPH.
Tilley, D.J. 2007. Reintroducing native plants to the American West. Aberdeen Plant Materials Center, Aberdeen, ID, USA: US Department of Agriculture. Available: http://plant-materials.nrcs.usda.gov/idpmc/publications.html. Accessed February 22, 2008.
Utah Climate Summaries. 2008. Available: http://www.wrcc.dri.edu/summary/climsmut.html. Accessed on February 25, 2008.
Utah Division of Wildlife Resources. 2007.
Woods, A.J., D.A. Lammers, S.A. Bryce, J.M. Omernik, R.L. Denton, M. Domeier, and J.A. Comstock. 2001. Ecoregions of Utah (color poster with map, descriptive text, summary tables, and photographs). Reston, Virginia, U.S. Geological Survey (map scale 1:1,175,000).
Contributors
David J. Somorville
V. Keith Wadman
Sarah Quistberg
Approval
Kendra Moseley, 6/12/2025
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
| Author(s)/participant(s) | V. Keith Wadman (NRCS retired), Shane A. Green (NRCS) |
|---|---|
| Contact for lead author | shane.green@ut.usda.gov |
| Date | 02/10/2013 |
| Approved by | Kendra Moseley |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Very minor. Slight rill development may be evident on this site following significant storm or snow melt events. The presence of rills may also be more apparent where run-on from adjacent upland sites or exposed bedrock concentrate flows. Rill development will be less that 1" deep, moderately short (< 6’) and somewhat widely spaced 8’ – 10’. -
Presence of water flow patterns:
Evidence of stable overland water flow is apparent in the reference community; increased flow activity may be observed immediately following significant weather events. Flow patterns are normally <20 feet long, follow natural contours, and are typically spaced 10 to 15 feet apart. -
Number and height of erosional pedestals or terracettes:
Slight evidence of pedestals or terracettes caused by accelerated water erosion may be evident in the reference community. 1 – 2 inches of elevational mounding under Winterfat and Shadscale canopies and within biological soil crusts is normal and may not be water erosion caused. There are no exposed roots around perennial grass bunches. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
30-50% bare ground (soil with no protection from raindrop impact). Herbaceous communities are most likely to have lower values. As species composition by shrubs increases, bare ground is likely to increase. Poorly developed biological soil crust that is susceptible to raindrop splash erosion should be recorded as bare ground. Very few if any bare spaces of greater than 1 square foot. -
Number of gullies and erosion associated with gullies:
A few developed gully channels are a normal component of this site. Gullies associated with reference areas will typically have stable, partially vegetated sides and bottoms with no evidence of head-cutting. Some evidence of disturbance may be evident following significant weather events or when gullies convey runoff from higher elevation rocky or naturally eroding areas. -
Extent of wind scoured, blowouts and/or depositional areas:
Some minor evidence of wind generated soil movement is present in reference communities. Slight depositional mounding in perennial grass bunches, under Winterfat and Shadscale canopies and within biological soil crusts is a normal characteristic of this site. -
Amount of litter movement (describe size and distance expected to travel):
Most litter resides in place within or under plant canopies. Some movement of the finest material (< 1/8” or less) may move (1’ – 2’) in the direction of prevailing winds or down slope if being transported by water. Little accumulation is observed behind obstructions. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
This site should have a soil stability rating of 4 to 5. Surface textures are typically silt loams containing very few coarse fragments. Where surface soil is lost, a slight increased silt percentage may occur in the remaining soil material. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
(Bandag) Soil surface 0-5 inches. Texture is a loam; color is light yellowish brown (10YR6/4); and structure is moderate medium platy. Ochric epipedon ranges to 10 inches. Use the specific information for the soil you are assessing found in the published soil survey to supplement this description. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
The presents of healthy perennial bunchgrasses, Winterfat and Shadscale in the reference community provides for the best infiltration and least runoff from storm events and snow melt. As perennial vegetation decreases and bare ground increases, runoff increases and soil loss is accelerated. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. Soils are deep to very deep. -
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sprouting Shrubs, (Winterfat and Four-wing Saltbush) > Non-sprouting Shrubs, (Shadscale) > cool season grasses, (Indian ricegrass and Bottlebrush squirreltail).Sub-dominant:
Non-sprouting shrubs, (Bud sage and Nevada jointfir) > Rhizomatous Grasses (Western Wheatgrass) >> Perennial Forbs, (Scarlet Globemallow).Other:
Sprouting Shrubs, (Low rabbitbrush) > Perennial Forbs, (Utah milkvetch)Additional:
Moss and lichen communities will normally be found under plant canopies while the cyanobacteria will be found throughout the site. Functional/structural groups may appropriately contain non-native species if their ecological function is the same as the native species in the reference state. Perennial and annual forbs can be expected to vary widely in their expression in the plant community based upon departures from average growing conditions. -
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
During years with average to above-average precipitation, there should be very little recent mortality or decadence apparent in either the shrubs or grasses. During severe (multi-year) drought or insect infestations up to 20% of the winterfat may die. There may be partial mortality of individual bunchgrasses and other shrubs during severe drought. -
Average percent litter cover (%) and depth ( in):
Litter cover ranges from 10 to 20% with a spike when Bud Sage drops its leaves. Depth varies from ½ - ¾ inch with depth increasing near plant canopies. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Annual production in air-dry herbage should be approximately 500#/acre on an average year, but could range from 200 to 650#/acre during periods of prolonged drought or above average precipitation. Even the most stable communities exhibit a range of production values. Production will vary between communities and across the MRLA. Refer to the community descriptions in the ESD. Production will differ across the MLRA due to the naturally occurring variability in weather, soils, and aspect. The biological processes on this site are complex; therefore, representative values are presented in a land management context. -
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
Cheatgrass, Russian thistle, annual mustards and halogeton are likely to invade this site. -
Perennial plant reproductive capability:
All perennial plants should have the ability to reproduce sexually or asexually, except in drought years. Density of plants indicates that plants reproduce at level sufficient to fill available resource. Within capability of site there are no restrictions on seed or vegetative reproductive capacity. Some seedling requirement should be observed during years with average or above average moisture years.
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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