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Conservation Service

Ecological site R023XY602OR

ARID NORTH 8-10 PZ

Accessed: 12/21/2024

Home / Esd catalog / MLRA 023X / Ecological site R023XY602OR

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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.

Table 1. Dominant plant species

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

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Physiographic features

This site occurs on north facing side-slopes of basin hills and low mountains. Slopes range from 10-80%, with gradients of 20 to 70% being most common. Elevations vary from 4400-5500 feet.

Table 2. Representative physiographic features

Landforms	(1) Hill (2) Mountain slope
Flooding frequency	None
Ponding frequency	None
Elevation	4,400 – 5,500 ft
Slope	20 – 70%
Aspect	N

Climatic features

The annual precipitation averages 8-10 inches, most of which occurs during the months of October through March. The mean annual air temperature is 48 degrees F. Temperature extremes range from 110 to -30 degrees F. The period for optimum Plant growth is from April through early June.

Table 3. Representative climatic features

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

Figure 2. Annual precipitation pattern

Figure 3. Annual average temperature pattern

Soil features

The soils of this site are shallow to very shallow over a strongly cemented duripan, bedrock, or clay layer. Typically the surface is a very gravelly or cobbly sandy clay
loam over a very cobbly clay loam subsoil. Permeability is moderate to moderately slow. The available water holding capacity is about .5 to 3 inches for the profile. The potential for erosion is high. See Appendix II for soils that correlate to this site.

Table 4. Representative soil features

Surface texture	(1) Very cobbly sandy clay loam (2) Very gravelly sandy clay loam
Family particle size	(1) Clayey
Permeability class	Moderately slow to moderate
Available water capacity (0-40in)	0.5 – 3 in

Ecological dynamics

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: Plant community phase change is driven by infrequent fire. Wyoming and basin big sagebrush decline after fire while Thurber’s needlegrass, Indian ricegrass and other grasses increase. May see a temporary increase in rabbitbrush after fire. Time facilitates the reintroduction of sagebrush. 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 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. The timing and/or intensity of 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 Indian ricegrass 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.

State and transition model

Custom diagram

Standard diagram

Figure 4. 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 reference native plant community is dominated by Wyoming big sagebrush and bluebunch wheatgrass. Thurber’s needlegrass and Cusick’s bluegrass are prominent. Spiny hopsage, Sandberg bluegrass, bottlebrush squirreltail and a variety of forbs are present. Vegetative composition of the community is approximately 70 percent grasses, 10 percent forbs and 20 percent shrubs. The approximate ground cover is 50 to 60 percent (basal and crown).

Figure 5. 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	250	400	500
Shrub/Vine	200	320	400
Forb	50	80	100
Total	500	800	1000

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Grass/Grasslike
1	Perennial, moderately deep rooted, bunchgrass			240–360
	bluebunch wheatgrass	PSSPS	Pseudoroegneria spicata ssp. spicata	240–360	–
2	Perennial, moderately deep rooted, bunchgrass			0–64
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	0–40	–
	Idaho fescue	FEID	Festuca idahoensis	0–24	–
3	Perennial, shallow rooted, bunchgrass			40–80
	Sandberg bluegrass	POSE	Poa secunda	40–80	–
	milkvetch	ASTRA	Astragalus	3–6	–
	lupine	LUPIN	Lupinus	3–6	–
4	Other perennial bunchgrass			16–40
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	37–75	–
	yellow rabbitbrush	CHVIS5	Chrysothamnus viscidiflorus ssp. viscidiflorus var. stenophyllus	4–19	–
	silver sagebrush	ARCA13	Artemisia cana	4–19	–
	spiny hopsage	GRSP	Grayia spinosa	4–19	–
	Indian ricegrass	ACHY	Achnatherum hymenoides	0–16	–
	squirreltail	ELEL5	Elymus elymoides	0–16	–
	greasewood	SAVE4	Sarcobatus vermiculatus	0–8	–
	rubber rabbitbrush	ERNAS	Ericameria nauseosa ssp. nauseosa var. salicifolia	0–4	–
Forb
5	Perennial forbs			16–80
	common yarrow	ACMI2	Achillea millefolium	0–16	–
	pussytoes	ANTEN	Antennaria	0–16	–
	rockcress	ARABI2	Arabis	0–16	–
	milkvetch	ASTRA	Astragalus	0–16	–
	arrowleaf balsamroot	BASA3	Balsamorhiza sagittata	0–16	–
	mariposa lily	CALOC	Calochortus	0–16	–
	Indian paintbrush	CASTI2	Castilleja	0–16	–
	tapertip hawksbeard	CRAC2	Crepis acuminata	0–16	–
	fleabane	ERIGE2	Erigeron	0–16	–
	buckwheat	ERIOG	Eriogonum	0–16	–
	lupine	LUPIN	Lupinus	0–16	–
	phlox	PHLOX	Phlox	0–16	–
	deathcamas	ZIGAD	Zigadenus	0–16	–
Shrub/Vine
6	Dominant, evergreen, non-sprouting shrubs			96–200
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	80–160	–
	Wyoming big sagebrush	ARTRW8	Artemisia tridentata ssp. wyomingensis	16–40	–
7	Common, evergreen, non-sprouting shrub			8–24
	spiny hopsage	GRSP	Grayia spinosa	8–24	–
8	Other shrubs			16–48
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	0–16	–
	rubber rabbitbrush	ERNA10	Ericameria nauseosa	0–16	–
	spineless horsebrush	TECA2	Tetradymia canescens	0–16	–
	littleleaf horsebrush	TEGL	Tetradymia glabrata	0–16	–

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)
Contact for lead author
Date
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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 plant reproductive capability:

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