Ecological site R024XY608OR

R024XY016OR	LOAMY 8-10 PZ Loamy 8-10PZ (shallower soil depth, upland position, lower production, different composition – moderate rooted bunchgrasses dominant/ Thurber's needlegrass (ACTH7)- bluebunch wheatgrass (PSSPS)- Indan ricegrass (ACHY))
R024XY004OR	DRY FLOODPLAIN 6-10 PZ Dry Floodplain (longer available seasonal water table, higher production, different composition – Basin wildrye (LECI4) strongly dominant, Indian ricegrass (ACHY) absent)
R024XY609OR	DROUGHTY BOTTOM 6-10 PZ Droughty Bottom 6-10 PZ (longer available seasonal water table, higher production, different composition – Basin wildrye (LECI4) strongly dominant, Indian ricegrass (ACHY) minor)

R024XY609OR	DROUGHTY BOTTOM 6-10 PZ Droughty Bottom 6-10 PZ (longer available seasonal water table, higher production, different composition – Basin wildrye (LECI4) strongly dominant, Indian ricegrass (ACHY) minor)

Tree	Not specified
Shrub	(1) Artemisia tridentata ssp. tridentata (2) Grayia spinosa
Herbaceous	(1) Leymus cinereus (2) Achnatherum hymenoides

Landforms	(1) Basin floor (2) Valley
Runoff class	Low to medium
Flooding duration	Brief (2 to 7 days) to very brief (4 to 48 hours)
Flooding frequency	Occasional to rare
Elevation	3800 – 4500 ft
Slope	0 – 3 %
Water table depth	72 in
Aspect	Aspect is not a significant factor

Frost-free period (characteristic range)	40-70 days
Freeze-free period (characteristic range)	80-100 days
Precipitation total (characteristic range)	10-10 in
Frost-free period (actual range)	40-70 days
Freeze-free period (actual range)	80-110 days
Precipitation total (actual range)	10-10 in
Frost-free period (average)	60 days
Freeze-free period (average)	90 days
Precipitation total (average)	10 in

Parent material	(1) Alluvium (2) Lacustrine deposits
Surface texture	(1) Ashy loam (2) Ashy fine sandy loam (3) Extremely gravelly sandy loam
Family particle size	(1) Loamy-skeletal (2) Coarse-loamy (3) Fine-loamy
Drainage class	Well drained to moderately well drained
Permeability class	Rapid to moderately slow
Soil depth	60 – 0 in
Surface fragment cover <=3"	0 – 65 %
Surface fragment cover >3"	0 – 5 %
Available water capacity (0-40in)	8 – 10 in
Calcium carbonate equivalent (Depth not specified)	Not specified
Soil reaction (1:1 water) (0-40in)	7.4 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	0 – 65 %
Subsurface fragment volume >3" (Depth not specified)	0 – 5 %

Ecological dynamics

The potential native plant community is dominated by basin wildrye, Wyoming and basin big sagebrush. Indian ricegrass and spiny hopsage are prominent. Shadscale saltbush occurs sporadically. Thurber’s needlegrass and a variety of other grasses and forbs are present. Vegetative composition of the community is approximately 75 percent grasses, 5 percent forbs and 20 percent shrubs. The approximate ground cover is 50 to 60 percent (basal and crown).

Range in Characteristics:
Production increases at the upper end of the precipitation zone and with increasing surface runoff and deep subsurface moisture. Basin wild rye increases with increasing available moisture. Indian ricegrass increases on droughty sites with coarse surfaces. Thurber’s needlegrass increases on loamy droughty sites. Spiny hopsage and other salt brush species increase on calcareous arid sites. Wyoming and basin big sagebrush increases with precipitation and decreasing aridic conditions.

Response to Disturbance - States:
When the condition of the site deteriorates as a result of over grazing basin wildrye, Indian ricegrass and other deep rooted perennial bunchgrass will decrease. Basin big sagebrush, spiny hopsage and bare ground increases. Squirreltail increases and annuals sparingly invade. With further deterioration shrubs continue to increase and bare ground markedly increases. Where present, active ephemeral channels show varying degrees of incision. Production decreases and site deterioration continues to occur in a cyclic pattern.

State and transition model

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Ecosystem states

1. Reference Plant Community

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Reference Plant Community

Community 1.1
Reference Plant Community

The reference native plant community is dominated by basin wildrye, Wyoming and basin big sagebrush. Indian ricegrass and spiny hopsage are prominent. Shadscale saltbush occurs sporadically. Thurber’s needlegrass and a variety of other grasses and forbs are present. Vegetative composition of the community is approximately 75 percent grasses, 5 percent forbs and 20 percent shrubs. The approximate ground cover is 50 to 60 percent (basal and crown).

Figure 7. 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	525	675	900
Shrub/Vine	140	180	240
Forb	35	45	60
Total	700	900	1200

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Dominant, deep rooted bunchgrass			270–360
	basin wildrye	LECI4	Leymus cinereus	270–360	–
2	Sub-dominant, moderate rooted bunchgrass			90–180
	Indian ricegrass	ACHY	Achnatherum hymenoides	90–180	–
3	Common, moderate rooted bunchgrasses			90–180
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	45–90	–
	bluebunch wheatgrass	PSSPS	Pseudoroegneria spicata ssp. spicata	45–90	–
4	Other perennial grasses			40–80
	needle and thread	HECO26	Hesperostipa comata	18–45	–
	beardless wildrye	LETR5	Leymus triticoides	5–18	–
	Sandberg bluegrass	POSE	Poa secunda	5–10	–
	squirreltail	ELEL5	Elymus elymoides	5–10	–
Forb
5	Perennial forbs			30–80
	lupine	LUPIN	Lupinus	5–15	–
	common yarrow	ACMI2	Achillea millefolium	5–15	–
	milkvetch	ASTRA	Astragalus	5–15	–
	hawksbeard	CREPI	Crepis	5–10	–
	evening primrose	OENOT	Oenothera	5–10	–
	phlox	PHLOX	Phlox	5–10	–
	scarlet globemallow	SPCO	Sphaeralcea coccinea	0–5	–
Shrub/Vine
6	Dominant, evergreen, non-sprouting shrubs			70–135
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	45–90	–
	Wyoming big sagebrush	ARTRW8	Artemisia tridentata ssp. wyomingensis	25–70	–
7	Sub-dominant, evergreen, non-sprouting shrub			20–45
	spiny hopsage	GRSP	Grayia spinosa	20–45	–
8	Other shrubs			20–80
	shadscale saltbush	ATCO	Atriplex confertifolia	5–20	–
	bud sagebrush	PIDE4	Picrothamnus desertorum	0–15	–
	littleleaf horsebrush	TEGL	Tetradymia glabrata	0–10	–
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	5–10	–
	rubber rabbitbrush	ERNA10	Ericameria nauseosa	0–10	–
	broom snakeweed	GUSA2	Gutierrezia sarothrae	0–10	–

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	08/19/2026
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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Natural ResourcesConservation Service

Ecological site R024XY608OR

ARID BOTTOM 6-10 PZ

Last updated: 10/22/2024 Accessed: 08/19/2026

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Ecological site concept

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Table 1. Dominant plant species

Natural Resources
Conservation Service

ARID BOTTOM
6-10 PZ

Last updated: 10/22/2024
Accessed: 08/19/2026