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Ecological site R023XY412OR

GRAVELLY RIDGE
16+ PZ

Accessed: 04/22/2026

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General information

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.

Similar sites

R023XY218OR	THIN SURFACE CLAYPAN 10-16 PZ Thin Surface Claypan 10-16" PZ (thinner soil surface, lower precip).
R023XY507OR	CLAYPAN 16-25 PZ Claypan 16-25" PZ
R023XY410OR	GRAVELLY RIDGE 12-16 PZ Gravelly Ridge 12-16" PZ (lower precip.)

R023XY218OR

THIN SURFACE CLAYPAN 10-16 PZ

Thin Surface Claypan 10-16" PZ (thinner soil surface, lower precip).

R023XY507OR

CLAYPAN 16-25 PZ

Claypan 16-25" PZ

R023XY410OR

GRAVELLY RIDGE 12-16 PZ

Gravelly Ridge 12-16" PZ (lower precip.)

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	Not specified

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Physiographic features

This site occurs on ridgetops and shoulders in mountainous areas. Slopes range from 3 to 30%. Elevations ranges from 7000 to 8500 feet.

Table 2. Representative physiographic features

Landforms	(1) Mountain (2) Ridge
Elevation	7000 – 8500 ft
Slope	3 – 30 %
Aspect	Aspect is not a significant factor

Climatic features

The annual precipitation ranges from 16 to 20 inches, most of which occurs in the form of snow during December to March. Spring rains are common. The soil temperature regime is cryic. Extreme temperatures range from 80 degrees F. to -30 degrees F. The frost-free period is less than 50 days. The optimum period for plant growth is June to mid-August.

Table 3 Representative climatic features

Frost-free period (average)	50 days
Freeze-free period (average)	0 days
Precipitation total (average)	0 in

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Figure 2. Monthly precipitation range

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Figure 3. Monthly average minimum and maximum temperature

Soil features

The soils in this site are medium textured and well drained, contain a high amount of rock fragments throughout the profile, and are over highely fractured bedrock. The soils are shallowor deep to bedrock. The shallow soils typically contain 20-50 percent rock fragments throughout the profile. The deep soils typically contain 50 to 80 percent rock fragments throughout the profile. Permeabilty is moderate or moderately slow. Teha vailagle water holding capacity (AWC) is about 2 to 5 inches for the profile. Rock fragments are typically gravel size (less than 3 inches in diameter).

Table 4. Representative soil features

Drainage class	Well drained
Permeability class	Moderate to moderately slow

Ecological dynamics

Range in characteristics:
The reference native plant community is dominated by Rough fescue, and Low sagebrush. Idaho fescue and Sandberg bluegrass are common in the stand. All species of this site are represented by diminutive plants, with the shrubs commonly having a flat top growth form due to blowing snow and other severe growing conditions. The vegetative composition of the community is approximately 80 percent grasses, 10 percent forbs, and 10 percent shrubs.

Four states have been identified for this site: a reference state; a state with the presence of annuals; a state that has Juniper and Low sagebrush co-dominant on the site, and a state with annual dominance.

Reference: Stable plant community affected infrequently by fire. Sites are dominated with low sagebrush with some sites exhibiting a small percentage of old growth juniper. Infrequent fire (> 80 to 100 year intervals) maintained site dynamics. Fire reduced shrub cover in a mosaic, patchy pattern. The introduction of invasive annual grasses and forbs transitions into the state 2.

State 2: Compositionally similar to the reference state with a trace of cheatgrass and/or medusahead and other annual weeds. Ecological function has not changed, however the resiliency of the state has been reduced by the presence of invasive weeds. Infrequent fire (> 80 to 100 years) reduces shrub cover, removes young juniper and promotes grass production while time since fire allows shrub recovery. Mismanagement of grazing facilitates an increase in Sandberg’s bluegrass, weedy species, young juniper and low sagebrush. Bunchgrasses decline in production and density. Prescribed grazing can reverse the trend. Los of deep-rooted perennial bunchgrasses and an increase in young Juniper brings the site to State 3.

State 3: Low sagebrush and possibly young juniper dominated with minimal perennial, deep-rooted grasses. Cheatgrass and/or medusahead along with other weedy forbs are increased in density and cover. Sandberg’s bluegrass cover and vigor declining. Water flow paths evident. Sagebrush and possibly juniper control site resources. Catastrophic wildfire leading to annual dominated plant community will take the site to State 4.

State 4: Cheatgrass and/or medusahead dominated. Few old growth juniper may be present. Rabbitbrush increased with few to no low sagebrush. Wind and water erosion drive site processes.

Response to Disturbance:
If heavy grazing causes site deterioration, rough fescue and Idaho fescue decrease in the stand and the composition of low sagebrush increases. With further deterioration, rough fescue and Idaho fescue are nearly eliminated while Sandberg's bluegrass, squirreltail and forbs increase. On severely disturbed areasof this site, the plant composition is comprised largely of low sagebrush and Sandberg bluegrass. This site is very suscepible to soil erosion and the resulting loss of productive potential.

State and transition model

Custom diagram

Standard diagram

Figure 4. Group 10, STM

More interactive model formats are also available. View Interactive Models

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Historic Climax Plant Community

State 1 submodel, plant communities

1.1. Historic Climax Plant Community

State 1
Historic Climax Plant Community

Community 1.1
Historic Climax Plant Community

The potential native plant community is dominated by rough fescue and low sagebrush. Idaho fescue and Sandberg bluegrass are common in the stand. All species of this site are represented by diminutive plants, with the shrubs commonly having a flat top growth form due to blowing snow and other severe growing conditions. Vegetative composition is about 80 percent grasses, 10 percent forbs, and 10 percent shrubs.

Additional community tables

Table 5. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Interpretations

Animal community

Livestock Grazing:
Thiss ite si suitable for cattle, horse and sheep use in summer and fall under a planned grazing system. Deferred grazing is recommended in atleast one in three years.
Wildlife:
This site provides habitat to mule deer, bighorn sheep, pronghorn antelope, and sage grouse.

Hydrological functions

The soils of this site have moderate infiltration rates and medium to rapid runoff potential. The hydrologic soil group is B.

Recreational uses

Recreation consists of hunting, hiking, backpacking and rock hounding. Because of the diversity of wild flowers, this site provides an aesthetically pleasing display of color during late spring and early summer.

Other information

Coarse fragments in the soil and/or shallow depth to bedrock hinder range seeding, excavation for pipelines and fence construction.

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	08/17/2012
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

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 to some pedestals on shallow rooted grasses
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, Moderate 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 = 3-5
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Medium textured (silt loams and gravelly loams) well drained soils that are shallow to seep to bedrock: Low OM (1-2%)
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Moderate ground cover (50-60%) and gentle to moderate slopes (3-30%) 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:
Rough fescue > Idaho fescue > Low sagebrush > Sandberg bluegrass > forbs > other grasses > other shrubs

Sub-dominant:

Other:

Additional:
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: 1000, Normal: 800, Unfavorable: 600 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:
Perennial brush species, Sandberg bluegrass, Squirreltail, and forbs will increase with deterioration of plant community, while Rough and Idaho fescues descrease in the stand.
Perennial plant reproductive capability:
All species should be capable of reproducing annually

Download reference sheet

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