Natural Resources
Conservation Service
Ecological site R034AY122WY
Loamy Green River and Great Divide Basins (Ly)
Last updated: 9/28/2023
Accessed: 11/21/2024
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
| R034AY104WY |
Clayey Green River and Great Divide Basins (Cy) Clayey |
|---|---|
| R034AY150WY |
Sandy Green River and Great Divide Basins (Sy) Sandy |
| R034AY162WY |
Shallow Loamy Green River and Great Divide Basins (SwLy) Shallow Loamy |
Similar sites
| R034AY222WY |
Loamy Foothills and Basins West (Ly) Loamy (Ly) 10-14W has higher production. |
|---|---|
| R034AY104WY |
Clayey Green River and Great Divide Basins (Cy) Clayey (Cy) 7-9GR has heavier soil textures and more rhizomatous wheatgrass. |
| R034AY150WY |
Sandy Green River and Great Divide Basins (Sy) Sandy (Sy) 7-9GR has coarser soil textures and more needleandthread and Indian ricegrass. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
Not specified |
Physiographic features
This site will usually occur in an upland position on relatively flat to moderately sloping land on all exposures.
Table 2. Representative physiographic features
| Landforms |
(1)
Alluvial fan
(2) Ridge (3) Stream terrace |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 6,000 – 7,200 ft |
| Slope | 60% |
| Ponding depth |
Not specified |
| Aspect | Aspect is not a significant factor |
Climatic features
Annual precipitation ranges from 7-9 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 July 15. Some green up of cool season plants may occur in September if moisture is available.
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 “Bitter Creek”, ”Farson ”, “Rock Springs FAA AP”, and “Wamsutter” in Sweetwater County; “Church Buttes Gas PLT”, and Mountain View” in Uinta County; “Fontenelle”, “La Barge”, and “Sage 4 NNW” in Lincoln County; and “Big Piney” in Sublette County.
Table 3. Representative climatic features
| Frost-free period (average) | 94 days |
|---|---|
| Freeze-free period (average) | 114 days |
| Precipitation total (average) | 8 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Figure 4. Annual precipitation pattern
Figure 5. Annual average temperature pattern
Influencing water features
There are no water features associated with this site.
Soil features
The soils of this site are moderately deep to very deep (greater than 15" to bedrock), well drained & moderately permeable. Thin coarse-loamy surface layers are common. Layers of the soil most influential to the plant community varies from 3 to 6 inches thick. Textures range from loams to very fine sandy loam.
Major Soil Series correlated to this site includes: Fraddle, Garsid, Langspring, Monte, McCullen, Sagecreek and some phases of the Clowers series.
Other Soil Series correlated to this site in MLRA 34 include: Talamantes and some phases of the Derrick and Tresano series.
Table 4. Representative soil features
| Surface texture |
(1) Loam (2) Clay loam (3) Fine sandy loam |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately slow to moderate |
| Soil depth | 15 – 60 in |
| Surface fragment cover <=3" | Not specified |
| Surface fragment cover >3" | Not specified |
| Available water capacity (0-40in) |
2.6 – 6 in |
| Calcium carbonate equivalent (0-40in) |
15% |
| Electrical conductivity (0-40in) |
8 mmhos/cm |
| Sodium adsorption ratio (0-40in) |
5 |
| Soil reaction (1:1 water) (0-40in) |
7.4 – 9 |
| Subsurface fragment volume <=3" (Depth not specified) |
Not specified |
| Subsurface fragment volume >3" (Depth not specified) |
Not specified |
Ecological dynamics
As this site deteriorates because of a combination of frequent and severe grazing, species such as big sagebrush, rabbitbrush, phlox, and yarrow will increase. Cool-season bunchgrasses such as bluebunch wheatgrass, Indian ricegrass, and needleandthread will decrease in frequency and production.
These plant communities narratives may not represent every possibility, but they probably are the most prevalent and repeatable plant communities. The plant composition tables shown above have been developed from the best available knowledge at the time of this revision. As more data is collected, some of these plant communities may be revised or removed, and new ones may be added. None of these plant communities should necessarily be thought of as “Desired Plant Communities”. According to the USDA NRCS National Range and Pasture Handbook, Desired Plant Communities (DPC’s) will be determined by the decision-makers and will meet minimum quality criteria established by the NRCS. The main purpose for including any description of a plant community here is to capture the current knowledge and experience at the time of this revision.
The Reference 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.
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
Mixed Grass/Big Sagebrush (Reference)
Community 1.1
Mixed Grass/Big Sagebrush (Reference)
The interpretive plant community for this site is the Reference Plant Community. This state evolved with grazing by large herbivores and is well suited for grazing by domestic livestock. Potential vegetation is estimated at 75% grasses or grass-like plants, 10% forbs, and 15% woody plants. The major grasses include thickspike wheatgrass, needleandthread, Indian ricegrass, bluebunch wheatgrass, prairie junegrass, and bottlebrush squirreltail. Other grasses occurring in the state may include Sandberg and Canby bluegrass, threadleaf and needleleaf sedge, and plains reedgrass. Wyoming big sagebrush is the dominant woody plant. Other woody species may include green rabbitbrush, bud sagebrush, shadscale, spiny hopsage, and winterfat. A typical plant composition for this state consists of thickspike wheatgrass 10-30%, needleandthread 10-20%, Indian ricegrass 10-20%, up to 10% prairie junegrass, up to 10% bottlebrush squirreltail, up to 10% bluebunch wheatgrass, other grasses and grass-like plants 5-15%, perennial forbs 5-15%, Wyoming big sagebrush 5-15%, and 5-15% other woody species. The overstory of sagebrush and understory of grass and forbs provide a diverse plant community that will support domestic livestock and wildlife such as mule deer and antelope. Ground cover, by ocular estimate, varies from 20-35%. The total annual production (air-dry weight) of this state is about 500 lbs./acre, but it can range from about 300 lbs./acre in unfavorable years to about 700 lbs./acre in above average years. This plant community is extremely stable and well adapted to the Cool Central Desertic Basins and Plateaus 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 Big Sagebrush/Bunchgrass State. • Heavy Continuous Season-long Grazing and No Fire will convert this plant community to the Big Sagebrush/Rhizomatous Wheatgrass State. • Wildfire with Heavy Continuous Season-long Grazing will convert this plant community to the Douglas Rabbitbrush/Rhizomatous Wheatgrass State.
Figure 6. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 225 | 375 | 525 |
| Shrub/Vine | 45 | 75 | 105 |
| Forb | 30 | 50 | 70 |
| Total | 300 | 500 | 700 |
Figure 7. Plant community growth curve (percent production by month). WY0401, 7-9GR, 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/Bunchgrass
Community 2.1
Big Sagebrush/Bunchgrass
This plant community is the result of long-term protection from grazing and fire. Wyoming big sagebrush dominates the site, often exceeding 20-40% annual production and lowering herbaceous forage production. Bunchgrasses such as bluebunch wheatgrass, bottlebrush squirreltail, needleandthread and Indian ricegrass dominate the understory. The total annual production (air-dry weight) of this state is about 350 pounds per acre, but it can range from about 100 lbs./acre in unfavorable years to about 500 lbs./acre in above average years. 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. Transitions or 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 Reference Plant Community (Mixed Grass/Big Sagebrush 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 Douglas Rabbitbrush/Rhizomatous Wheatgrass State).
Figure 8. Plant community growth curve (percent production by month). WY0401, 7-9GR, 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
Big Sagebrush/Rhizomatous Wheatgrass
Community 3.1
Big Sagebrush/Rhizomatous Wheatgrass
This plant community is the result of frequent and severe grazing. A thick canopy of Wyoming big sagebrush and rabbitbrush dominate, often exceeding 40% of the annual production. Thickspike wheatgrass, Letterman needlegrass, and bluegrasses dominate the understory with decreased amounts of bluebunch wheatgrass, Indian ricegrass, and needleandthread. The total annual production (air-dry weight) of this state is about 175 pounds per acre, but it can range from about 100 lbs./acre in unfavorable years to about 350 lbs./acre in above average years. 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. Transitions or 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 Reference Plant Community (Mixed Grass/Big Sagebrush 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 Douglas Rabbitbrush/Rhizomatous Wheatgrass State).
Figure 9. Plant community growth curve (percent production by month). WY0401, 7-9GR, 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
Douglas Rabbitbrush/Rhizomatous Wheatgrass
Community 4.1
Douglas Rabbitbrush/Rhizomatous Wheatgrass
This plant community is the result of severe disturbance such as brush management or wildfire followed by improper grazing. With sagebrush removed, it is dominated by Douglas rabbitbrush. Rhizomatous wheatgrasses, low growing bunchgrasses such as Sandberg bluegrass, and unpalatable annual and perennial forbs dominate the herbaceous understory. There is a substantial amount of bare ground. The total annual production (air-dry weight) of this state is about 100 pounds per acre, but it can range from about 50 lbs./acre in unfavorable years to about 250 lbs./acre in above average years. 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 and blowing soil. The watershed is functioning at risk. Transitions or pathways leading to other plant communities are as follows: • Chemical Brush Management followed by deferment for 1 to 2 years as part of a Prescribed Grazing plan will return this state to near Reference Plant Community (Mixed Grass/Big Sagebrush State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges.
Figure 10. Plant community growth curve (percent production by month). WY0401, 7-9GR, 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 |
Transition T1-2
State 1 to 2
Nonuse and No Fire will convert this plant community to the Big Sagebrush/Bunchgrass State
Transition T1-3
State 1 to 3
Heavy Continuous Season-long Grazing and No Fire will convert this plant community to the Big Sagebrush/Rhizomatous Wheatgrass State.
Transition T1-4
State 1 to 4
Wildfire with Heavy Continuous Season-long Grazing will convert this plant community to the Douglas Rabbitbrush/Rhizomatous Wheatgrass State.
Restoration pathway R2-1
State 2 to 1
Brush Management followed by deferment for 1 to 2 years as part of a Prescribed Grazing plan will return this state to near Reference Plant Community (Mixed Grass/Big Sagebrush State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges.
Transition T2-4
State 2 to 4
Brush Management or wildfire followed by Heavy Continuous Season-long Grazing will convert this plant community to the Douglas Rabbitbrush/Rhizomatous Wheatgrass State).
Restoration pathway R3-1
State 3 to 1
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 Sagebrush State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges.
Transition T3-4
State 3 to 4
Brush Management or wildfire followed by Heavy Continuous Season-long Grazing will convert this plant community to the Douglas Rabbitbrush/Rhizomatous Wheatgrass State).
Restoration pathway R4-1
State 4 to 1
Chemical Brush Management followed by deferment for 1 to 2 years as part of a Prescribed Grazing plan will return this state to near Reference Plant Community (Mixed Grass/Big Sagebrush State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges.
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 50–150 | |||||
| thickspike wheatgrass | ELLAL | Elymus lanceolatus ssp. lanceolatus | 50–150 | – | ||
| 2 | 50–100 | |||||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 50–100 | – | ||
| 3 | 50–100 | |||||
| needle and thread | HECO26 | Hesperostipa comata | 50–100 | – | ||
| 4 | 5–50 | |||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 5–50 | – | ||
| 5 | 5–50 | |||||
| squirreltail | ELEL5 | Elymus elymoides | 5–50 | – | ||
| 6 | 5–50 | |||||
| prairie Junegrass | KOMA | Koeleria macrantha | 5–50 | – | ||
| 7 | 25–75 | |||||
| Grass, perennial | 2GP | Grass, perennial | 0–25 | – | ||
| needleleaf sedge | CADU6 | Carex duriuscula | 0–25 | – | ||
| threadleaf sedge | CAFI | Carex filifolia | 0–25 | – | ||
| plains reedgrass | CAMO | Calamagrostis montanensis | 0–25 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–25 | – | ||
|
Forb
|
||||||
| 8 | 25–75 | |||||
| Forb, perennial | 2FP | Forb, perennial | 0–25 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 0–25 | – | ||
| rosy pussytoes | ANRO2 | Antennaria rosea | 0–25 | – | ||
| milkvetch | ASTRA | Astragalus | 0–25 | – | ||
| Indian paintbrush | CASTI2 | Castilleja | 0–25 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 0–25 | – | ||
| larkspur | DELPH | Delphinium | 0–25 | – | ||
| fleabane | ERIGE2 | Erigeron | 0–25 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–25 | – | ||
| aster | EUCEP2 | Eucephalus | 0–25 | – | ||
| toadflax | LINAR | Linaria | 0–25 | – | ||
| granite prickly phlox | LIPU11 | Linanthus pungens | 0–25 | – | ||
| desertparsley | LOMAT | Lomatium | 0–25 | – | ||
| beardtongue | PENST | Penstemon | 0–25 | – | ||
| spiny phlox | PHHO | Phlox hoodii | 0–25 | – | ||
| stemless mock goldenweed | STAC | Stenotus acaulis | 0–25 | – | ||
| clover | TRIFO | Trifolium | 0–25 | – | ||
| deathcamas | ZIGAD | Zigadenus | 0–25 | – | ||
|
Shrub/Vine
|
||||||
| 9 | 25–75 | |||||
| big sagebrush | ARTR2 | Artemisia tridentata | 25–75 | – | ||
| 10 | 25–75 | |||||
| prairie sagewort | ARFR4 | Artemisia frigida | 0–25 | – | ||
| shadscale saltbush | ATCO | Atriplex confertifolia | 0–25 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–25 | – | ||
| spiny hopsage | GRSP | Grayia spinosa | 0–25 | – | ||
| winterfat | KRLA2 | Krascheninnikovia lanata | 0–25 | – | ||
| bud sagebrush | PIDE4 | Picrothamnus desertorum | 0–25 | – | ||
Interpretations
Animal community
Mixed Grass/Big Sagebrush Plant Community(HCPC): Suitable thermal and escape cover for mule deer may be limited due to the low height of woody plants. However, sagebrush, which can approach 15% protein and 40-60% digestibility, provides important winter forage for mule deer and antelope. Year-round habitat is provided for sage grouse and many other sagebrush obligate species such as the sage sparrow, Brewer’s sparrow, sage thrasher, pygmy rabbit, sagebrush vole, horned lizard, and pronghorn antelope. Other birds that would frequent this plant community include horned larks and golden eagles.
Big Sagebrush/Bunchgrass Plant Community: This plant community may be useful for the same wildlife that would use the Historic Climax Plant Community.
Big Sagebrush/Rhizomatous Wheatgrass 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.
Douglas Rabbitbrush/Rhizomatous Wheatgrass Plant Community: These communities provide limited forage for antelope and mule deer due to low production and lack of sagebrush. They may be used as a foraging site by sage grouse if proximal to woody cover.
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.
Plant Community Production (lb./ac) and Carrying Capacity* (AUM/ac)
Mixed Grass/Big Sagebrush (HCPC) 300-700 lb./ac and .15 AUM/ac
Big Sagebrush/Bunchgrass 100-500 lb./ac and .1 AUM/ac
Big Sagebrush/Rhizomatous Wheatgrass 100-300 lb./ac and .05 AUM/ac
Douglas Rabbitbrush/Rhizomatous Wheatgrass 50-250 lb./ac and .03 AUM/ac
* - 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. 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.
Contributors
Karen Clause
Approval
Kirt Walstad, 9/28/2023
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, J. Haverkamp, B. Brazee, E. Bainter |
|---|---|
| Contact for lead author | karen.clause@wy.usda.gov or 307-367-2257 |
| Date | 03/16/2007 |
| Approved by | Kirt Walstad |
| 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 20-50%. -
Number of gullies and erosion associated with gullies:
Active gullies should not be present. -
Extent of wind scoured, blowouts and/or depositional areas:
Minimal to nonexistent. -
Amount of litter movement (describe size and distance expected to travel):
Herbaceous litter expected to move only in small amounts (to leeward side of shrubs) due to wind. Large woody debris from sagebrush will show no movement. -
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 3.0 or greater. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Typically an A-horizon of 3-12 inches (7-30 cm) with weak to medium sub-angular blocky or sometimes granular or platy structure that is brown to grayish brown (i.e. 10YR 5/3 or 5/2) in color with OM of .5 to 1%. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Plant community consists of 55-70% grasses, 15% forbs, and 15-30% shrubs. Evenly distributed plant canopy (30-50%) and litter plus moderate to moderately rapid infiltration rates result in minimal runoff. Basal cover is typically less than 5% for this site and does very little to effect 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. A coarse, dry subsurface will often refuse a probe, causing misidentification of a compaction layer. Most soil profiles must be described by hand dug holes. -
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>> cool season rhizomatous grasses=perennial shrubs>perennial forbs>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 5-35% of total canopy measurement with total litter (including beneath the plant canopy) from 10-60% expected. Herbaceous litter depth is typically very shallow, ranging from 1-5mm. Woody litter can be up to a couple inches (4-6cm). -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
English: 300-700 lb/ac (500 lb/ac average); Metric: 336-784 kg/ha (560 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 60% is the most common indicator of a threshold being crossed. Rabbitbrush, Sandberg bluegrass, and phlox are common increasers. Annual weeds such as halogeton, kochia, and Russian thistle are common invasive species in disturbed sites. -
Perennial plant reproductive capability:
All species are capable of reproducing, except in drought years.
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