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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
R011XY013OR Clayey 8-11 PZ
Clayey 8-11 PZ
R011XY016OR Sandy 8-11 PZ
Sandy 8-11 PZ
R011XY018OR Shallow Loam 8-11 PZ
Shallow Loam 8-11 PZ
R011XY020OR South Slopes 8-11 PZ
South Slopes 8-11 PZ
R011XY032OR Silty North Slopes 8-11 PZ
Silty North Slopes 8-11 PZ
R011XY034OR Sandy North Slopes 8-11 PZ
Sandy North Slopes 8-11 PZ
Similar sites
R011XY013OR Clayey 8-11 PZ
Clayey 8-11 PZ (clayey surface, different composition-beardless wheatgrass dominant, Thurber's neeedlegrass minor)
R011XY018OR Shallow Loam 8-11 PZ
Shallow Loam 8-11 PZ (shallower soil, lower production)
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Artemisia tridentata ssp. wyomingensis
(2) Grayia spinosaHerbaceous (1) Pseudoroegneria spicata ssp. inermis
(2) Achnatherum thurberianumPhysiographic features
This site occurs on low elevation terraces in the Malheur, Owyhee and adjacent Snake River drainage. Slopes typically range from 0 to 12%. Elevations vary from 2,100 to 3,200 feet.
Table 2. Representative physiographic features
Landforms (1) Terrace
Elevation 2100 – 3200 ft Slope 0 – 12 % Aspect Aspect is not a significant factor Climatic features
The annual precipitation ranges from 8 to 11 inches, most of which occurs in the form of rain during the months of December through April. The soil temperature regime is mesic with a mean air temperature of 53 degrees F. Temperature extremes range from 110 to -10 degrees F. The frost free period ranges from 150 to 190 days. The optimum growth period for plant growth is late March through June.
Table 3 Representative climatic features
Frost-free period (average) 190 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 very deep and well drained. Typically the surface layer is a silt loam to a very fine sandy loam 8 to 16 inches thick. The subsoil is a silt loam to silty clay loam 15 to 25 inches thick. Depth to lacustrine or alluvial sediments ranges from 20 to greater than 60 inches. An indurate pan may be present. Permeability is moderate. The available water holding capacity (AWC) is about 4 to 6 inches for the profile. The erosion potential is moderate.
Table 4. Representative soil features
Surface texture (1) Silt loam
(2) Very fine sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate to moderately slow 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, spiny hopsage and beardless wheatgrass. Thurber’s needlegrass is prominent. Sandberg bluegrass is the dominant shallow rooted perennial grass. A variety of forbs and shrubs are present. Vegetative composition of the community is approximately 75 percent grasses, 10 percent forbs and 15 percent shrubs. The approximate ground cover is 60 to 70 percent (basal and crown).
Range in Characteristics:
Wyoming big sagebrush and spiny hopsage are co-dominant with Wyoming big sagebrush increasing at the upper end of the precipitation zone and spiny hopsage on droughtier sites. Beardless wheatgrass increases on silty surfaces. Thurber’s needlegrass increases on very fine sandy loam surfaces and on droughtier sites. Needle and thread is present on coarser surfaces. Sandberg bluegrass increases on silty surfaces in association with a strong microbiotic crust. Winterfat increases in lower precipitation areas on silts. 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 beardless wheatgrass and Thurber’s needlegrass rapidly decreases. Wyoming big sagebrush, basin big sagebrush and Sandberg bluegrass increase. Cheatgrass, other annuals, biennial weeds and bulbous bluegrass invade. With fire and continued disturbance big sagebrush is severely impacted. Rabbitbrush increases slightly and annuals and noxious biennial forbs strongly 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 (degraded without fire); POSE-POBU/biennial forbs and BRTE/biennial forbs (following fire on degraded range)
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 textEcosystem states
State 1 submodel, plant communities
State 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe potential native plant community is dominated by Wyoming big sagebrush, spiny hopsage and beardless wheatgrass. Thurber’s needlegrass is prominent. Sandberg bluegrass is the dominant shallow rooted perennial grass. A variety of forbs and shrubs are present. Vegetative composition of the community is approximately 75 percent grasses, 10 percent forbs and 15 percent shrubs. The approximate ground cover is 60 to 70 percent (basal and crown).
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 375 525 750 Shrub/Vine 75 105 150 Forb 50 70 100 Total 500 700 1000 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 bunchgrasses 490–630 beardless wheatgrass PSSPI Pseudoroegneria spicata ssp. inermis 280–350 – Thurber's needlegrass ACTH7 Achnatherum thurberianum 210–280 – 4 Sub-dominant, perennial, shallow rooted grass 14–35 Sandberg bluegrass POSE Poa secunda 14–35 – 5 Other perennial grasses 35–94 bluebunch wheatgrass PSSPS Pseudoroegneria spicata ssp. spicata 7–28 – Indian ricegrass ACHY Achnatherum hymenoides 7–14 – squirreltail ELEL5 Elymus elymoides 7–14 – needle and thread HECO26 Hesperostipa comata 7–14 – basin wildrye LECI4 Leymus cinereus 7–14 – foxtail wheatgrass PSSA2 ×Pseudelymus saxicola 0–10 – Forb8 Dominant, perennial forbs 49–91 arrowleaf balsamroot BASA3 Balsamorhiza sagittata 14–21 – fleabane ERIGE2 Erigeron 7–14 – buckwheat ERIOG Eriogonum 7–14 – desertparsley LOMAT Lomatium 7–14 – phlox PHLOX Phlox 7–14 – common yarrow ACMI2 Achillea millefolium 7–14 – 9 Other perennial forbs 21–84 milkvetch ASTRA Astragalus 3–7 – hawksbeard CREPI Crepis 3–7 – plains pricklypear OPPO Opuntia polyacantha 3–7 – lupine LUPIN Lupinus 3–7 – hoary tansyaster MACA2 Machaeranthera canescens 0–4 – beardtongue PENST Penstemon 0–4 – scarlet globemallow SPCO Sphaeralcea coccinea 0–4 – deathcamas ZIGAD Zigadenus 0–4 – common woolly sunflower ERLA6 Eriophyllum lanatum 0–4 – haplopappus HAPLO11 Haplopappus 0–4 – western stoneseed LIRU4 Lithospermum ruderale 0–4 – woodland-star LITHO2 Lithophragma 2–4 – mariposa lily CALOC Calochortus 0–4 – bastard toadflax COMAN Comandra 0–4 – onion ALLIU Allium 2–4 – pussytoes ANTEN Antennaria 2–4 – Shrub/Vine11 Dominant shrubs 70–140 spiny hopsage GRSP Grayia spinosa 35–70 – 15 Other shrubs 8–49 basin big sagebrush ARTRT Artemisia tridentata ssp. tridentata 4–7 – fourwing saltbush ATCA2 Atriplex canescens 0–7 – rubber rabbitbrush ERNA10 Ericameria nauseosa 4–7 – broom snakeweed GUSA2 Gutierrezia sarothrae 0–7 – winterfat KRLA2 Krascheninnikovia lanata 0–7 – granite prickly phlox LIPU11 Linanthus pungens 0–7 – littleleaf horsebrush TEGL Tetradymia glabrata 0–7 – Interpretations
Animal community
Livestock Grazing:
This site is suitable for livestock grazing use in the late fall, winter and early spring 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 beardless wheatgrass and Thurber’s needlegrass. 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 wintering. Antelope and mule deer make excellent use of the site for winter and early 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 the beardless wheatgrass and Thurber’s needlegrass deep rooted bunchgrass component is greater than 70 percent of potential.
Supporting information
Contributors
T.Bloomer, E,Petersen & A.Bahn
T.Bloomer, E.Petersen, A.BahnApproval
Kirt Walstad, 5/13/2025
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) Bob Gillaspy Contact for lead author State Rangeland Management Specialist for NRCS Oregon Date 11/09/2016 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, except following extremely high intensity storms when short (less than 1 meter) flow patterns may appear on steeper slopes. Minimal evidence of past or current soil deposition or erosion. -
Number and height of erosional pedestals or terracettes:
None, except few pedestals or terracettes on steeper slopes. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
20% - 35% bare ground, typically bare patches are associated with shrubs. Larger bare patches may be associated with ant mounds, rodent, and/or other natural disturbances. -
Number of gullies and erosion associated with gullies:
None. -
Extent of wind scoured, blowouts and/or depositional areas:
None. Wind erosion hazard is moderate. -
Amount of litter movement (describe size and distance expected to travel):
Litter size is Small/Fine. Litter movement is limited, minimal, and short, associated with water flow patterns following extremely high intensity storms. Litter also may be moved during intense wind storms. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Site is Slightly to Moderately resistant to erosion. Stability class (Herrick et al. 2001) anticipated to be 3-6 at surface under perennial vegetation. Stability class at surface in the interspaces is anticipated to be less than or equal to that under perennial vegetation. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface layer structure is weak fine granular to moderate medium platy. The A horizon has a dry color of 6 and is 3 - 16 inches thick. The Soil Organic Matter (SOM) content is low to moderate (0.5 to 3.0%). -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Plant foliar cover and basal cover with small gaps between plants should reduce raindrop impact and slow overland flow, providing increased time for infiltration to occur. High herbaceous vegetation on this site will retain more water from precipitation. Moderate ground cover (40-60%) and gentle slopes (2-15%) moderately 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:
Cool Season Deep Rooted Perennial Bunchgrass [Bluebunch Wheatgrass >= Thurber's Needlegrass] > Shrubs [sagebrush and hopsage]Sub-dominant:
Perennial forbs >= other grasses > other shrubsOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Grasses will nearly always show some mortality and decadence. Normal decadence and mortality expected on other plants. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Low 500 lbs/acre, Representative Value 700 lbs/acre, High 1000 lbs/acre -
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:
Annuals (Cheatgrass, Medusahead, and forbs) and bulbous bluegrass 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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