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Ecological site R023XY308OR

NORTH SLOPES 10-12 PZ

Accessed: 11/23/2024

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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

R023XY212OR	LOAMY 10-12 PZ Loamy 10-12" PZ
R023XY300OR	SOUTH SLOPES 10-12 PZ South Slopes 8-12" PZ
R023XY312OR	SHALLOW NORTH 12-16 PZ Shallow North 12-16" PZ

R023XY212OR

LOAMY 10-12 PZ

Loamy 10-12" PZ

R023XY300OR

SOUTH SLOPES 10-12 PZ

South Slopes 8-12" PZ

R023XY312OR

SHALLOW NORTH 12-16 PZ

Shallow North 12-16" PZ

Similar sites

R023XY318OR	LOAMY 12-16 PZ Loamy 12-16" PZ (non-aspect site at higher precipitation)
R023XY310OR	NORTH SLOPES 12-16 PZ North Slopes 12-16" PZ (higher precipitation)

R023XY318OR

LOAMY 12-16 PZ

Loamy 12-16" PZ (non-aspect site at higher precipitation)

R023XY310OR

NORTH SLOPES 12-16 PZ

North Slopes 12-16" PZ (higher precipitation)

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Artemisia tridentata ssp. tridentata
Herbaceous	(1) Festuca idahoensis (2) Pseudoroegneria spicata ssp. spicata

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Physiographic features

This site is on north-facing hillslopes and escarpments. Slopes range from 20 to 60 percent. Elevations range from 4500 to 6000 feet.

Table 2. Representative physiographic features

Landforms	(1) Escarpment (2) Hill
Elevation	1,372 – 1,829 m
Slope	20 – 60%
Aspect	N

Climatic features

The annual precipitation is 10 to 12 inches most of which occurs in the form of snow during November to March. Spring rains are common. The soil temperature regime is frigid. Extreme air temperatures range from 100 degrees F to -30 degrees F. The frost-free period is about 50 to 90 days. The optimum period for plant growth is from early May to mid-July.

Table 3. Representative climatic features

Frost-free period (average)	90 days
Freeze-free period (average)	0 days
Precipitation total (average)	305 mm

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soils in this site are medium textured throughout, moderately-deep to deep, and well-drained. The soils are formed in colluvium and/or residuum. The surface permeability is moderate and the subsoil has moderately slow permeability. The available water holding capacity (AWC) is 1 to 4 inches for the profile. The soil has a dark colored surface 20 or more inches thick which contains 25 to 60 percent rock fragments. The subsoil contains 20 to 80 percent rock fragments.

Table 4. Representative soil features

Parent material	(1) Colluvium – basalt (2) Residuum – welded tuff
Surface texture	(1) Extremely cobbly loam (2) Very gravelly loam
Family particle size	(1) Loamy
Drainage class	Well drained
Permeability class	Moderate to moderately slow
Soil depth	51 – 152 cm
Surface fragment cover <=3"	35 – 60%
Available water capacity (0-101.6cm)	1.52 – 10.16 cm
Soil reaction (1:1 water) (0-101.6cm)	6.6 – 7.8
Subsurface fragment volume >3" (Depth not specified)	35 – 80%

Ecological dynamics

Range in Characteristics:

The reference native plant community is dominated by Idaho fescue and Wyoming big sagebrush. Bluebunch wheatgrass is prominent in the understory. Vegetative composition is about 75 percent grasses, 10 percent forbs, and 15 percent shrubs.

Bluebunch wheatgrass increases as aspect becomes more southerly. Gravels in the surface layers favor increases in Thurber's needlgrass.

Four states have been identified for this site: a reference state; a state with the presence of annuals; a state with a shrub/annual co-dominance; and a state with annual dominance.

Reference State: Plant community phase change is driven by infrequent fire. Wyoming and basin big sagebrush decline after fire while Thurber’s needlegrass, Idaho fescue and other grasses increase. Rabbitbrush may temporarily increase after fire. Time facilitates the reintroduction of sagebrush. The introduction of invasive annual grasses and forbs transitions into state 2.

State 2: Compositionally similar to the reference state with a trace of cheatgrass and weedy forbs. Ecological function has not changed, however the resiliency of the state has been reduced by the presence of invasive weeds. Prescribed grazing and infrequent fire (> 50 year return interval) maintain state dynamics. Improper grazing or prolonged drought favors Wyoming and basin big sagebrush, squirreltail and Sandberg’s bluegrass. Prescribed grazing and/or release from drought may reverse the decline in needlegrass and Idaho fescue production. Infrequent fire reduces the shrub community and promotes the bunchgrass component. Mismanaged grazing and/or prolonged drought leads to a biotic threshold and into state 3.

State 3: Wyoming and basin big sagebrush is decadent with little recruitment. The perennial grass component is significantly reduced in both density and productivity. Cheatgrass and/or annual forbs and/or Sandberg’s bluegrass along with sagebrush control site resources and drive ecological dynamics. Bare ground is abundant. Spatial and temporal energy capture and nutrient cycling has been truncated. Infiltration may be reduced due to lack of ground cover. Risk of soil erosion by both wind and water is increased. Catastrophic wildfire will lead to an abiotic threshold and into state 4.

State 4: Cheatgrass and/or annual weed dominated plant community with limited to no shrub or perennial grass component. Soil erosion and redistribution along with changes in dynamic soil properties affect the hydrologic cycle and thus the nutrient cycle. Harsh environmental factors increase state resiliency to change. This state has a reduced likelihood of occurring or persisting due to the frigid soil temperature regime.

Response to Disturbance:

If heavy grazing causes site deterioration, Idaho fescue decreases and big sagebrush increases. On severely disturbed areas of this site, green rabbitbrush, prickly gilia, and vetch may be prominent.

State and transition model

Custom diagram

Standard diagram

Figure 3. Group 6, 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. Reference State

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Reference State

Community 1.1
Reference Plant Community

The potential native plant community is dominated by Idaho fescue and Wyoming big sagebrush. Bluebunch wheatgrass is prominent in the understory. Vegetative composition is about 75 percent grasses, 10 percent forbs, and 15 percent shrubs. Approximate ground cover is 50 to 65 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 (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Grass/Grasslike	588	841	1093
Shrub/Vine	118	168	219
Forb	78	112	146
Total	784	1121	1458

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (kg/hectare)	Foliar cover (%)
Grass/Grasslike
1	Perennial, deep-rooted, dominant			448–673
	Idaho fescue	FEID	Festuca idahoensis	448–673	–
2	Perennial, moderately-deep rooted bunchgrass			112–168
	bluebunch wheatgrass	PSSP6	Pseudoroegneria spicata	112–168	–
4	Perennial, shallow-rooted, bunchgrass			78–168
	Cusick's bluegrass	POCU3	Poa cusickii	56–112	–
	Sandberg bluegrass	POSE	Poa secunda	22–56	–
5	Other perennial grasses, all			11–34
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	0–11	–
	squirreltail	ELEL5	Elymus elymoides	0–11	–
	prairie Junegrass	KOMA	Koeleria macrantha	0–11	–
Forb
7	Perennial, all, dominant			34–67
	tapertip hawksbeard	CRAC2	Crepis acuminata	11–22	–
	phlox	PHLOX	Phlox	11–22	–
	vetch	VICIA	Vicia	11–22	–
9	Other perennial forbs, all			11–45
	naked mariposa lily	CANU2	Calochortus nudus	0–11	–
	fleabane	ERIGE2	Erigeron	0–11	–
	granite prickly phlox	LIPU11	Linanthus pungens	0–11	–
	lupine	LUPIN	Lupinus	0–11	–
Shrub/Vine
11	Evergreen			78–168
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	56–112	–
	Wyoming big sagebrush	ARTRW8	Artemisia tridentata ssp. wyomingensis	22–56	–
15	Other shrubs			22–56
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	0–22	–
	slender buckwheat	ERMI4	Eriogonum microthecum	0–22	–
	antelope bitterbrush	PUTR2	Purshia tridentata	0–22	–

Interpretations

Animal community

Livestock grazing:

This site is suitable for livestock grazing use in spring, summer, and fall. Grazing management should be keyed to Idaho fescue. Deferred grazing is recommended at least once every three years. On slopes greater than 50 percent, cattle use will be reduced.

Native Wildlife Associated with the Climax Community:

Mule deer
Bighorn Sheep
Quail
Burrowing rodents
Rabbits

Mule deer use this site in spring, summer, and fall.

Hydrological functions

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

Recreational uses

This site can provide upland game hunting.

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	State Rangeland Management Specialist for NRCS - OR
Date	08/17/2012
Approved by	Bob Gillaspy
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
None, Moderate sheet & rill erosion hazard
Presence of water flow patterns:
None to some
Number and height of erosional pedestals or terracettes:
None to very few terracettes
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
2-8%
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 = 3-5
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Deep well drained very gravelly to extremely cobbly loam; weak thin platy to weak fine subangular block structure 7 to 15 inches thick, dry color value 4 - 6: Moderate OM (1-3%)
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Moderate to significant ground cover (50-65%) and moderate to very steep slopes (20-70%) 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:
Idaho fescue > Bluebunch wheatgrass > shrubs > other grasses > forbs

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: 1300, Normal: 1000, Unfavorable: 700 lbs/acre/year at high RSI (RPC)
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:
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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