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Ecological site R011XY034OR

Sandy North Slopes 8-11 PZ

Last updated: 9/23/2020
Accessed: 11/13/2024

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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.

MLRA notes

Major Land Resource Area (MLRA): 011X–Snake River Plains

Major Land Resource Area (MLRA): 011X–Snake River Plains

Precipitation or Climate Zone: 8-11” P.Z.

Ecological site concept

Site does not receive additional moisture
Soils are:
Not saline or saline sodic
Deep to very deep, with <35% coarse fragments (by volume), not skeletal
not strongly or violently effervescent in the surface mineral 10”
Surface textures range from loamy fine sand to loamy sand the surface mineral 4”
Slope is <30%
Clay content is =<35% in surface mineral 4”
Site does not have an argillic horizon with >35% clay

Associated sites

R011XY012OR	Silty 8-11 PZ Silty 8-11 PZ
R011XY016OR	Sandy 8-11 PZ Sandy 8-11 PZ
R011XY032OR	Silty North Slopes 8-11 PZ Silty North Slopes 8-11 PZ

R011XY012OR

Silty 8-11 PZ

Silty 8-11 PZ

R011XY016OR

Sandy 8-11 PZ

Sandy 8-11 PZ

R011XY032OR

Silty North Slopes 8-11 PZ

Silty North Slopes 8-11 PZ

Similar sites

R011XY016OR	Sandy 8-11 PZ Sandy 8-11 PZ (non-aspect site, lower production)
R011XY032OR	Silty North Slopes 8-11 PZ Silty North Slopes 8-11 PZ (silty surface, different composition - beardless wheatgrass dominant)

R011XY016OR

Sandy 8-11 PZ

Sandy 8-11 PZ (non-aspect site, lower production)

R011XY032OR

Silty North Slopes 8-11 PZ

Silty North Slopes 8-11 PZ (silty surface, different composition - beardless wheatgrass dominant)

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Atriplex canescens (2) Artemisia tridentata ssp. wyomingensis
Herbaceous	(1) Hesperostipa comata (2) Poa secunda

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Physiographic features

This site occurs on low elevation north aspects of terraces in the Malheur, Owyhee and adjacent Snake River drainage. Slopes typically range from 12 to 60%. Elevations vary from 2,100 to 3,000 feet.

Table 2. Representative physiographic features

Landforms	(1) Terrace
Elevation	640 – 914 m
Slope	12 – 60%
Aspect	N

Climatic features

The annual precipitation ranges from 8 to 11 inches, most of which occurs in the form of rain during the months of December through April. The soil temperature regime is mesic with a mean air temperature of 53 degrees F. Temperature extremes range from 110 to -10 degrees F. The frost free period ranges from 120 to 170 days. The optimum growth period for plant growth is late March through June.

Table 3. Representative climatic features

Frost-free period (average)	170 days
Freeze-free period (average)
Precipitation total (average)	279 mm

Soil features

The soils of this site are typically deep and well to somewhat excessively drained. Typically the surface layer is a fine sandy loam to a loamy fine sand. The subsoil is a loamy sand to sand 15 to 40 inches thick. Depth to lacustrine, alluvial or tuffaceous sediments ranges from 40 to greater than 60 inches. Permeability is moderately rapid to rapid. The available water holding capacity (AWC) is about 4 to 8 inches for the profile. The erosion potential, both wind and water, is severe.

Table 4. Representative soil features

Parent material	(1) Eolian sands – rhyolite
Surface texture	(1) Fine sandy loam (2) Loamy fine sand
Family particle size	(1) Sandy
Drainage class	Well drained to somewhat excessively drained
Permeability class	Moderately rapid to rapid
Soil depth	102 – 152 cm
Available water capacity (0-101.6cm)	10.16 – 15.24 cm

Ecological dynamics

The potential native plant community is dominated by four-wing saltbush and needle and thread. Wyoming big sagebrush and Indian ricegrass are prominent. Sandberg bluegrass, forbs and a variety of other shrubs are present. Vegetative composition of the community is approximately 80 percent grasses, 5 percent forbs and 15 percent shrubs. The approximate ground cover is 60 to 70 percent (basal and crown).

Range in Characteristics:
Variability in plant composition on this site results from variations in soil surface texture. Four-wing saltbush and needle and thread increase on loamy sand surfaces. Indian ricegrass increases on coarse sandy surfaces. Thurber’s needlegrass increases on fine sandy loam surfaces. Antelope bitterbrush occurs over gravels. Production increases at the upper end of the precipitation zone.

Response to Disturbance:
Disturbances that impact the condition of this site include overgrazing by large ungulates, fire, droughts that impact the hydrologic functions of these low-lying sites, and outside anthropogenic impacts that affect site hydrology which will impact water availability for the reference plants. Any disturbance that continues long enough or is of great enough severity will reduce reference plant vigor and cover rapidly.
When the condition of the site deteriorates as a result of over grazing four-wing saltbush, needle and thread and Indian ricegrass decrease. Wyoming big sagebrush, rabbitbrush, broom snakeweed and sand dropseed increase. Cheatgrass invades along with other annuals and biennial weeds. Bare ground increases. With fire and continued disturbance fourwing saltbush sagebrush is severely impacted. Rabbitbrush increases slightly and annuals and noxious biennial forbs continue to invade. Under deteriorated conditions excessive wind erosion in the bare soil interspaces reduces the site potential. Small migration dunes, blowouts and hummocks develop. Water erosion increases with excessive erosion most pronounced in drainage areas where deep incised gulley’s form.

States: ARTRW/BRTE-bare ground; BRTE/biennial forbs-bare ground (following fire on degraded range)

**The State-and-Transition Model represents only the Reference Plant Community phase due to limited time, data, and literature support at the time of development. Future work will be needed to describe dynamics, alterative states and land use models.

State and transition model

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. Reference Plant Community

State 1
Historic Climax Plant Community

Community 1.1
Reference Plant Community

The reference plant community is dominated by four-wing saltbush and needle and thread. Wyoming big sagebrush and Indian ricegrass are prominent. Sandberg bluegrass, forbs and a variety of other shrubs are present. Vegetative composition of the community is approximately 80 percent grasses, 5 percent forbs and 15 percent shrubs. The approximate ground cover is 60 to 70 percent (basal and crown).

Figure 1. 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	628	807	1076
Shrub/Vine	118	151	202
Forb	39	50	67
Total	785	1008	1345

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	Dominant, perennial, deep rooted bunchgrass			605–807
	needle and thread	HECO26	Hesperostipa comata	605–807	–
2	Sub-dominant, perennial, deeprooted bunchgrass			50–101
	Indian ricegrass	ACHY	Achnatherum hymenoides	50–101	–
4	Dominant, perennial, shallow-rooted grass			20–50
	Sandberg bluegrass	POSE	Poa secunda	20–50	–
5	Other perennial grasses			20–101
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	6–20	–
	beardless wheatgrass	PSSPI	Pseudoroegneria spicata ssp. inermis	6–20	–
	thickspike wheatgrass	ELLA3	Elymus lanceolatus	6–20	–
	basin wildrye	LECI4	Leymus cinereus	0–20	–
	foxtail wheatgrass	PSSA2	×Pseudelymus saxicola	0–11	–
	sand dropseed	SPCR	Sporobolus cryptandrus	0–11	–
	squirreltail	ELEL5	Elymus elymoides	6–11	–
Forb
8	Dominant, perennial forbs			30–50
	arrowleaf balsamroot	BASA3	Balsamorhiza sagittata	20–30	–
	buckwheat	ERIOG	Eriogonum	10–20	–
9	Other forbs			30–101
	common yarrow	ACMI2	Achillea millefolium	6–10	–
	milkvetch	ASTRA	Astragalus	6–10	–
	fleabane	ERIGE2	Erigeron	6–10	–
	western stoneseed	LIRU4	Lithospermum ruderale	0–10	–
	desertparsley	LOMAT	Lomatium	6–10	–
	lupine	LUPIN	Lupinus	0–10	–
	phlox	PHLOX	Phlox	6–10	–
	scarlet globemallow	SPCO	Sphaeralcea coccinea	0–6	–
	plains pricklypear	OPPO	Opuntia polyacantha	0–6	–
	beardtongue	PENST	Penstemon	0–6	–
	common woolly sunflower	ERLA6	Eriophyllum lanatum	0–6	–
	hawksbeard	CREPI	Crepis	2–6	–
	onion	ALLIU	Allium	2–6	–
Shrub/Vine
11	Dominant shrubs			40–101
	fourwing saltbush	ATCA2	Atriplex canescens	20–50	–
15	Other shrubs			20–101
	spiny hopsage	GRSP	Grayia spinosa	11–30	–
	winterfat	KRLA2	Krascheninnikovia lanata	0–30	–
	antelope bitterbrush	PUTR2	Purshia tridentata	11–30	–
	horsebrush	TETRA3	Tetradymia	0–20	–
	granite prickly phlox	LIPU11	Linanthus pungens	6–20	–
	broom snakeweed	GUSA2	Gutierrezia sarothrae	6–20	–
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	6–20	–
	rubber rabbitbrush	ERNA10	Ericameria nauseosa	6–20	–
	green rabbitbrush	ERTE18	Ericameria teretifolia	6–20	–

Interpretations

Animal community

Livestock Grazing:
This site is suitable for livestock grazing use in the late fall, winter and early spring under a planned grazing system. Use should be postponed until the soils are firm enough to prevent trampling damage and soil compaction. Grazing management should be keyed for needle and thread and four wing saltbush. Deferred grazing or rest is recommended at least once every three years.

Native Wildlife Associated with the Potential Climax Community:
This site is commonly used by pronghorn antelope, mule deer, rabbits, rodents, upland birds and various predators. Antelope and mule deer make excellent use of the site for spring forage.

Hydrological functions

The soils of this site are subject to both wind and water erosion. When the hydrologic cover is high they have high wind erosion resistance, low runoff potential and high infiltration rates. Hydrologic cover is high when needle and thread and other deep rooted bunchgrass components is greater than 70 percent of potential.

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	11/13/2024
Approved by	Kendra Moseley
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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