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.
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.
The soils of this site are shallow to bedrock. They formed in colluvium over residuum derived from sandstone, quartz-diorite, or limestone and shale. Surface textures are silt loams to loamy sands and are cobbly to extremely cobbly. Rock fragments are visible on the soil surface and make up greater than 35 percent of the soil volume. These soils are well drained, slightly acidic, and moderately permeable. Depth typically ranges from 10 to 20 inches. Water holding capacity is low, ranging from 0.2 to 1.6 inches of total water throughout the profile. The soil moisture regime is xeric and the soil temperature regime is frigid.
Species that are not a part of the climax that are most likely to invade the site under excessive grazing use are cheatgrass, annual forbs, curlycup gumweed, houndstongue, flannel mullein, tarweed, rubber rabbitbrush and snakeweed. Gambel oak will increase and may become almost a pure stand under excessive grazing use or repeated range fires.
This site occurs on moderately steep to very steep mountain slopes, canyons and ridges. It is most commonly found at elevations between 6,600 and 7,500 feet, but can extend to elevations as low as 5,600 or as high as 7,600 feet. Runoff is typically high for this site.
Table 2. Representative physiographic features
Landforms
(1) Mountain slope (2) Ridge (3) Canyon
Runoff class
High to very high
Flooding frequency
None
Ponding frequency
None
Elevation
5,600–7,600 ft
Slope
15–70%
Aspect
Aspect is not a significant factor
Climatic features
The climate of this site is characterized by cold, snowy winters and cool dry summers. The average annual precipitation ranges from 18 to 26 inches. Distribution is about 65 percent during the plant dormant period (October through March). This winter moisture is the most dependable supply for plant growth. Lower precipitation and high evaporation-transpiration rates during July, August and September causes a reduction in plant growth for all species and dormancy in many of the forbs and grasses.
Table 3. Representative climatic features
Frost-free period (average)
99 days
Freeze-free period (average)
128 days
Precipitation total (average)
26 in
Bar
Line
Figure 2. Monthly precipitation range
Bar
Line
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Due to its landscape position, this site is not typically influenced by streams or wetlands.
Wetland description
N/A
Soil features
The soils of this site are shallow to bedrock. They formed in colluvium over residuum derived from sandstone, quartz-diorite, or limestone and shale. Surface textures are silt loams to loamy sands and are cobbly to extremely cobbly. Rock fragments are visible on the soil surface and make up greater than 35 percent of the soil volume. These soils are well drained, slighlty acidic, and moderately permeable. Depth typically ranges from 10 to 20 inches. Water holding capacity is low, ranging from 0.2 to 1.6 inches of total water throughout the profile. The soil moisture regime is xeric and the soil temperature regime is frigid.
Soil Survey Area: Soil Components (Map Units in parentheses)
Heber Valley Area (UT622): Brad (BHF); Van Wagoner (VMF, VWF);
Table 4. Representative soil features
Parent material
(1) Colluvium–limestone and shale (2) Residuum–limestone and shale (3) Sandstone (4) Quartz-diorite
Surface texture
(1) Cobbly sandy loam
(2) Extremely cobbly loamy sand
(3) Very cobbly silt loam
Family particle size
(1) Loamy
Drainage class
Well drained
Permeability class
Moderate to moderately rapid
Soil depth
10–20 in
Surface fragment cover <=3"
14–32%
Surface fragment cover >3"
12–31%
Available water capacity (0-40in)
0.2–1.6 in
Calcium carbonate equivalent (0-40in)
15%
Electrical conductivity (0-40in)
2 mmhos/cm
Sodium adsorption ratio (0-40in)
Not specified
Soil reaction (1:1 water) (0-40in)
6.1–7.3
Subsurface fragment volume <=3" (Depth not specified)
18–35%
Subsurface fragment volume >3" (Depth not specified)
23–42%
Ecological dynamics
This site is characterized by gambel oak dominance with perennial bunchgrasses and forbs in the interspaces. Historically, wildfires rejuvenated aging oak stands every 40 to 80 years on this site. Gambel oak resprouts vigorously after fire and oak stem density decreases steadily as time without wildfire increases. On higher elevation sites, mature oak can be invaded by juniper or Douglas-fir. These resinous conifers increase the likelihood of wildfire which removes the invaders and resets the oak to vigorous resprouting and site dominance.
Reference State (State 1)
The reference state for the mountain loam (oak) site was determined by study of relic areas that have been protected from altered disturbance regimes and are considered to be representative of the historic climax plant community. Literature reviews, trends in plant community dynamics, and historical accounts are also considered.
State 1, the reference state, represents the historic plant communities of the mountain loam (oak) site and the naturally occurring dynamics associated with those communities. This state includes all known biotic communities that would exist under natural disturbance regimes and current climatic conditions. The dominant overstory species is Gambel oak (Quercus gambelii) with the understory dominated by the perennial bunchgrasses slender wheatgrass (Elymus trachycaulus) and/or bluebunch wheatgrass (Elymus spicata). The plant communities in state 1 are naturally resistant to disturbance and resilient following disturbance due to favorable amounts of precipitation and the ability of Gambel oak to resprout following disturbance. Wildfire is the predominant disturbance affecting ecological processes and is the primary factor driving plant community change in this state. The common fire return interval is 35 to 100 years and plant recovery following a wildfire is rapid, often with Gambel oak resprouting within the same growing season.
Community Phase 1.1 Gambel oak / Perennial bunchgrasses
This plant community consists of mature Gambel oak trees that dominate the overstory and slender wheatgrass and/or bluebunch wheatgrass that dominate the understory. Mountain brome, Geyer sedge, as well as other cool season grasses may be present. Common shrubs and forbs are mountain snowberry, Saskatoon serviceberry, thickleaf peavine, and a suite of other species adapted to grow either in the interspaces or under the canopy of Gambel oak stands. Bare ground is not common and no non-native plants are present.
Community Pathway 1.1a Wildfire --This pathway often occurs late in the growing season when precipitation is low and fuel load is at its peak. Gambel oak is at peak underground carbohydrate storage around this time of year, which provides the energy needed for resprouting.
Community Pathway 1.1b No Fire --This pathway is a subsequent step in natural succession that occurs when fire free periods approach their upper limits and allow fire sensitive species to encroach into Gambel oak sites.
Community Phase 1.2 Post-fire community / Resprouting gambel oak thicket
This plant community consists of young Gambel oak shoots that are beginning to reestablish following a wildfire. Burned trunks will usually be visible above the new growth. The gambel oak suckers often form dense thickets of foliage up to several feet in height which effectively intercept sunlight and crowd out potential invaders. Given adequate recovery time of a few months to a year, the interspaces will exhibit native buchgrasses and forbs, but few shrubs.
Community Pathway 1.2a Natural Succession—As the post-fire community ages, Gambel oak becomes less dominant near the soil surface, but maintains its dominance in the canopy. Perennial grasses become more robust and the plant community becomes more diverse with the establishment of shrubs and shade sensitive species.
Community Phase 1.3 Encroachment by Other Tree Species
This plant community is comparable in composition to community 1.1 with the addition of fire sensitive tree species such as Rocky mountain Douglas fir, Canyon maple, and white fir. The percent composition of these tree species is relatively low (3 to 5 percent).
Community Pathway 1.3a Wildfire-- This pathway often occurs late in the growing season when precipitation is low and fuel load is at its peak. Gambel oak also is at peak carbohydrate storage around this time of year, an adaptation which provides the energy needed to resprout and maintain its niche.
Transition 1-- Invasive Plants
Transition from Reference State (State 1) to current Potential State (State 2)
This transition occurs when non-native or invasive species become established in the plant community. Common invasive species include dalmatian toadflax, annual forbs, dandelion, houndstongue, rubber rabbitbrush, broom snakeweed, and cheatgrass. Intermediate wheatgrass, smooth brome, and Kentucky bluegrass may also spread into the site. Events that may facilitate the establishment of non-native plants are wildfire, introduction of livestock, seeding, and recreation.
Current Potential State (State 2)
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 native species, and a different climate. State 2 is a description of the ecological site shortly following Euro-American settlement.
Community Phase 2.1 Gambel oak / Slender wheatgrass
Phase 2.1 is 10 to 20 percent grasses, 0 to 15 percent forbs and 80 to 90 percent shrubs by air-dry weight. After a fire, Gambel oak sprouts vigorously and suppresses perennial grass and forb production. Non-native species are present, but not dominant.
Community Pathway 2.1a Wildfire -- This pathway often occurs late in the growing season when precipitation is low and fuel load is at its peak. Gambel oak is at peak underground carbohydrate storage around this time of year, which provides the energy needed for resprouting.
Community Pathway 2.1b No Fire -- This pathway is a subsequent step in natural succession that occurs when fire free periods approach their upper limits and allow fire sensitive species to encroach into Gambel oak sites.
Community Pathway 2.1c Prescribed Fire and Re-seed – This pathway occurs when land owners and/or land managers are attempting to improve the vigor of the native plant community.
Community Pathway 2.1d Continuous Heavy Grazing – This pathway occurs when improper grazing continues for extended periods of time not allowing for native plants to recover, ultimately lowering the health and vigor of these plants to compete with available resources.
Community Phase 2.2 Resprouting Gambel oak thicket
Phase 2.2 is 20 to 40 percent grasses, 10 to 25 percent forbs, and 50 to 70 percent shrubs. Gambel oak stem density is less than phase 1.1, though oak production may be higher. Non-native species are present, but not dominant.
Community Pathway 2.2a Natural Succession on the site
Community Phase 2.3 Encroachment by other tree species
Phase 2.3 is characterized by encroachment of conifer species including Douglas fir, juniper and pinyon. Higher elevations of this ecological site are more susceptible to conifer encroachment. At lower elevations, this phase is characterized by decadent Gambel oak with patches of young sprouts. Gambel oak dies naturally around 80 years of age and promptly responds with vigorous young sprouts to replace the oak foliage. Native species are present, but not dominant
Community Pathway 2.3a Wildfire -- This pathway often occurs late in the growing season when precipitation is low and fuel load is at its peak. Gambel oak is at peak underground carbohydrate storage around this time of year, which provides the energy needed for resprouting.
Community Pathway 2.3b Brush Management (Fire) and re-seeding – Utilization of techniques such as prescribed fire and range seeding can reduce composition of invading conifers as well as temporarily reduce competition from oak to allow for the herbaceous component to become established.
Community Pathway 2.3c Continuous Heavy Grazing -- This pathway occurs when improper grazing continues for extended periods of time not allowing for native herbaceous plants and shrubs to recover, ultimately lowering the health and vigor of these plants to compete with available resources.
Community Phase 2.4 Seeded Gambel oak Woodland
Phase 2.4 is an aerial seeding following fire. Both native and non-native perennial grasses and forbs are included in most seed mixes. Under proper grazing, native grass and forb species can outcompete introduced species and dominate the understory within 5-10 years.
Community Pathway 2.4a Wildfire -- This pathway often occurs late in the growing season when precipitation is low and fuel load is at its peak. Gambel oak is at peak underground carbohydrate storage around this time of year, which provides the energy needed for resprouting.
Community Pathway 2.4b Natural Succession/prescribed grazing – This pathway can occur through natural succession and prescribed grazing. Over time the oak will begin to be the dominant aspect on the site, and with proper grazing management the herbaceous understory and shrubs will maintain health and vigor on the site.
Community Pathway 2.4c Continuous Heavy Grazing -- This pathway occurs when improper grazing continues for extended periods of time not allowing for native herbaceous plants and shrubs to recover, ultimately lowering the health and vigor of these plants to compete with available resources.
Community Phase 2.5 Overgrazed Gambel oak
Phase 2.5 displays a reduction in the herbaceous understory and shrub component do to improper grazing/browsing from livestock and wildlife.
Community Pathway 2.5a No Fire – lack of fire over time will allow other tree species to naturally encroach into the site.
Community Pathway 2.5b Brush Management (Mechanical) and re-seeding -- utilization of techniques such as mechanical brush management and range seeding can reduce composition of oak to allow for the herbaceous component to become established.
Community Pathway 2.5c Natural succession and prescribed grazing – practicing prescribed grazing over time will allow the herbaceous and shrub components to become established on this site.
Transition 2 Noxious Weed Invasion / Repeated Wildfires
Transition from State 2 to State 3
Transition 3 Prescribed Grazing (Goats)
Transition from State 2 to State 4
State 3 Noxious Weed State
State 3 is characterized by a dominance of non-native noxious weeds. The threshold has been crossed into State 3 and the dynamics of this site will likely prohibit the return back into State 2 without and extraordinary amount of external inputs.
Community Phase 3.1 Broadleaf weed dominates interspaces
Native herbaceous and shrub species have largely been replaced by prolific noxious weeds establishment which generally flourish in sites where there is a short fire return interval. This process makes it incredibly hard for native herbaceous species to become reestablished on the site. Gambel oak is able to remain on this site by utilizing available resources due to its extensive root system and its sprouting abilities following wildfire.
Community Pathway 3.1a Wildfire – The nature of this site with the abundance of noxious weeds/fine fuels shortens the fire return interval compared to the historic fire regime.
Community Phase 3.2 Weed co-dominant with resprouting Gambel oak
Following a wildfire, the herbaceous weed component and sprouting Gambel oak will dominate this site.
Community Pathway 3.2a Natural Succession – Due to the nature of this site, there is often a frequent fire return interval which will return this site back to Community Phase 3.1.
State 4: Herbaceous State:
Utilizing browsing animals such as goats, the threshold from State 2 is crossed in to this State. Browsing animals will shift the competitive advantage to the herbaceous component leaving the site devoid of Gambel oak and dominated by the herbaceous understory.
The general view of this site is Gambel oak. The composition by air-dry weight is approximately 40 percent perennial grasses, 10 percent forbs, and 50 percent shrubs.
Figure 4. 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
475
575
625
Grass/Grasslike
380
460
500
Forb
98
115
125
Total
953
1150
1250
Table 6. Ground cover
Tree foliar cover
0%
Shrub/vine/liana foliar cover
39-41%
Grass/grasslike foliar cover
24-26%
Forb foliar cover
9-11%
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
–
–
–
9-11%
>1 <= 2
–
–
24-26%
–
>2 <= 4.5
–
–
–
–
>4.5 <= 13
–
39-41%
–
–
>13 <= 40
–
–
–
–
>40 <= 80
–
–
–
–
>80 <= 120
–
–
–
–
>120
–
–
–
–
Additional community tables
Table 8. Community 1.1 plant community composition
This site provides a fairly good balance of nutritious forage. Sheep, cattle, and horses do well grazing during the spring, summer, and fall seasons.
Wildlife potential is fair to poor for open land, good to fair for woodland, very poor for wetland and good to fair for rangelands.
It is good habitat for chukers, quail, mule deer, elk, songbirds, squirrels, snowshoe hare, cottontails, bobcat, and coyotes. It is fair habitat for cougars, bear, golden eagle, hawks and small mammals.
Hydrological functions
The hydrologic group for these soils is d. When the vegetation is in good condition the hydrologic curve number is 80.
Recreational uses
This site has excellent potential 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 late into the fall. It has shrubs which offer screening for camping and picnicking. Hunting is good for upland game birds, snowshoe hare, elk and mule deer. Fishing is opportune on streams through and adjacent to this site. This site has values for snowmobiling and skiing during a fairly
Wood products
Fence posts and stays can be harvested from the Gambel oak. This species also supplies fireplace wood, campfire wood, and materials for knick-knacks and novelties.
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
Alexander, R. R. 1985. Major habitat types, community types, and plant communities in the Rocky Mountains. USDA- Forest Service Rocky Mountain Forest and Range Experiment Station. General technical report RM-123. 105p.
Alexander 1988. Forest vegetation on National Forests in the Rocky Mountain and Intermountain Regions: Habitat types and community types. USDA- Forest Service Rocky Mountain Forest and Range Experiment Station. General technical report RM-162. 47p.
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]
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
11/15/2012
Approved by
Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on
Annual Production
Indicators
Number and extent of rills:
Rare to Slight. Slight 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:
Slight. Some slight 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 20% - 30%. Soil surface may be covered by 20 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 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):
(Brad) Soil surface 0-3 inches. Surface texture is a loam which may have an organic mat of partially decomposed leaves and twigs 1 inch deep on the surface; color is brown (7.5YR 4/3); and structure is single grain. Mollic epipedon ranges to 10 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 and cryptogamic crusting, where present, also protect soil surface 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. Bedrock occurs at about 10 inches. 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):
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):
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 1100 - 1200 #/acre on an average year but could range from 900 - 1300 #/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, alyssum, mustard species, Canada thistle, black medic, Utah juniper.
Perennial plant reproductive capability:
All perennial plants should have the ability to reproduce in all years, except in extreme drought years. Gambel oak sprouts vigorously following fire. There are no restrictions on either seed or vegetative reproduction. Some seedling recruitment of major species is expected to be present during average and above average growing years.
The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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