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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.
Associated sites
R010XY005OR Loamy Bottom
Loamy Bottom, mesic, 5000#/acre normal
Similar sites
R010XY005OR Loamy Bottom
Loamy Bottom, mesic, 5000#/acre normal
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Artemisia tridentata ssp. tridentata
Herbaceous (1) Leymus cinereus
(2) Pseudoroegneria spicata ssp. spicataPhysiographic features
This site occurs adjacent to and on the floodplains of ephemeral streams. It is at the upper end of drainages occupying broad to narrow swale areas. Slopes range from 2 to 12%. Elevations range from 2,100 to 4,000 feet.
Table 2. Representative physiographic features
Landforms (1) Flood plain
(2) Swale
Flooding frequency None Ponding frequency None Elevation 2100 – 4000 ft Slope 2 – 12 % Water table depth 60 in Aspect Aspect is not a significant factor Climatic features
The annual precipitation ranges from 12 to 16 inches, most of which occurs in the form of snow during the months of November through March. Ephemeral subsurface moisture augments the precipitation. Localized convection storms occasionally occur during the summer. The soil temperature regime is mesic to frigid near mesic with a mean annual air temperature of 50 degrees F. Temperature extremes range from 100 to -10 degrees F. The frost-free period ranges from 60 to 130 days. The optimum growth period for native plants is from April through June.
Table 3 Representative climatic features
Frost-free period (average) 130 days Freeze-free period (average) Precipitation total (average) 20 in ">Influencing water features
Soil features
The soils of this site are recent, deep to very deep and well drained. Typically the surface layer is a silt loam about 10 inches thick. The subsoil is a silty clay loam over 40 inches thick. The substratum varies from alluvium to bedrock. Gravel content in the profile ranges from 0 to 30 percent. Permeability is moderate. The available water holding capacity (AWC) is about 8 to 10 inches for the profile. Seasonal subsurface flows from adjacent slopes augment the available water. The potential for erosion is moderate.
Table 4. Representative soil features
Surface texture (1) Silt loam
Family particle size (1) Clayey
Drainage class Well drained Permeability class Moderate Soil depth 50 in Surface fragment cover <=3" 0 – 30 % Available water capacity
(0-40in)8 – 10 in Ecological dynamics
Range In Characteristics:
The amount of basin wildrye in relation to bluebunch wheatgrass is dependent on the extent and duration of lateral subsurface water flows. Basin wildrye increases and bluebunch wheatgrass decreases on swales receiving subsurface flows late into the growing season. This would be on swales with large drainage areas. Conversely, bluebunch wheatgrass would increase on swales with limited drainage areas. This would typically be at the upper ends of watersheds where drainage area is limited. Production follows a similar pattern increasing on swales with large drainage areas. As a fire susceptable site, the amount of basin big sagebrush is influenced by fire frequency.
Response To Disturbance:
If the condition of the site deteriorates as a result of overgrazing, basin wildrye, bluebunch wheatgrass, and Idaho fescue decrease. Bluegrasses invade and basin big sagebrush increases. With further deterioration, annuals invade and useable forage production decreases. Streambanks become unstable from loss of vegetation and channels degrade, becoming deeper and wider in the process. Subsurface flows are affected. Peak discharges increase, the water table drops and storage of water for late season use is reduced. Erosion from concentrated flows reduces the site potential and contributes to downstream sedimentation.State and transition model
Custom diagramStandard diagram
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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 1
ReferenceCommunity 1.1
Reference Plant CommunityThe potential native plant community is dominated by basin wildrye and bluebunch wheatgrass. Basin big sagebrush and Idaho fescue are common. Prairie junegrass, Thurber needlegrass, bluegrasses, and a variety of forbs are present. Vegetative composition is approximately 90 percent grasses, 2 percent forbs, and 8 percent shrubs. Approximate ground cover is 70-80 percent (basal and crown).
Figure 1. 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 1800 2250 2700 Shrub/Vine 160 200 240 Forb 40 50 60 Total 2000 2500 3000 Figure 2. Plant community growth curve (percent production by month). OR4161 , B10 JD FAN & SWALE 9-16. B10B FAN, SWALE, Gumbo, & JD Sandy Lm 9-16 RPC Growth Curve.
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 5 10 30 35 10 0 5 5 0 0 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Perennial, deep rooted, dominant 1625–2750 basin wildrye LECI4 Leymus cinereus 1000–1500 – bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 375–750 – Idaho fescue FEID Festuca idahoensis 250–500 – 2 Perennial, deep rooted, sub-dominant 50–125 Thurber's needlegrass ACTH7 Achnatherum thurberianum 50–125 – 4 Perennial, shallow rooted, sub-dominant 75–200 prairie Junegrass KOMA Koeleria macrantha 50–125 – bluegrass POA Poa 25–75 – 5 Other perennial grasses 50–200 sedge CAREX Carex 0–50 – squirreltail ELEL5 Elymus elymoides 0–50 – western wheatgrass PASM Pascopyrum smithii 0–50 – Sandberg bluegrass POSE Poa secunda 0–50 – Forb7 Perennial, dominant 50–100 buckwheat ERIOG Eriogonum 25–50 – lupine LUPIN Lupinus 25–50 – 9 Other perennial forbs 25–100 common yarrow ACMI2 Achillea millefolium 0–25 – white sagebrush ARLU Artemisia ludoviciana 0–25 – milkvetch ASTRA Astragalus 0–25 – tapertip hawksbeard CRAC2 Crepis acuminata 0–25 – fleabane ERIGE2 Erigeron 0–25 – western stoneseed LIRU4 Lithospermum ruderale 0–25 – desertparsley LOMAT Lomatium 0–25 – phlox PHLOX Phlox 0–25 – ragwort SENEC Senecio 0–25 – deathcamas ZIGAD Zigadenus 0–25 – Shrub/Vine11 Perennial, Evergreen, Dominant 50–125 basin big sagebrush ARTRT Artemisia tridentata ssp. tridentata 50–125 – 12 Perennial, Evergreen, Sub-dominant 25–50 green rabbitbrush ERTE18 Ericameria teretifolia 25–50 – 14 Perennial, Deciduous, Sub-dominant 25–50 wax currant RICE Ribes cereum 25–50 – 15 Other shrubs 50–200 antelope bitterbrush PUTR2 Purshia tridentata 0–50 – horsebrush TETRA3 Tetradymia 0–50 – Tree16 Perennial, Evergreen, Dominant 0–50 western juniper JUOC Juniperus occidentalis 0–50 – Interpretations
Animal community
Livestock Grazing:
This site is suited to use by cattle, sheep, and horses in late spring, summer and fall under a planned grazing system. Limitations in the spring are saturated wet soils and unstable banks. Use should be postponed until the soils are firm enough to prevent trampling damage and soil compaction. Improvement and/or maintenance of herbaceous bank protection should be considered during all seasons, particularly going into winter for spring runoff protection.
Native Wildlife Associated With The Potential Climax Community:
Deer
Antelope
Elk
Hawks
Songbirds
Rodents
This site will offer food and cover for mule deer, elk, antelope, rodents, and a variety of birds. It it an important wintering area for mule deer, antelope and elk.
Hydrological functions
The soils are in hydrologic group B. The soils of this site have moderately low runoff potential.
Wood products
This site is susceptible to an increase in western juniper. Where this has occurred, the site will yield fence posts, firewood, and specialty products.
Other information
The soils in this site have good water holding capacities providing late season water for plant growth and slow water releases to streams. Increase in western juniper and the subsequent competition for moisture will lead to a reduction of available forage. Overgrazing can easily reduce ground cover and accelerate soil loss. Improving infiltration and permeability, and reducing runoff should be the immediate goal of juniper control. When incised channels are present, rehabilitation will markedly improve production, reduce downstream sedimentation and restore good hydrologic characteristics. On altered site the reintroduction of deep rooted plants may be needed to fully restore the site potential.
Supporting information
Contributors
Bob Gillaspy
Cici Brooks
J. Thompson, A. Bahn
M. Parks (OSU)Approval
Kirt Walstad, 4/10/2025
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 07/19/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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PrintThe Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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