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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.
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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.
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous Not specified
Physiographic features
This site usually occurs in an upland position on relatively flat to moderately sloping land on all exposures.
Table 2. Representative physiographic features
Landforms (1) Alluvial fan
(2) Hill
(3) Plateau
Ponding frequency None Elevation 5500 – 7500 ft Slope 0 – 30 % Ponding depth 0 in Aspect Aspect is not a significant factor Climatic features
Annual precipitation ranges from 10-14 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.
Daytime winds are generally stronger than nighttime and occasional strong storms may bring brief periods of high winds with gusts to more than 50 mph.
Growth of native cool season plants begins about April 15 and continues to about June 15. Some green up of cool season plants usually occurs in September.
The following information is from the “Laramie” climate station:
Minimum Maximum 5 yrs. out of 10 between
Frost-free period (days): 57 149 June 1 – September 16
Freeze-free period (days): 94 183 May 15 – September 28
Annual Precipitation (inches): 5.8 17.34
Mean annual precipitation: 11.53 inches
Mean annual air temperature: 42.2 F (30.4 F Avg. Min. to 53.9 F 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 ”Dixon ” and “Medicine Bow”.Table 3 Representative climatic features
Frost-free period (average) 150 days Freeze-free period (average) 180 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Stream type: None
Soil features
The soils of this site are deep to moderately deep (greater than 20" to bedrock) & well-drained. Textures range from loams to very fine sandy loam.
Table 4. Representative soil features
Surface texture (1) Loam
(2) Clay loam
(3) Fine sandy loam
Family particle size (1) Loamy
Drainage class Moderately well drained to well drained Permeability class Moderately slow to moderate Soil depth 20 – 60 in Surface fragment cover <=3" 0 – 20 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)2.5 – 6 in Calcium carbonate equivalent
(0-40in)0 – 15 % Electrical conductivity
(0-40in)0 – 8 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)6.6 – 8.4 Subsurface fragment volume <=3"
(Depth not specified)0 – 10 % Subsurface fragment volume >3"
(Depth not specified)0 – 5 % Ecological dynamics
As this site deteriorates from improper grazing management, woody species such as big sagebrush and rubber rabbitbrush will increase. Bunchgrasses such as needle and thread, bluebunch wheatgrass, and green needlegrass will decrease in frequency and production. These are usually replaced by prairie junegrass, Sandberg bluegrass, blue grama, and several undesirable forbs.
Big sagebrush will become dominant on some areas with an absence of fire. Wildfires are often actively controlled so chemical control using herbicides has replaced the historic role of fire on this site. Recently, prescribed burning has regained some popularity.
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
Custom diagramStandard diagram
More interactive model formats are also available. View Interactive Models
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 5 submodel, plant communities
State 1
Rhizomatous Wheatgrass/Needle and Thread Plant Community (HCPC)Community 1.1
Rhizomatous Wheatgrass/Needle and Thread Plant Community (HCPC)The interpretive plant community for this site is the Historic Climax Plant Community. Potential vegetation is estimated at 80% grasses or grass-like plants, 10% forbs and 10% woody plants.
The major grasses include rhizomatous wheatgrass, needle and thread, bluebunch wheatgrass, and green needlegrass. Big sagebrush and rubber rabbitbrush are the major woody plants.
A typical plant composition for this state consists of rhizomatous wheatgrass 30-40%, needle and thread 10-20%, bluebunch wheatgrass 5-15%, green needlegrass 5-10%, muttongrass 5-10%, perennial forbs 5-10%,and big sagebrush 5-15%. Ground cover, by ocular estimate, varies from 30-40%.
The total annual production (air-dry weight) of this state is about 1100 pounds per acre, but it can range from about 600lbs./acre in unfavorable years to about 1400 lbs./acre in above average years.
This state is extremely stable and well adapted to the Cool Central Desertic Basins and Plateaus climate. 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:
• Continuous Season-long Grazing will convert the plant community to the Big Sagebrush/Mid Grass Plant Community if big sagebrush is present at 5-10%.
• Moderate Continuous Season-long Grazing or Continuous Spring Grazing will convert the plant community to the Blue Grama Sod Plant Community
• Heavy Continuous Season Long Grazing with Wild Fire will convert this plant community to the Rabbitbrush/Cheatgrass plant community.Figure 4. Annual production by plant type (representative values) or group (midpoint values)
Figure 5. Plant community growth curve (percent production by month). WY0901 , 34AI, Upland Sites. All 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 10 35 40 10 0 5 0 0 0 State 2
Big Sagebrush/Mid Grass Plant CommunityCommunity 2.1
Big Sagebrush/Mid Grass Plant CommunityThis plant community is the result of continuous season long grazing of the HCPC. Big sagebrush dominates the site with an understory of rhizomatous Wheatgrass and needle and thread. Prairie junegrass, threadleaf sedge, blue grama, and other short grass and grasslike plants begin to increase in frequency and production. When compared to the HCPC, big sagebrush has increased to 25-35%
The total annual production (air-dry weight) of this state is about 1000 pounds per acre, but it can range from about 500 lbs./acre in unfavorable years to about 1300 lbs./acre in above average years.
The soil is protected and erosion may increase if management is not changed. The biotic integrity may be reduced due to loss of mid grasses and change in structure. The watershed is functioning but some disturbances could put it at risk
Transitional pathways leading to other plant communities are as follows:
• Brush Management and Prescribed Grazing will return this state to near Historic Climax Plant Community (Rhizomatous Wheatgrass/Needle and Thread Plant Community).
• Brush Management with Heavy Continuous Season-long Grazing will convert the plant community to the Heavy Brush Plant Community.
• Heavy Continuous Season-long Grazing will convert the plant community to the Blue Grama Sod Plant Community.Figure 6. Plant community growth curve (percent production by month). WY0901 , 34AI, Upland Sites. All 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 10 35 40 10 0 5 0 0 0 State 3
Blue Grama Sod Plant CommunityCommunity 3.1
Blue Grama Sod Plant CommunityThis plant community is a result of moderate to heavy continuous season-long grazing or continuous spring grazing in the absence of big Sagebrush. Needle and thread and bluebunch wheatgrass give dominance to shorter stature grasses such as blue grama, prairie junegrass, Sandberg bluegrass, and threadleaf sedge. Rhizomatous wheatgrasses have also decreased. Forbs such as hoods phlox, yarrow, and fringed sagewort are common.
The total annual production (air-dry weight) of this state is about 700 pounds per acre, but it can range from about 400 lbs./acre in unfavorable years to about 900 lbs./acre in above average years.
This state is somewhat stable but vulnerable to excessive erosion. The biotic integrity of this plant community is at risk or non-functioning. The watershed is usually at risk or non-functioning as bare ground increases.
Transitional pathways leading to other plant communities are as follows:
• Mechanical Treatment (Chiseling, etc.) followed by Prescribed Grazing or Long-term Prescribed Grazing may eventually return this state to near Historic Climax Plant Community (Rhizomatous Wheatgrass/Needle and Thread Plant Community).
• Mechanical Treatment followed by Moderate Continuous Season Long Grazing will lead this community to the Rabbitbrush/Cheatgrass Plant Community.Figure 7. Plant community growth curve (percent production by month). WY0901 , 34AI, Upland Sites. All 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 10 35 40 10 0 5 0 0 0 State 4
Rabbitbrush/Cheatgrass Plant CommunityCommunity 4.1
Rabbitbrush/Cheatgrass Plant CommunityThis plant community is a result of moderate to heavy continuous season-long grazing following fire or other practices designed to remove big sagebrush. Most desirable species have been removed allowing establishment of rabbitbrush (prolific sprouter) cheatgrass and other annuals. Prickly pear cactus is a large component of this community and provides refuge and seed source for blue grama, needle and thread, and other species.
The total annual production (air-dry weight) of this state is about 400 pounds per acre, but it can range from about 50 lbs./acre in unfavorable years to about 600 lbs./acre in above average years.
This state is unstable and vulnerable to excessive erosion. The biotic integrity of this plant community is at risk or non-functioning. The watershed is usually at risk or non-functioning as bare ground increases.
Transitional pathways leading to other plant communities are as follows:
Brush Management (chemical), Chemical Seedbed Preparation and Reseeding followed by Prescribed Grazing or Long-term Prescribed Grazing may eventually return this state to near Historic Climax Plant Community (Rhizomatous Wheatgrass/Needle and Thread Plant Community).Figure 8. Plant community growth curve (percent production by month). WY0901 , 34AI, Upland Sites. All 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 10 35 40 10 0 5 0 0 0 State 5
Heavy Brush Plant CommunityCommunity 5.1
Heavy Brush Plant CommunityThis plant community is the result of heavy continuous season long grazing or continuous spring grazing. Big sagebrush dominates the site with a sparse understory of rhizomatous Wheatgrass and needle and thread. Prairie junegrass, threadleaf sedge, blue grama, and other short grass and grasslike plants are present but provide insignificant amount to total production. When compared to the HCPC, big sagebrush has increased to 40-50%. This community is susceptible to invasion by cheatgrass and other noxious weeds.
The total annual production (air-dry weight) of this state is about 600 pounds per acre, but it can range from about 400 lbs./acre in unfavorable years to about 800 lbs./acre in above average years.
This state is unstable and vulnerable to excessive erosion. The biotic integrity is reduced due to loss production. The watershed is functioning at risk
Transitional pathways leading to other plant communities are as follows:
• Brush Management, Reseeding and Long Term Prescribed Grazing will return this state to near Historic Climax Plant Community (Rhizomatous Wheatgrass/Needle and Thread Plant Community).
• Brush Management with Long Term Prescribed Grazing will convert the plant community similar to the Big Sagebrush/Mid Grass Plant Community.
• Heavy Continuous Season-long Grazing following Brush Management (mechanical or fire) or Wild Fire will convert the plant community to the Rabbitbrush/Cheatgrass Plant Community.Figure 9. Plant community growth curve (percent production by month). WY0901 , 34AI, Upland Sites. All 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 10 35 40 10 0 5 0 0 0 Additional community tables
Table 5. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 330–440 western wheatgrass PASM Pascopyrum smithii 330–440 – 2 110–220 needle and thread HECO26 Hesperostipa comata 110–220 – 3 55–165 bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 55–165 – 4 55–110 green needlegrass NAVI4 Nassella viridula 55–110 – 5 55–110 muttongrass POFE Poa fendleriana 55–110 – 6 55–220 Grass, perennial 2GP Grass, perennial 0–55 – ACBL Achnatherum ×bloomeri 0–55 – Indian ricegrass ACHY Achnatherum hymenoides 0–55 – blue grama BOGR2 Bouteloua gracilis 0–55 – needleleaf sedge CADU6 Carex duriuscula 0–55 – threadleaf sedge CAFI Carex filifolia 0–55 – plains reedgrass CAMO Calamagrostis montanensis 0–55 – squirreltail ELEL5 Elymus elymoides 0–55 – prairie Junegrass KOMA Koeleria macrantha 0–55 – mountain muhly MUMO Muhlenbergia montana 0–55 – Sandberg bluegrass POSE Poa secunda 0–55 – Forb7 55–165 Forb, perennial 2FP Forb, perennial 0–55 – yarrow ACHIL Achillea 0–55 – prairie sagewort ARFR4 Artemisia frigida 0–55 – larkspur DELPH Delphinium 0–55 – beardtongue PENST Penstemon 0–55 – spiny phlox PHHO Phlox hoodii 0–55 – scarlet globemallow SPCO Sphaeralcea coccinea 0–55 – Shrub/Vine8 55–165 big sagebrush ARTR2 Artemisia tridentata 55–165 – 9 0–55 yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 0–55 – 10 0–55 Shrub (>.5m) 2SHRUB Shrub (>.5m) 0–55 – Table 6. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 7. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 4.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 5.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
Animal Community – Wildlife Interpretations
Rhizomatous Wheatgrass/Needle and Thread Plant Community (HCPC): The predominance of grasses in this plant community favors grazers and mixed feeders such as antelope and elk. Suitable thermal and escape cover is limited to topographical variances. When found adjacent to sagebrush dominated sites, this plant community may provide brood rearing and foraging opportunities for sage grouse, as well as lek sites. Other birds and mammals visit this site and may include meadow larks, raptors, rabbits, and ground squirrels.
Big Sagebrush/Mid Grass Plant Community: This plant community may be useful for the same wildlife that would use the Historic Climax Plant Community. Additional cover is available in this community but foraging resources have been reduced.
Blue Grama Sod Plant Community: This plant community may be beneficial 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.
Rabbitbrush/Cheatgrass Plant Community: This plant community provides very little wildlife habitat. Some forage value and cover may be attributed to this community.
Heavy Brush Plant Community: This plant community may be useful for the same wildlife that would use the Historic Climax Plant Community. Additional cover is available in this community but foraging resources have been reduced.
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)
Rhizomatous Wheatgrass/Needle and Thread (HCPC) 600-1400 0.4
Big Sagebrush/Mid Grass 500-1300 0.3
Blue Grama Sod 400-900 0.2
Rabbitbrush/Cheatgrass 50-600 0.06
Heavy Brush 400-800 0.2
* - 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, with localized areas in hydrologic groups A and C. Infiltration ranges from rapid to moderate. Runoff potential for this site varies from low to moderate depending on soil hydrologic group and ground cover. In many cases, areas with greater than 75% ground cover have the greatest potential for high infiltration and lower runoff. 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).
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 and shrubs. Litter typically falls in place, and signs of movement are not common. Chemical and physical crusts are rare to non-existent. Cryptogrammic crusts are present, but only cover 1-2% of the soil surface.Recreational uses
This site provides hunting opportunities for upland game species. The wide variety of plants which bloom from spring until fall have esthetic values that appeal to visitors.
Wood products
No appreciable wood products are present on the site.
Other products
None noted.
Supporting information
Inventory data references
Information presented here has been derived from NRCS clipping data and other inventory data. Field observations from range trained personnel were also used. 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 69 1967-1988 WY Carbon & others
Contributors
B. Brazee
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 05/01/2005 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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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 20-30% occurring in small areas throughout site -
Number of gullies and erosion associated with gullies:
Active gullies should not be present -
Extent of wind scoured, blowouts and/or depositional areas:
None -
Amount of litter movement (describe size and distance expected to travel):
Little to no plant litter movement. Plant litter remains in place and is not moved by erosional forces. -
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 70% or greater of soil surface and maintains soil surface integrity. Soil Stability class is anticipated to be 5 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. Healthy deep rooted native grasses enhance infiltration and reduce runoff. 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:
Cool Season mid stature grasses >> Short stature grasses/grasslikes > Forbs = Shrubs -
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 25-35% with depths of 0.25 to 1.0 inches -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
1100 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:
Blue grama, Threadleaf sedge, Fringed sagewort, Prickly Pear, Big sagebrush, Broom Snakeweed, Annuals and Species found on Noxious Weed List -
Perennial plant reproductive capability:
All species are capable of reproducing
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