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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
R009XY021OR Shallow Clayey 17-22 PZ
Shallow Clayey 14-17" PZ
R009XY025OR Very Shallow 14-18 PZ
Very Shallow 14-18" PZ
R009XY031OR Shallow South 14+ PZ
Shallow South 14" +
Similar sites
R009XY015OR Clayey 14-17 PZ
Clayey 14-17 PZ
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous Not specified
Physiographic features
This site occurs near forestland on basalt tablelands. It is typically on the northwestern edge of the blue mountains as one of the last grassland sites before the forest. Slopes generally range from 0 to 12%, but occasionally to 20%. Elevation varies from 2000 to 3800 feet.
Table 2. Representative physiographic features
Landforms (1) Alluvial fan
Elevation 2000 – 3400 ft Slope 0 – 12 % Aspect Aspect is not a significant factor Climatic features
The annual precipitation ranges from 14 to 17 inches, most of which occurs in the form of snow during the months of November through March followed by ample spring rainfall. Localized, occasionally severe, convectional storms occur during the summer. The soil temperature regime is mesic with a mean annual air temperature of 48 degrees F. Temperature extremes range from 110 to -40 degrees F. Teh frost free period ranges from 90 to 130 days. The optimum period for plant growth is from late April to mid-July.
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 moderately deep to deep over basalt bedrock or duripan and are well drained. Typically the surface layer is a silt loam or loam. The subsoil is silt loam, silty clay loam, or clay loam. Coarse fragments may occur in the lower subsoil. Permeability is moderate above the duripan or bedrock. The available water holding capacity (AWC) is about 5 to 10 inches for the profile. The potential for ersion is moderate.
Table 4. Representative soil features
Surface texture (1) Silt loam
(2) Loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate Ecological dynamics
Range in Characteristics:
Variablity in plant composition and yeild is dependent on aspect and soil depth rather than on precipitation and elevation ranges that occur within the site. There tends to be a higher proportion of bluebunch wheatgrass and lower overall production on south and southwesterly slopes. Conversely, Idaho fescue is in higher proportion with higher overall production on north slopes with approximately 40 inches depth.
Response to Disturbance:
If the site condition deteriorates as a result of overgrazing, Idaho fescue decreases and bluebunch wheatgrass increases. Idaho fescue is the prefered species during early summer. with further deterioration, bluebunch wheatgrass decreases. Annual fescues, chaetgrass and other annuals rapidly invade. Smaller amounts of various bluegrasses such as bulbous and Canada bluegrass invade. Under deteriorated conditions, annuals and unpalatable forbs dominate.
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
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe potential native plant community is strongly dominanted by Idaho fescue. Bluebunch wheatgrass is prominent in the stand. The vegetative composition of the community is approximately 95 percent grasses and 5 percent forbs.
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 1312 1488 1664 Forb 32 72 112 Total 1344 1560 1776 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 1120–1280 Idaho fescue FEID Festuca idahoensis 1120–1280 – 2 Perennial Deep-rooted Sub-dominant 160–320 bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 160–320 – 4 Perennial Shallow-rooted Sub-dominant 16–32 prairie Junegrass KOMA Koeleria macrantha 16–32 – Sandberg bluegrass POSE Poa secunda 16–32 – Forb7 Perennial All Dominant 16–48 common yarrow ACMI2 Achillea millefolium 16–48 – 9 PPFF 16–64 agoseris AGOSE Agoseris 2–8 – milkvetch ASTRA Astragalus 2–8 – brodiaea BRODI Brodiaea 2–8 – hawksbeard CREPI Crepis 2–8 – fleabane ERIGE2 Erigeron 2–8 – buckwheat ERIOG Eriogonum 2–8 – desertparsley LOMAT Lomatium 2–8 – lupine LUPIN Lupinus 2–8 – Interpretations
Animal community
Livestock Grazing:
This site is suited to use by cattle and sheep in the summer and fall. It has few limitations. Care should be taken to aviod trampling damage and soil compaction when soils are wet.
Wildlife:
This site is important as a late fall, winter and spring grazing site for deer and elk.
Native Wildlife Associated With The Potential Climax Community:
Rodents, songbirds, Red-tailed hawk, Coyote, mule deer, rocky mountain elk.Hydrological functions
The hydrologic cover condition is good at higher condition classes. The soils are dominantly in hydrologic group B.
Recreational uses
On the northwestern edge of the Blue Mountians this site occurs on ridgetops as one of the last grassland sites before the forest. It provides a pleasing visual diversity near the forests.
Other information
This site has potential for range seeding when it occurs in large enough units. As a complex with shallow sites the potential for range seeding is often low because it occurs as small mounds (biscuts).
Supporting information
Contributors
AV 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 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 (75-80%) and gentle slopes (0-12% sometimes to 20%) 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:
Idaho fescue > Bluebunch wheatgrass > other forbs >common yarrow > Sandberg bluegrass = Prairie junegrassSub-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: 2000, Normal: 1600, Unfavorable: 1100 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:
With deterioration of plant community, annual fescues, cheatgrass, and medusahead invade sites that have lost deep rooted perennial grass funtional groups -
Perennial plant reproductive capability:
All species should be capable of reproducing annually
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