Natural Resources
Conservation Service
Ecological site R043BY206WY
Clayey Overflow Foothills and Mountains West
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
| R043BY204WY |
Clayey Foothills and Mountains West Clayey |
|---|---|
| R043BY230WY |
Overflow Foothills and Mountains West Overflow |
Similar sites
| R043BY230WY |
Overflow Foothills and Mountains West Overflow (Ov), 15-19W has coarser soil textures. |
|---|---|
| R034AY206WY |
Clayey Overflow Foothills and Basins West (CyO) Clayey Overflow (CyO), 10-14W has lower production and no Idaho fescue. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
Not specified |
Physiographic features
This site occurs on gently sloping to moderately sloping flood plains, canyons, and small valley bottoms along intermittent streams.
Table 2. Representative physiographic features
| Landforms |
(1)
Alluvial fan
(2) Stream terrace |
|---|---|
| Flooding duration | Very brief (4 to 48 hours) |
| Flooding frequency | Frequent |
| Ponding frequency | None |
| Elevation | 1,707 – 2,530 m |
| Slope | 1 – 10% |
| Ponding depth | 0 cm |
Climatic features
Annual precipitation ranges from 15-19 inches per year. Wide fluctuations may occur in yearly precipitation and result in more dry years than those with more than normal precipitation. Temperatures show a wide range between summer and winter and between daily maximums and minimums. This is predominantly due to the high elevation and dry air, which permits rapid incoming and outgoing radiation. Cold air outbreaks in winter move rapidly from northwest to southeast and account for extreme minimum temperatures. Extreme storms may occur during the winter, but most severely affect ranch operations during late winter and spring.
Prevailing winds are from the southwest, and strong winds are less frequent than over other areas of Wyoming. Occasional storms, however, can bring brief periods of high winds with gusts exceeding 50 mph.
Growth of native cool season plants begins about May 15 and continues to about August 15.
The following information is from the “Jackson” climate station:
Minimum Maximum 5 yrs. out of 10 between
Frost-free period (days): 12 60 July 9 – August 12
Freeze-free period (days): 42 100 June 20 – August 26
Annual Precipitation (inches): <11.98 >19.69 (2 years in 10)
Mean annual precipitation: 17.00 inches
Mean annual air temperature: 38.9?F (23.3?F Avg. Min. to 54.5?F Avg. Max.)
For detailed information visit the Natural Resources Conservation Service National Water and Climate Center at http://www.wcc.nrcs.usda.gov/cgibin/state.pl?state=wy website. Other climate stations representative of this precipitation zone include ”Afton” in Lincoln County; and “Darwin Ranch” in Teton County.
Table 3. Representative climatic features
| Frost-free period (average) | 60 days |
|---|---|
| Freeze-free period (average) | 100 days |
| Precipitation total (average) | 483 mm |
Figure 2. Monthly average minimum and maximum temperature
Influencing water features
Soil features
The soils of this site are moderately deep (greater than 20” to bedrock) to very deep, well-drained soils with textures that vary from the finer portions of silty clay loams to sandy clay loams and clay loams. These soils occur in playa areas or along stream courses which receive periodic overflow from adjacent slopes. Erosion is slight except for some stream bank cutting. Infiltration and water movement is good. Root penetration is deep.
Table 4. Representative soil features
| Surface texture |
(1) Clay loam (2) Clay (3) Sandy clay loam |
|---|---|
| Family particle size |
(1) Clayey |
| Drainage class | Moderately well drained to well drained |
| Permeability class | Moderately slow to slow |
| Soil depth | 51 – 152 cm |
| Surface fragment cover <=3" | 0% |
| Surface fragment cover >3" | 0% |
| Available water capacity (0-101.6cm) |
7.11 – 14.48 cm |
| Calcium carbonate equivalent (0-101.6cm) |
0 – 5% |
| Electrical conductivity (0-101.6cm) |
0 – 8 mmhos/cm |
| Sodium adsorption ratio (0-101.6cm) |
0 – 10 |
| Soil reaction (1:1 water) (0-101.6cm) |
6.6 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
0% |
| Subsurface fragment volume >3" (Depth not specified) |
0% |
Ecological dynamics
As this site deteriorates, woody species such as snowberry, silver and mountain big sagebrush, and green rabbitbrush will increase. Rhizomatous wheatgrass and Letterman needlegrass will also increase. Kentucky bluegrass and introduced forbs such as dandelion often invade. Cool season grasses such as basin wildrye, western needlegrass, Canby bluegrass, and slender wheatgrass 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
Rhizomatous Wheatgrass/Basin Wildrye Plant Community (HCPC)
Community 1.1
Rhizomatous Wheatgrass/Basin Wildrye 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 suited for grazing by domestic livestock. Potential vegetation is estimated at 70% grasses or grass-like plants, 15% forbs and 15% woody plants. The major grasses include rhizomatous wheatgrass, Idaho fescue, basin wildrye, and slender wheatgrass. Other grasses/grasslikes may include big, Canby, mutton, and Sandberg bluegrass, blue wildrye, bluebunch wheatgrass, bottlebrush squirreltail, Letterman, Columbia, and western needlegrass, sun sedge, oniongrass, spike fescue, timber oatgrass, and prairie junegrass. Woody plants may include chokecherry, snowberry, serviceberry, woods rose, silver and mountain big sagebrush, and green rabbitbrush. A typical plant community consists of rhizomatous wheatgrass 10-20%, Idaho fescue 5-15%, basin wildrye 5-10%, slender wheatgrass 1-10%, other perennial grasses 10-25%, perennial forbs 5-15%, and 5-15% woody plants. Ground cover, by ocular estimate, varies from 60-75%. The total annual production (air-dry weight) of this state is about 2500 pounds per acre, but it can range from about 1500 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: WY0202 Growth curve name: 15-19W, EXTRA WATER SITES Growth curve description: OV, CYO EXTRA WATER SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 40 30 15 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 and additional moisture 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: • Continuous Season-Long Grazing will convert this plant community to the Mountain Big Sage/Wheatgrass State.
Figure 3. Annual production by plant type (representative values) or group (midpoint values)
Figure 4. Plant community growth curve (percent production by month). WY0202, 15-19W Extra water sites - LL, Ov, CyO, SL.
| 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 | 0 | 10 | 40 | 30 | 15 | 5 | 0 | 0 | 0 |
State 2
Mountain Big Sage/Idaho Fescue Plant Community
Community 2.1
Mountain Big Sage/Idaho Fescue Plant Community
This plant community evolved under continuous grazing by domestic livestock. Dominant grasses include Idaho fescue, rhizomatous wheatgrass, needleleaf sedge, and Sandberg bluegrass. Mountain big sagebrush has increased, with annual production often exceeding 40%. Silver sagebrush and rabbitbrush are of secondary importance. The total annual production (air-dry weight) of this state is about 1800 pounds per acre, but it can range from about 800 lbs./acre in unfavorable years to about 2300 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: WY0202 Growth curve name: 15-19W, EXTRA WATER SITES Growth curve description: OV, CYO EXTRA WATER SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 40 30 15 5 0 0 0 (Monthly percentages of total annual growth) The state is moderately stable and somewhat vulnerable to excessive erosion. The biotic integrity of this plant community is usually intact. However, it can be at risk depending on how far a shift has occurred in plant composition toward mountain big sagebrush. The watershed is usually functioning. However, it can become at risk when canopy cover of big sagebrush and/or bare ground increases. 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 eventually result in a plant community very similar to the Historic Climax Plant Community (Rhizomatous wheatgrass/Basin Wildrye State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges. • Brush Management or Wildfire followed by Continuous Season-long Grazing will result in the Silver Sage/Kentucky Bluegrass State.
Figure 5. Plant community growth curve (percent production by month). WY0202, 15-19W Extra water sites - LL, Ov, CyO, SL.
| 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 | 0 | 10 | 40 | 30 | 15 | 5 | 0 | 0 | 0 |
State 3
Silver Sage/Kentucky Bluegrass Plant Community
Community 3.1
Silver Sage/Kentucky Bluegrass Plant Community
This plant community is the result of improper grazing use after wildfire or brush management practices. Sprouting woody species such as silver sagebrush and rabbitbrush dominate this state. Noxious weeds such as Canada thistle and cheatgrass may invade. Basin wildrye and mountain big sage have been lost or only occasional remnants remain. The total annual production (air-dry weight) of this state is about 900 pounds per acre, but it can range from about 500 lbs./acre in unfavorable years to about 1900 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: WY0202 Growth curve name: 15-19W, EXTRA WATER SITES Growth curve description: OV, CYO EXTRA WATER SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 40 30 15 5 0 0 0 (Monthly percentages of total annual growth) The biotic integrity is threatened by the invasion of noxious weeds. The soil of this state is not protected. The watershed may produce excessive runoff. Transitional 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 over the long-term will return this state to near Historic Climax Plant Community (Rhizomatous Wheatgrass/Basin Wildrye State). Care should be taken when planning brush management to consider wildlife habitat and critical winter ranges. • Chemical Brush Management followed by Continuous Season-long Grazing will result in the Kentucky Bluegrass/Forb State.
Figure 6. Plant community growth curve (percent production by month). WY0202, 15-19W Extra water sites - LL, Ov, CyO, SL.
| 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 | 0 | 10 | 40 | 30 | 15 | 5 | 0 | 0 | 0 |
State 4
Kentucky Bluegrass/Forb Plant Community
Community 4.1
Kentucky Bluegrass/Forb Plant Community
This plant community is the result of long-term improper grazing use after wildfire or a series of brush management practices. Kentucky bluegrass and weedy forbs such as mountain dandelion dominate this state. Sprouting woody species such as silver sagebrush and rabbitbrush may be present, but often all shrubs are gone from this state. Noxious weeds such as musk and Canada thistle often invade. The total annual production (air-dry weight) of this state is about 500 pounds per acre, but it can range from about 300 lbs./acre in unfavorable years to about 800 lbs./acre in above average years. The following is the growth curve of this plant community expected during a normal year: Growth curve number: WY0202 Growth curve name: 15-19W, EXTRA WATER SITES Growth curve description: OV, CYO EXTRA WATER SITES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 0 0 0 0 10 40 30 15 5 0 0 0 (Monthly percentages of total annual growth) The biotic integrity is threatened by the invasion of noxious weeds. The soil of this state is not protected. The watershed may produce excessive runoff. Transitional pathways leading to other plant communities are as follows: • Prescribed Grazing over the long-term will eventually return this state to near the Silver Sage/Kentucky Bluegrass State.
Figure 7. Plant community growth curve (percent production by month). WY0202, 15-19W Extra water sites - LL, Ov, CyO, SL.
| 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 | 0 | 10 | 40 | 30 | 15 | 5 | 0 | 0 | 0 |
Additional community tables
Table 5. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 140–280 | |||||
| basin wildrye | LECI4 | Leymus cinereus | 140–280 | – | ||
| 2 | 140–420 | |||||
| Idaho fescue | FEID | Festuca idahoensis | 140–420 | – | ||
| 3 | 280–560 | |||||
| western wheatgrass | PASM | Pascopyrum smithii | 280–560 | – | ||
| 4 | 140–280 | |||||
| slender wheatgrass | ELTR7 | Elymus trachycaulus | 140–280 | – | ||
| 5 | 280–701 | |||||
| Grass, perennial | 2GP | Grass, perennial | 0–140 | – | ||
| Letterman's needlegrass | ACLE9 | Achnatherum lettermanii | 0–140 | – | ||
| western needlegrass | ACOC3 | Achnatherum occidentale | 0–140 | – | ||
| mountain brome | BRMA4 | Bromus marginatus | 0–140 | – | ||
| sun sedge | CAINH2 | Carex inops ssp. heliophila | 0–140 | – | ||
| timber oatgrass | DAIN | Danthonia intermedia | 0–140 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 0–140 | – | ||
| blue wildrye | ELGL | Elymus glaucus | 0–140 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 0–140 | – | ||
| spike fescue | LEKI2 | Leucopoa kingii | 0–140 | – | ||
| oniongrass | MEBU | Melica bulbosa | 0–140 | – | ||
| muttongrass | POFE | Poa fendleriana | 0–140 | – | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–140 | – | ||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 0–140 | – | ||
|
Forb
|
||||||
| 6 | 140–420 | |||||
| Forb, perennial | 2FP | Forb, perennial | 0–140 | – | ||
| common yarrow | ACMI2 | Achillea millefolium | 0–140 | – | ||
| agoseris | AGOSE | Agoseris | 0–140 | – | ||
| rosy pussytoes | ANRO2 | Antennaria rosea | 0–140 | – | ||
| sandwort | ARENA | Arenaria | 0–140 | – | ||
| milkvetch | ASTRA | Astragalus | 0–140 | – | ||
| Indian paintbrush | CASTI2 | Castilleja | 0–140 | – | ||
| fireweed | CHAN9 | Chamerion angustifolium | 0–140 | – | ||
| springbeauty | CLAYT | Claytonia | 0–140 | – | ||
| larkspur | DELPH | Delphinium | 0–140 | – | ||
| fleabane | ERIGE2 | Erigeron | 0–140 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–140 | – | ||
| aster | EUCEP2 | Eucephalus | 0–140 | – | ||
| bedstraw | GALIU | Galium | 0–140 | – | ||
| geranium | GERAN | Geranium | 0–140 | – | ||
| avens | GEUM | Geum | 0–140 | – | ||
| American licorice | GLLE3 | Glycyrrhiza lepidota | 0–140 | – | ||
| pea | LATHY | Lathyrus | 0–140 | – | ||
| stoneseed | LITHO3 | Lithospermum | 0–140 | – | ||
| lupine | LUPIN | Lupinus | 0–140 | – | ||
| creeping barberry | MARE11 | Mahonia repens | 0–140 | – | ||
| bluebells | MERTE | Mertensia | 0–140 | – | ||
| monkeyflower | MIMUL | Mimulus | 0–140 | – | ||
| ragwort | PACKE | Packera | 0–140 | – | ||
| beardtongue | PENST | Penstemon | 0–140 | – | ||
| phacelia | PHACE | Phacelia | 0–140 | – | ||
| phlox | PHLOX | Phlox | 0–140 | – | ||
| cinquefoil | POTEN | Potentilla | 0–140 | – | ||
| buttercup | RANUN | Ranunculus | 0–140 | – | ||
| stonecrop | SEDUM | Sedum | 0–140 | – | ||
| starwort | STELL | Stellaria | 0–140 | – | ||
| goldenbanner | THERM | Thermopsis | 0–140 | – | ||
| western meadow-rue | THOC | Thalictrum occidentale | 0–140 | – | ||
| clover | TRIFO | Trifolium | 0–140 | – | ||
| American vetch | VIAM | Vicia americana | 0–140 | – | ||
|
Shrub/Vine
|
||||||
| 7 | 140–420 | |||||
| Shrub, deciduous | 2SD | Shrub, deciduous | 0–140 | – | ||
| Tree, deciduous | 2TD | Tree, deciduous | 0–140 | – | ||
| Saskatoon serviceberry | AMAL2 | Amelanchier alnifolia | 0–140 | – | ||
| silver sagebrush | ARCA13 | Artemisia cana | 0–140 | – | ||
| big sagebrush | ARTR2 | Artemisia tridentata | 0–140 | – | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–140 | – | ||
| quaking aspen | POTR5 | Populus tremuloides | 0–140 | – | ||
| chokecherry | PRVIV | Prunus virginiana var. virginiana | 0–140 | – | ||
| Woods' rose | ROWOW | Rosa woodsii var. woodsii | 0–140 | – | ||
| elderberry | SAMBU | Sambucus | 0–140 | – | ||
| western snowberry | SYOC | Symphoricarpos occidentalis | 0–140 | – | ||
Interpretations
Animal community
Animal Community – Wildlife Interpretations
Rhizomatous Wheatgrass/Basin Wildrye Plant Community (HCPC): The high degree of plant species and structural diversity, additional moisture, and woody plants in this community favors a large variety of wildlife. Woody plants provide suitable thermal and escape cover for mule deer, elk, and antelope. This community provides habitat for a wide array of small mammals such as jackrabbits, cottontail rabbits, mice, and voles so diverse prey populations are available for badgers, fox, coyotes, and raptors such as red-tail and Swainson’s hawks. Birds such as sage sparrow, Brewer’s sparrow, and the sage thrasher will utilize this community for nesting and foraging.
Mountain Big Sage/Idaho Fescue Plant Community: This plant community may be useful for the same wildlife that would use the Historic Climax Plant Community. However, the plant community composition is less diverse, and thus, less apt to meet the seasonal needs of these animals.
Silver Sage/Kentucky Bluegrass Plant Community: The plant community composition is much less diverse, and thus, less apt to meet the seasonal needs of many wildlife dependent on big sagebrush.
Kentucky Bluegrass/Forb Plant Community: The plant community composition is much less diverse, and thus, less apt to meet the seasonal needs of many wildlife dependent on big sagebrush. Lack of woody plants may provide opportunities for sage grouse leks.
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/Basin Wildrye (HCPC) 1500-3000 .7
Mountain Big Sage/Idaho Fescue 800-2300 .6
Silver Sage/Kentucky Bluegrass 500-1900 .3
Kentucky Bluegrass/Forb 300-800 .16
* - 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 rate is moderately slow to slow. Runoff potential for this site varies from moderate to high 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. 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
SCS-RANGE-417 58 1966-1986 WY Lincoln & others
Contributors
K. Clause
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
| Author(s)/participant(s) | K. Clause, E. Bainter |
|---|---|
| Contact for lead author | karen.clause@wy.usda.gov or 307-367-2257 |
| Date | 03/16/2007 |
| Approved by | E. Bainter |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rare to nonexistent. -
Presence of water flow patterns:
Water flow patterns sometimes evident in ephemeral floodplain zone where this site occurs. -
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 5-10%. -
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 in water flow patterns. -
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):
Described A-horizons are up to 30 inches (76 cm) with a dark gray color (10YR 4/1) and weak to moderate granular or platy structure. Organic matter is typically 3 to 6%. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Plant community consists of 70-85% grasses, 15% forbs, and 0-15% shrubs. Dense plant canopy (75-95%) and litter, despite slow infiltration rates, results in minimal runoff. Basal cover is typically greater than 5% for this site and effectively reduces 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):
No compaction layer exists. -
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 forbs=perennial shrubs>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 1-20% of total canopy measurement with total litter (including beneath the plant canopy) from 80-95% expected. Herbaceous litter depth typically ranges from 15-30 mm. Woody litter can be up to several inches (>8 cm). -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
English: 1500-3000 lb/ac (2500 lb/ac average); Metric: 1680-3360 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 20%, noxious weed invasion, and/or presence of Kentucky bluegrass are the most common indicators of a threshold being crossed. Rabbitbrush, mountain silver sagebrush, and Sandberg bluegrass are common increasers. Common dandelion, thistles, and Kentucky bluegrass are common invasive species on disturbed sites. -
Perennial plant reproductive capability:
All species are capable of reproducing, except in drought years.
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