Natural Resources
Conservation Service
Ecological site R010XB028OR
JD Shrubby Mountain
12-16 PZ
Last updated: 4/10/2025
Accessed: 07/09/2026
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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
R010XB046OR JD Shrubby Mountain South 12-16 PZ
Steeper south slopes, lower production, dominated by bluebunch wheatgrass
R010XB071OR JD Shrubby Mountain North 12-16 PZ
Steeper north slopes, more shrubs (including wild crab apple)
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Purshia tridentata
(2) Artemisia tridentata ssp. vaseyanaHerbaceous (1) Festuca idahoensis
Physiographic features
This site occurs on terraces, tablelands, and mountain plateaus. Slopes range from 0 to 12 percent. Elevations range from 4,000 to 6,000 feet.
Table 2. Representative physiographic features
Landforms (1) Terrace
(2) Mountain
(3) Plateau
Flooding frequency None Ponding frequency None Elevation 4000 – 6000 ft Slope 0 – 12 % Water table depth 60 in 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 November through March. Localized, occasionally severe, convectional storms occur during the summer. The soil temperature regime is frigid to near frigid with a mean annual air temperature of 43 degrees F. Temperature extremes range from 90 to -30 degrees F. The frost-free period ranges from 40 to 80 days. The optimum period for plant growth is from April through July.
Table 3 Representative climatic features
Frost-free period (average) 80 days Freeze-free period (average) 40 days 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 and well-drained. Depth can range from shallow to deep. Typically the surface layer is a cobbly loam to gravelly loam about 7 inches thick. The subsoil is a very shaly loam to a clay loam about 28 inches thick. Depth to shale or highly fractured bedrock ranges from 10 to 40 inches. Permeability is slow to moderate. The available water holding capacity is about 1.4 to 4 inches for the profile. The potential for erosion is moderate to severe.
Table 4. Representative soil features
Surface texture (1) Very cobbly loam
(2) Very stony loam
(3) Gravelly loam
Family particle size (1) Clayey
Drainage class Well drained Permeability class Moderate to moderately slow Soil depth 10 – 40 in Surface fragment cover <=3" 11 – 20 % Surface fragment cover >3" 4 – 27 % Available water capacity
(0-40in)1.4 – 4.1 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)6.1 – 7.8 Subsurface fragment volume >3"
(Depth not specified)22 – 34 % Ecological dynamics
Range in Characteristics:
Bluebunch wheatgrass increases on southerly facing slopes. Thurber needlegrass will increase with more coarse surface texture.
Response to Disturbance:
Overgrazing may cause a decrease in deep-rooted perennial bunchgrass, primarily Idaho fescue and bluebunch wheatgrass. Unpalatable species such as sagebrush and juniper increase and the percentage of squirreltail may also increase. As grass cover declines the potential for weed invasion and expansion of juniper increases. 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 this site 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
North facing aspects respond 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. Sagebrush and 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 potential native plant community is dominated by mountain big sagebrush, antelope bitterbrush, and Idaho fescue. Basin big sagebrush, bluebunch wheatgrass, basin wildrye, and Thurber needlesgrass are prominent in the stand. Vegetative composition of the community by air-dry weight is approximately 65 percent grasses, 10 percent forbs, and 25 percent shrubs and trees. Foliar cover of ponderosa pine ranges to a maximum of 5 percent with a minimum 10 percent antelope bitterbrush. Approximate ground cover is 60-70 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 650 975 1300 Shrub/Vine 230 345 460 Forb 100 150 200 Tree 20 30 40 Total 1000 1500 2000 Figure 5. Plant community growth curve (percent production by month). OR4181 , B10 JD higher elev. RPC. B10XB JD higher elev. 12-16 PZ RPC.
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 25 25 20 10 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 Perennial, deep-rooted, dominant 750–1050 Idaho fescue FEID Festuca idahoensis 750–1050 – 2 Perennial, deep-rooted, sub-dominant 135–420 bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 75–225 – Thurber's needlegrass ACTH7 Achnatherum thurberianum 30–120 – basin wildrye LECI4 Leymus cinereus 15–45 – California brome BRCA5 Bromus carinatus 15–30 – 4 Perennial, shallow-rooted 30–75 bluegrass POA Poa 30–75 – 5 Other perennial grasses 30–45 sedge CAREX Carex 0–30 – squirreltail ELEL5 Elymus elymoides 0–30 – prairie Junegrass KOMA Koeleria macrantha 0–30 – Sandberg bluegrass POSE Poa secunda 0–30 – Forb7 Perennial, dominant 45–90 arrowleaf balsamroot BASA3 Balsamorhiza sagittata 15–30 – buckwheat ERIOG Eriogonum 15–30 – lupine LUPIN Lupinus 15–30 – 9 Other perennial forbs 15–75 common yarrow ACMI2 Achillea millefolium 0–15 – pussytoes ANTEN Antennaria 0–15 – Indian paintbrush CASTI2 Castilleja 0–15 – tapertip hawksbeard CRAC2 Crepis acuminata 0–15 – fleabane ERIGE2 Erigeron 0–15 – waterleaf HYDRO4 Hydrophyllum 0–15 – stoneseed LITHO3 Lithospermum 0–15 – desertparsley LOMAT Lomatium 0–15 – bluebells MERTE Mertensia 0–15 – phlox PHLOX Phlox 0–15 – buttercup RANUN Ranunculus 0–15 – ragwort SENEC Senecio 0–15 – deathcamas ZIGAD Zigadenus 0–15 – Shrub/Vine13 Deciduous, dominant 225–300 antelope bitterbrush PUTR2 Purshia tridentata 225–300 – 14 Evergreen, subdominant 45–120 mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 45–120 – 15 Other shrubs 30–75 Saskatoon serviceberry AMAL2 Amelanchier alnifolia 0–30 – basin big sagebrush ARTRT Artemisia tridentata ssp. tridentata 0–30 – curl-leaf mountain mahogany CELE3 Cercocarpus ledifolius 0–30 – rabbitbrush CHRYS9 Chrysothamnus 0–30 – granite prickly phlox LIPU11 Linanthus pungens 0–30 – currant RIBES Ribes 0–30 – common snowberry SYAL Symphoricarpos albus 0–30 – horsebrush TETRA3 Tetradymia 0–30 – Tree16 Evergreen trees 15–45 western juniper JUOC Juniperus occidentalis 0–30 – ponderosa pine PIPO Pinus ponderosa 15–30 – Interpretations
Animal community
Livestock Grazing:
This site is suited to use by cattle, horses, and sheep in late spring, summer, and fall under a planned grazing system. Use should be postponed until the soils are firm enough to avoid trampling damage and soil compaction.
Native Wildlife Associated with the Potential Climax Community:
Mule deer
Elk
Songbirds
Rodents
Pronghorn antelope
Sage grouse
Hawks
This site may support mule deer, pronghorn antelope, sage grouse, rodents, and a variety of birds. Antelope bitterbrush provides important winter browse for mule deer and elk.Hydrological functions
The soils are in hydrologic groups B and C. The soils of this site have moderately low to moderately high runoff potential.
Wood products
This site is susceptible to increase in western juniper. Where this has occured, the site will yield fence posts, firewood, and other specialty products.
Other information
Increase in western juniper and the subsequent competition for moisture will lead to a reduction of soil cover and accelerated soil loss. Improving infiltration and permeability, and reducing runoff should be the immediate goal of juniper control.
Supporting information
Contributors
A. Bahn, J. Thompson, H. Barrett
Bob Gillaspy
Cici Brooks
M. Parks (OSU)Approval
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, Bruce Franssen Contact for lead author Oregon State Rangeland Management Specialist Date 04/23/2003 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None to some -
Presence of water flow patterns:
None to some -
Number and height of erosional pedestals or terracettes:
None to some -
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 -
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 = 4-6 -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
weak medium platy to subangular blocky structure, dry color value 4-5, 2-9 inches thick; moderate (1-4 percent) soil organic matter -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Moderate ground cover (60-70%) and gentle slopes (0-12%) 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:
Perennial, cool-season, deep-rooted bunchgrassesSub-dominant:
Deciduous shrubOther:
Forbs, other grassesAdditional:
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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):
1500 lbs/ac -
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:
Perennial brush species will increase with deterioration of plant community. 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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