Natural Resources
Conservation Service
Ecological site R010XC033OR
SR Cool
12-16 PZ
Last updated: 4/10/2025
Accessed: 06/07/2026
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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
R010XC029OR SR Shallow Cool 12-16 PZ
SR Shallow Cool 12-16 PZ (stony loam surface texture, shallower soil depth, lower production)
R010XC039OR SR Very Shallow 12-16 PZ
SR Very Shallow 12-16 PZ (very shallow soil depth, lower production, different omposition – ARRI2/POSE association)
R010XC047OR SR Mountain South 12-16 PZ
SR Mountain South 12-16 PZ (south aspect, lower production, different composition – higher proportion of PSSPS)
R010XC054OR SR Mountain Shallow South 12-16 PZ
SR Mountain Shallow South 12-16 PZ (south aspect, shallower soil depth, different composition – higher proportion of PSSPS)
R010XC068OR SR Cool Mountain North 12-16 PZ
SR Cool Mountain North 12-16 PZ (north aspect, higher production)
R010XC075OR SR Mountain Shallow North 12-16 PZ
SR Mountain Shallow North 12-16 PZ (north aspect, shallower soil depth, lower production)
Similar sites
R010XC075OR SR Mountain Shallow North 12-16 PZ
SR Mountain Shallow North 12-16 PZ (north aspect, shallower soil depth, lower production)
R010XC066OR SR Mountain North 12-16 PZ
SR Mountain North 12-16 PZ (higher elevation, north aspect, higher production, different composition – higher proportion of ARTRV)
R010XC037OR SR Mountain Shallow 12-16 PZ
SR Mountain Shallow 12-16 PZ (higher elevation, stony loam surface texture, shallower soil depth, lower production, different composition – higher proportion of ARTRV)
R010XC032OR SR Mountain 12-16 PZ
SR Mountain 12-16 PZ (higher elevation, different composition – higher proportion of ARTRV)
R010XC068OR SR Cool Mountain North 12-16 PZ
SR Cool Mountain North 12-16 PZ (north aspect, higher production)
R010XC029OR SR Shallow Cool 12-16 PZ
SR Shallow Cool 12-16 PZ (shallower soil depth, lower production)
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Artemisia tridentata ssp. vaseyana
(2) Artemisia tridentata ssp. tridentataHerbaceous (1) Festuca idahoensis
Physiographic features
This site occurs on terraces, tablelands and rolling uplands. Slopes typically range from 2 to 12%. Elevations typically range from 3,000 to 3,800 feet.
Table 2. Representative physiographic features
Landforms (1) Terrace
(2) Hill
Flooding frequency None Ponding frequency None Elevation 3000 – 3800 ft Slope 2 – 12 % 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 December through March. Localized convection storms occasionally occur during the summer. The soil temperature regime is nesic near frigid to frigid with a mean air temperature of 45 degrees F. Temperature extremes range from 90 to -20 degrees F. The frost free period ranges from less than 50 to 90 days. The optimum growth period for plant growth is late April through June.
Table 3 Representative climatic features
Frost-free period (average) 90 days Freeze-free period (average) Precipitation total (average) 20 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">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 loam to clay loam about 12 inches thick. The subsoil is a clay loam to clay about 22 inches thick. Depth to an indurated pan or bedrock ranges from 20 to 60 inches. Permeability is moderate. The available water holding capacity (AWC) is about 4 to 8 inches for the profile. The erosion potential is moderate.
Table 4. Representative soil features
Parent material (1) Volcanic ash – rhyolite
(2) Loess – basalt
Surface texture (1) Loam
(2) Clay loam
Family particle size (1) Clayey
Drainage class Moderately well drained to well drained Permeability class Moderately slow to moderate Soil depth 20 – 60 in Surface fragment cover <=3" 0 – 24 % Surface fragment cover >3" 0 – 4 % Available water capacity
(0-40in)4 – 8 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Subsurface fragment volume <=3"
(Depth not specified)3 – 20 % Ecological dynamics
The potential native plant community is dominated by Idaho fescue and a complex of mountain, xeric and basin big sagebrush. Bluebunch wheatgrass and Sandberg bluegrass are common along with a variety of forbs. Thurber’s needlegrasses, wild crab apple and antelope bitterbrush occur sporadically. Vegetative composition of the community is approximately 75 percent grasses, 10 percent forbs and 15 percent shrubs. Approximate ground cover is 70 to 80 percent (basal and crown).
Range in Characteristics:
Idaho fescue increases on silt loam surfaces. Needlegrasses increase on coarser surfaces and over shallower depths. Bluebunch wheatgrass increases on slight south and west exposures. Mountain big sagebrush increases in relationship to xeric and basin big sagebrush with elevation. Deciduous shrubs increase at the upper end of the precipitation zone and over gravelly and fractured substratums. Production increases with soil depth and precipitation.
Response to Disturbance - States:
If the condition of the site deteriorates as a result of overgrazing, Idaho fescue decreases. Needlegrasses maintain a presence, big sagebrush (mountain, basin & xeric) rapidly increases and juniper invades from higher elevation rock outcrops. With continued overgrazing, neeedlegrasses decrease, big sagebrush dominates the overstory and Sandberg bluegrass, a shallow rooted perennial dominates the understory. Annual invasion is limited unless ground disturbance occurs. With further deterioration and lack of fire juniper invasion continues, shrubs decrease and bare ground increases. With fire and heavy use or ground disturbance, annuals and Sandberg or bulbous bluegrass increase. Bare ground increases and excessive erosion contributes to downstream sedimentation.
States: ARTRV-X-T/POSE-Bare Ground; JUOC/ARTRV-X-T/POSE-Bare Ground; POSE-POBU -Annuals-Bare Ground
Juniper Response:
Fine fuel reduction from improper grazing and fire suppression has led to an increase in the historical fire return interval on many western rangelands. A reduction in fire frequency on these sites leads to an increase in juniper cover, a decrease in sagebrush cover followed by a decrease in herbaceous cover and understory diversity. As juniper encroaches on north facing aspects sagebrush declines with a subsequent decrease in forbs, bluebunch wheatgrass and needlegrass. Idaho fescue becomes the primary herbaceous species occurring under the canopy of the juniper trees. Sandberg’s bluegrass increases in the plant community on lower elevation north slopes and warmer non-aspect sites while bare ground increases in the interspaces between trees. Bitterbrush is more resistant to juniper encroachment than sagebrush and maintains its presence in the community, however vigor and fitness (seed production) may be thwarted. The potential for soil erosion increases as the juniper woodland matures and the understory plant community cover declines. The combined effect of overgrazing and juniper invasion increases the rate of decline in ecological function and the probability of crossing a threshold is high.
Treatment Response:
This site responds positively to juniper removal if soil erosion is not significant. Seeding may be necessary if there are less than 1-2 bunchgrass plants per meter square in the understory. Forbs may also need to be seeded if adult plants are no longer present in the understory.State and transition model
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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 reference native plant community is dominated by Idaho fescue and a complex of mountain, xeric and basin big sagebrush. Bluebunch wheatgrass and Sandberg bluegrass are common along with a variety of forbs. Thurber’s needlegrasses, wild crab apple and antelope bitterbrush occur sporadically. Vegetative composition of the community is approximately 75 percent grasses, 10 percent forbs and 15 percent shrubs. Approximate ground cover is 70 to 80 percent (basal and crown).
Figure 4. 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 900 1125 1350 Shrub/Vine 180 225 270 Forb 120 150 180 Total 1200 1500 1800 Figure 5. Plant community growth curve (percent production by month). OR4481 , B10 SR Mtn, Cool & No 12-16pz. SR Mtn, Cool & No 12-16pz 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 0 10 30 30 15 5 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 Dominant, moderate rooted bunchgrass 600–900 Idaho fescue FEID Festuca idahoensis 600–900 – 2 Sub-dominant, moderate rooted bunchgrasses 225–675 bluebunch wheatgrass PSSPS Pseudoroegneria spicata ssp. spicata 150–450 – Thurber's needlegrass ACTH7 Achnatherum thurberianum 75–225 – 3 Common, perennial, shallow rooted grass 30–75 Sandberg bluegrass POSE Poa secunda 30–75 – 4 Other perennial grasses 50–180 western needlegrass ACOC3 Achnatherum occidentale 15–45 – threadleaf sedge CAFI Carex filifolia 15–45 – needle and thread HECO26 Hesperostipa comata 15–45 – prairie Junegrass KOMA Koeleria macrantha 15–45 – basin wildrye LECI4 Leymus cinereus 15–45 – threadleaf sedge CAFI Carex filifolia 15–30 – squirreltail ELEL5 Elymus elymoides 10–30 – slender wheatgrass ELTRT Elymus trachycaulus ssp. trachycaulus 10–30 – Forb5 Dominant, perennial, forbs 130–200 arrowleaf balsamroot BASA3 Balsamorhiza sagittata 30–45 – parsnipflower buckwheat ERHE2 Eriogonum heracleoides 30–45 – milkvetch ASTRA Astragalus 15–30 – desertparsley LOMAT Lomatium 15–30 – lupine LUPIN Lupinus 15–30 – phlox PHLOX Phlox 10–20 – common yarrow ACMI2 Achillea millefolium 10–20 – fleabane ERIGE2 Erigeron 10–20 – 6 Other forbs 30–120 hawksbeard CREPI Crepis 5–15 – buckwheat ERIOG Eriogonum 5–15 – stoneseed LITHO3 Lithospermum 5–15 – stonecrop SEDUM Sedum 0–10 – bastard toadflax COMAN Comandra 2–10 – bushy bird's beak CORA5 Cordylanthus ramosus 0–5 – woodland-star LITHO2 Lithophragma 2–5 – agoseris AGOSE Agoseris 2–5 – onion ALLIU Allium 2–5 – pussytoes ANTEN Antennaria 2–5 – brodiaea BRODI Brodiaea 2–5 – mariposa lily CALOC Calochortus 2–5 – Indian paintbrush CASTI2 Castilleja 2–5 – deathcamas ZIGAD Zigadenus 2–5 – owl's-clover ORTHO Orthocarpus 0–5 – sagebrush buttercup RAGL Ranunculus glaberrimus 2–5 – Shrub/Vine7 Dominant, evergreen, non-sprouting shrubs 100–270 mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 45–120 – big sagebrush ARTRX Artemisia tridentata ssp. xericensis 30–75 – basin big sagebrush ARTRT Artemisia tridentata ssp. tridentata 30–75 – 8 Other shrubs 50–250 Saskatoon serviceberry AMAL2 Amelanchier alnifolia 0–45 – threetip sagebrush ARTR4 Artemisia tripartita 0–45 – wild crab apple PERA4 Peraphyllum ramosissimum 0–45 – antelope bitterbrush PUTR2 Purshia tridentata 0–45 – wax currant RICE Ribes cereum 0–30 – Woods' rose ROWO Rosa woodsii 0–30 – snowberry SYMPH Symphoricarpos 0–30 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 5–30 – milkvetch ASTRA Astragalus 15–30 – buckwheat ERIOG Eriogonum 15–30 – desertparsley LOMAT Lomatium 15–30 – lupine LUPIN Lupinus 15–30 – littleleaf horsebrush TEGL Tetradymia glabrata 0–15 – Interpretations
Animal community
Livestock Grazing:
This site is suitable for livestock grazing use in the late spring, summer, 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 Idaho fescue. Deferred grazing or rest is recommended at least once every three years.
Wildlife Associated with the Site:
This site is commonly used by mule deer, elk, antelope, rabbits, rodents, upland birds and various predators. It is a preferred site for upland bird nesting and rearing areas. Mule deer and elk make excellent use of the site for spring and late fall forage.
Hydrological functions
The soils of this site are typically in an upland topographic position. They have moderate high runoff potential and medium infiltration rates when the hydrologic cover is good. Under frozen ground conditions runoff potential is significantly increased. This occurs more frequently when perennial bunchgrass cover is negligible. Hydrologic cover is good when the Idaho fescue and other moderate rooted bunchgrass components are greater than 70 percent of potential.
Other information
Juniper invasion is a major risk on this site. Control measures include prescribed burning and/or cutting followed by rest to improve vigor, density and seed production of existing perennial bunchgrasses. Consider seeding following control measures if an inadequate stand of bunchgrass is present.
Supporting information
Contributors
Bob Gillaspy
G. Kuehl, H. Barrett, A. Bahn
M. Parks (OSU)
T. Bloomer, E. Petersen, A. Bahn
T.Bloomer, B.Gillaspy, E.Petersen, 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 NRCS Oregon State Rangeland Management Specialist Date 04/24/2003 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None -
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):
2-12% -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None -
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):
Moderate resistant to erosion: aggregate stability = 3-5 -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
weak fine to medium granular to subangular blocky structure, dry color value 4-5, 8-16 inches thick; moderate SOM (1-4%) -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Significant ground cover (60-80%) 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:
Deep-rooted, perennial, cool-season bunchgrassesSub-dominant:
Evergreen shrubs > deciduous shrubsOther:
Forbs > other grasses > treesAdditional:
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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: 1800, Normal: 1500, Unfavorable: 1200 lbs/acre/year -
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:
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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