Natural Resources
Conservation Service
Ecological site R010XC020OR
SR Loamy
9-12 PZ
Last updated: 4/10/2025
Accessed: 07/10/2026
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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
R010XC021OR SR Clayey 9-12 PZ
SR Clayey 9-12 PZ
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R010XC035OR SR Shallow 9-12 PZ
SR Shallow 9-12 PZ
R010XC043OR SR South 9-12 PZ
SR South 9-12" PZ
R010XC063OR SR Droughty North 9-12 PZ
SR Droughty North 9-12 PZ
R010XC064OR SR North 9-12 PZ
SR North 9-12" PZ
Similar sites
R010XC035OR SR Shallow 9-12 PZ
SR Shallow 9-12 PZ (shallower depth, lower production)
R010XC021OR SR Clayey 9-12 PZ
SR Clayey 9-12 PZ (fine surface texture, clayey subsoil at shallower depth, different composition - bluebunch wheatgrass strongly dominant)
BX010X00C022 Silty 9-12 PZ Snake River Warm Plains
SR Silty 9-12 PZ (very fine sandy loam to silt surface, lower elevation, different composition – beardless wheatgrass dominant)
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Artemisia tridentata ssp. wyomingensis
(2) Peraphyllum ramosissimumHerbaceous (1) Pseudoroegneria spicata
(2) Achnatherum thurberianumPhysiographic features
This site occurs on terraces, tablelands, and rolling uplands. Slopes range from 0 to 12 percent. Elevations range from 2000 to 3500 feet.
Table 2. Representative physiographic features
Landforms (1) Terrace
(2) Hill
Elevation 2000 – 3500 ft Slope 0 – 12 % Water table depth 60 in Aspect Aspect is not a significant factor Climatic features
The annual precipitation ranges from 9 to 12 inches, most of which occurs in the form of snow during the months of December through March. Localized, occasionally severe, convectional storms occur during the summer. The soil temperature regime is mesic with a mean annual air temperature of 52 degrees F. Temperature extremes range from 100 to -10 degrees F. The frost-free period ranges from 110 to 140 days. The optimum period for plant growth is from April through June.
Table 3 Representative climatic features
Frost-free period (average) 140 days Freeze-free period (average) Precipitation total (average) 10 in ">Influencing water features
Soil features
The soils of this site are typically moderately deep to deep and well drained. Typically the surface layer is a silt loam, channery loam or fine sandy loam 6 to 10 inches thick. The subsoil is a loam to clay loam 10 to 25 inches thick. Depth to an indurated pan, lacustrine or alluvial sediments, or bedrock is 20 to greater than 40 inches. Permeability is moderate. The available water holding capacity (AWC) is about 4 to 6 inches for the profile. The erosion potential is moderate to severe.
Table 4. Representative soil features
Parent material (1) Eolian deposits – rhyolite
Surface texture (1) Silt loam
(2) Fine sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate Soil depth 20 – 60 in Available water capacity
(0-40in)4 – 6 in Ecological dynamics
The potential native plant community is dominated by Wyoming big sagebrush, bluebunch wheatgrass and Thurber’s needlegrass. Basin big sagebrush, needle and thread and basin wildrye are present. Sandberg bluegrass is the dominant shallow rooted perennial grass. A variety of forbs are common. Vegetative composition of the community is approximately 80 percent grasses, 10 percent forbs and 10 percent shrubs. The approximate ground cover is 70 to 80 percent (basal and crown).
Range in Characteristics:
Bluebunch wheatgrass increases on silt loam surfaces. Thurber’s needlegrass increases on fine sandy loam surfaces and on droughtier sites. Needle and thread increases on coarse textured surfaces. Wyoming big sagebrush is clearly dominant at lower precipitations while basin big sagebrush increases at higher precipitation. Crab apple and antelope bitterbrush increase over fractured bedrock and over sediments including those interlaid with diatomaceous earth. Production increases at the upper end of the precipitation zone.
Response to Disturbance:
When the condition of the site deteriorates as a result of over grazing bluebunch wheatgrass and Thurber’s needlegrass rapidly decreases. Wyoming big sagebrush and Sandberg bluegrass increase. Cheatgrass, medusahead, other annuals, biennial weeds and bulbous bluegrass are strong invaders. With fire and continued disturbance sagebrush is severely impacted, rabbitbrush increases slightly and annuals and noxious biennial forbs continue to invade. Bare ground increases and excessive erosion contributes to downstream sedimentation. The excessive erosion is most pronounced in drainage areas where deep incised gulley’s form.
States: ARTRW/POSE-BRTE; POSE-POBU/biennial forbs or BRTE-TACA8/biennial forbs (following fire on degraded range)State and transition model
Custom diagramStandard diagram
Figure 2. State and Transition Model
More interactive model formats are also available. View Interactive Models
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
ReferenceCommunity 1.1
ReferencePlant CommunityThe potential native plant community is dominated by Wyoming big sagebrush, bluebunch wheatgrass and Thurber’s needlegrass. Basin big sagebrush, needle and thread and basin wildrye are present. Sandberg bluegrass is the dominant shallow rooted perennial grass. A variety of forbs are common. Vegetative composition of the community is approximately 80 percent grasses, 10 percent forbs and 10 percent shrubs. The approximate ground cover is 70 to 80 percent (basal and crown).
Figure 3. 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 640 800 1120 Shrub/Vine 80 100 140 Forb 80 100 140 Total 800 1000 1400 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Dominant, perennial, deep-rooted bunchgrass 400–500 bluebunch wheatgrass PSSPS Pseudoroegneria spicata ssp. spicata 400–500 – 2 Sub-dominant, perennial, deep-rooted bunchgrass 200–300 Thurber's needlegrass ACTH7 Achnatherum thurberianum 200–300 – 4 Sub-dominan, perennial, shallow-rooted grass 10–30 Sandberg bluegrass POSE Poa secunda 10–30 – 5 Other perennial grasses 85–250 needle and thread HECO26 Hesperostipa comata 50–150 – basin wildrye LECI4 Leymus cinereus 30–80 – Cusick's bluegrass POCU3 Poa cusickii 0–15 – beardless wheatgrass PSSPI Pseudoroegneria spicata ssp. inermis 0–15 – Idaho fescue FEID Festuca idahoensis 0–15 – foxtail wheatgrass PSSA2 ×Pseudelymus saxicola 0–10 – squirreltail ELEL5 Elymus elymoides 5–10 – Forb7 Dominant, perennial forb 20–50 arrowleaf balsamroot BASA3 Balsamorhiza sagittata 20–50 – 8 Sub-dominant, perennial forbs 30–60 buckwheat ERIOG Eriogonum 10–20 – desertparsley LOMAT Lomatium 10–20 – lupine LUPIN Lupinus 10–20 – phlox PHLOX Phlox 10–20 – 9 10–30 common yarrow ACMI2 Achillea millefolium 0–10 – agoseris AGOSE Agoseris 0–10 – onion ALLIU Allium 0–10 – pussytoes ANTEN Antennaria 0–10 – milkvetch ASTRA Astragalus 0–10 – mariposa lily CALOC Calochortus 0–10 – Indian paintbrush CASTI2 Castilleja 0–10 – bastard toadflax COMAN Comandra 0–10 – hawksbeard CREPI Crepis 0–10 – fleabane ERIGE2 Erigeron 0–10 – common woolly sunflower ERLA6 Eriophyllum lanatum 0–10 – haplopappus HAPLO11 Haplopappus 0–10 – woodland-star LITHO2 Lithophragma 0–10 – stoneseed LITHO3 Lithospermum 0–10 – hoary tansyaster MACA2 Machaeranthera canescens 0–10 – beardtongue PENST Penstemon 0–10 – deathcamas ZIGAD Zigadenus 0–10 – Shrub/Vine11 Dominant, evergreen shrub 50–100 Wyoming big sagebrush ARTRW8 Artemisia tridentata ssp. wyomingensis 50–100 – 12 Deciduous 50–130 wild crab apple PERA4 Peraphyllum ramosissimum 30–80 – antelope bitterbrush PUTR2 Purshia tridentata 20–50 – 13 Evergreen 10–30 basin big sagebrush ARTRT Artemisia tridentata ssp. tridentata 10–30 – 15 Other shrubs 10–30 threetip sagebrush ARTR4 Artemisia tripartita 0–10 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 0–10 – rubber rabbitbrush ERNA10 Ericameria nauseosa 0–10 – littleleaf horsebrush TEGL Tetradymia glabrata 0–10 – Interpretations
Animal community
Livestock Grazing:
This site is suitable for livestock grazing use in the spring, and fall under a planned grazing system. Use should be postponed until the soils are firm enough to prevent trampling damage and soil compaction. Grazing management should be keyed for bluebunch wheatgrass. Deferred grazing or rest is recommended at least once every three years.
Native Wildlife Associated with the Potential Climax Community:
This site is commonly used by pronghorn antelope, mule deer, rabbits, rodents, upland birds and various predators. It is a preferred site for sage grouse nesting, rearing and wintering. Antelope and mule deer make excellent use of the site for winter and spring forage.Hydrological functions
The soils of this site are typically in an upland topographic position. They have moderate runoff potential and medium infiltration rates when the hydrologic cover is high. Hydrologic cover is high when bluebunch wheatgrass and other deep rooted bunchgrass component is greater than70 percent of potential. The soils are in hydrologic groups B and C.
Supporting information
Contributors
A. Bahn, H. Futter, K. Danks, H. Barrett
EAP
M. Parks (OSU)
T.Bloomer,E.Petersen,B.Gillaspy,A.BahnApproval
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) Jeff Repp and Bruce Frannsen Contact for lead author State Rangeland Management Specialist for NRCS – Oregon Date 08/07/2012 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None, moderate to severe sheet & rill erosion hazard -
Presence of water flow patterns:
None -
Number and height of erosional pedestals or terracettes:
None -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
5-15% -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None, moderate wind erosion hazard -
Amount of litter movement (describe size and distance expected to travel):
Fine - limited movement -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Moderately resistant to erosion: aggregate stability = 3-5 -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Moderately deep to deep, well drained silt loams, channery loams, or fine sandy loam about 8" thick: moderate OM (1-3%) -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Moderate to significant ground cover (60-70%) and gentle slopes (2-12%) effectively limit rainfall impact and overland flow -
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:
Bluebunch wheatgrass > Thurber needlegrass > forbs > Wyoming big sagebrush > other grasses > other shrubsSub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Normal decadence and mortality expected -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Favorable: 1400, Normal: 1000, Unfavorable: 800 lbs/acre/year at high RSI (HCPC) -
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:
Western Juniper readily invades the site. Cheatgrass and Medusahead invade sites that have lost deep rooted perennial grass functional groups. -
Perennial plant reproductive capability:
All species should be capable of reproducing annually
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