Natural Resources
Conservation Service
Ecological site R009XY050OR
Loamy Bench
10-15 PZ
Last updated: 5/05/2025
Accessed: 04/19/2026
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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
R009XY003OR Fan 10-15 PZ
Fan 10-15" PZ
R009XY051OR Loamy South 10-15 PZ
Loamy South 10-15" PZ
R009XY052OR Loamy Shallow South 10-15 PZ
Loamy Shallow South 10-15" PZ
R009XY053OR Very Shallow South 10-15 PZ
Very Shallow South 10-15" PZ
R009XY054OR Loamy North 10-15 PZ
Loamy North 10-15" PZ
Similar sites
R009XY003OR Fan 10-15 PZ
Fan 10-15" PZ (higher production )
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous Not specified
Physiographic features
This site occurs on benches along the lower slopes of canyons. Slopes range from 0 to 30% with slopes of 2 to 15% being most typical. Elevation varies from 800 to 2800 feet.
Table 2. Representative physiographic features
Landforms (1) Canyon
Elevation 800 – 2800 ft Slope 2 – 15 % Aspect Aspect is not a significant factor Climatic features
The annual precipitation ranges from 10 to 15 inches. The precipiattion occurs as rain and snow during the months of November through March. Localized, occasionally severe, convection storms occur during the summer. The mean annual air temperature is approximatley 50 degrees F. Extreme temperatures range from 100 degrees F. to -20 degrees F. Soil temperature regimes are mesic. The frost-free period ranges from 90 to 140 days. The period of optimum plant growth is from April through mid July.
Table 3 Representative climatic features
Frost-free period (average) 140 days Freeze-free period (average) Precipitation total (average) 20 in ">Influencing water features
Soil features
The soils of the site are formed in deep alluvium, colluvium and loess. They are moderately deep to deep. Typically the surface layer is a silt loam or gravelly silt loam over a loamy to cobbly clay loam subsoil. Stoniness is variable. Soil permeabilty is moderate. The available water holding capacity (AWC) is 6 to 10 inches. The erosion potential is moderate.
Table 4. Representative soil features
Surface texture (1) Silt loam
(2) Very gravelly silt loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate Ecological dynamics
Range in Characteristics:
Variablity in plant composition and productin is dependent on soil depth and surface texture. Bluebunch wheatgrass increases on fine textured surfaces and sand drop seed increases on coarse textured surfaces. Produciton increases with soil depth.
Response to Disturbance:
If the condition of the site deteriorates as a result of overgrazing, bluebunch wheatgrass decreases. Sand dropseed increases along with lesser amounts of red threeawn. Cheatgrass, Japanese brome, annula fescues and a variety of unpalatable forbs including goatweed invade. With further deterioration, sand drop seed decreases, annuals and threeawn continue to increase, forage production decreases, areas of bare ground appear and soil erosion accelerates.State and transition model
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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
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe potential native plant community is dominanted by bluebunch wheatgrass. Sand dropseed is common. Sandberg bluegrass is present along with a variety of forbs. Shrubs are minor. The potential vegetative composition is approximately 90 percent grass, 5 percent forbs and 5 percent shrubs.
Figure 2. 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 830 975 1120 Forb 40 90 140 Shrub/Vine 20 40 60 Total 890 1105 1320 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 Sub-dominant 700–800 bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 700–800 – 2 Perennial Deep-rooted Sub-dominant 100–200 sand dropseed SPCR Sporobolus cryptandrus 100–200 – 5 PPGG 30–120 purple threeawn ARPU9 Aristida purpurea 8–30 – needle and thread HECO26 Hesperostipa comata 8–30 – prairie Junegrass KOMA Koeleria macrantha 8–30 – Sandberg bluegrass POSE Poa secunda 8–30 – Forb7 Perennial All Dominant 30–90 common yarrow ACMI2 Achillea millefolium 10–30 – milkvetch ASTRA Astragalus 10–30 – plains pricklypear OPPO Opuntia polyacantha 10–30 – 9 PPFF 10–50 agoseris AGOSE Agoseris 1–5 – shaggy fleabane ERPU2 Erigeron pumilus 1–5 – aster EUCEP2 Eucephalus 1–5 – hairy false goldenaster HEVI4 Heterotheca villosa 1–5 – hawkweed HIERA Hieracium 1–5 – desertparsley LOMAT Lomatium 1–5 – lupine LUPIN Lupinus 1–5 – beardtongue PENST Penstemon 1–5 – phacelia PHACE Phacelia 1–5 – phlox PHLOX Phlox 1–5 – narrowleaf skullcap SCAN3 Scutellaria angustifolia 1–5 – Shrub/Vine15 SSSS 20–60 Saskatoon serviceberry AMAL2 Amelanchier alnifolia 5–12 – netleaf hackberry CELAR Celtis laevigata var. reticulata 5–12 – buckthorn RHAMN Rhamnus 5–12 – smooth sumac RHGL Rhus glabra 5–12 – western poison ivy TORY Toxicodendron rydbergii 5–12 – Interpretations
Animal community
Livestock Grazing:
This site is suited to spring, fall and winter use by cattle, sheep and horses under aplanned grazing system. The key species is bluebunch wheatgrass. Bluebunch wheatgrass can be damaged if heavily grazed during periods of flowering and seed formation when root reserves and soil moisture is low. Use in the spring should be postponed until the soils are firm enough to prevent plant crown trampling damage and soil compaction.
Wildlife:
When the ecological condition is high this site provides fod for deer, elk, and other mammals and upland birds. It is an important wintering area fro deer and elk.
Native Wildlife Associated with The Potetial Climax Community:
Mule deer, whitetail deer, elk, rodents and a variety of upland birds use this site for food.Hydrological functions
The soils of this site have excellent water holding capacities providing late season water for plant grwoth. The hydroogic cover condition is excellent when the ecological condition is high.
Other information
When in poor condiditon this site has a high potential for mechanical range seeding.
Supporting information
Contributors
A. Bahn
Justin GredvigApproval
Kirt Walstad, 5/05/2025
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 Contact for lead author Oregon NRCS State Rangeland Management Specialist Date 07/30/2012 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None to some, moderate sheet & rill erosion hazard -
Presence of water flow patterns:
None to some -
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):
5-10% -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None, slight 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 = 2-4 -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Moderately deep to deep, well drained, with a silt loam or gravelly silt loam surface; moderate OM (2-4%) -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Significant ground cover (90-100%) and gentle slopes (0-30%) 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 > Sand dropseed > forbs > other grasses > 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):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Favorable: 1200, 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:
Sand dropseed and three-awn will increase with deterioration of plant community. Annual bromes and annual fescues invade sites that have lost deep rooted perennial grass functional groups. Excessive erosion may occur, deteriorating site potential. -
Perennial plant reproductive capability:
All species should be capable of reproducing annually
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