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Ecological site R009XY051OR

Loamy South
10-15 PZ

Last updated: 5/05/2025
Accessed: 07/17/2026

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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.

Associated sites

R009XY003OR	Fan 10-15 PZ Fan 10-15" PZ
R009XY050OR	Loamy Bench 10-15 PZ Loamy Bench 10-15" PZ
R009XY052OR	Loamy Shallow South 10-15 PZ Loamy Shallow South 10-15" PZ
R009XY053OR	Very Shallow South 10-15 PZ Very Shallow South 10-15" PZ
R009XY054OR	Loamy North 10-15 PZ Loamy North 10-15" PZ

Similar sites

R009XY050OR	Loamy Bench 10-15 PZ Loamy Bench 10-15" PZ (higher production)
R009XY052OR	Loamy Shallow South 10-15 PZ Loamy Shallow South 10-15" PZ (lower produciton)

R009XY050OR

Loamy Bench 10-15 PZ

Loamy Bench 10-15" PZ (higher production)

R009XY052OR

Loamy Shallow South 10-15 PZ

Loamy Shallow South 10-15" PZ (lower produciton)

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	Not specified

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Physiographic features

This site occurs on south facing slopes of canyons. Slopes range from 15 to 60% with slopes of 30 to 60% being the most typical. Elevation varies from 800 to 2800 feet.

Table 2. Representative physiographic features

Landforms	(1) Canyon
Elevation	800 – 2800 ft
Slope	15 – 60 %
Aspect	S

Climatic features

The annual precipitation ranges from 10 to 15 inches. Teh precipitaion occurs as rain and snow during the months of November through March. Localized, occasionally severe, convection storms occur during the summer. The mean annual air temperature is approximately 50 degrees F. Extereme temperatures range from 100 degrees F. to -20 degrees F. Soil temperature regimes are mesic. The frost-free period ranges from 90 to 140 days. The period of optimum plant growth is from early April through June.

Table 3 Representative climatic features

Frost-free period (average)	140 days
Freeze-free period (average)
Precipitation total (average)	20 in

Soil features

The soils of this site are formed in colluvium and loess over old, lower miocene basalt bedrock. They are moderately deepto very deep. Typically the surface layer is a silt loam to an extremely stony clay loam over loamy to cobbly clay loam subsoil. Stoniness is variable. Soil permeabilty is moderate. The available water holding capactity (AWC) i 6 to 10 inches. The erosion potential is moderate.

Table 4. Representative soil features

Surface texture	(1) Sandy loam (2) Extremely stony clay loam
Family particle size	(1) Loamy
Drainage class	Well drained
Permeability class	Moderate

Ecological dynamics

Range in Characteristics:
Variability in plant composition and production is dependant on soil depth, surface texture and aspect. Bluebunch wheatgrass increases on fine textured surfaces. Sand drop seed increaseson coarse textured surfaces and on low elevation droughty slopes. Production increases with soil depth.
Response to Disturbance:
If the condition of the site deteriorates as a result of overgrazing, bluebunch wheatgrass decreases. Sand dropseed increases along with lesser amounts of red threeawn. Cheatgrass, Japanese brome, annual fescues and a variety of unpalatable forbs invade. With further deterioration, sand dropseed decreases, annuals and three awn continue to increase, forage production decreases, annuals and threeawn continue to increase, forage production decreases, areas of bare ground appear and soil erosion accelerates.

State and transition model

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Standard diagram

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 bluebunch wheatgrass. Sand dropseed is common. Sandberg bluegrass is present along with a variety of forbs. Shrubs are rare. The potential vegetative composition is approximately 95 percent grass 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	704	796	888
Forb	32	72	112
Shrub/Vine	0	24	48
Total	736	892	1048

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Perennial Deep-rooted Dominant			640–720
	bluebunch wheatgrass	PSSP6	Pseudoroegneria spicata	640–720	–
2	Perennial Deep-rooted Sub-dominant			40–120
	sand dropseed	SPCR	Sporobolus cryptandrus	40–120	–
5	PPGG			24–48
	purple threeawn	ARPU9	Aristida purpurea	12–24	–
	Sandberg bluegrass	POSE	Poa secunda	12–24	–
Forb
7	Perennial All Dominant			24–72
	common yarrow	ACMI2	Achillea millefolium	8–24	–
	milkvetch	ASTRA	Astragalus	8–24	–
	plains pricklypear	OPPO	Opuntia polyacantha	8–24	–
9	PPFF			8–40
	agoseris	AGOSE	Agoseris	1–3	–
	buckwheat	ERIOG	Eriogonum	1–3	–
	shaggy fleabane	ERPU2	Erigeron pumilus	1–3	–
	aster	EUCEP2	Eucephalus	1–3	–
	hairy false goldenaster	HEVI4	Heterotheca villosa	1–3	–
	hawkweed	HIERA	Hieracium	1–3	–
	desertparsley	LOMAT	Lomatium	1–3	–
	lupine	LUPIN	Lupinus	1–3	–
	beardtongue	PENST	Penstemon	1–3	–
	phacelia	PHACE	Phacelia	1–3	–
	phlox	PHLOX	Phlox	1–3	–
	narrowleaf skullcap	SCAN3	Scutellaria angustifolia	1–3	–
Shrub/Vine
15	SSSS			0–48
	netleaf hackberry	CELAR	Celtis laevigata var. reticulata	0–24	–
	smooth sumac	RHGL	Rhus glabra	0–24	–

Interpretations

Animal community

Livestock Grazing:
This site is suited to spring, fall and winter use by cattle, sheep and horses under a plannned grazing system. The key species is bluebunch wheatgrass. Bluebunch wheatgrass can be damaged if heavily grazed during periods of flowering and seed formation when root reserves and soil moisture is low. Use in the spring should be postponed until the soils are firm enough to prevent trampling damage, soil compaction and soil mass movement.
Wildlife:
Whne the eceological condition is high this site provides food for deer, elk, other mammals and upland birds. It is an important wintering area for deer and elk.
Native Wildlife Associated With The Potential Climax Community:
Mule deer, White-tail deer, elk, rodents and a variety of upland birds use this site.

Hydrological functions

The soils of this site, particularly the silt loams, have good intake rates and excellent water holding capacities providing extended seasonal water for plant growth. The hydrologic cover condition is good when the ecological condition is high.

Other information

When in poor condition this site has a high potential for mechanical range seeding on moderate slopes and a low potential on steep slopes. Technology for seeding steep slopes is currently not available.

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

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 very deep, well drained, with a silt loam to extremely stony clay oam 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 (80-90%) and moderately steep slopes (15-60%) 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:
Bluebunch wheatgrass > Sand dropseed > forbs > other grasses > 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:
Sand dropseed and three-awn will increase with deterioration of plant community. Annual bromes and annual fescues invade sites that have lost deep rooted perennial grass functional groups. Excessive erosion may occur, deteriorating site potential.
Perennial plant reproductive capability:
All species should be capable of reproducing annually

Download reference sheet

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