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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.
Associated sites
R043BY130WY Overflow High Mountains
Overflow
R043BY162WY Shallow Loamy High Mountains
Shallow Loamy
Similar sites
R043BY222WY Loamy Foothills and Mountains West
Loamy (Ly) 15-19W has lower production.
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous Not specified
Physiographic features
This site occurs on gentle to steep mountain slopes.
Table 2. Representative physiographic features
Landforms (1) Hill
(2) Alluvial fan
(3) Stream terrace
Flooding frequency None Ponding frequency None Elevation 6500 – 12000 ft Slope 2 – 30 % Ponding depth 0 in Climatic features
Annual precipitation is fairly evenly distributed through the year and averages over 20 inches. Snows are heavy and usually remain in place during the winter. Annual snowfall averages 150 to 200 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.
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 June 1 at lower elevations, as late as July 15 at higher elevations, and continues until the beginning of September.
The following information is from the “Moran 5 WNW” climate station:
Table 3 Representative climatic features
Frost-free period (average) 50 days Freeze-free period (average) 90 days Precipitation total (average) 30 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
Figure 4. Annual precipitation pattern
Figure 5 Annual average temperature pattern
">Influencing water features
Soil features
The soils of this site are moderately deep (greater than 20" to bedrock) to very deep and well-drained with textures ranging from very fine sandy loams through clay loams. Some soils have a lime horizon below 3 feet. The overlying soil is usually noncalcareous.
Table 4. Representative soil features
Surface texture (1) Gravelly 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 due to a combination of frequent and severe grazing, species such as three-tip and mountain big sagebrush, buckwheat, and yarrow will increase. Rhizomatous wheatgrass and less palatable grasses such as Letterman needlegrass increase. Kentucky bluegrass may invade. Cool-season grasses such as bluebunch wheatgrass and Columbia needlegrass will decrease in frequency and production.
Mountain big sagebrush will become dominant with the 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
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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 1
Mixed Grass/Mountain Big Sage Plant Community (HCPC)Community 1.1
Mixed Grass/Mountain Big Sage Plant Community (HCPC)The interpretive plant community for this site is the Historic Climax Plant Community. This state evolved with grazing by large herbivores and is well suited for grazing by domestic livestock. Potential vegetation is estimated at 70% grasses or grass-like plants, 20% forbs, and 10% woody plants.
The major grasses include Idaho fescue, Columbia needlegrass, slender wheatgrass, and bluebunch wheatgrass. Other grasses may include mutton and Cusick bluegrass, bentgrass, prairie junegrass, Letterman, Richardson, and western needlegrass, sun and dunehead sedge, one-spike and timber oatgrass, thickspike wheatgrass, mountain and nodding brome, tufted hairgrass, spike trisetum, and oniongrass. Mountain big sagebrush is the dominant woody plant. Other woody species may include snowberry, serviceberry, silver and three-tip sagebrush, and green rabbitbrush.
A typical plant composition for this state consists of Idaho fescue 15-25%, Columbia needlegrass 15-25%, slender wheatgrass 10-20%, bluebunch wheatgrass 10-15%, other grasses and grass-like plants 10-20%, perennial forbs 10-20%, mountain big sagebrush 5-10%, and 5-10% other woody species. Ground cover, by ocular estimate, varies from 70-75%.
The total annual production (air-dry weight) of this state is about 2500 lbs./acre, but it can range from about 1800 lbs./acre in unfavorable years to about 3000 lbs./acre in above average years.
The following is the growth curve of this plant community expected during a normal year:
Growth curve number: WY0101
Growth curve name: 20+M, UPLAND SITES
Growth curve description: ALL UPLAND SITES
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
0 0 0 0 5 30 40 20 5 0 0 0
(Monthly percentages of total annual growth)
This plant community is extremely stable and well adapted to the Central Rocky Mountains 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:
• Nonuse and No Fire will convert this plant community to the Mountain Big Sage/Mixed Grass State.
• Heavy Continuous Season-long Grazing and No Fire will convert this plant community to the Dense Shrub/Forb State.
• Wildfire with Heavy Continuous Season-long Grazing will convert this plant community to the Three-tip Sage/Rabbitbrush State.
Figure 6. Annual production by plant type (representative values) or group (midpoint values)
State 2
Mountain Big Sage/Mixed Grass Plant CommunityCommunity 2.1
Mountain Big Sage/Mixed Grass Plant CommunityThis plant community is the result of long-term protection from grazing and fire. Mountain big sagebrush dominates the site, often exceeding 20-50% annual production and lowering herbaceous forage production. Bunchgrasses such as bluebunch wheatgrass, Columbia needlegrass, Idaho fescue, and mountain brome dominate the understory.
The total annual production (air-dry weight) of this state is about 2000 pounds per acre, but it can range from about 1500 lbs./acre in unfavorable years to about 2500 lbs./acre in above average years.
The following is the growth curve of this plant community expected during a normal year:
Growth curve number: WY0101
Growth curve name: 20+M, UPLAND SITES
Growth curve description: ALL UPLAND SITES
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
0 0 0 0 5 30 40 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:
• Brush Management followed by deferment for 1 to 2 years as part of a Prescribed Grazing plan will return this state to near Historic Climax Plant Community (Mixed Grass/Mountain Big Sage State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges.
• Brush Management followed by Heavy Continuous Season-long Grazing will convert this plant community to the Three-tip Sage/Rabbitbrush State.
• Continuous Season-long Grazing and No Fire will convert this plant community to the Dense Shrub/Forb State.
State 3
Dense Shrub/Forb Plant CommunityCommunity 3.1
Dense Shrub/Forb Plant CommunityThis plant community is the result of heavy, continuous season-long grazing and protection from fire. Mountain big sagebrush eventually dominates this plant community with its annual production often exceeding 50%. Forbs such as yarrow, phlox, lupine, larkspur, buckwheat, and pussytoes increase. Grasses such as mutton bluegrass, Letterman needlegrass, and rhizomatous wheatgrass increase in proportion to other grasses.
The total annual production (air-dry weight) of this state is about 1500 pounds per acre, but it can range from about 1000 lbs./acre in unfavorable years to about 2000 lbs./acre in above average years.
The following is the growth curve of this plant community expected during a normal year:
Growth curve number: WY0101
Growth curve name: 20+M, UPLAND SITES
Growth curve description: ALL UPLAND SITES
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
0 0 0 0 5 30 40 20 5 0 0 0
(Monthly percentages of total annual growth)
Soil erosion is accelerated because of increased bare ground. The biotic community has been compromised, but is relatively stable. The watershed is functioning, but is at risk of further degradation. Water flow patterns and pedestals are obvious. Infiltration is reduced and runoff is increased.
Transitional pathways leading to other plant communities are as follows:
• Brush Management followed by deferment for 1 to 2 years as part of a Prescribed Grazing plan will return this state to near Historic Climax Plant Community (Mixed Grass/Big Sage State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges.
• Brush Management or Wildfire followed by Heavy Continuous Season-long Grazing will convert this plant community to the Three-tip Sage/Rabbitbrush State).
State 4
Three-tip Sage/Rabbitbrush Plant CommunityCommunity 4.1
Three-tip Sage/Rabbitbrush Plant CommunityThis plant community is the result of brush management or wildfire followed by improper grazing management practices. With mountain big sagebrush removed, it is dominated by sprouting shrubs such as green rabbitbrush and three-tip sage. Rhizomatous wheatgrasses, Letterman needlegrass and unpalatable annual and perennial forbs dominate the herbaceous understory. Forbs such as prairie smoke, lupine, and thistles are common. There is a substantial amount of bare ground.
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 1500 lbs./acre in above average years.
The following is the growth curve of this plant community expected during a normal year:
Growth curve number: WY0101
Growth curve name: 20+M, UPLAND SITES
Growth curve description: ALL UPLAND SITES
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
0 0 0 0 5 30 40 20 5 0 0 0
(Monthly percentages of total annual growth)
The soil is not protected and erosion will increase if management is not changed. The biotic integrity may be reduced due to low vegetative production. The watershed is functioning at risk.
Transitions or pathways leading to other plant communities are as follows:
It is not often practicable or economically feasible to convert this plant community.
Additional community tables
Table 5. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 375–625 Idaho fescue FEID Festuca idahoensis 375–625 – 2 375–625 Columbia needlegrass ACNE9 Achnatherum nelsonii 375–625 – 3 250–500 slender wheatgrass ELTR7 Elymus trachycaulus 250–500 – 4 250–375 bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 250–375 – 5 250–500 Grass, perennial 2GP Grass, perennial 0–125 – Letterman's needlegrass ACLE9 Achnatherum lettermanii 0–125 – Richardson's needlegrass ACRI8 Achnatherum richardsonii 0–125 – bentgrass AGROS2 Agrostis 0–125 – mountain brome BRMA4 Bromus marginatus 0–125 – Porter brome BRPO2 Bromus porteri 0–125 – needleleaf sedge CADU6 Carex duriuscula 0–125 – threadleaf sedge CAFI Carex filifolia 0–125 – sun sedge CAINH2 Carex inops ssp. heliophila 0–125 – dunhead sedge CAPH2 Carex phaeocephala 0–125 – California oatgrass DACA3 Danthonia californica 0–125 – timber oatgrass DAIN Danthonia intermedia 0–125 – onespike danthonia DAUN Danthonia unispicata 0–125 – squirreltail ELELE Elymus elymoides ssp. elymoides 0–125 – thickspike wheatgrass ELLAL Elymus lanceolatus ssp. lanceolatus 0–125 – prairie Junegrass KOMA Koeleria macrantha 0–125 – basin wildrye LECI4 Leymus cinereus 0–125 – oniongrass MEBU Melica bulbosa 0–125 – Cusick's bluegrass POCU3 Poa cusickii 0–125 – muttongrass POFE Poa fendleriana 0–125 – spike trisetum TRSP2 Trisetum spicatum 0–125 – Forb6 250–500 Forb, perennial 2FP Forb, perennial 0–125 – common yarrow ACMI2 Achillea millefolium 0–125 – giant hyssop AGAST Agastache 0–125 – agoseris AGOSE Agoseris 0–125 – onion ALLIU Allium 0–125 – pussytoes ANTEN Antennaria 0–125 – milkvetch ASTRA Astragalus 0–125 – balsamroot BALSA Balsamorhiza 0–125 – Indian paintbrush CASTI2 Castilleja 0–125 – hawksbeard CREPI Crepis 0–125 – larkspur DELPH Delphinium 0–125 – buckwheat ERIOG Eriogonum 0–125 – aster EUCEP2 Eucephalus 0–125 – elkweed FRSP Frasera speciosa 0–125 – geranium GERAN Geranium 0–125 – avens GEUM Geum 0–125 – common sneezeweed HEAU Helenium autumnale 0–125 – sunflower HELIA3 Helianthus 0–125 – pea LATHY Lathyrus 0–125 – flax LINUM Linum 0–125 – stoneseed LITHO3 Lithospermum 0–125 – desertparsley LOMAT Lomatium 0–125 – lupine LUPIN Lupinus 0–125 – creeping barberry MARE11 Mahonia repens 0–125 – bluebells MERTE Mertensia 0–125 – locoweed OXYTR Oxytropis 0–125 – ragwort PACKE Packera 0–125 – beardtongue PENST Penstemon 0–125 – phacelia PHACE Phacelia 0–125 – phlox PHLOX Phlox 0–125 – buttercup RANUN Ranunculus 0–125 – western coneflower RUOC2 Rudbeckia occidentalis 0–125 – ragwort SENEC Senecio 0–125 – meadow-rue THALI2 Thalictrum 0–125 – clover TRIFO Trifolium 0–125 – American vetch VIAM Vicia americana 0–125 – violet VIOLA Viola 0–125 – mule-ears WYAM Wyethia amplexicaulis 0–125 – mountain deathcamas ZIEL2 Zigadenus elegans 0–125 – Shrub/Vine7 125–250 mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 125–250 – 8 0–125 Shrub, deciduous 2SD Shrub, deciduous 0–125 – Shrub, evergreen 2SE Shrub, evergreen 0–125 – Tree, deciduous 2TD Tree, deciduous 0–125 – Tree, evergreen 2TE Tree, evergreen 0–125 – Saskatoon serviceberry AMAL2 Amelanchier alnifolia 0–125 – silver sagebrush ARCA13 Artemisia cana 0–125 – threetip sagebrush ARTR4 Artemisia tripartita 0–125 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 0–125 – snowberry SYMPH Symphoricarpos 0–125 – 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 (%) Interpretations
Animal community
Animal Community – Wildlife Interpretations
Mixed Grass/Mountain Big Sage Plant Community (HCPC): This plant community provides suitable thermal and escape cover for mule deer, elk, and antelope. Sagebrush, which can approach 15% protein and 40-60% digestibility, provides important winter forage for mule deer and elk. Birds that would frequent this plant community include horned larks and golden eagles.
Mountain Big Sage/Mixed Grass Plant Community: This plant community may be useful for the same wildlife that would use the Historic Climax Plant Community.
Dense Shrub/Forb 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.
Three-tip Sage/Rabbitbrush Plant Community: This plant community provides limited forage for elk and mule deer due to low production and lack of palatable sagebrush species.
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)
Mixed Grass/Mountain Big Sage (HCPC) 1800-3000 0.8
Mountain Big Sage/Mixed Grass 1500-2500 0.6
Dense Shrub/Forb 1000-2000 0.47
Three-tip Sage/Rabbitbrush 500-1500 0.3
* - 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. Cryptogamic 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 an esthetic value that appeals to visitors.
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
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 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 0-10%. -
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 3 (interspaces) to 6 (under plant canopy), but average values should be 4.0 or greater. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil data is limited for this site. Soil OM of 6-16% is expected. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Plant community consists of 60-70% grasses, 20% forbs, and 10-20% shrubs. Evenly distributed plant canopy (60-95%) and litter plus moderate infiltration rates result in minimal runoff. Basal cover is typically greater than 15% for this site and does affect runoff on this site. -
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>tall, cool season bunchgrasses=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 5-40% of total canopy measurement with total litter (including beneath the plant canopy) from 50-90% expected. Herbaceous litter depth typically ranges from 5-15mm. 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: 1800-3000 lb/ac (2500 lb/ac average); Metric 2016-3360 kg/ha (2800 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 30% is the most common indicator of a threshold being crossed. Rabbitbrush, Sandberg bluegrass, buckwheat, phlox, and yarrow are common increasers. Kentucky bluegrass, common dandelion, thistles, and annual weeds 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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