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Ecological site R024XY634OR

SODIC SOUTH SLOPES 8-10 PZ

Accessed: 12/21/2024

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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.

Ecological site concept

ESC transferred from D23 to D24 with utilization of the same 3 digit site number. Occurs on the western edge of 23, bordering 6
ESIS says mod well to somewhat poorly drained. ESC does not match any soils correlated to it. Spp comp is questionable: PIDE4 and SAVE4 and ARTRW w/ PSSP as other? Similar to 24-22.

Associated sites

R024XY016OR	LOAMY 8-10 PZ Loamy 8-10 PZ (non-aspect, lower salts and carbonates, different composition – ARTRW8 and ACTH7 dominant, PSSPS prominent, SAVE4 absent)
R024XY030OR	LOAMY SLOPES 6-10 PZ Loamy Slopes 6-10 PZ (lower production, warmer south slope, different composition – ARTRW8 and ACHY dominant w/GRSP and ACTH7 present)
R024XY032OR	ARID SOUTH SLOPES 6-10 PZ Arid South Slopes 6-10 PZ (shallower soil, lower production, warmer south slope, different composition – ARTRW8 and ACHY dominant w/ACTH7 common, SADO4 and PSSPS present)
R024XY113OR	SODIC FAN 6-10 PZ Sodic Fan 6-10 PZ (fan position, very deep sandy loam to loam, different composition – ARTRT and ACHY dominant, LECI4 and SAVE4 common)
R024XY638OR	SOUTH SLOPES 8-10 PZ South Slopes 8-10 PZ (lower salts and carbonates, different composition – ARTRW8 and PSSPS dominant w/ACTH7 near co-dominant and SAVE4 absent)
R024XY640OR	STONY ALKALINE SLOPES 6-10 PZ Stony Alkaline Slopes 6-10 PZ (lower production, warmer southwest slope, different composition – SAVE4 and ACHY dominant w/ATCO and HECO26 common)

Similar sites

R024XY032OR	ARID SOUTH SLOPES 6-10 PZ Arid South Slopes 6-10 PZ (shallower soil, lower production, warmer south slope, different composition – ARTRW8 and ACHY dominant w/ACTH7 common, SADO4 and PSSPS present)
R024XY030OR	LOAMY SLOPES 6-10 PZ Loamy Slopes 6-10 PZ (lower production, warmer south slope, different composition – ARTRW8 and ACHY dominant w/GRSP and ACTH7 present)
R024XY638OR	SOUTH SLOPES 8-10 PZ South Slopes 8-10 PZ (lower salts and carbonates, different composition – ARTRW8 and PSSPS dominant w/ACTH7 near co-dominant and SAVE4 absent)
R024XY640OR	STONY ALKALINE SLOPES 6-10 PZ Stony Alkaline Slopes 6-10 PZ (lower production, warmer southwest slope, different composition – SAVE4 and ACHY dominant w/ATCO and HECO26 common)
R024XY637OR	SODIC NORTH SLOPES 8-10 PZ Sodic North Slopes 8-10 PZ (higher production, cooler north slope, different composition – ARTRW8 and PSSPS dominant w/SAVE4 common)
R024XY113OR	SODIC FAN 6-10 PZ Sodic Fan 6-10 PZ (fan position, very deep sandy loam to loam, different composition – ARTRT and ACHY dominant, LECI4 and SAVE4 common)

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Artemisia tridentata subsp. wyomingensis (2) Sarcobatus vermiculatus
Herbaceous	(1) Achnatherum hymenoides

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Physiographic features

This site occurs on south and west facing aspects of terraces and hills adjacent to alkaline lake basins. Slopes typically range from 15 to 30%. Elevation varies from 4000 to 4600 feet.

Table 2. Representative physiographic features

Landforms	(1) Lake terrace (2) Alluvial fan (3) Hill
Elevation	4,000 – 4,600 ft
Slope	15 – 30%
Aspect	S, SW

Climatic features

The annual precipitation ranges from 8 to 10 inches, most of which occurs in the form of rain and snow during the months of December through March. The soil temperature regime is mesic with a mean air temperature of 48 degrees F. Temperature extremes range from 110 to -20 degrees F. The frost free period ranges from 80 to 110 days. The optimum growth period for plant growth is from April through early June.

Table 3. Representative climatic features

Frost-free period (average)	110 days
Freeze-free period (average)	0 days
Precipitation total (average)	10 in

Soil features

The soils of this site are typically moderately deep to deep over alluvial and lacustrine sediments. Soils are sodium affected with a loamy surface texture over a loam to clay loam subsoil. Sodic conditions are mild at the surface increasing with depth. Cobbles are common throughout. A desert pavement is common. Permeability is moderate. The available water holding capacity (AWC) is about 4 to 6 inches for the profile. The potential for erosion is moderate.

Table 4. Representative soil features

Parent material	(1) Eolian deposits – rhyolite
Surface texture	(1) Cobbly loam (2) Sandy loam
Family particle size	(1) Loamy
Drainage class	Moderately well drained to somewhat poorly drained
Permeability class	Moderate to moderately slow
Soil depth	20 – 60 in
Available water capacity (0-40in)	4 – 6 in
Calcium carbonate equivalent (0-40in)	Not specified
Electrical conductivity (0-40in)	Not specified
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	Not specified

Ecological dynamics

The potential native plant community is dominated by Wyoming big sagebrush and Indian ricegrass. Greasewood and basin wildrye are common. Thurber’s needlegrass, Sandberg bluegrass, bottlebrush squirreltail, a variety of forbs and minor amounts of other salt desert shrubs are present. Vegetative composition of the community is approximately 55 percent grasses, 5 percent forbs and 40 percent shrubs. The approximate ground cover is 50 to 60 percent (basal and crown).

Range in Characteristics:
The depth to a restrictive layer and apect influences the composition and production of the site. Production will increase with greater soil depth and at the upper end of the precipitation zone. Indian ricegrass and needlegrasses increase on coarser surfaces and on droughty slopes. Greasewood and other salt tolerant shrubs increase in areas with higher sodic conditions. Basin wildrye increases with increased available sub-surface moisture. Bluebunch wheatgrass increases on a silty surface. On older stable higher terraces an erosion pavement has accumulated with a distinctive desert varnish. The distinctive dark color is due to precipitated concentrates of manganese and lesser amounts of iron.
Response to Disturbance - States:
If the condition of the site deteriorates as a result of over grazing, Indian ricegrass, needlegrasses and basin wildrye will decrease in the stand. Wyoming and basin big sagebrush, greasewood, squirreltail and Sandberg bluegrass will increase. Annuals will invade. With further deterioration, annuals continue to invade and bare ground increases. Erosion accelerates and site productivity decreases. The invasion of annuals and the natural re-establishment of native perennials are limited on eroded surfaces and in areas of dense cobbles and heavy erosion pavement.

States: ARTRW8(T)-SAVE4/ELEL5-POSE-annuals, bare ground with erosion pavement

State and transition model

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Standard diagram

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Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Referemce Plant Community

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Referemce Plant Community

Community 1.1
Reference Plant Community

The reference native plant community is dominated by Wyoming big sagebrush and Indian ricegrass. Greasewood and basin wildrye are common. Thurber’s needlegrass, Sandberg bluegrass, bottlebrush squirreltail, a variety of forbs and minor amounts of other salt desert shrubs are present. Vegetative composition of the community is approximately 55 percent grasses, 5 percent forbs and 40 percent shrubs. The approximate ground cover is 50 to 60 percent (basal and crown).

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	220	330	440
Shrub/Vine	160	240	320
Forb	20	30	40
Total	400	600	800

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	Dominant, moderate rooted bunchgrass			180–240
	Indian ricegrass	ACHY	Achnatherum hymenoides	180–240	–
2	Common, moderate rooted bunchgrasses			24–60
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	12–30	–
	squirreltail	ELEL5	Elymus elymoides	12–30	–
3	Common, deep rooted bunchgrass			12–30
	basin wildrye	LECI4	Leymus cinereus	12–30	–
4	Common, shallow rooted bunchgrass			12–30
	Sandberg bluegrass	POSE	Poa secunda	12–30	–
5	Other, perennial grasses			30–90
	needle and thread	HECO26	Hesperostipa comata	5–20	–
	beardless wildrye	LETR5	Leymus triticoides	5–20	–
	bluebunch wheatgrass	PSSPS	Pseudoroegneria spicata ssp. spicata	5–20	–
	foxtail wheatgrass	PSSA2	×Pseudelymus saxicola	0–10	–
	Webber needlegrass	ACWE3	Achnatherum webberi	0–5	–
Forb
6	Perennial forbs			30–60
	milkvetch	ASTRA	Astragalus	3–10	–
	buckwheat	ERIOG	Eriogonum	5–10	–
	granite prickly phlox	LIPU11	Linanthus pungens	0–10	–
	lupine	LUPIN	Lupinus	5–10	–
	common yarrow	ACMI2	Achillea millefolium	3–8	–
	phlox	PHLOX	Phlox	3–8	–
	fleabane	ERIGE2	Erigeron	3–8	–
	tapertip hawksbeard	CRAC2	Crepis acuminata	2–5	–
	evening primrose	OENOT	Oenothera	2–5	–
	Indian paintbrush	CASTI2	Castilleja	0–2	–
	Douglas' dustymaiden	CHDO	Chaenactis douglasii	0–2	–
	nodding thelypody	THFL3	Thelypodium flexuosum	0–2	–
	deathcamas	ZIGAD	Zigadenus	0–2	–
Shrub/Vine
8	Dominant, evergreen, non-sprouting shrub			40–90
	Wyoming big sagebrush	ARTRW8	Artemisia tridentata ssp. wyomingensis	30–60	–
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	10–30	–
9	Sub-dominant, deciduous, non-sprouting shrub			60–90
	greasewood	SAVE4	Sarcobatus vermiculatus	60–90	–
10	Common shrubs			30–90
	shadscale saltbush	ATCO	Atriplex confertifolia	10–30	–
	spiny hopsage	GRSP	Grayia spinosa	10–30	–
	bud sagebrush	PIDE4	Picrothamnus desertorum	10–30	–
11	Other shrubs			30–60
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	5–15	–
	rubber rabbitbrush	ERNA10	Ericameria nauseosa	0–15	–
	littleleaf horsebrush	TEGL	Tetradymia glabrata	5–15	–
	shortspine horsebrush	TESP2	Tetradymia spinosa	0–15	–

Interpretations

Animal community

This site is suitabity for livestock grazing use in the late spring and fall and winter under a planned grazing system. Use should be postponed until the soils are firm enough to prevent trampling damage and soil compaction. Care should be taken to avoid plant crown damage and soil movement when the soils are wet. Grazing management should be keyed to Indian ricegrass, needlegrasses and basin wildrye. These bunchgrasses can be severely damaged if heavily grazed during periods of flowering and grass seed formation before root reserves have accumulated and soil moisture is low. Deferred grazing or rest is recommended at least once every three years.

Wildlife
This site offers food and cover for mule deer, antelope, desert bighorn sheep and a variety of birds, rodents and associated predators. It is an important spring, fall and winter use area for mule deer, antelope and desert bighorn sheep.

Hydrological functions

The soils of this site have a moderate to high runoff potential. Hydrologic cover is good when the Indian ricegrass and needlegrass component is greater than 70 percent of potential. The soils are in hydrologic group C.

Other information

This site has limited potential for range seeding due to steepness and a usual stony surface. Extended drought can inhibit germination and establishment of available species.

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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