Natural Resources
Conservation Service
Ecological site R049XA160WY
Shallow Igneous (Foothills and Mountains Southeast)
Accessed: 11/13/2024
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
| R049XA116WY |
Igneous (Foothills and Mountains Southeast) Igneous |
|---|
Similar sites
| R049XA116WY |
Igneous (Foothills and Mountains Southeast) Igneous, 049XA116WY has lower production |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
Not specified |
Physiographic features
This site is found in an upland position on rolling to steep mountain slopes
and ridges
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Ridge (3) Escarpment |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 6,500 – 8,500 ft |
| Slope | 5 – 70% |
| Ponding depth |
Not specified |
| Aspect | Aspect is not a significant factor |
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 1 and continues to about August 1.
The following information is from the “Hecla 1E” climate station:
Minimum Maximum 5 yrs. out of 10 between
Frost-free period (days): 93 151 May 20 – September 14
Freeze-free period (days): 106 184 May 9 – September 26
Annual Precipitation (inches): 9.56 24.23
Mean annual precipitation: 16.04 inches
Mean annual air temperature: 44.7F (32.1F Avg. Min. to 57.2F Avg. Max.)
For detailed information visit the Natural Resources Conservation Service National Water and Climate Center at http://www.wcc.nrcs.usda.gov/ website. Other climate station(s) representative of this precipitation zone include ”Glenrock 14 SSE”, “Foxpark” and “Horse Creek 2 NW”.
Table 3. Representative climatic features
| Frost-free period (average) | 151 days |
|---|---|
| Freeze-free period (average) | 184 days |
| Precipitation total (average) | 19 in |
Influencing water features
Soil features
These shallow, well drained soils are on bedrock-controlled mountain sides and foothills. Coarse fragment percentage is commonly more than 35 percent, but may be less in the surface layer.
Major Soil Series correlated to this site include:
Table 4. Representative soil features
| Surface texture |
(1) Gravelly loam (2) Cobbly sandy loam (3) Very cobbly |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained to somewhat excessively drained |
| Permeability class | Moderate to moderately rapid |
| Soil depth | 10 – 20 in |
| Surface fragment cover <=3" | 10 – 25% |
| Surface fragment cover >3" | 20 – 45% |
| Available water capacity (0-40in) |
0.6 – 1.2 in |
| Calcium carbonate equivalent (0-40in) |
Not specified |
| Electrical conductivity (0-40in) |
Not specified |
| Sodium adsorption ratio (0-40in) |
Not specified |
| Soil reaction (1:1 water) (0-40in) |
5.6 – 7.2 |
| Subsurface fragment volume <=3" (Depth not specified) |
15 – 30% |
| Subsurface fragment volume >3" (Depth not specified) |
30 – 50% |
Ecological dynamics
As this site deteriorates because of a combination of frequent and severe grazing, species such as Sandberg bluegrass, threadleaf sedge, prairie junegrass unpalatable forbs, and threetip sagebrush will increase. Grasses such as bluebunch wheatgrass, Montana wheatgrass, and Parry’s oatgrass will decrease in frequency and production.
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
More interactive model formats are also available.
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View Interactive Models
Click on state and transition labels to scroll to the respective text
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 1
Bluebunch wheatgrass, Idaho fescue, Threetip sagebrush Plant Community
Community 1.1
Bluebunch wheatgrass, Idaho fescue, Threetip sagebrush Plant Community
This plant community is the interpretive plant community for this site and is considered to be the Historic Climax Plant Community (HCPC). This plant community evolved with grazing by large herbivores and is well suited for grazing by domestic livestock. This plant community can be found on areas that are properly managed with grazing, and sometimes on areas receiving occasional short periods of rest. The potential vegetation is about 65% grasses or grass-like plants, 15% forbs, and 25% woody plants. The major grasses include bluebunch wheatgrass, and Idaho fescue. Other grasses occurring on the state include slimstem muhly, threadleaf sedge, Sandberg bluegrass, Canby bluegrass and Parry’s oatgrass. A variety of forbs also occur. Threetip sagebrush can be a conspicuous element of this state. Plant diversity is high. The total annual production (air-dry weight) of this state is about 900 lbs./acre, but it can range from about 600 lbs./acre in unfavorable years to about 1,200 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: Growth curve name: Growth curve description: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 5 20 45 20 5 5 0 0 0 (Monthly percentages of total annual growth) This plant community is extremely stable and well adapted to the climatic conditions. The diversity in plant species allows for high drought tolerance. 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: • No use and no fire for 20 years or more will convert this plant community to the Low Plant Density, Decadent Plants Community. • Moderate, continuous season-long grazing will convert the plant community to the Mixed Brush/Grass Plant Community.
Figure 2. Annual production by plant type (representative values) or group (midpoint values)
Figure 3. Plant community growth curve (percent production by month). WY1001, 15-19SE 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 |
| 0 | 0 | 0 | 5 | 20 | 45 | 20 | 5 | 5 | 0 | 0 | 0 |
State 2
Mixed Brush/Grass Plant Community
Community 2.1
Mixed Brush/Grass Plant Community
Historically, this plant community evolved under grazing and a low fire frequency. Currently, it is found under moderate, season-long grazing by livestock. Cool-season grasses make up the majority of the understory with the balance made up of annual cool-season grasses, and miscellaneous forbs. Dominants include threadleaf sedge, western wheatgrass, and Sandberg bluegrass. Forbs commonly found in this plant community include Hoods phlox and western yarrow. When compared to the Historic Climax Plant Community, threetip sagebrush has increased but does not produce the thick canopy cover found on sites with moderately deep to deep soils. Production of cool-season grasses has been reduced. The mixture of sagebrush, grass and forbs provide a diverse plant community that will support domestic livestock and wildlife such as mule deer and antelope. The total annual production (air-dry weight) of this state is about 650 pounds per acre, but it can range from about 450 lbs./acre in unfavorable years to about 850 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: Growth curve name: Growth curve description: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 5 20 45 20 5 5 0 0 0 (Monthly percentages of total annual growth) This plant community is resistant to change. The herbaceous species present are well adapted to grazing; however, species composition can be altered through long-term overgrazing. If the herbaceous component is intact, it tends to be resilient if the disturbance is not long-term. Transitions or pathways leading to other plant communities are as follows: • Prescribed grazing, will convert this plant community to the Bluebunch wheatgrass, Idaho fescue, Threetip sagebrush Plant Community. The probability of this occurring is high. • Frequent and severe grazing, will convert the plant community to the Threetip sagebrush, Sandberg bluegrass, Threadleaf sedge Plant Community. The probability of this occurring is high. If bare areas exist, along with no recovery periods from grazing, annuals can invade and plants not as resistant to grazing will be reduced.
Figure 4. Plant community growth curve (percent production by month). WY1001, 15-19SE 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 |
| 0 | 0 | 0 | 5 | 20 | 45 | 20 | 5 | 5 | 0 | 0 | 0 |
State 3
Low Plant Density, Decadent Plants Community
Community 3.1
Low Plant Density, Decadent Plants Community
This plant community is the result of long-term protection from grazing and fire. At first, excessive litter builds up shading out some of the grasses and forbs. Other plants become decadent with low vigor. Bunch grasses often develop dead centers. Eventually, the interspaces between plants increase in size leaving more soil surface exposed. Organic matter oxidizes in the air rather than being incorporated into the soil. The dominant plants tend to be somewhat similar to those found in the Historic Climax Plant Community. Weedy species and sedges have increased. Noxious weeds may invade the state if a seed source is present. Plant diversity is moderate to high. The total annual production (air-dry weight) of this state is about 750 pounds per acre, but it can range from about 600 lbs./acre in unfavorable years to about 900 lbs./acre in above average years. The following is the growth curve of the plant community expected during a normal year: Growth curve number: Growth curve name: Growth curve description: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 5 20 45 20 5 5 0 0 0 (Monthly percentages of total annual growth) This plant community is not resistant to change and is more vulnerable to severe disturbance than the HCPC. The introduction of grazing quickly changes the plant community. Soil erosion is accelerated because of increased bare ground. Water flow patterns and pedestaling are obvious. Infiltration is reduced and runoff is increased. Transitions or pathways leading to other plant communities are as follows: • Prescribed grazing, will return this plant community to at or near the Bluebunch wheatgrass, Idaho fescue, Threetip sagebrush Plant Community.
Figure 5. Plant community growth curve (percent production by month). WY1001, 15-19SE 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 |
| 0 | 0 | 0 | 5 | 20 | 45 | 20 | 5 | 5 | 0 | 0 | 0 |
State 4
Threetip sagebrush, Sandberg bluegrass, Threadleaf sedge Plant Community
Community 4.1
Threetip sagebrush, Sandberg bluegrass, Threadleaf sedge Plant Community
This plant community is created when the Mixed Brush/Grass Plant Community is subjected to frequent and severe grazing. Threetip sagebrush, Sandberg bluegrass, cudweed sagewort, hairy goldenaster, and threadleaf sedge will dominate the state. Compared to the HCPC, threetip sagebrush has increased. Virtually all cool-season mid-grasses are severely decreased. Plant diversity is low. The total annual production (air-dry weight) of this state is about 350 pounds per acre, but it can range from about 200 lbs./acre in unfavorable years to about 450 lbs./acre in above average years. The following is the growth curve of the plant community expected during a normal year: Growth curve number: Growth curve name: Growth curve description: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 5 20 45 20 5 5 0 0 0 (Monthly percentages of total annual growth) This plant community is relatively stable and somewhat resistant to overgrazing. The low growing grasses, sedges and threetip sagebrush effectively compete against the establishment of perennial cool-season grasses. The watershed is usually functioning. The biotic integrity is reduced by the lack of diversity in the plant community. Transitions or pathways leading to other plant communities are as follows: • Prescribed grazing will eventually return this plant community to the Mixed Brush/Grass Plant Community. • Long-term, prescribed grazing will eventually return this plant community to at or near the Bluebunch wheatgrass, Idaho fescue, Threetip sagebrush Plant Community.
Figure 6. Plant community growth curve (percent production by month). WY1001, 15-19SE 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 |
| 0 | 0 | 0 | 5 | 20 | 45 | 20 | 5 | 5 | 0 | 0 | 0 |
Additional community tables
Table 5. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 135–585 | |||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 90–225 | – | ||
| Idaho fescue | FEID | Festuca idahoensis | 90–225 | – | ||
| slimstem muhly | MUFI | Muhlenbergia filiculmis | 45–135 | – | ||
| 2 | 225–405 | |||||
| Grass, perennial | 2GP | Grass, perennial | 0–45 | – | ||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 0–45 | – | ||
| threadleaf sedge | CAFI | Carex filifolia | 0–45 | – | ||
| Parry's oatgrass | DAPA2 | Danthonia parryi | 0–45 | – | ||
| onespike danthonia | DAUN | Danthonia unispicata | 0–45 | – | ||
| Montana wheatgrass | ELAL7 | Elymus albicans | 0–45 | – | ||
| needle and thread | HECO26 | Hesperostipa comata | 0–45 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–45 | – | ||
| mountain muhly | MUMO | Muhlenbergia montana | 0–45 | – | ||
| mat muhly | MURI | Muhlenbergia richardsonis | 0–45 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 0–45 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–45 | – | ||
|
Forb
|
||||||
| 3 | 45–135 | |||||
| Forb, perennial | 2FP | Forb, perennial | 0–45 | – | ||
| yarrow | ACHIL | Achillea | 0–45 | – | ||
| rosy pussytoes | ANRO2 | Antennaria rosea | 0–45 | – | ||
| prairie sagewort | ARFR4 | Artemisia frigida | 0–45 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 0–45 | – | ||
| milkvetch | ASTRA | Astragalus | 0–45 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–45 | – | ||
| hairy false goldenaster | HEVI4 | Heterotheca villosa | 0–45 | – | ||
| beardtongue | PENST | Penstemon | 0–45 | – | ||
| spiny phlox | PHHO | Phlox hoodii | 0–45 | – | ||
| cinquefoil | POTEN | Potentilla | 0–45 | – | ||
| stonecrop | SEDUM | Sedum | 0–45 | – | ||
|
Shrub/Vine
|
||||||
| 4 | 45–135 | |||||
| threetip sagebrush | ARTR4 | Artemisia tripartita | 45–135 | – | ||
| 5 | 0–45 | |||||
| winterfat | KRLA2 | Krascheninnikovia lanata | 0–45 | – | ||
| 6 | 45–135 | |||||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 0–45 | – | ||
| black sagebrush | ARNO4 | Artemisia nova | 0–45 | – | ||
| big sagebrush | ARTR2 | Artemisia tridentata | 0–45 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–45 | – | ||
| rubber rabbitbrush | ERNA10 | Ericameria nauseosa | 0–45 | – | ||
| antelope bitterbrush | PUTR2 | Purshia tridentata | 0–45 | – | ||
Interpretations
Animal community
Animal Community – Wildlife Interpretations
Bluebunch wheatgrass, Idaho fescue, Threetip sagebrush Plant Community (HCPC): The predominance of grasses in this plant community favors grazers and mixed-feeders, such as bison, elk, and antelope. Suitable thermal and escape cover for deer may be limited due to the low quantities of woody plants. However, topographical variations could provide some escape cover. Birds that would frequent this plant community include Western meadowlarks, horned larks, and golden eagles. Many grassland obligate small mammals would occur here.
Mixed Brush/Grass Plant Community: The combination of an overstory of sagebrush and an understory of grasses and forbs provide a very diverse plant community for wildlife. The crowns of sagebrush tend to break up hard crusted snow on winter ranges, so mule deer and antelope may use this state for foraging and cover year-round, as would cottontail and jack rabbits. Brewer’s sparrows’ nest in big sagebrush plants, and hosts of other nesting birds utilize stands in the 20-30% cover range.
Low Plant Density, Decadent Plants Community: This plant community can provide important winter foraging for elk, mule deer and antelope, as sagebrush can approach 15% protein and 40-60% digestibility during that time.
Threetip sagebrush, Sandberg bluegrass, Threadleaf sedge Plant Community: This plant community may be useful for the same large grazers 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.
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, Idaho fescue, Threetip sagebrush 900 .3
Mixed Brush/Grass 650 .2
Low Plant Density, Decadent Plants 750 .25
Threetip sagebrush, Sandberg bluegrass, Threadleaf sedge 350 .1
* - 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 moderate to moderately rapid because of the shallow soils and low available water capacity. Runoff potential for this site varies from moderate to high. In many cases, areas with greater than 75% ground cover have the greatest potential for high infiltration and lower runoff; however, with AWC of 0.6-1.2 inch and shallow soil, runoff potential will still be quite high. An example of an exception would be where short-grasses form a strong sod and dominate the site. Areas where ground cover is less than 50% have the greatest potential to have reduced infiltration and higher runoff (refer to Part 630, NRCS National Engineering Handbook for detailed hydrology information).
Recreational uses
This site provides hunting opportunities for upland game species. The wide variety of plants which bloom from spring until fall have an esthetic value that appeals to visitors.
Wood products
No appreciable wood products are present on the site.
Other products
None noted.
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 was also used.
Inventory Data References
Data Source Number of Records Sample Period State County
SCS-RANGE-417 24 1963 -1987 WY Albany & others
Other references
Other sources used as references include: High Plains Regional Climate Center, USDA NRCS Water and Climate Center, USDA NRCS National Range and Pasture Handbook, and USDA NRCS Soil Surveys from various counties.
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) | |
|---|---|
| Contact for lead author | |
| Date | 03/01/2005 |
| Approved by | E. Bainter |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rills should not be present -
Presence of water flow patterns:
Barely observable -
Number and height of erosional pedestals or terracettes:
Essentially non-existent -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground is 40-50% occurring in small areas throughout site -
Number of gullies and erosion associated with gullies:
Active gullies should be restricted to areas of concentrated water flow patterns on steeper slopes -
Extent of wind scoured, blowouts and/or depositional areas:
Small scoured sites may be observed -
Amount of litter movement (describe size and distance expected to travel):
Litter movement is little to none based on topography and water flow patterns -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Plant cover and litter is at 50% or greater of soil surface and maintains soil surface integrity. Soil Stability class is anticipated to be 4 or greater. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Use Soil Series description for depth and color of A-horizon -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Grass canopy and basal cover should reduce raindrop impact and slow overland flow providing increased time for infiltration to occur. Infiltration is moderate. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
No compaction layer or soil surface crusting should be present. -
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 stature Cool Season Grasses > Shrubs > Forbs -
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Very Low -
Average percent litter cover (%) and depth ( in):
Average litter cover is 15-25% with depths of 0.25 to 0.5 inches -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
900 lbs/ac -
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:
Threadleaf sedge, Threetip sagebrush, Unpalatable Forbs, Species found on Noxious Weed List -
Perennial plant reproductive capability:
All species are capable of reproducing
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