Natural Resources
Conservation Service
Ecological site R047XA418UT
Mountain Loam
(bigtooth maple)
Last updated: 2/05/2025
Accessed: 07/11/2026
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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.
Classification relationships
Modal Soil: Bertag Silt Loam, 10 to 50 percent – fine, montmorillonitic, frigid, pachic Ultic Argixerolls
Ecological site concept
These soils formed primarily in colluvium derived from sandstone and limestone. Shale and quartzite are less common soil parent materials for this site. These soils are deep, well-drained,and have dark surface layers up to several feet in depth. Rock fragments may or may not be present on the soil surface. Some gravels and cobbles are usually present in the soil profile, but make up less than 35 percent of the soil volume. Some soils may have lime layers below about 36 inches but the overlying soil is usually noncalcareous and slightly acidic. Permeability is moderate to moderately rapid. Water holding capacity ranges from 3.9 to 7.5 inches of water in the upper 40 inches of soil. The soil moisture regime is xeric and the soil temperature regime is frigid.
Associated sites
R047XA406UT Mountain Gravelly Loam (mountain big sagebrush)
R047XA430UT Mountain Loam (mountain big sagebrush)
R047XA473UT Mountain Very Steep Stony Loam (browse)
Similar sites
R047XA432UT Mountain Loam (oak)
This site is dominated by Gambel oak, a clonal tall shrub species adapted to slightly drier and warmer sites than Canyon maple. Gambel oak do not occur in Cache valley where this site is most common.
R047XA510UT High Mountain Loam (bigtooth maple)
This site occurs in a higher ecological zone with a shorter growing season and higher annual precipitation. The annual forb production is much greater on the high mountain loam site.
Table 1. Dominant plant species
Tree (1) Acer grandidentatum
Shrub (1) Artemisia tridentata ssp. vaseyana
Herbaceous Not specified
Physiographic features
This site occurs on mountain slopes and alluvial fans between 5,000 and 9,000 feet in elevation. It is most commonly found on east and northeast aspects, but may occur on other aspects as well. Slopes are gentle to very steep ranging from 10 to 70 percent. Runoff is medium and flooding and ponding do not occur on the site.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
(2) Alluvial fan
(3) Mountain
Flooding frequency None Ponding frequency None Elevation 5000 – 9000 ft Slope 10 – 70 % Aspect 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 15 to 22 inches with an average of around 19. Distribution is 55 to 60 percent during the plant dormant period (October to March). Winter snow and spring rain provide the most dependable supply of moisture for plant growth.
Table 3 Representative climatic features
Frost-free period (average) 120 days Freeze-free period (average) 150 days Precipitation total (average) 20 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
Figure 4. Annual precipitation pattern
Figure 5 Annual average temperature pattern
">Influencing water features
Due to its landscape position, this site is not typically influenced by streams or wetlands.
Wetland description
N/A
Soil features
These soils formed primarily in colluvium derived from sandstone and limestone. Shale and quartzite are less common soil parent materials for this site. These soils are deep, well-drained,and have dark surface layers up to several feet in depth. Rock fragments may or may not be present on the soil surface. Some gravels and cobbles are usually present in the soil profile, but make up less than 35 percent of the soil volume. Some soils may have lime layers below about 36 inches but the overlying soil is usually noncalcareous and slightly acidic. Permeability is moderate to moderately rapid. Water holding capacity ranges from 3.9 to 7.5 inches of water in the upper 40 inches of soil. The soil moisture regime is xeric and the soil temperature regime is frigid.
Table 4. Representative soil features
Surface texture (1) Silt loam
(2) Gravelly silt loam
(3) Gravelly loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate to moderately rapid Soil depth 60 – 0 in Surface fragment cover <=3" 0 – 21 % Surface fragment cover >3" 0 – 3 % Available water capacity
(0-40in)3.9 – 7.5 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)5.1 – 7.3 Subsurface fragment volume <=3"
(Depth not specified)11 – 26 % Subsurface fragment volume >3"
(Depth not specified)8 – 20 % 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 and horses as the proportion of browse 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, fuel wood harvest, 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.
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.
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, or 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 & 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 revisionState and transition model
Custom diagramStandard diagram
Figure 6. 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 textEcosystem states
T1A - introduction of exotic species T2A - Sustained heavy grazing State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Reference StateThe 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 the familiarity of rangeland relict areas where they exist. The least modified plant community would have been dominated by bigtooth maple (Acer grandidentatum). Rocky Mountain juniper (Juniperus scopulorum) may also have been a common associate. The understory shrubs would have included mountain big sagebrush (Artemisia tridentata ssp. vaseyana), antelope bitterbrush (Purshia tridentata), and chokecherry (Prunus virginiana). Forbs would have included common yarrow (Achillea millefolium), arrowleaf balsamroot (Balsamorhiza sagittata), sticky purple geranium (Geranium viscosissimum), milkvetch (Astragalus spp.), and buckwheats (Eriogonum spp.), among others. Bluebunch wheatgrass (Pseudoroegneria spicata), basin wildrye (Leymus cinereus), and muttongrass (Poa fendleriana) would have been the dominant grasses (1.1). 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 document.
Community 1.1
scattered bigtooth maple/ diverse understory of grasses, forbs, & low shrubsThis community is characterized by scattered bigtooth maple with a diverse understory of grasses, forbs and low shrubs.
Figure 7. 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)Shrub/Vine 660 740 820 Grass/Grasslike 495 555 615 Forb 330 370 410 Tree 165 185 205 Total 1650 1850 2050 Table 6. Ground cover
Tree foliar cover 20-30% Shrub/vine/liana foliar cover 10-20% Grass/grasslike foliar cover 10-20% Forb foliar cover 0-10% 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/
GrasslikeForb <0.5 – – – – >0.5 <= 1 – – – 4-6% >1 <= 2 – – 14-16% – >2 <= 4.5 – 14-16% – – >4.5 <= 13 24-26% – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – State 2
Thickened Bigtooth Maple and Low Shrubs StateState 2 is a description of the ecological site shortly following Euro-American settlement, which has been influenced by the introduction of several non-native plants and animals, possible extinctions of native species, and a different climate. The plant community will be very similar to State 1 with the exception that some introduced species are likely to be present. The herbaceous species still left in the understory are those more tolerant of grazing pressure and/or are relatively unpalatable to livestock such as Woods’ rose (Rosa woodsii) and mule-ears (Wyethia amplexicaulis). This state has potential of accelerated soil erosion. Where accelerated soil erosion has not yet occurred, the potential for stability in this state is high.
Community 2.1
thickened bigtooth maple & low shrubs/ diminished native perennial herbsThis community is characterized by thickened bigtooth maple and low shrubs, such as mountain big sagebrush, antelope bitterbrush, Woods’ rose, and chokecherry. While native perennial herbs have diminished, some, including arrowleaf balsamroot, common yarrow, and mules-ear are present.
State 3
Re-sprouting Shrubs/ Introduced Non-natives StateThis state occurs following heavy, sustained grazing in conjunction with tree removal for firewood and fence-posts.
Community 3.1
re-sprouting lower statured tall & low shrubs/ invasive understoryThis state is characterized by re-sprouting lower statured tall and low shrubs, such as yellow rabbitbrush (Chrysothamnus viscidiflorus), rubber rabbitbrush (Ericameria nauseosa), and broom snakeweed (Gutierrezia sarothrae). Among the few native grasses are an abundance of non-native grasses such as cheatgrass.
Transition T1A
State 1 to 2The simultaneous introduction of exotic species, both plants and animals, possible extinctions of native flora and fauna, and climate change has caused State 1 to transition to State 2. The advent of heavy continuous season-long grazing by livestock and fire prevention also contributed to this transition. Reversal of such historic changes (i.e. a return pathway) back to State 1 is not practical.
Transition T2A
State 2 to 3Firewood harvest and/or wildfire will remove the trees while continued heavy livestock grazing during the growing season will further reduce the understory and open it up to introduced non-native species such as cheatgrass (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=BRTE" target="_blank" title="Open in plants.usda.gov"><i>Bromus tectorum</i></a>) and bulbous bluegrass (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=POBU" target="_blank" title="Open in plants.usda.gov"><i>Poa bulbosa</i></a>). A key indicator of the approach to this transition is the reduction of desirable forage and a loss of larger stems of maple. Sustained heavy grazing is the trigger for this transition.
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Tree0 Dominant Trees 90–180 bigtooth maple ACGRG Acer grandidentatum var. grandidentatum 90–180 – 4 Sub-dominant Tree 0–90 Rocky Mountain juniper JUSC2 Juniperus scopulorum 0–90 – Shrub/Vine0 Dominant Shrubs 198–360 mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 90–180 – chokecherry PRVI Prunus virginiana 54–90 – antelope bitterbrush PUTR2 Purshia tridentata 54–90 – 3 Sub-Dominant Shrubs 198–504 Shrub (>.5m) 2SHRUB Shrub (>.5m) 90–180 – alderleaf mountain mahogany CEMO2 Cercocarpus montanus 18–54 – yellow rabbitbrush CHVIV4 Chrysothamnus viscidiflorus ssp. viscidiflorus var. viscidiflorus 18–54 – broom snakeweed GUSA2 Gutierrezia sarothrae 18–54 – creeping barberry MARE11 Mahonia repens 18–54 – Woods' rose ROWO Rosa woodsii 18–54 – mountain snowberry SYOR2 Symphoricarpos oreophilus 18–54 – Grass/Grasslike0 Dominant Grasses 252–540 bluebunch wheatgrass PSSP6 Pseudoroegneria spicata 90–180 – basin wildrye LECI4 Leymus cinereus 90–180 – muttongrass POFE Poa fendleriana 54–90 – California brome BRCA5 Bromus carinatus 18–90 – 1 Sub-Dominant Grasses 324–792 Grass, annual 2GA Grass, annual 90–180 – Grass, perennial 2GP Grass, perennial 90–180 – Columbia needlegrass ACNE9 Achnatherum nelsonii 18–54 – Geyer's sedge CAGE2 Carex geyeri 18–54 – slender wheatgrass ELTR7 Elymus trachycaulus 18–54 – oniongrass MEBU Melica bulbosa 18–54 – western wheatgrass PASM Pascopyrum smithii 18–54 – Kentucky bluegrass POPR Poa pratensis 18–54 – Sandberg bluegrass POSE Poa secunda 18–54 – Forb2 Sub-Dominant Forbs 450–1170 Forb, annual 2FA Forb, annual 90–180 – Forb, perennial 2FP Forb, perennial 90–180 – common yarrow ACMI2 Achillea millefolium 18–54 – nettleleaf giant hyssop AGUR Agastache urticifolia 18–54 – white sagebrush ARLU Artemisia ludoviciana 18–54 – lesser rushy milkvetch ASCO12 Astragalus convallarius 18–54 – arrowleaf balsamroot BASA3 Balsamorhiza sagittata 18–54 – gypsyflower CYOF Cynoglossum officinale 18–54 – shortstem buckwheat ERBR5 Eriogonum brevicaule 18–54 – sticky purple geranium GEVI2 Geranium viscosissimum 18–54 – common motherwort LECA2 Leonurus cardiaca 18–54 – tailcup lupine LUCAC3 Lupinus caudatus ssp. caudatus 18–54 – western coneflower RUOC2 Rudbeckia occidentalis 18–54 – yellow salsify TRDU Tragopogon dubius 18–54 – stinging nettle URDI Urtica dioica 18–54 – mule-ears WYAM Wyethia amplexicaulis 18–54 – Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) 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 balanced nutrition for grazing animals. It should be grazed in spring, summer, and fall.
This site is good for woodland and rangeland habitat.
It provides good to fair habitat for songbirds, chukars, quail, forest grouse, squirrels, snowshoe hares, coyotes, mule deer and elk, especially in areas where oak brush is interspersed with grassy openings.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 55 to 50. When range condition has declined from climax, field investigation is needed in order to determine hydrologic curve numbers.
Recreational uses
This site has values for open space and aesthetics. It has a large number of forbs and shrubs which have flowers in bloom from early spring throughout the summer and into the fall. Gently sloping areas provide good camping and picnicking areas. Hunting for elk and mule deer is good on this site.
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, though they tend to rot more quickly than wood from other native plants.
Supporting information
Inventory data references
Information presented here has been derived from NRCS clipping data and other inventory data. Field observations from range trained personnel were also used.
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]
Western Regional Climate Center, Western U.S. Climate Historical Summaries. Available at: http://www.wrcc.dri.edu/summary/Climsmut.html. Accessed 30 July 2008.
Web Soil Survey, Official Soil Series Descriptions. Available at: http://soils.usda.gov/technical/classification/osd/index.html. Accessed 12 June 2009.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), Shane A. Green Contact for lead author shane.green@ut.usda.gov Date 10/24/2012 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
None to Rare. Some minor rill development may occur on steeper slopes (> 20%) or on areas located below exposed bedrock or other water shedding areas where increased runoff may occur. Where these rills are present, they should be fairly short (3-6 feet), < 1 inch deep and somewhat widely spaced (4-8 feet). Minor rill development may be observed on all slopes following major thunderstorm or spring runoff events but should heal during the next growing season. -
Presence of water flow patterns:
Rare. Some very minor evidence of water flow patterns may be found winding around perennial plant bases. They show little evidence of current erosion. They are expected to be short (3-6 feet), stable, sinuous and normally not connected. There may be very minor evidence of deposition. Evidence of water flow may increase somewhat in slopes > 20%. -
Number and height of erosional pedestals or terracettes:
Perennial vegetation shows little evidence of erosional pedestalling (1 to 2% of individual plants). Plant roots are covered and most litter remains in place around plant crowns. Terracettes should be absent or, if present, stable. A slight increase in both pedestal and terracette development may occur with increasing slope. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground ranges from 10% - 20%. Soil surface may be covered by 0 to 35% coarse fragments. Bare ground openings should not be greater than 1 foot in diameter and should normally not be connected. -
Number of gullies and erosion associated with gullies:
None to Very Rare at site level. Scattered landscape level gully channels, however, are a normal component of basin/range environments. Where landscape gullies are present, they should be stable, partially vegetated on their sides and bottoms, with no evidence of head-cutting. Some slight increase in disturbance may be evident following significant weather events or when gullies convey considerable runoff from higher elevation rocky or naturally eroding areas. -
Extent of wind scoured, blowouts and/or depositional areas:
None. No evidence of wind generated soil movement is present. Wind caused blowouts and deposition are not present. -
Amount of litter movement (describe size and distance expected to travel):
Most litter resides in place with some redistribution caused by water movement. Minor litter removal may occur in flow channels with deposition occurring within 1 to 2 feet at points of obstruction. The majority of litter accumulates at the base of plants. Some grass leaves and small twigs (grass stems) may accumulate in soil depressions adjacent to plants. Woody stems are not likely to move. However, some litter movement is expected (up to 6 feet) with increases in slopes >20% and/or increased runoff resulting from heavy thunderstorms. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
This site should have a soil stability rating of 5 or 6 under the plant canopies, and a rating of 4 to 5 in the interspaces. The average rating should be a 5. Soil surface textures are typically loams, very fine sandy loams and silt loams. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
(Elzinga) Soil surface 0-22 inches. Surface texture is a silt loam which may have an organic mat of partially decomposed leaves and twigs 1 inch deep on the surface; color is very dark gray (10YR 3/1); and structure weak fine and medium granular. Mollic epipedon ranges from 20 to 36 inches. Use the specific information for the soil you are assessing found in the published soil survey to supplement this description. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Perennial vegetation produces sufficient cover and spatial arrangement to intercept most raindrops and reduce raindrop splash erosion. Litter on soil surface also protects soil from splash erosion and encourages a higher rate of infiltration. Plant spatial distribution should slow runoff, allowing additional time for infiltration. Bare spaces are expected to be small and irregular in shape and are usually not connected. Vegetative structure is usually adequate to capture snow and ensure that snowmelt occurs in a controlled manner, allowing maximum time for infiltration, and reducing runoff and erosion in all but the most extreme storm events. When perennial grasses and shrubs decrease due to natural events including drought, insect damage, etc., which reduce ground cover and increase bare ground, runoff is expected to increase and associated infiltration reduced. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. Some soils may have natural textural variability within their profiles, these should not be mistaken for a compaction pan. -
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:
Trees (canyon maple, Rocky Mountain juniper) >> Perennial bunchgrasses (bluebunch wheatgrass, basin wildrye), = > Non-sprouting shrub (mountain big sagebrush, bitterbrush)Sub-dominant:
Rhizomatous grasses (slender wheatgrass, western wheatgrass) > Sprouting shrubs (green rabbitbrush, mountain snowberry) > Perennial forbs (arrowleaf balsamroot).Other:
A wide variety of other perennial grasses and both perennial and annual forbs can be expected to occur in the plant community.Additional:
Natural disturbance regimes include fire, drought, and insects. Assumed fire cycle of 40 to 60+ years. Functional/structural groups may appropriately contain non-native species if their ecological function is the same as the native species in the reference. Following a disturbance such as fire, drought, rodents or insects that remove woody vegetation, forbs and perennial grasses (herbaceous species) may dominate the community for a period of time. If a disturbance has not occurred for an extended period of time, woody species may continue to increase. These conditions would reflect different functional community phases within the reference state. -
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
All age classes of perennial grasses should be present under average to above average growing conditions with age class expression likely subdued during periods of extended drought. Slight decadence in the principle shrubs could occur near the end of the fire cycle or during periods of extended drought, or insect infestations. In general, a mix of age classes should be expected with some dead and decadent plants present. -
Average percent litter cover (%) and depth ( in):
Litter cover will be heavier under plants. Most litter will be herbaceous and depths of 1 to 3 inches would be considered normal. Perennial vegetation should be well distributed on the site. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Annual production in air-dry herbage should be approximately 1800 - 1900 #/acre on an average year but could range from 1700 - 2000 #/acre during periods of prolonged drought or above average precipitation. -
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:
Cheatgrass, Allysum, mustard species, Canada thistle, black medic, Rocky Mountain juniper. -
Perennial plant reproductive capability:
All perennial plants should have the ability to reproduce in all years, except in extreme drought years. Green rabbitbrush sprouts vigorously following fire. There are no restrictions on either seed or vegetative reproduction. Some seedling recruitment of major species is present during average and above average growing years.
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