Natural Resources
Conservation Service

Ecological site R028AY431UT

Mountain Loam (Mountain Big Sagebrush)

Last updated: 6/12/2025
Accessed: 08/14/2026

Home / esd CATALOG / MLRA 028A / ecological site R028AY431UT

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.

MLRA notes

Major Land Resource Area (MLRA): 028A–Ancient Lake Bonneville

This site is located in MLRA 47, Wasatch Mountains.

Ecological site concept

This site is located on mountain slopes and valley sides on gentle to steep slopes (1 to 60 percent) between 4,900 and 8,000 feet (1,493 to 2,438 meters). The soil is fine to loamy-skeletal and is greater than 20 inches to a restrictive layer. The soil may have a restrictive layer between 20 and 60 inches to bedrock. The soil was formed in colluvium, residuum and/or alluvium derived from quartzite, limestone, sandstone, and conglomerate. The precipitation ranges from 17 to 33 inches (432 to 838 mm). The dominant vegetation is mountain big sagebrush (Artemisia tridentata ssp. vaseyana) and bluebunch wheatgrass (Pseudoroegneria spicata). This site is located in MLRA 47, Wasatch Mountains.

Similar sites

R047XA430UT	Mountain Loam (mountain big sagebrush) This site occurs in MLRA 47 to the east. These two sites may have been used interchangeably.

R047XA430UT

Mountain Loam (mountain big sagebrush)

This site occurs in MLRA 47 to the east. These two sites may have been used interchangeably.

Table 1. Dominant plant species

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

Download full description

Physiographic features

This site is located on mountain slopes and valley sides on gentle to steep slopes (1 to 60 percent) between 4,900 and 8,000 feet (1,493 to 2,438 meters). Flooding does not occur on this site.

Table 2. Representative physiographic features

Landforms	(1) Mountain slope (2) Valley side
Flooding frequency	None
Ponding frequency	None
Elevation	4900 – 8000 ft
Slope	1 – 60 %
Aspect	Aspect is not a significant factor

Climatic features

The climate is characterized by warm, dry summers, cold, snowy winters and moist springs. The average annual precipitation is between 17 and 33 inches. October through May is the wettest part of the year and June through August are the driest. The effective moisture for plant growth is the portion that falls during the plant dormant period, which wets the soil deeply in the spring.

Table 3 Representative climatic features

Frost-free period (characteristic range)
Freeze-free period (characteristic range)
Precipitation total (characteristic range)	20-30 in
Frost-free period (average)
Freeze-free period (average)
Precipitation total (average)	30 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Influencing water features

Due to its landscape position, this site is not typically influenced by streams or wetlands. It can sometimes be influenced by overland flow during heavy thunder storms and/or during wetter spring runoff periods.

Soil features

The characteristic soils of this site are moderately deep to deep and well drained. The soil was formed in colluvium, residuum and/or alluvium derived from quartzite, limestone, sandstone, and conglomerate. The surface horizon has a loam texture with gravels often occurring on the surface. Rock fragments may occur on the soil surface and make up less than 35 percent of the soil cover and less than 55 percent of the subsoil volume. Available water capacity ranges from 1.4 to 7.5 inches in the upper 40 inches of soil. These soils are neutral and are not calcareous on the surface. The soil moisture regime is xeric and the soil temperature regime is frigid.

Soil Map Units that may contain this site:
Soil Survey Area: Soil Components (Map units in parentheses)
Box Elder County, Utah, Eastern Part (UT602): Manila (MCG)
Cache Valley Area, Parts of Cache and Box Elder Counties (UT603): Despain (AOE2, HIB)

Table 4. Representative soil features

Parent material	(1) Alluvium – limestone and sandstone (2) Colluvium – quartzite (3) Residuum – conglomerate
Surface texture	(1) Gravelly loam
Drainage class	Well drained to somewhat excessively drained
Permeability class	Slow to moderate
Depth to restrictive layer	20 – 60 in
Soil depth	20 – 60 in
Surface fragment cover <=3"	5 – 20 %
Surface fragment cover >3"	0 – 5 %
Available water capacity (Depth not specified)	1.4 – 7.5 in
Electrical conductivity (Depth not specified)	0 – 2 mmhos/cm
Soil reaction (1:1 water) (Depth not specified)	6.1 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	8 – 18 %
Subsurface fragment volume >3" (Depth not specified)	9 – 37 %

Ecological dynamics

This site is found in the Great Salt Lake Area of the Basin and Range Ecological Provence. It developed under the natural ecological conditions found there, including the normal influences of native wildlife herbivory, fire and climate. Mountain big sagebrush and bluebunch wheatgrass are the dominant plants on this site. Various other shrubs, grasses, and forbs can also occur.

The state and transition model for the site was developed from information from a similar site developed in the adjacent MLRA to the east, Wasatch and Uinta Mountains 47, Mountain Loam (mountain big sagebrush) (R047XA430UT). Two possible stable states have been hypothesized for this ecological site. These plant communities may not represent every possibility, but they are the most prevalent and repeatable plant communities. As data is collected, some of these plant communities may be revised or removed and new ones may be added. None of these plant communities should necessarily be thought of as the “desired plant community”. According to the USDA NRCS National Range and Pasture Handbook, the desired plant community will be determined by the decision makers and will meet minimum quality criteria established by the NRCS. The main purpose for including any description of a plant community here is to capture the current knowledge and experience at the time of this revision. Specific community phases and transitions will be described in the narratives below.

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 State

SWAPAEH

2. Current Potential State

SWAPAEH

State 1 submodel, plant communities

1.1. Mountain big sagebrush-steppe

State 2 submodel, plant communities

2.1. Mountain big sagebrush-steppe/non-native species

State 1
Reference State

The Reference State represents the natural range of variability under a typical pre-European disturbance regime. This site lacks data to support more than one potential plant community. As additional data is collected, more plant communities may be added

Community 1.1
Mountain big sagebrush-steppe

This plant community is dominated by mountain big sagebrush and bluebunch wheatgrass.

State 2
Current Potential State

The Current Potential State is similar to the Reference State, but with the addition of non-native species in the plant community. The addition of non-native species can reduce the resiliency of the site under the typical disturbance regime.

Community 2.1
Mountain big sagebrush-steppe/non-native species

The plant community is dominated by mountain big sagebrush and bluebunch wheatgrass with a small percentage of non-native species.

Transition T1A
State 1 to 2

Introduction of non-native species.

Additional community tables

Table 5. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 6. Community 2.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

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	08/14/2026
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:

Download reference sheet

Natural ResourcesConservation Service