Search

Search for a Major Land Resource Area or ecological site by name and/or ID.

Natural Resources
Conservation Service

Ecological site R010XY125OR

Gravelly Fan 12-16 PZ

Accessed: 12/21/2024

Home / Esd catalog / MLRA 010X / Ecological site R010XY125OR

USC

Metric

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.

Table 1. Dominant plant species

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

Download full description

Physiographic features

This site occurs on fans near and at the outlets of ephemeral streams. Braiding is common. It often occurs along major rivers and streams as a series of coalescing fans. Slopes range from 2 to 15 percent. Elevation varies from 2100 to 4500 feet.

Table 2. Representative physiographic features

Landforms	(1) Fan (2) Braided stream
Elevation	2,100 – 4,500 ft
Slope	2 – 15%
Water table depth	60 in
Aspect	Aspect is not a significant factor

Climatic features

The annual precipitation ranges from 12 to 16 inches, most of which occurs in the form of snow during the months of November through March. A seasonal supply of deep subsurface moisture augments the precipitation. Localized convectional storms occasionally occur during the summer. The soil temperature regime is typically near frigid with a mean annual air temperature of 50 degrees F. Temperature extremes range from 100 to -20 degrees F. The frost-free period ranges from 60 to 130 days. The optimum growth period for native plants is from April through June.

Table 3. Representative climatic features

Frost-free period (average)	130 days
Freeze-free period (average)	0 days
Precipitation total (average)	16 in

Soil features

The soils of this site are recent, deep to very deep, skeletal and well-drained. Typically the surface layer is a gravelly or shaly loam about 30 inches thick. The subsoil is a gravelly or shaly loam over 20 inches thick. The substratum is alluvium. Permeability is moderate. The available water holding capacity (AWC) is about 8 to 10 inches for the profile. Deep seasonal subsurface flows augment the availabe water. The potential for erosion is moderate.

Table 4. Representative soil features

Surface texture	(1) Gravelly fine sandy loam
Family particle size	(1) Loamy
Drainage class	Well drained
Permeability class	Moderate
Soil depth	50 in
Available water capacity (0-40in)	8 – 10 in

Ecological dynamics

Range in Characteristics:

Basin wildrye is dominant with production dependent on the extent and duration of lateral subsurface water flows. Bluebunch wheatgrass increases on drier areas with limited subsurface flows. Production follows a similar pattern, increasing on fans that receive late subsurface flows from large drainage areas. Idaho fescue increases on northerly aspects. As a fire susceptible site, the amount of basin big sagebrush and juniper, is influenced by fire frequency.

Response to Disturbance:

If the condition of the site deteriorates as a result of overgrazing, basin wildrye and Idaho fescue decrease. Bluebunch wheatgrass and bluegrasses increase. With further deterioration, basin big sagebrush continues to increase and annuals and juniper invade. Basin big sagebrush effectively replaces basin wildrye in the use of deep moisture. Streambanks become unstable from loss of vegetation and channels degrade, becoming wider in the process. Bareground increases, filtering capacity is lost, and downstream sedimentation increases.

State and transition model

Custom diagram

Standard diagram

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 Plant Community

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Reference Plant Community

Community 1.1
Reference Plant Community

The potential native plant community is dominated by basin wildrye and bluebunch wheatgrass. Basin big sagebrush, Idaho fescue, and Thurber needlegrass are common in the stand. Rabbitbrush, bluegrasses, and a variety of forbs are present. Vegetative composition of the community is approximately 90 percent grasses, 2 percent forbs, and 8 percent shrubs. Approximate ground cover is 80-90 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 (lb/acre)	Representative value (lb/acre)	High (lb/acre)
Grass/Grasslike	2370	3060	3750
Shrub/Vine	60	135	210
Forb	90	150	210
Tree	30	45	60
Total	2550	3390	4230

Figure 2. Plant community growth curve (percent production by month). OR4451, B10 SR Fan and Swale, 9-16 pz . SR Fan and Swale, 9-16 pz RPC Growth Curve.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	0	5	10	25	25	20	5	5	5	0	0

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, deep-rooted, dominant			1800–2400
	basin wildrye	LECI4	Leymus cinereus	1800–2400	–
2	Perennial, deep-rooted, sub-dominant			510–1200
	bluebunch wheatgrass	PSSP6	Pseudoroegneria spicata	300–600	–
	Idaho fescue	FEID	Festuca idahoensis	150–450	–
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	60–150	–
5	Other perennial grasses, all			60–150
	squirreltail	ELEL5	Elymus elymoides	0–50	–
	prairie Junegrass	KOMA	Koeleria macrantha	0–50	–
	Sandberg bluegrass	POSE	Poa secunda	0–50	–
Forb
7	Perennial, all, dominant			60–120
	milkvetch	ASTRA	Astragalus	30–60	–
	lupine	LUPIN	Lupinus	30–60	–
9	Other perennital forbs, all			30–90
	common yarrow	ACMI2	Achillea millefolium	0–10	–
	white sagebrush	ARLU	Artemisia ludoviciana	0–10	–
	arrowleaf balsamroot	BASA3	Balsamorhiza sagittata	0–10	–
	tapertip hawksbeard	CRAC2	Crepis acuminata	0–10	–
	fleabane	ERIGE2	Erigeron	0–10	–
	buckwheat	ERIOG	Eriogonum	0–10	–
	stoneseed	LITHO3	Lithospermum	0–10	–
	desertparsley	LOMAT	Lomatium	0–10	–
	phlox	PHLOX	Phlox	0–10	–
Shrub/Vine
11	Perennial, evergreen, dominant			30–150
	basin big sagebrush	ARTRT	Artemisia tridentata ssp. tridentata	30–150	–
12	Perennial, evergreen, sub-dominant			30–60
	rabbitbrush	CHRYS9	Chrysothamnus	30–60	–
Tree
16	Perennial, evergreen, dominant			30–60
	western juniper	JUOC	Juniperus occidentalis	30–60	–

Interpretations

Animal community

Livestock Grazing:

This site is suited to use by cattle, sheep, and horses in all seasons under a planned grazing system. Limitations in the spring are wet soils and unstable banks. Use should be postponed until the soils are firm enough to prevent trampling damage and soil compaction, yet while soil moisture is adequate to allow the completion of the plant growth cycle. As a sediment deposition area, improvement and/or maintenance of herbaceous cover should be considered during all seasons, particularly in the fall and winter for spring runoff protection and sediment deposition.

Native Wildlife Associated with the Potential Climax Community:

Deer
Antelope
Elk
Hawks
Songbirds
Rodents

This site will offer food and cover for mule deer, antelope, elk, rodents, and a variety of birds. It is an important wintering area for mule deer and elk.

Hydrological functions

The soils are in hydrologic group B. The soils of this site have moderately low runoff potential. This site is potentially subject to three high flow periods: low elevation snowmelt, high elevation snowmelt, and summer cloudburst flow.

Wood products

This site is susceptible to increase in western juniper. Where this has occurred, the site will yield fence posts, firewood, and specialty products.

Other information

The soils in this site have good water holding capacities providing late season water for plant growth and slow water release to streams. Increase in western juniper and the subsequent competition for moisture will lead to a reduction of availabe forage. Overgrazing can easily reduce ground cover and accelerate soil loss. Improving infiltration and permeability, and reducing runoff should be the immediate goal of juniper control. When incised channels are present, rehabilitation will markedly improve production, reduce downstream sedimentation and restore good hydrologic characteristics. On altered sites, the reintroduction of basin wildrye may be needed to fully restore the site 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
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:

Download reference sheet