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Ecological site R047XA510UT

High Mountain Loam (bigtooth maple)

Last updated: 2/05/2025
Accessed: 04/11/2025

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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.

MLRA notes

Major Land Resource Area (MLRA): 047X–Wasatch and Uinta Mountains

MLRA 47 occurs in Utah (86 percent), Wyoming (8 percent), Colorado (4 percent), and Idaho (2 percent). It encompasses approximately 23,825 square miles (61,740 square kilometers). The northern half of this area is in the Middle Rocky Mountains Province of the Rocky Mountain System. The southern half is in the High Plateaus of the Utah Section of the Colorado Plateaus Province of the Intermontane Plateaus. Parts of the western edge of this MLRA are in the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. The MLRA includes the Wasatch Mountains, which trend north and south, and the Uinta Mountains, which trend east and west. The steeply sloping, precipitous Wasatch Mountains have narrow crests and deep valleys. Active faulting and erosion are a dominant force in controlling the geomorphology of the area. The Uinta Mountains have a broad, gently arching, elongated shape. Structurally, they consist of a broadly folded anticline that has an erosion-resistant quartzite core. The Wasatch and Uinta Mountains have an elevation of 4,900 to about 13,500 feet (1,495 to 4,115 meters).
The mountains in this area are primarily fault blocks that have been tilted up. Alluvial fans at the base of the mountains are recharge zones for the basin fill aquifers. An ancient shoreline of historic Bonneville Lake is evident on the footslopes along the western edge of the area. Rocks exposed in the mountains are mostly Mesozoic and Paleozoic sediments, but Precambrian rocks are exposed in the Uinta Mountains. The Uinta Mountains are one of the few ranges in the United States that are oriented west to east. The southern Wasatch Mountains consist of Tertiary volcanic rocks occurring as extrusive lava and intrusive crystalline rocks.
The average precipitation is from 8 to 16 inches (203 to 406 mm) in the valleys and can range up to 73 inches (1854 mm) in the mountains. In the northern and western portions of the MLRA, peak precipitation occurs in the winter months. The southern and eastern portions have a greater incidence of high-intensity summer thunderstorms; hence, a significant amount of precipitation occurs during the summer months. The average annual temperature is 30 to 50 degrees Fahrenheit (-1 to 15 C). The freeze-free period averages 140 days and ranges from 60 to 220 days, generally decreasing in length with elevation.
The dominant soil orders in this MLRA are Aridisols, Entisols, Inceptisols, and Mollisols. The lower elevations are dominated by a frigid temperature regime, while the higher elevations experience cryic temperature regimes. Mesic temperature regimes come in on the lower elevations and south facing slopes in the southern portion of this MLRA. The soil moisture regime is typically xeric in the northern part of the MLRA, but grades to ustic in the extreme eastern and southern parts. The mineralogy is generally mixed and the soils are very shallow to very deep, generally well-drained, and loamy or loamy–skeletal.

LRU notes

Major Land Resource Unit 47A is located in the northern half of the Middle Rocky Mountains Province of the Rocky Mountain System. This MLRA includes the Wasatch Mountains which tend to run north and south. These steeply sloping, precipitous mountains have narrow crests and deep valleys. They are primarily fault blocks that have been tilted up. The alluvial fans located at the base of these mountains are important recharge zones for valley aquifers.

Ecological site concept

The soils in this site formed in colluvium derived from limestone, sandstone, shale and various igneous rocks. They are moderately deep to deep, well-drained and have dark-colored surface layers that constitute a mollic epipedon. Rock fragments may be visible on the soil surface. The profile may contain greater than 35 percent gravel, but most often contains smaller amounts. These soils are well-drained, moderately slow to moderate, with neutral to acidic pH. Available water holding capacity ranges from 3.6 to 5.1 inches of water in the upper 40 inches of soil. The soil moisture regime is ustic and the soil temperature regime is cryic

Associated sites

R047XA461UT	Mountain Stony Loam (mountain big sagebrush)
R047XA402UT	Mountain Clay (slender wheatgrass)

R047XA461UT

Mountain Stony Loam (mountain big sagebrush)

R047XA402UT

Mountain Clay (slender wheatgrass)

Similar sites

R047XA418UT	Mountain Loam (bigtooth maple)

R047XA418UT

Mountain Loam (bigtooth maple)

Table 1. Dominant plant species

Tree	(1) Acer grandidentatum
Shrub	(1) Physocarpus malvaceus
Herbaceous	Not specified

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Physiographic features

This site is found on mountainsides and hillslopes at elevations between 5,200 and 9,000 feet. It commonly occurs on North and East facing aspects and on slopes ranging from 30 to 70 percent. Occasionally this site is found on gentler slopes. Runoff is medium and flooding and ponding do not occur on this site.

Table 2. Representative physiographic features

Landforms	(1) Mountainside (2) Hillslope
Flooding frequency	None
Ponding frequency	None
Elevation	5,200 – 9,000 ft
Slope	30 – 70%
Aspect	N, NE, E

Climatic features

The climate of this site is characterized by cold snowy winters and cool dry summers. The average annual precipitation ranges from 22 to 35 inches. Distribution is 55 to 60 percent during the plant dormant period (October to March). This is the most dependable supply for plant growth. Lower precipitation and high evapotranspiration rates during July, August and September cause a reduction in growth of all plant species and dormancy in many of the grasses and forbs.

Table 3. Representative climatic features

Frost-free period (average)	67 days
Freeze-free period (average)	80 days
Precipitation total (average)	29 in

Figure 2. Annual precipitation pattern

Figure 3. Annual average temperature pattern

Soil features

The soils in this site formed in colluvium derived from limestone, sandstone, shale and various igneous rocks. They are moderately deep to deep, well-drained and have dark-colored surface layers that constitute a mollic epipedon. Rock fragments may be visible on the soil surface. The profile typically has less than 35 percent gravel, but in some locations may contain greater than 35 percent gravel. These soils are well-drained, moderately slow to moderate, with neutral to acidic pH. Available water holding capacity ranges from 3.6 to 5.1 inches of water in the upper 40 inches of soil. The soil moisture regime is ustic and the soil temperature regime is cryic.

Modal Soil: Nordic GR-L, 30-60% — loamy-skeletal, mixed Cryic Palebotolls

Table 4. Representative soil features

Surface texture	(1) Gravelly loam (2) Cobbly loam (3) Loam
Family particle size	(1) Loamy
Drainage class	Well drained
Permeability class	Moderately slow to moderate
Soil depth	40 – 60 in
Surface fragment cover <=3"	14 – 22%
Surface fragment cover >3"	14%
Available water capacity (0-40in)	3.6 – 5.1 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)	5.6 – 7.3
Subsurface fragment volume <=3" (Depth not specified)	27 – 30%
Subsurface fragment volume >3" (Depth not specified)	9 – 14%

Ecological dynamics

It is impossible to determine in any quantitative detail the historic climax plant community (HCPC) for this ecological site because of the lack of direct historical documentation preceding all human influence. In some areas, the earliest reports of dominant plants include the cadastral survey conducted by the General Land Office, which began in the late 19th century for this area (Galatowitsch 1990). However, up to the 1870s the Shoshone Indians, prevalent in northern Utah and neighboring states, grazed horses and set fires to alter the vegetation for their needs (Parson 1996). In the 1860s, Europeans brought cattle and horses to the area, grazing large numbers of them on unfenced parcels year-long (Parson 1996). Itinerant and local sheep flocks followed, largely replacing cattle as the browse component increased.

Below is a State and Transition Model diagram that illustrates the “phases” (common plant communities), and “states” (aggregations of those plant communities) that can occur on the site. Differences between phases and states depend primarily upon observations of a range of disturbance histories in areas where this ESD is represented. These situations include grazing gradients to water sources, fence-line contrasts, patches with differing dates of fire, herbicide treatment, tillage, etc. Reference State 1 illustrates the common plant communities that probably existed just prior to European settlement.

The major successional pathways within states, (“community pathways”) are indicated by arrows between phases. “Transitions” are indicated by arrows between states. The drivers of these changes are indicated in codes decipherable by referring to the legend at the bottom of the page and by reading the detailed narratives that follow the diagram. The transition between Reference State 1 and State 2 is considered irreversible because of the naturalization of exotic species of both flora and fauna, possible extinction of native species, and climate change. There may have also been accelerated soil erosion.

The plant communities shown in this State and Transition Model may not represent every possibility, but are probably the most prevalent and recurring plant communities. As more monitoring data are collected, some phases or states may be revised, removed, and new ones may be added. None of these plant communities should necessarily be thought of as “Desired Plant Communities.” According to the USDA NRCS National Range and Pasture Handbook (USDA-NRCS 2003), Desired Plant Communities (DPC’s) will be determined by the decision-makers and will meet minimum quality criteria established by the NRCS. The main purpose for including descriptions of a plant community is to capture the current knowledge at the time of this revision.

State and transition model

Custom diagram

Standard diagram

Figure 4. State and Transition Model

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

2. Overgrown/ Depauperate Understory/ Introduced State

3. Lessened Tree Canopy/ Improved Understory State

T1a	-	introduction of exotic species, climate change, and the advent of intense season-long livestock grazing
T2a	-	elective harvest of stems, wildfire, excessive livestock grazing, brush management
R3a	-	Heavy, continuous, season-long grazing, fire control

State 1 submodel, plant communities

1.1. shorter trees & shrubs/ richer understory

1.2. taller trees & some shrubs/ reduced understory

1.1a	-	lack of fire
1.2a	-	Fire or tree management

State 2 submodel, plant communities

2.1. taller, denser trees & shrubs/ reduced understory

State 3 submodel, plant communities

3.1. thinned tree canopy/ understory re-establishment

State 1
Reference State

The Reference State is a description of this ecological site just prior to Euro-American settlement but long after the arrival of Native Americans. The description of the Reference State was determined by NRCS Soil Survey Type Site Location information and familiarity with rangeland relict areas where they exist. Shorter trees and shrub forms of bigtooth maple (Acer grandidentatum), quaking aspen (Populus tremuloides), and Rocky Mountain juniper (Juniperus scopulorum) would have made up the upper canopy. Other shrubs would have included mallow ninebark (Physocarpus malvaceus) and mountain snowberry (Symphoricarpos oreophilus). Understory shrubs would have been composed primarily of creeping barberry (Mahonia repens), Oregon boxleaf (Paxistima myrsinites), Woods' rose (Rosa woodsii). Grasses would have included blue wildrye (Elymus glaucus), mountain brome (Bromus marginatus), and slender wheatgrass (Elymus trachycaulus). Forbs would have included tall ragwort (Senecio serra), western coneflower (Rudbeckia occidentalis), silvery lupine (Lupinus argenteus), and nettleleaf giant hyssop (Agastache urticifolia) among others. The average fire return interval would have ranged from approximately 50 to 60 years, which would have been the driving factor behind changes in relative abundance and size of trees and associated understory richness. Shorter trees and shrubs with an understory rich in forbs and grasses (1.1) would have been found following recent wildfire events (1.2a). As the length of time elapsed since the fire lengthened (1.1a), trees would have increased both in height and density, while the understory would have lessened (1.2). A more complete list of species by lifeform for the Reference State is available in accompanying tables in the “Plant Community Composition by Weight and Percentage” section of this ESD document.

Community 1.1
shorter trees & shrubs/ richer understory

This plant community would have been characterized by shorter trees and shrubs with a relatively rich understory of smaller shrubs, forbs, and grasses. Bigtooth maple would have been the dominant woody species. The understory would have consisted of a mixture of species including mallow ninebark, mountain snowberry, creeping barberry, Oregon boxleaf, Woods' rose, blue wildrye, mountain brome, tall ragwort, silvery lupine, along with several other herbaceous species.

Figure 5. 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)
Forb	1400	1500	1600
Tree	720	800	850
Grass/Grasslike	280	300	525
Shrub/Vine	140	200	275
Total	2540	2800	3250

Table 6. Ground cover

Tree foliar cover	69-71%
Shrub/vine/liana foliar cover	19-21%
Grass/grasslike foliar cover	9-11%
Forb foliar cover	4-6%
Non-vascular plants	0%
Biological crusts	0%
Litter	0%
Surface fragments >0.25" and <=3"	0%
Surface fragments >3"	0%
Bedrock	0%
Water	0%
Bare ground	0%

Table 7. Canopy structure (% cover)

Height Above Ground (ft)	Tree	Shrub/Vine	Grass/ Grasslike	Forb
<0.5	–	–	–	–
>0.5 <= 1	–	–	–	4-6%
>1 <= 2	–	–	9-11%	–
>2 <= 4.5	–	19-21%	–	–
>4.5 <= 13	–	–	–	–
>13 <= 40	69-71%	–	–	–
>40 <= 80	–	–	–	–
>80 <= 120	–	–	–	–
>120	–	–	–	–

Community 1.2
taller trees & some shrubs/ reduced understory

This phase would have been characterized by increased amounts and height of trees and shrubs, namely bigtooth maple, aspen, and Rocky Mountain juniper, with a corresponding decrease in understory richness.

Pathway 1.1a
Community 1.1 to 1.2

As the length of time elapsed since last fire increased (i.e. approaching 50 to 60 years), the trees and shrubs would have grown in both height and density, thus shading out some of the understory.

Pathway 1.2a
Community 1.2 to 1.1

Wildfire would temporarily reduce the tree and shrub component allowing the native perennial grasses and forbs to dominate.

State 2
Overgrown/ Depauperate Understory/ Introduced State

State 2 is very similar to State 1 in form and function, with the exception of the presence of non-native plants and animals, possible extinctions of some native species, and a different climate. State 2 is a description of the ecological site shortly following Euro-American settlement and should be considered the current potential. Heavy season-long livestock grazing was prevalent on these sites starting in the 1860s up through the 1950s, which had its most noticeable impact on diminishing the understory.

Community 2.1
taller, denser trees & shrubs/ reduced understory

This plant community is characterized by a taller, denser stand of trees, primarily bigtooth maple and Rocky Mountain juniper, but with a markedly reduced understory. A small component of non-native species may also be present such as cheatgrass (Bromus tectorum), smooth brome (Bromus inermis), or Kentucky bluegrass (Poa pratensis).

State 3
Lessened Tree Canopy/ Improved Understory State

Tree and brush removal by chemical, fire, and/or fuel wood cutting, helped to thin the tree canopy and provide for the re-establishment of the understory shrubs, forbs, and grasses.

Community 3.1
thinned tree canopy/ understory re-establishment

This plant community is characterized by a thinned canopy of bigtooth maple, aspen, and junipers, and re-established understory species such as mallow ninebark, mountain snowberry, creeping barberry, Oregon boxleaf, Woods' rose, blue wildrye, mountain brome, tall ragwort, silvery lupine, along with several other herbaceous species.

Transition T1a
State 1 to 2

The simultaneous introduction of exotic species, both plants and animals, possible extinctions of native flora and fauna, climate change, and the advent of intense season-long livestock grazing has caused State 1 to transition to State 2. Reversal of such historic changes (i.e. a return pathway) back to State 1 is not practical.

Transition T2a
State 2 to 3

This transition occurred where there was selective harvest of stems for fuel wood and tapping the maple for sugar. Unburned slash with abundant leaf fall makes this vegetation susceptible to wildfire. The root sprouting of maple and other dominants makes it resilient, however. Excessive livestock grazing has been the major agent of positive feedback to accelerated soil erosion and vegetational change. Reduction of livestock numbers and season of use result in a rapid recovery of the perennial dominance. Brush management, whether by chemical means (e.g. 2,4-D, tebuthiron) or prescribed fire, will cause State 2 to transition to State 3. Cutting the trees for use as fuel wood was prevalent in some areas, which opened up the canopy allowing the understory components to re-establish abundantly if not excessively grazed.

Restoration pathway R3a
State 3 to 2

Heavy continuous season long grazing will deplete the understory, decrease the chance of wildfire, and allow tree species to regain in dominance.

Additional community tables

Table 8. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Tree
1	Dominant Trees			560–700
	bigtooth maple	ACGR3	Acer grandidentatum	560–700	–
	bigtooth maple	ACGR3	Acer grandidentatum	140–280	–
	quaking aspen	POTR5	Populus tremuloides	140–280	–
4	Sub-Dominant Trees			35–84
	Rocky Mountain juniper	JUSC2	Juniperus scopulorum	28–84	–
	quaking aspen	POTR5	Populus tremuloides	28–84	–
Shrub/Vine
2	Dominant Shrubs			140–280
	mountain snowberry	SYOR2	Symphoricarpos oreophilus	140–280	–
	mallow ninebark	PHMA5	Physocarpus malvaceus	140–280	–
3	Sub-Dominant Shrubs			35–84
	Shrub (>.5m)	2SHRUB	Shrub (>.5m)	140–280	–
	Saskatoon serviceberry	AMALS	Amelanchier alnifolia var. semiintegrifolia	28–84	–
	creeping barberry	MARE11	Mahonia repens	28–84	–
	Oregon boxleaf	PAMY	Paxistima myrsinites	28–84	–
	chokecherry	PRVI	Prunus virginiana	28–84	–
	Woods' rose	ROWO	Rosa woodsii	28–84	–
	mountain snowberry	SYOR2	Symphoricarpos oreophilus	28–84	–
Grass/Grasslike
3	Dominant Grasses			250–450
	California brome	BRCA5	Bromus carinatus	84–140	–
	blue wildrye	ELGL	Elymus glaucus	84–140	–
	slender wheatgrass	ELTR7	Elymus trachycaulus	84–140	–
1	Sub-Dominant Grasses			35–90
	Grass, annual	2GA	Grass, annual	140–280	–
	Grass, perennial	2GP	Grass, perennial	140–280	–
	Geyer's sedge	CAGE2	Carex geyeri	28–84	–
	basin wildrye	LECI4	Leymus cinereus	28–84	–
	oniongrass	MEBU	Melica bulbosa	28–84	–
	muttongrass	POFE	Poa fendleriana	28–84	–
Forb
2	Sub-Dominant Forbs			1400–1600
	Forb, annual	2FA	Forb, annual	700–840	–
	Forb, perennial	2FP	Forb, perennial	700–840	–
	common yarrow	ACMI2	Achillea millefolium	28–84	–
	nettleleaf giant hyssop	AGUR	Agastache urticifolia	28–84	–
	elkweed	FRSP	Frasera speciosa	28–84	–
	northern bedstraw	GABO2	Galium boreale	28–84	–
	common cowparsnip	HEMA80	Heracleum maximum	28–84	–
	Nevada pea	LALA3	Lathyrus lanszwertii	28–84	–
	tailcup lupine	LUCAC3	Lupinus caudatus ssp. caudatus	28–84	–
	feathery false lily of the valley	MARAR	Maianthemum racemosum ssp. racemosum	28–84	–
	tall fringed bluebells	MECI3	Mertensia ciliata	28–84	–
	western sweetroot	OSOC	Osmorhiza occidentalis	28–84	–
	western coneflower	RUOC2	Rudbeckia occidentalis	28–84	–
	tall ragwort	SESE2	Senecio serra	28–84	–
	western valerian	VAOC2	Valeriana occidentalis	28–84	–

Interpretations

Animal community

This site has a fair amount of grass, a small amount of forbs, and an exceptionally high amount of shrubs. There is a large variety of species. This site is especially valuable to sheep but can also be used by cattle and horses. This combination of plants provides a balanced nutrition for grazing animals. It should be grazed in spring, summer and fall.
It is fair to poor for openland habitat, good for woodland habitat, very poor for wetland habitat and good for rangeland habitat.
It provides good to fair habitat for chukars, quail, forest grouse, mule deer, elk, squirrels, snowshoe rabbits, songbirds, and coyotes, especially in those areas where oakbrush is interspersed with grassy openings. It is fair to poor habitat for bobcats, cougars, golden eagles, and bear.

Hydrological functions

Soil series in this site are grouped into b and c hydrologic groups. They have moderately low to moderately high runoff potential. When the vegetation is in climax (potential), the hydrologic curves for the soils in b hydrologic group are 45 to 40 and those in c hydrologic group are 50 to 55. When range condition has declined from climax, field investigation is needed in order to determine hydrologic curve numbers.

Recreational uses

This site has good values for aesthetics and natural beauty. It has a large number of forbs and shrubs which have flowers in bloom from early spring throughout the summer and into the fall. It has a combination of grasses, forbs, small shrubs and large shrubs which offer some possibilities for screening and value as camping and picnicking areas. Hunting for elk and mule deer is good to excellent on this site. Fishing is opportune on streams through and adjacent to this site. This site has some value for snowmobiling through a fairly long period of the winter season.

Wood products

No values exist for lumber. Some values exist for fuel for campfires and fireplace wood from bigtooth maple. This species also provides fence posts and fence stays.

Supporting information

Inventory data references

When available, monitoring data (of various types) were employed to validate more subjective inferences made in this diagram. See the complete files in the office of the State Range Conservationist for more details.

Other references

Galatowitsch, S.M. 1990. Using the original land survey notes to reconstruct pre-settlement landscapes in the American West. Great Basin Naturalist: 50(2): 181-191. Keywords: [Western U.S., conservation, history, human impact]

Parson, R. E. 1996. A History of Rich County. Utah State Historical Society, County Commission, Rich County, Utah. Keywords: [Rich County, Utah, Historic land use, European settlements]

USDA-NRCS. 2003. National Range and Pasture Handbook. in USDA, editor, USDA-Natural Resources Conservation Service-Grazing Lands Technology Institute. Keywords: [Western US, Federal guidelines, Range pasture management]

Contributors

Darryl Trickler, G. Brock Benson

Approval

Kendra Moseley, 2/05/2025

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)	V. Keith Wadman (NRCS Retired).
Contact for lead author	shane.green@ut.usda.gov
Date	11/05/2012
Approved by	Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on	Annual Production