Natural Resources
Conservation Service
Ecological site R026XY111NV
SHALLOW LOAM 12-14 P.Z.
Last updated: 4/10/2024
Accessed: 11/12/2024
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): 026X–Carson Basin and Mountains
The area lies within western Nevada and eastern California, with about 69 percent being within Nevada, and 31 percent being within California. Almost all this area is in the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. Isolated north-south trending mountain ranges are separated by aggraded desert plains. The mountains are uplifted fault blocks with steep side slopes. Most of the valleys are drained by three major rivers flowing east across this MLRA. A narrow strip along the western border of the area is in the Sierra Nevada Section of the Cascade-Sierra Mountains Province of the Pacific Mountain System. The Sierra Nevada Mountains are primarily a large fault block that has been uplifted with a dominant tilt to the west. This structure leaves an impressive wall of mountains directly west of this area. This helps create a rain shadow affect to MLRA 26. Parts of this eastern face, but mostly just the foothills, mark the western boundary of this area. Elevations range from about 3,806 feet (1,160 meters) on the west shore of Pyramid Lake to 11,653 feet (3,552 meters) on the summit of Mount Patterson in the Sweetwater Mountains.
Valley areas are dominantly composed of Quaternary alluvial deposits with Quaternary playa or alluvial flat deposits often occupying the lowest valley bottoms in the internally drained valleys, and river deposited alluvium being dominant in externally drained valleys. Hills and mountains are dominantly Tertiary andesitic flows, breccias, ash flow tuffs, rhyolite tuffs or granodioritic rocks. Quaternary basalt flows are present in lesser amounts, and Jurassic and Triassic limestone and shale, and Precambrian limestone and dolomite are also present in very limited amounts. Also of limited extent are glacial till deposits along the east flank of the Sierra Nevada Mountains, the result of alpine glaciation.
The average annual precipitation in this area is 5 to 36 inches (125 to 915 millimeters), increasing with elevation. Most of the rainfall occurs as high-intensity, convective storms in spring and autumn. Precipitation is mostly snow in winter. Summers are dry. The average annual temperature is 37 to 54 degrees F (3 to 12 degrees C). The freeze-free period averages 115 days and ranges from 40 to 195 days, decreasing in length with elevation.
The dominant soil orders in this MLRA are Aridisols and Mollisols. The soils in the area dominantly have a mesic soil temperature regime, an aridic or xeric soil moisture regime, and mixed or smectitic mineralogy. They generally are well drained, are clayey or loamy and commonly skeletal, and are very shallow to moderately deep.
This area supports shrub-grass vegetation characterized by big sagebrush. Low sagebrush and Lahontan sagebrush occur on some soils. Antelope bitterbrush, squirreltail, desert needlegrass, Thurber needlegrass, and Indian ricegrass are important associated plants. Green ephedra, Sandberg bluegrass, Anderson peachbrush, and several forb species also are common. Juniper-pinyon woodland is typical on mountain slopes. Jeffrey pine, lodgepole pine, white fir, and manzanita grow on the highest mountain slopes. Shadscale is the typical plant in the drier parts of the area. Sedges, rushes, and moisture-loving grasses grow on the wettest parts of the wet flood plains and terraces. Basin wildrye, alkali sacaton, saltgrass, buffaloberry, black greasewood, and rubber rabbitbrush grow on the drier sites that have a high concentration of salts.
Some of the major wildlife species in this area are mule deer, coyote, beaver, muskrat, jackrabbit, cottontail, raptors, pheasant, chukar, blue grouse, mountain quail, and mourning dove. The species of fish in the area include trout and catfish. The Lahontan cutthroat trout in the Truckee River is a threatened and endangered species.
LRU notes
The Bodie Hills LRU straddles the California-Nevada state boundary, just north of Mono Lake. The area is underlain by late Miocene age volcanic fields with upper Miocene and Pliocene sedimentary deposits over top. The youngest faults in the area are north and north-east striking. Extensive zones of hydrothermally altered rocks and large mineral deposits, including gold and silver rich veins, formed during hydrothermally active periods of the Miocene (John et al. 2015). A primary distinguishing factor between the Bodie Hills and other hills in MLRA 26 is the dominance of volcanic parent material. Elevations range from 2170 to 2650 meters and slopes typically range from 5 to 35 percent. FFD range from 75-105.
Ecological site concept
The Shallow Loam 12-14 P.Z. site occurs on plateaus and mountain sideslopes. The soils are shallow, well drained soils that formed in residuum and colluvium derived from andesite or tuff breccia with surficial additions of eolian volcanic ash. The dominant vegetation is mountain sagebrush (Artemisia tridentata ssp. vaseyana), Thurber's needlegrass (Achnatherum thurberianum), and bitterbrush (Purshia tridentata).
Associated sites
| R026XF060CA |
Ashy Claypan 12-14 P.Z. |
|---|---|
| R026XY105NV |
GRAVELLY LOAMY SLOPE 14-16 P.Z. |
Similar sites
| R026XY052NV |
SHALLOW LOAM 16+ P.Z. PUTR2 absent; LEKI2 dominant grass |
|---|---|
| R026XY015NV |
SHALLOW LOAM 10-12 P.Z. Less productive site |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Artemisia tridentata ssp. vaseyana |
| Herbaceous |
(1) Achnatherum thurberianum |
Physiographic features
The Shallow Loam 12-14 P.Z. site occurs on plateaus and mountain sideslopes. Slopes range from 8 to 75 percent, but slope gradients of 8 to 30 percent are most typical. Elevations range from 5900 to 8800 feet.
Table 2. Representative physiographic features
| Landforms |
(1)
Plateau
(2) Mountain slope |
|---|---|
| Elevation | 5,900 – 8,800 ft |
| Slope | 8 – 30% |
| Aspect | Aspect is not a significant factor |
Climatic features
The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 12 to 14 inches, the mean annual temperature is 43 to 45 degrees F., and the frost-free period is 60 to 80 days.
Nevada’s climate is predominantly arid, with large daily ranges of temperature, infrequent severe storms, heavy snowfall in the higher mountains, and great location variations with elevation. Three basic geographical factors largely influence Nevada’s climate: continentality, latitude, and elevation. Continentality is the most important factor. The strong continental effect is expressed in the form of both dryness and large temperature variations. Nevada lies on the eastern, lee side of the Sierra Nevada Range, a massive mountain barrier that markedly influences the climate of the State. The prevailing winds are from the west, and as the warm moist air from the Pacific Ocean ascend the western slopes of the Sierra Range, the air cools, condensation occurs and most of the moisture falls as precipitation. As the air descends the eastern slope, it is warmed by compression, and very little precipitation occurs. The effects of this mountain barrier are felt not only in the West but throughout the state, with the result that the lowlands of Nevada are largely desert or steppes. The temperature regime is also affected by the blocking of the inland-moving maritime air. Nevada sheltered from maritime winds, has a continental climate with well-developed seasons and the terrain responds quickly to changes in solar heating.
Nevada lies within the mid-latitude belt of prevailing westerly winds which occur most of the year. These winds bring frequent changes in weather during the late fall, winter and spring months, when most of the precipitation occurs. To the south of the mid-latitude westerlies, lies a zone of high pressure in subtropical latitudes, with a center over the Pacific Ocean. In the summer, this high-pressure belt shifts northward over the latitudes of Nevada, blocking storms from the ocean. The resulting weather is mostly clear and dry during the summer and early fall, with scattered thundershowers. The eastern portion of the state receives significant summer thunderstorms generated from monsoonal moisture pushed up from the Gulf of California, known as the North American monsoon. The monsoon system peaks in August and by October the monsoon high over the Western U.S. begins to weaken and the precipitation retreats southward towards the tropics (NOAA 2004).
Table 3. Representative climatic features
| Frost-free period (characteristic range) | |
|---|---|
| Freeze-free period (characteristic range) | |
| Precipitation total (characteristic range) | 12-14 in |
| Frost-free period (average) | 70 days |
| Freeze-free period (average) | |
| Precipitation total (average) | 13 in |
Figure 1. Monthly precipitation range
Figure 2. Monthly average minimum and maximum temperature
Figure 3. Annual precipitation pattern
Figure 4. Annual average temperature pattern
Influencing water features
There are no influencing water features associated with this site.
Soil features
The soils are shallow, well drained soils that formed in residuum and colluvium derived from andesite or tuff breccia with surficial additions of eolian volcanic ash. Rock fragments in the control section averages 35 to 60 percent, mainly gravel. The soils have an argillic horizon and mollic epipedon. The soils are moist in winter and spring and dry from July through October. The soil moisture regime is aridic bordering on xeric. The soil temperature regime is frigid. Soil series associated with this site are Halfash and Roadside.
Table 4. Representative soil features
| Parent material |
(1)
Eolian deposits
(2) Colluvium – andesite (3) Colluvium – tuff breccia (4) Residuum – andesite (5) Residuum – tuff breccia |
|---|---|
| Surface texture |
(1) Very gravelly, ashy loamy sand (2) Very gravelly, ashy sandy loam |
| Family particle size |
(1) Ashy-skeletal |
| Drainage class | Well drained |
| Permeability class | Moderately slow to moderately rapid |
| Soil depth | 14 – 25 in |
| Surface fragment cover <=3" | 19 – 43% |
| Surface fragment cover >3" | 4 – 23% |
| Available water capacity (0-40in) |
2.5 – 3.2 in |
| Calcium carbonate equivalent (0-40in) |
Not specified |
| Electrical conductivity (0-40in) |
2 mmhos/cm |
| Sodium adsorption ratio (0-40in) |
Not specified |
| Soil reaction (1:1 water) (0-40in) |
6.1 – 7.8 |
| Subsurface fragment volume <=3" (Depth not specified) |
32 – 44% |
| Subsurface fragment volume >3" (Depth not specified) |
2 – 22% |
Ecological dynamics
Nutrients are being cycled through deep-rooted perennial grasses, shrubs and forbs. Energy capture occurs throughout the entire growing season such that this plant community’s site resiliency is maintained. With a lengthened fire return interval (>30 years) an increase in sagebrush cover occurs until mountain big sagebrush dominates resource use. This results in a decrease in cover, vigor and reproduction of the perennial bunchgrasses. Roundleaf snowberry and other woody plants will also increase in prevalence.
Fire Ecology:
Presettlement fire return intervals in mountain big sagebrush communities varied from 15-25 years. Mountain big sagebrush is highly susceptible to injury from fire. Plants are readily killed in all seasons, even light severity fires. Mountain big sagebrush plants top-killed by fire will not resprout.
Season of burning and environmental conditions impact antelope bitterbrush ability to survive fire and sprout. Antelope bitterbrush is very susceptible to fire kill. It is considered a weak sprouter and is often killed by summer or fall fire. Antelope bitterbrush in some areas may sprout after light-severity spring fire. High fuel consumptions increase antelope bitterbrush mortality and therefore favors seedling establishment. Thurber needlegrass is classified as moderately resistant, but depending on season of burn, phenology, and fire severity, this perennial bunchgrass is moderately to severely damaged by fire. Burning has been found to decrease the vegetation and reproductive vigor. Early season burning is more damaging to this needlegrass than late season burning.
Prairie Junegrass is reported as showing little or no damage to moderate damage from fire. The small stature of prairie Junegrass and coarse textured foliage aid in protection of these meristimatic tissue areas. Possessing coarsely textured foliage and a small clump size also limits the potential for fire damage.
State and Transition Model Narrative Group 12:
This is a text description of the states, phases, transitions, and community pathways possible in the State and Transition model for the MLRA 26 Disturbance Response Group 12. Site included in this DRG are: R026XY005NV, R026XY105NV, R026XY046NV, R026XY006NV, R026XY048NV, R026XY111NV, R026XY040NV, R026XY106NV, R026XY089NV, R026XF057CA, R026XF063CA, and R026XF064CA.
Reference State 1.0:
The Reference State 1.0 represents the natural range of variability of this site under pristine conditions. The reference state has three general community phases: a shrub-grass dominant phase, a perennial grass dominant phase and a shrub dominant phase. State dynamics are maintained by interactions between climatic patterns and disturbance regimes. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Plant community phase changes are primarily driven by fire, periodic drought, and/or insect or disease attack.
Community Phase 1.1:
Needlegrasses, basin wildrye, and mountain big sagebrush dominate the site. Bitterbrush may be a significant component. Pinyon and juniper may be present.
Community Phase Pathway 1.1a, from phase 1.1 to 1.2:
Fire would decrease or eliminate the overstory of sagebrush and allow for the perennial bunchgrasses and perennial forbs to dominate the site. Fires would typically be small and patchy due to low fuel loads. Low severity fire creates sagebrush/grass mosaic. High severity fire significantly reduces sagebrush cover and leads to early/mid-seral community, dominated by grasses and forbs.
Community Phase Pathway 1.1b, from phase 1.1 to 1.3:
Time and lack of disturbance such as fire or drought allow for an increase in mountain big sagebrush. Excessive herbivory and/or long-term drought may also reduce perennial understory.
Community Phase 1.2:
This community phase is characteristic of a post-disturbance, early- to mid-seral plant community. Needlegrasses, basin wildrye, and perennial grasses and forbs dominate. Mountain big sagebrush is a minor component. Bitterbrush may be sprouting. Forbs may increase.
Community Phase Pathway 1.2a, from phase 1.2 to 1.1:
Time and lack of disturbance allows for sagebrush to reestablish.
Community Phase 1.3:
Mountain big sagebrush increases in the absence of disturbance and becomes dominant. Bitterbrush may be a significant component. Needlegrasses and other perennial grasses are reduced. Squirreltail and/or bluegrasses may increase. Pinyon and juniper may be present.
Community Phase Pathway 1.3a, from phase 1.3 to 1.2:
Fire. A low severity fire creates a sagebrush/grass mosaic, while a high-severity fire reduces sagebrush to trace amounts.
T1A: Transition from Reference State 1.0 to Current Potential State 2.0
Trigger: This transition is caused by the introduction of non-native annual weeds, such as cheatgrass, mustard and Russian thistle (Salsola tragus).
Slow variables: Over time the annual non-native plants will increase within the community, decreasing organic matter inputs from deep-rooted perennial bunchgrasses. This results in reductions in soil water availability for perennial bunchgrasses.
Threshold: Any amount of introduced non-native species causes an immediate decrease in the resilience of the site. Annual non-native species cannot be easily removed from the system and have the potential to significantly alter disturbance regimes from their historic range of variation.
T1B: Transition from Reference State 1.0 to Shrub State 3.0
Trigger: Inappropriate, long-term grazing of perennial bunchgrasses during the growing season would favor shrubs and initiate transition to Community Phase 3.1.
Slow variables: Long term decrease in deep-rooted perennial grass density.
Threshold: Loss of deep-rooted perennial bunchgrasses changes spatial and temporal nutrient cycling and nutrient redistribution and reduces soil organic matter and soil moisture.
T1C: Transition from Reference State 1.0 to Tree State 5.0
Trigger: Time and lack of disturbance or management action allows pinyon or juniper to dominate. This may be coupled with grazing management that favors tree establishment by reducing understory herbaceous competition for site resources.
Feedbacks and ecological processes: Trees increasingly dominate use of soil water, contributing to reductions in soil water availability to grasses and shrubs. Overtime, grasses and shrubs are outcompeted. Reduced herbaceous and shrub production slows soil organic matter inputs and increases soil erodibility through loss of cover and root structure.
Slow variables: Over time the abundance and size of trees will increase.
Threshold: Trees dominate ecological processes and the number of shrub skeletons exceed number of live shrubs.
Current Potential State 2.0:
This state is similar to the Reference State 1.0. Ecological function has not changed, however, the resiliency of the state has been reduced by the presence of invasive weeds. This state has four general community phases. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads and retention of organic matter and nutrients. Positive feedbacks decrease ecosystem resilience and stability of the state. These include the non-natives high seed output, persistent seed bank, rapid growth rate, ability to cross pollinate and adaptations for seed dispersal. Additionally, the presence of highly flammable, non-native species reduces State resilience because these species can promote fire where historically fire has been infrequent leading to positive feedbacks that further the degradation of the system.
Community Phase 2.1:
Needlegrasses, basin wildrye and mountain big sagebrush dominate the site. Bitterbrush may be a significant component. Pinyon and juniper may be present. Annual non-native species present.
Community Phase Pathway 2.1a, from phase 2.1 to 2.2:
Fire. Low severity fire creates sagebrush/grass mosaic while a high severity fire significantly reduces sagebrush cover and leads to early/mid-seral community dominated by grasses and forbs. Non-native annual species present.
Community Phase Pathway 2.1b, from phase 2.1 to 2.3:
Time, lack of disturbance, long-term drought, grazing management that favors shrubs or combinations of these would allow the sagebrush overstory to increase and dominate the site, causing a reduction in the perennial bunchgrasses.
Community Phase 2.2:
This community phase is characteristic of a post-disturbance, early-seral plant community. Needlegrasses and other perennial grasses and perennial forbs dominate. Mountain big sagebrush is a minor component. Bitterbrush may be sprouting. Forbs may increase. Annual non-native species are present.
Community Phase Pathway 2.2a, from phase 2.2 to 2.1:
Absence of disturbance over time allows for the sagebrush to recover. This may be combined with grazing management that favors shrubs.
Community Phase Pathway 2.2b, from Phase 2.2 to 2.4:
Higher than normal spring precipitation favors annual non-native species such as cheatgrass. Non-native annual species will increase in production and density throughout the site. Shrub removal or prescribed burning may increase invasive annuals. Perennial bunchgrasses may also increase in production.
Community Phase 2.3:
Mountain big sagebrush is dominant and the perennial understory is reduced. Bitterbrush may be a significant component. Bluegrass may increase. Pinyon and juniper may be present. Annual non-native species are present.
Community Phase Pathway 2.3a, from phase 2.3 to 2.1:
Low severity fire creates sagebrush/grass mosaic. Other disturbances/practices include brush management with minimal soil disturbance leading to a reduction in sagebrush.
Community Phase Pathway 2.3b, from phase 2.3 to 2.2:
High severity fire or brush management with minimal soil disturbance significantly reduces sagebrush and leads to early/mid-seral community.
Community Phase Pathway 2.3c, from phase 2.3 to 2.4:
Fall and spring growing season conditions that favor the germination and production of non-native annual grasses.
Community Phase 2.4:
This community is at risk of crossing to an annual state. Native bunchgrasses and forbs still comprise 50% or more of the understory annual production, however non-native annual grasses are nearly codominant. If this site originated from phase 2.3 there may be significant shrub cover as well. Annual production and abundance of these annuals may increase drastically in years with heavy spring precipitation. This site is susceptible to further degradation from grazing, drought, and fire.
Community Phase Pathway 2.4a, from phase 2.4 to 2.2:
Growing season conditions favoring perennial bunchgrass production and reduced cheatgrass production.
Community Phase Pathway 2.4b, from phase 2.4 to 2.3:
Growing season conditions favoring perennial bunchgrass production and reduced cheatgrass production.
T2A: Transition from Current Potential State 2.0 to Shrub State 3.0:
Trigger: Inappropriate, long-term grazing of perennial bunchgrasses during growing season would favor shrubs and initiate transition to Community Phase 3.1.
Slow variables: Long term declines in deep-rooted perennial grass density.
Threshold: Loss of deep-rooted perennial bunchgrasses changes spatial and temporal nutrient cycling and nutrient redistribution and reduces soil organic matter.
T2B: Transition from Current Potential State 2.0 to Annual State 4.0:
Trigger: Fire and/or multiple fires lead to plant community phase 4.1, inappropriate grazing management that favors shrubs in the presence of non-native annual species leads to community phase 4.2.
Slow variables: Increased production and cover of non-native annual species.
Threshold: Loss of deep-rooted perennial bunchgrasses and shrubs truncates, spatially and temporally, nutrient capture and cycling within the community. Increased, continuous fine fuels from annual non-native plants modify the fire regime by changing intensity, size and spatial variability of fires.
T2C: Transition from Current Potential 2.0 to Tree State 5.0:
Trigger: Time and lack of disturbance or management action allows pinyon and juniper to dominate. This may be coupled with grazing management that favors tree establishment by reducing understory herbaceous competition for site resources.
Feedbacks and ecological processes: Trees increasingly dominate use of soil water, contributing to reductions in soil water availability to grasses and shrubs. Overtime, grasses and shrubs are outcompeted. Reduced herbaceous and shrub production slows soil organic matter inputs and increases soil erodibility through loss of cover and root structure.
Slow variables: Over time the abundance and size of trees will increase.
Threshold: Trees dominate ecological processes and number of shrub skeletons exceed the number of live shrubs.
Shrub State 3.0:
This state has two community phases: a mountain big sagebrush dominated phase and a squirreltail-dominated phase. This state is a product of many years of heavy grazing during time periods harmful to perennial bunchgrasses. Squirreltail will increase with a reduction in deep rooted perennial bunchgrass competition and become the dominant grass. Sagebrush and bitterbrush dominate the overstory. Sagebrush canopy cover is high and sagebrush may be decadent, reflecting stand maturity and lack of seedling establishment due to competition with mature plants. The shrub overstory and bluegrass understory dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed.
Community Phase 3.1:
This site is at risk of transitioning to another state. Mountain big sagebrush, possibly decadent, dominates the overstory. Antelope bitterbrush may be a significant component. Deep-rooted perennial bunchgrasses are present in only trace amounts and may be absent from the community. Squirreltail may be dominant in the understory. Understory may be sparse, with bare ground increasing. Pinyon and/or juniper may be present as a result of encroachment from neighboring sites and lack of disturbance. Annual non-native species are present to increasing.
Community Phase Pathway 3.1a, from phase 3.1 to 3.2:
Fire reduces or eliminates the overstory of sagebrush. Non-native annual species increase with higher-than-normal spring precipitation.
Community Phase 3.2:
Squirreltail dominates the site. Needlegrasses and other perennial grasses are reduced. Mountain big sagebrush is reduced or missing. Bitterbrush may be sprouting. Annual non-native species are increasing and may be co-dominant in the understory.
Community Phase Pathway 3.2a, from phase 3.2 to 3.1:
Absence of disturbance over time would allow for sagebrush and other shrubs to recover.
T3A: Transition from Shrub State 3.0 to Annual State 4.0:
Trigger: Fire or inappropriate grazing management can eliminate the squirreltail understory and transition to community phase 4.1 or 4.2.
Slow variable: Increased seed production and cover of annual non-native species.
Threshold: Increased, continuous fine fuels modify the fire regime by changing intensity, size and spatial variability of fires. Changes in plant community composition and spatial variability of vegetation due to the loss of perennial bunchgrasses and big sagebrush truncate energy capture and impact the nutrient cycling and distribution.
T3B: Transition from Shrub State 3.0 to Tree State 5.0:
Trigger: Time and lack of disturbance allows for maturation of the tree community. This may be coupled with grazing management that favors shrub and tree growth.
Slow variable: Over time, with lack of fire, the abundance and size of trees increase.
Threshold: Trees overtop mountain big sagebrush and out-compete shrubs for water and sunlight. Shrub skeletons exceed live shrubs with minimal recruitment of new cohorts. Bare ground areas are large and connected.
R3A: Restoration from Shrub State 3.0 to Seeded State 6.0:
Brush management and seeding of crested wheatgrass and/or other desired species. Presence of non-native annual species will make this restoration pathway difficult.
Annual State 4.0:
This state has two community phases, both characterized by a dominance of non-native annual grasses and forbs. Shrub cover is present in one phase, while the other is primarily annual grasses. Sagebrush and/or rabbitbrush may dominate the overstory. Annual non-native species dominate the understory. Ecological dynamics are significantly altered in this state. Annual non-native species create a highly combustible fuel bed that shortens the fire return interval. Nutrient cycling is spatially and temporally truncated as annual plants contribute significantly less to deep soil carbon. Because this is a productive site, some deep-rooted perennial grasses may remain, even in the annual state. Without management, it is unlikely these plants will be able to recruit in the presence of dominant annual grasses.
Community Phase 4.1:
Annual non-native plants such as cheatgrass dominate the site. This phase may have seeded species present if resulting from a failed seeding attempt. Needlegrasses, mountain big sagebrush, and other shrubs are only present in trace amounts and may be missing from the community.
Community Phase Pathway 4.1a, from phase 4.1 to phase 4.2:
Time and lack of disturbance allows for shrubs to reestablish. Probability of sagebrush reestablishment is extremely low.
Community Phase 4.2:
Annual non-native species, primarily cheatgrass, dominate the understory. Sprouting shrubs dominate the overstory. Perennial bunchgrasses are a minor component or missing. Seeded species may be present.
Community Phase Pathway 4.2a, from phase 4.2 to 4.1:
Fire kills non-sprouting shrubs and allows annual non-native species to dominate site.
Tree State 5.0:
This state is characterized by a dominance of pinyon and/or juniper in the overstory. It occurs where sagebrush sites exist adjacent to stands of trees. Big sagebrush and perennial bunchgrasses may still be present, but they are no longer controlling site resources. Skeletons of dead sagebrush plants are apparent. Soil moisture, soil nutrients, soil organic matter distribution and nutrient cycling have been spatially and temporally altered.
Community Phase 5.1:
Pinyon and juniper dominate. Trees are actively growing with noticeable leader growth. Mountain big sagebrush is stressed and dying. Needlegrass and other perennial grasses reduced. Annual non-native species are present under tree canopies. Bare ground interspaces are large and connected.
Community Phase Pathway 5.1a, from phase 5.1 to 5.2:
Absence of disturbance over time allows for tree cover and density to further increase and out-compete the herbaceous understory species for sunlight and water.
Community Phase 5.2:
Pinyon and/or juniper dominate the site and tree leader growth is minimal. Annual non-native species may be the dominant understory species and will typically be found under tree canopies. Trace amounts of sagebrush may be present, however dead skeletons will be more numerous than living sagebrush. Bunchgrass may or may not be present. Bare ground areas are large and connected, and soil redistribution is apparent.
Community Phase Pathway 5.2a, from phase 5.2 to 5.1:
Tree thinning treatment (typically for fuels management) removes some tree cover and may allow sagebrush to survive. Without further management this pathway is temporary.
T5A: Transition from Tree State 5.0 to Annual State 4.0:
Trigger: Catastrophic crown fire would reduce or eliminate trees to transition the site to 4.1. Tree removal when annual non-natives such as cheatgrass are present would also transition the site to state 4.0.
Slow variable: Increased seed production and cover of annual non-native species.
Threshold: Increased, continuous fine fuels modify the fire regime by changing intensity, size and spatial variability of fires. Changes in plant community composition and spatial variability of vegetation due to the loss of perennial bunchgrasses and sagebrush truncate energy capture and impact the nutrient cycling and distribution.
R5A: Restoration from Tree State 5.0 to Shrub State 6.0:
Tree removal with minimum soil disturbance such as hand felling or mastication within community phase 5.1 when native grasses are still present.
R5B: Restoration from Tree State 5.0 to Seeded State 6.0:
Tree removal and seeding of desired species. Tree removal practices that minimize soil disturbance are recommended. Probability of success declines with increased presence of non-native annual species.
Seeded State 6.0:
This state has two community phases: a grass-dominated phase and a shrub dominated phase. This state is characterized by the dominance of seeded introduced wheatgrass species in the understory. Crested wheatgrass is a dominant plant in this phase. Conservation practices such as brush management and prescribed grazing should be used to maintain the perennial bunchgrasses and other desirable species.
Community Phase 6.1:
Seeded wheatgrasses and/or other seeded species dominate the community. Non-native annual species are present. Trace amounts of mountain big sagebrush may be present, especially if seeded.
Community Phase Pathway 6.1a, from phase 6.1 to 6.2:
Time and lack of disturbance allows shrubs to dominate. This process may be accelerated through inappropriate grazing management.
Community Phase 6.2:
Mountain big sagebrush and/or bitterbrush increases and dominates the overstory. Seeded wheatgrass species are a minor component. Annual non-native species may be present in trace amounts. Pinyon and/or juniper may be present.
Community Phase Pathway 6.2a, from phase 6.2 to 6.1:
Fire, brush management and/or Aroga moth infestation reduces sagebrush overstory and allows for seeded wheatgrasses or other seeded grasses to increase.
T6A: Transition from Seeded State 6.0 to Annual State 4.0:
Trigger: Catastrophic fire.
Slow variables: Increased production and cover of non-native annual species.
Threshold: Increased continuous fine fuels modify the fire regime by changing intensity, size, and spatial variability of fires. Changes in plant community composition and spatial variability of vegetation due to the loss of perennial bunchgrasses and sagebrush truncate energy capture spatially and temporally, thus impacting nutrient cycling and distribution.
T6B: Transition from Seeded State 6.0 to Tree State 5.0:
Trigger: Time and lack of disturbance or management action allows for pinyon and/or juniper to dominate. This may be coupled with grazing management that favors tree establishment by reducing understory herbaceous competition for site resources.
Slow variables: Over time, the abundance and size of trees will increase.
Threshold: Trees dominate ecological processes and number of shrub skeletons exceed number of live shrubs.
State and transition model
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Ecosystem states
State 1 submodel, plant communities
State 1
Reference Plant Community
Community 1.1
Reference Plant Community
The reference plant community is dominated by Thurber's needlegrass, bluegrass, mountain big sagebrush and antelope bitterbrush. Potential vegetative composition is about 50% grasses, 10% forbs and 40% shrubs and trees. Approximate ground cover (basal and crown) is 25 to 30 percent.
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) |
|---|---|---|---|
| Grass/Grasslike | 250 | 350 | 450 |
| Shrub/Vine | 195 | 270 | 340 |
| Forb | 50 | 70 | 90 |
| Tree | 5 | 10 | 20 |
| Total | 500 | 700 | 900 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Primary Perennial Grasses | 203–336 | ||||
| Thurber's needlegrass | ACTH7 | Achnatherum thurberianum | 175–245 | – | ||
| bluegrass | POA | Poa | 14–56 | – | ||
| prairie Junegrass | KOMA | Koeleria macrantha | 14–35 | – | ||
| 2 | Secondary Perennial Grasses | 35–70 | ||||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 7–21 | – | ||
| squirreltail | ELEL5 | Elymus elymoides | 7–21 | – | ||
|
Forb
|
||||||
| 3 | Perennial Forbs | 50–90 | ||||
| lupine | LUPIN | Lupinus | 14–35 | – | ||
| phlox | PHLOX | Phlox | 4–14 | – | ||
| rockcress | ARABI2 | Arabis | 4–14 | – | ||
| tapertip hawksbeard | CRAC2 | Crepis acuminata | 4–14 | – | ||
| buckwheat | ERIOG | Eriogonum | 4–14 | – | ||
|
Shrub/Vine
|
||||||
| 4 | Primary Shrubs | 175–280 | ||||
| mountain big sagebrush | ARTRV | Artemisia tridentata ssp. vaseyana | 140–210 | – | ||
| antelope bitterbrush | PUTR2 | Purshia tridentata | 35–70 | – | ||
| 5 | Secondary Shrubs | 14–35 | ||||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 4–14 | – | ||
| desert peach | PRAN2 | Prunus andersonii | 4–14 | – | ||
| currant | RIBES | Ribes | 4–14 | – | ||
| roundleaf snowberry | SYRO | Symphoricarpos rotundifolius | 4–14 | – | ||
|
Tree
|
||||||
| 6 | Evergreen | 5–20 | ||||
| Utah juniper | JUOS | Juniperus osteosperma | 3–10 | – | ||
| singleleaf pinyon | PIMO | Pinus monophylla | 3–10 | – | ||
Interpretations
Animal community
Livestock Interpretations:
This site is suitable for livestock grazing. Grazing management should be keyed to dominant perennial grass or palatable shrub production. Mountain big sagebrush is eaten by domestic livestock but has long been considered to be of low palatability, and a competitor to more desirable species. Antelope bitterbrush is important browse for livestock. Domestic livestock and mule deer may compete for antelope bitterbrush in late summer, fall, and/or winter. Cattle prefer antelope bitterbrush from mid-May through June and again in September and October. Thurber’s needlegrass species begin growth early in the year and remain green throughout a relatively long growing season. This pattern of development enables animals to use Thurber’s needlegrass when many other grasses are unavailable. Cattle prefer Thurber’s needlegrass in early spring before fruits have developed as it becomes less palatable when mature. Thurber’s needlegrasses are grazed in the fall only if the fruits are softened by rain. Bluegrass is a palatable species, but its production is closely tied to weather conditions. It produces little forage in drought years, making it a less dependable food source than other perennial bunchgrasses. All classes of livestock species utilize prairie Junegrass. Rapid seasonal development of prairie Junegrass provides good, early-spring forage for livestock.
Stocking rates vary over time depending upon season of use, climate variations, site, and previous and current management goals. A safe starting stocking rate is an estimated stocking rate that is fine tuned by the client by adaptive management through the year and from year to year.
Wildlife Interpretations:
Mountain big sagebrush is highly preferred and nutritious winter forage for mule deer and elk. Pronghorn antelope, mule deer, elk, and bighorn sheep utilize antelope bitterbrush extensively. Mule deer use of antelope bitterbrush peaks in September, when antelope bitterbrush may compose 91 percent of the diet. Winter use is greatest during periods of deep snow. Antelope bitterbrush seed is a large part of the diets of rodents, especially deer mice and kangaroo rats. Thurber needlegrass is valuable forage for wildlife. Bluegrass is desirable for pronghorn antelope and mule deer in the spring and preferable in the spring, summer, and fall for elk and desirable as part of their winter range. . Bluegrass leaves and seeds are eaten by numerous species of small mammals and songbirds. Bluegrass is often an important food of the cottontail rabbit and wild turkey. Prairie Junegrass is also utilized by bighorn sheep, mountain goats, elk, and mule deer in the spring and in fall after curing. Although, due to scattered distribution, prairie Junegrass does not maintain a significant role in the diet of most wildlife species The short stature and scattered distribution of prairie Junegrass provide minimum coverage for larger birds and mammals.
Sagebrush-grassland communities provide critical sage-grouse breeding and nesting habitats. Meadows surrounded by sagebrush may be used as feeding and strutting grounds. Sagebrush is a crucial component of their diet year-round, and sage-grouse select sagebrush almost exclusively for cover. Sage-grouse prefer mountain big sagebrush and Wyoming big sagebrush communities to basin big sagebrush communities.
Hydrological functions
Runoff is medium to very high. Permeability is moderately low to very slow.
Recreational uses
This site offers opportunities for hunting, camping, hiking and photography.
Other products
Native Americans used big sagebrush leaves and branches for medicinal teas, and the leaves as a fumigant. Bark was woven into mats, bags and clothing.
Other information
Antelope bitterbrush has been used extensively in land reclamation. Antelope bitterbrush enhances succession by retaining soil and depositing organic material and in some habitats and with some ecotypes, by fixing nitrogen. Prairie Junegrass can recolonize areas that have been subjected to severe water stress. Recolonization by prairie Junegrass provides protective cover to help subsequent post-drought, successional plant species growth.
Supporting information
Type locality
| Location 1: Mono County, CA | |
|---|---|
| Township/Range/Section | T6N R26E S32 |
| Latitude | 38° 19′ 33″ |
| Longitude | 119° 2′ 6″ |
| General legal description | On the Toiyabe National Forest, approximately 4.5 miles southeast of the Masonic Townsite. |
Other references
Fire Effects Information System (Online; http://www.fs.fed.us/database/feis/plants/).
USDA-NRCS Plants Database (Online; http://www.plants.usda.gov).
Contributors
ALM
Tamzen Stringham
Patti Novak-Echenique
Approval
Kendra Moseley, 4/10/2024
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) | G. Brackley |
|---|---|
| Contact for lead author | State Rangeland Management Specialist |
| Date | 08/01/2004 |
| Approved by | Kendra Moseley |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rills are rare. A few rills can be expected on steeper slopes in areas subjected to summer convection storms or rapid spring snowmelt. -
Presence of water flow patterns:
Water flow patterns are rare but can be expected in areas subjected to summer convection storms or rapid snowmelt. -
Number and height of erosional pedestals or terracettes:
Pedestals are rare. Occurrence is limited to areas of water flow patterns. Frost heaving of shallow-rooted plants should not be considered a "normal" condition. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground ~10-20 percent. -
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None -
Amount of litter movement (describe size and distance expected to travel):
Fine litter (foliage from grasses, shrubs, and annual & perennial forbs) expected to move distance of slope length during intense summer convection storms or rapid snowmelt events. Persistent litter (large woody material) will remail in place except during catastrophic events. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil stability values should be 3 to 5 on most soil textures found on this site. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface structure is weak fine subangular block. Soil surface colors are dark and soils are typified by a mollic epipedon. Organic carbon of the surface 2 to 3 inches is typically 0.5 to 2 percent dropping off quickly below. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Reference Plant Community: perennial herbaceous plants (especially deep-rooted bunchgrasses (Thurber's needlegrass) slow runoff and increase infiltration. Shrub canopy and associated litter break raindrop impact and provide opportunity for snow catch and accumulation on site. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Compacted layers are not typical. Subsoil argillic horizons are not to be interpreted as compacted layers. -
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:
Reference Plant Community: Deep-rooted cool season, perennial bunchgrasses >> tall shrubs >> shallow-rooted, cool season perennial grasses >Sub-dominant:
Deep-rooted, perennial forbs > associated shrubs > fibrous, shallow-rooted, cool-season, annual and perennial forbsOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Dead branches within individual shrubs common and standing dead shrub canopy material may be as much as 10% of total woody canopy. Some of the mature bunchgrasses (<10%) have dead centers. -
Average percent litter cover (%) and depth ( in):
Between plant interspaces -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season (through July) ~700 lbs/ac; Spring moisture significantly affects total 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:
Cheatgrass, Russian thistle, annual mustards are invaders on this site. Singleleaf pinyon, Utah juniper, mountain big sagebrush, antelope bitterbrush and Douglas rabbitbrush will increase as the site degrades. -
Perennial plant reproductive capability:
All functional groups should reproduce in average (normal) and above average growin seasons.
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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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