Natural Resources
Conservation Service
Ecological site R043BY272WY
Stony Foothills and Mountains West
Accessed: 11/24/2024
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.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
Associated sites
| R043BY262WY |
Shallow Loamy Foothills and Mountains West Shallow Loamy |
|---|---|
| R043BY270WY |
Steep Stony Foothills and Mountains West Steep Stony |
Similar sites
| R043BY212WY |
Gravelly Foothills and Mountains West Gravelly (Gr) 15-19W has western needlegrass and different shrub species. |
|---|---|
| R043BY270WY |
Steep Stony Foothills and Mountains West Steep Stony (St) 15-19W has higher production and different shrub species. |
| R043BY208WY |
Coarse Upland Foothills and Mountains West Coarse Upland (CU) 15-19W has higher production, larger coarse fragments (boulders), and different shrub species. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
Not specified |
Physiographic features
This site usually occurs on gentle mountain slopes, valley bottoms, and outwash fans.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Alluvial fan (3) Ridge |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 1,707 – 2,530 m |
| Slope | 0 – 30% |
| Ponding depth | 0 cm |
Climatic features
Annual precipitation ranges from 15-19 inches per year. Wide fluctuations may occur in yearly precipitation and result in more dry years than those with more than normal precipitation. Temperatures show a wide range between summer and winter and between daily maximums and minimums. This is predominantly due to the high elevation and dry air, which permits rapid incoming and outgoing radiation. Cold air outbreaks in winter move rapidly from northwest to southeast and account for extreme minimum temperatures. Extreme storms may occur during the winter, but most severely affect ranch operations during late winter and spring.
Prevailing winds are from the southwest, and strong winds are less frequent than over other areas of Wyoming. Occasional storms, however, can bring brief periods of high winds with gusts exceeding 50 mph.
Growth of native cool season plants begins about May 15 and continues to about August 15.
The following information is from the “Jackson” climate station:
Minimum Maximum 5 yrs. out of 10 between
Frost-free period (days): 12 60 July 9 – August 12
Freeze-free period (days): 42 100 June 20 – August 26
Annual Precipitation (inches): <11.98 >19.69 (2 years in 10)
Mean annual precipitation: 17.00 inches
Mean annual air temperature: 38.9?F (23.3?F Avg. Min. to 54.5?F Avg. Max.)
For detailed information visit the Natural Resources Conservation Service National Water and Climate Center at http://www.wcc.nrcs.usda.gov/cgibin/state.pl?state=wy website. Other climate stations representative of this precipitation zone include ”Afton” in Lincoln County; and “Darwin Ranch” in Teton County.
Table 3. Representative climatic features
| Frost-free period (average) | 60 days |
|---|---|
| Freeze-free period (average) | 100 days |
| Precipitation total (average) | 483 mm |
Figure 2. Monthly average minimum and maximum temperature
Influencing water features
Soil features
The soils of this site are moderately deep to deep (greater than 20” to bedrock), well-drained, and stony and/or bouldery. Coarse fragments are greater than 35 percent, by volume, within the first 20 inches of soil, usually increasing with depth. Roots penetrate the soil material to at least 20 inches in most places.
Table 4. Representative soil features
| Surface texture |
(1) Gravelly loam |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained to somewhat excessively drained |
| Permeability class | Moderately slow to moderately rapid |
| Soil depth | 51 – 152 cm |
| Surface fragment cover <=3" | 0 – 20% |
| Surface fragment cover >3" | 0 – 5% |
| Available water capacity (0-101.6cm) |
5.08 – 10.16 cm |
| Calcium carbonate equivalent (0-101.6cm) |
0 – 15% |
| Electrical conductivity (0-101.6cm) |
0 – 4 mmhos/cm |
| Sodium adsorption ratio (0-101.6cm) |
0 |
| Soil reaction (1:1 water) (0-101.6cm) |
6.6 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
10 – 30% |
| Subsurface fragment volume >3" (Depth not specified) |
0 – 15% |
Ecological dynamics
As this site deteriorates, species such as rhizomatous wheatgrass, Idaho fescue, timber oatgrass, green rabbitbrush, and low sagebrush will increase. Bluebunch wheatgrass, spike fescue, and bitterbrush will decrease in frequency and production. Cheatgrass and annual forbs often invade. This site has relatively low productivity potential, and is not well suited to grazing improvement practices unless treated as part of a larger unit containing more productive areas.
The Historic Climax Plant Community (description follows the plant community diagram) has been determined by study of rangeland relic areas, or areas protected from excessive disturbance. Trends in plant communities going from heavily grazed areas to lightly grazed areas, seasonal use pastures, and historical accounts have also been used.
The following is a State and Transition Model Diagram that illustrates the common plant communities (states) that can occur on the site and the transitions between these communities. The ecological processes will be discussed in more detail in the plant community narratives following the diagram.
State and transition model
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State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Bluebunch Wheatgrass/Bitterbrush Plant Community (HCPC)
Community 1.1
Bluebunch Wheatgrass/Bitterbrush Plant Community (HCPC)
The interpretive plant community for this site is the Historic Climax Plant Community. Potential vegetation is estimated at 55% grasses or grass-like plants, 10% forbs, and 35% woody plants. The major grasses include bluebunch wheatgrass, Idaho fescue, spike fescue, and rhizomatous wheatgrass. Other grasses include big, Canby, and mutton bluegrass, Letterman and Columbia needlegrass, basin wildrye, slender wheatgrass, mountain muhly, oniongrass, and prairie junegrass. The major woody plants are bitterbrush, low and mountain big sagebrush, green rabbitbrush, and serviceberry. Other woody plants may include black and threetip sagebrush and snowbrush ceanothus. A typical plant composition for this state consists of bluebunch wheatgrass 10-35%, Idaho fescue 5-10%, spike fescue 5-10%, rhizomatous wheatgrass 5-10%, other grasses and grass-like plants 10-20%, perennial forbs 5-10%, bitterbrush 1-10%, low sagebrush 1-10%, and up to 15% other woody plants. Ground cover, by ocular estimate, varies from 35-40%. The total annual production (air-dry weight) of this state is about 700 pounds per acre, but it can range from about 500 lbs./acre in unfavorable years to about 900 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: WY0201 Growth curve name: 15-19W, UPLAND SITES Growth curve description: ALL UPLAND SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 35 30 20 5 0 0 0 (Monthly percentages of total annual growth) The state is stable and well adapted to the Central Rocky Mountains climatic conditions. The diversity in plant species allows for high drought resistance. This is a sustainable plant community (site/soil stability, watershed function, and biologic integrity Transitions or pathways leading to other plant communities are as follows: • Severe Ground Disturbance with Heavy, Continuous Season-long Grazing will convert this plant community to the Cheatgrass/Forb State. • Continuous Season-long Grazing will convert the plant community to the Low Sage/Rhizomatous Wheatgrass State.
Figure 3. Annual production by plant type (representative values) or group (midpoint values)
Figure 4. Plant community growth curve (percent production by month). WY0201, 15-19W Upland sites.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 10 | 35 | 30 | 20 | 5 |
State 2
Low Sage/Rhizomatous Wheatgrass Plant Community
Community 2.1
Low Sage/Rhizomatous Wheatgrass Plant Community
This plant community is a result of improper grazing management practices. The stand is composed of almost entirely low sage and rhizomatous wheatgrass with such forbs as phlox and goldenweed present as well. This state is commonly found on exposed, windswept ridges that are subject to harsh climatic conditions as well as severe winter use due to their exposed nature. The total annual production (air-dry weight) of this state is about 400 pounds per acre, but it can range from about 200 lbs./acre in unfavorable years to about 700 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: WY0201 Growth curve name: 15-19W, UPLAND SITES Growth curve description: ALL UPLAND SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 35 30 20 5 0 0 0 (Monthly percentages of total annual growth) The state is stable and protected from excessive erosion. The biotic integrity of this plant community is usually intact, however forage value will decrease and wildlife values will shift toward different species. The watershed is functioning. Transitional pathways leading to other plant communities are as follows: • Severe Ground Disturbance followed by Heavy, Continuous Season-long Grazing will convert this plant community to the Cheatgrass/Forb State. • Prescribed Grazing will return this state to near Historic Climax Plant Community (Bluebunch Wheatgrass/Bitterbrush State).
Figure 5. Plant community growth curve (percent production by month). WY0201, 15-19W Upland sites.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 10 | 35 | 30 | 20 | 5 |
State 3
Cheatgrass/Forb Plant Community
Community 3.1
Cheatgrass/Forb Plant Community
This plant community is the result of wildfire or severe ground disturbance followed by improper grazing management practices. Cheatgrass invades, effectively decreasing the fire interval (fewer years between fire events) and limiting the ability for non-sprouting woody plants to reestablish. Other species include green rabbitbrush and rhizomatous wheatgrass. The total annual production (air-dry weight) of this state is about 250 pounds per acre, but it can range from about 100 lbs./acre in unfavorable years to about 600 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: WY0201 Growth curve name: 15-19W, UPLAND SITES Growth curve description: ALL UPLAND SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 35 30 20 5 0 0 0 (Monthly percentages of total annual growth) The state is unstable and vulnerable to excessive erosion. The biotic integrity of this plant community is at risk depending on how far a shift has occurred in plant composition toward cheatgrass and annual forbs. The watershed is usually at risk or nonfunctioning due to an increase in bare ground. Transitional pathways leading to other plant communities are as follows: It is not often practicable or economically feasible to convert this plant community at the present time.
Figure 6. Plant community growth curve (percent production by month). WY0201, 15-19W Upland sites.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 10 | 35 | 30 | 20 | 5 |
Additional community tables
Table 5. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 78–275 | |||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 78–275 | – | ||
| 2 | 39–78 | |||||
| Idaho fescue | FEID | Festuca idahoensis | 39–78 | – | ||
| 3 | 39–78 | |||||
| western wheatgrass | PASM | Pascopyrum smithii | 39–78 | – | ||
| 4 | 39–78 | |||||
| spike fescue | LEKI2 | Leucopoa kingii | 39–78 | – | ||
| 5 | 39–78 | |||||
| timber oatgrass | DAIN | Danthonia intermedia | 39–78 | – | ||
| 6 | 78–157 | |||||
| Grass, perennial | 2GP | Grass, perennial | 0–39 | – | ||
| Letterman's needlegrass | ACLE9 | Achnatherum lettermanii | 0–39 | – | ||
| Columbia needlegrass | ACNE9 | Achnatherum nelsonii | 0–39 | – | ||
| threadleaf sedge | CAFI | Carex filifolia | 0–39 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 0–39 | – | ||
| slender wheatgrass | ELTR7 | Elymus trachycaulus | 0–39 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–39 | – | ||
| basin wildrye | LECI4 | Leymus cinereus | 0–39 | – | ||
| oniongrass | MEBU | Melica bulbosa | 0–39 | – | ||
| mountain muhly | MUMO | Muhlenbergia montana | 0–39 | – | ||
| muttongrass | POFE | Poa fendleriana | 0–39 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–39 | – | ||
|
Forb
|
||||||
| 7 | 39–78 | |||||
| Forb, perennial | 2FP | Forb, perennial | 0–39 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 0–39 | – | ||
| agoseris | AGOSE | Agoseris | 0–39 | – | ||
| pussytoes | ANTEN | Antennaria | 0–39 | – | ||
| sandwort | ARENA | Arenaria | 0–39 | – | ||
| milkvetch | ASTRA | Astragalus | 0–39 | – | ||
| arrowleaf balsamroot | BASA3 | Balsamorhiza sagittata | 0–39 | – | ||
| sego lily | CANU3 | Calochortus nuttallii | 0–39 | – | ||
| Indian paintbrush | CASTI2 | Castilleja | 0–39 | – | ||
| hawksbeard | CREPI | Crepis | 0–39 | – | ||
| fleabane | ERIGE2 | Erigeron | 0–39 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–39 | – | ||
| aster | EUCEP2 | Eucephalus | 0–39 | – | ||
| bitter root | LERER | Lewisia rediviva var. rediviva | 0–39 | – | ||
| stoneseed | LITHO3 | Lithospermum | 0–39 | – | ||
| desertparsley | LOMAT | Lomatium | 0–39 | – | ||
| lupine | LUPIN | Lupinus | 0–39 | – | ||
| creeping barberry | MARE11 | Mahonia repens | 0–39 | – | ||
| bluebells | MERTE | Mertensia | 0–39 | – | ||
| locoweed | OXYTR | Oxytropis | 0–39 | – | ||
| beardtongue | PENST | Penstemon | 0–39 | – | ||
| phacelia | PHACE | Phacelia | 0–39 | – | ||
| phlox | PHLOX | Phlox | 0–39 | – | ||
| stonecrop | SEDUM | Sedum | 0–39 | – | ||
| clover | TRIFO | Trifolium | 0–39 | – | ||
| American vetch | VIAM | Vicia americana | 0–39 | – | ||
|
Shrub/Vine
|
||||||
| 8 | 8–78 | |||||
| antelope bitterbrush | PUTR2 | Purshia tridentata | 8–78 | – | ||
| 9 | 8–78 | |||||
| little sagebrush | ARAR8 | Artemisia arbuscula | 8–78 | – | ||
| 10 | 39–118 | |||||
| Saskatoon serviceberry | AMAL2 | Amelanchier alnifolia | 0–39 | – | ||
| black sagebrush | ARNO4 | Artemisia nova | 0–39 | – | ||
| big sagebrush | ARTR2 | Artemisia tridentata | 0–39 | – | ||
| threetip sagebrush | ARTR4 | Artemisia tripartita | 0–39 | – | ||
| snowbrush ceanothus | CEVE | Ceanothus velutinus | 0–39 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–39 | – | ||
| American red raspberry | RUID | Rubus idaeus | 0–39 | – | ||
Interpretations
Animal community
Animal Community – Wildlife Interpretations
Bluebunch Wheatgrass/Bitterbrush Plant Community (HCPC): When blown clear, this plant community provides limited winter forage for large grazers when snow depth prevents foraging on other sites. Otherwise, it is mostly used by wildlife in transit to other habitats.
Low Sage/Rhizomatous Wheatgrass Plant Community: This plant community may be useful for the same wildlife that would use the Historic Climax Plant Community. However, the plant community composition is less diverse, and thus, less apt to meet the seasonal needs of these animals.
Cheatgrass/Forb Plant Community: This plant community exhibits a low level of plant species diversity. In most cases, it is not a desirable plant community to select as a wildlife habitat management objective.
Animal Community – Grazing Interpretations
The following table lists suggested stocking rates for cattle under continuous season-long grazing under normal growing conditions. These are conservative estimates that should be used only as guidelines in the initial stages of the conservation planning process. Often, the current plant composition does not entirely match any particular plant community (as described in this ecological site description). Because of this, a field visit is recommended, in all cases, to document plant composition and production. More precise carrying capacity estimates should eventually be calculated using this information along with animal preference data, particularly when grazers other than cattle are involved. Under more intensive grazing management, improved harvest efficiencies can result in an increased carrying capacity. If distribution problems occur, stocking rates must be reduced to maintain plant health and vigor.
Plant Community Production Carrying Capacity*
(lb./ac) (AUM/ac)
Bluebunch Wheatgrass/Bitterbrush (HCPC) 500-900 .25
Low Sage/Rhizomatous Wheatgrass 200-700 .12
Cheatgrass/Forb 100-600 .08
* - Continuous, season-long grazing by cattle under average growing conditions.
Grazing by domestic livestock is one of the major income-producing industries in the area. Rangeland in this area may provide yearlong forage for cattle, sheep, or horses. During the dormant period, the forage for livestock use needs to be supplemented with protein because the quality does not meet minimum livestock requirements.
Hydrological functions
Water is the principal factor limiting forage production on this site. This site is dominated by soils in hydrologic group B and C, with localized areas in hydrologic group D. Infiltration ranges from moderately slow to moderate. Runoff potential for this site varies from low to moderate depending on soil hydrologic group and ground cover (refer to Part 630, NRCS National Engineering Handbook for detailed hydrology information).
Rills and gullies should not typically be present. Water flow patterns should be barely distinguishable if at all present. Pedestals are only slightly present in association with bunchgrasses. Litter typically falls in place, and signs of movement are not common. Chemical and physical crusts are rare to non-existent. Cryptogamic crusts are present, but only cover 1-2% of the soil surface.
Recreational uses
This site provides hunting opportunities for upland game species.
Wood products
No appreciable wood products are present on the site.
Supporting information
Inventory data references
Inventory Data References (narrative)
Information presented here has been derived from NRCS clipping data and other inventory data. Field observations from range trained personnel were also used. Those involved in developing this site include: Bill Christensen, Range Management Specialist, NRCS; Karen Clause, Range Management Specialist, NRCS; and Everet Bainter, Range Management Specialist, NRCS. Other sources used as references include: USDA NRCS Water and Climate Center, USDA NRCS National Range and Pasture Handbook, and USDA NRCS Soil Surveys from various counties.
Inventory Data References
Data Source Number of Records Sample Period State County
SCS-RANGE-417 58 1966-1986 WY Lincoln & others
Contributors
K. Clause
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) | K. Clause, E. Bainter |
|---|---|
| Contact for lead author | karen.clause@wy.usda.gov or 307-367-2257 |
| Date | 03/16/2007 |
| Approved by | E. Bainter |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rare to nonexistent. Where present, short and widely spaced. -
Presence of water flow patterns:
Barely observable. -
Number and height of erosional pedestals or terracettes:
Rare to nonexistent. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground can range from 0-30%. -
Number of gullies and erosion associated with gullies:
Active gullies should not be present. -
Extent of wind scoured, blowouts and/or depositional areas:
Rare to nonexistent. -
Amount of litter movement (describe size and distance expected to travel):
Herbaceous and large woody litter not expected to move. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil Stability Index ratings range from 2 (interspaces) to 6 (under plant canopy), but average values should be 3.5 or greater. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Currently no soil series are correlated to this ecological site. Soil Organic Matter of less than 3% is expected. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Plant community consists of 50-80% grasses, 10% forbs, and 10-40% shrubs. Evenly distributed plant canopy (50-75%) and litter plus moderate infiltration rates result in minimal runoff. Basal cover is typically less than 10% and marginally affects runoff on this site. Surface rock fragments of 20-50% provide stability to the site, but reduce infiltration. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. -
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:
Sub-dominant:
Other:
Additional:
Mid-size, cool season bunchgrasses>> perennial shrubs>perennial forbs=cool season rhizomatous grasses=short cool season bunchgrasses -
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Minimal decadence, typically associated with shrub component. -
Average percent litter cover (%) and depth ( in):
Litter ranges from 15-20% of total canopy measurement with total litter (including beneath the plant canopy) from 40-60% expected. Herbaceous litter depth typically ranges from 3-10mm. Woody litter can be up to a couple inches (4-6 cm). -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
English: 500-900 lb/ac (700 lb/ac average); Metric 560-1008 kg/ha (784 kg/ha average). -
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:
Bare ground greater than 50% is the most common indicator of a threshold being crossed. Rabbitbrush, Sandberg bluegrass, buckwheat, and phlox are common increasers. Annual weeds such as cheatgrass and mustards are common invasive species in disturbed sites. -
Perennial plant reproductive capability:
All species are capable of reproducing, except in extreme drought years.
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