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Ecological site R027XY032NV

SHALLOW CALCAREOUS LOAM 10-12 P.Z.

Last updated: 6/03/2024
Accessed: 07/18/2026

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General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

MLRA notes

Major Land Resource Area (MLRA): 027X–Fallon-Lovelock Area

Physiography
Found in the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus this area is characterized by isolated uplifted fault block mountain ranges trending north to south that are separated by broad, hydrologically closed basins. The entire area occurs in the rain-shadow of the Sierra Nevada mountains and is influenced by Pleistocene Lake Lahontan which reached its most recent high stand about 12,000 years ago. There is substantial evidence suggesting the western Great Basin has been the site of pluvial-interpluvial cycles for at least the past two million years.
The mountains and valleys are dissected by the Humboldt, Truckee, Carson, and Walker Rivers and their tributaries, all of which terminate within MLRA 27. Extensive playas can be found throughout this area and are the result of drying of ancient Lake Lahontan. Elevation generally ranges from 3,300 to 5,900 feet (1,005 to 1,800 meters) in valleys, but on some mountain peaks it is more than 7,870 feet (2,400 meters).

Geology
Landforms and soils of this MLRA have been heavily influenced by fluctuating lake level over the last 40,000 years. There is a level line evident on the higher slopes marking the former extent of glacial Lake Lahontan. Almost half of this area has surface deposits of alluvial valley fill influenced by lacustrine sediment. The rest has andesite and basalt rocks of different ages. Mesozoic and Tertiary intrusives are concentrated along the western border of the area, and Lower Volcanic Rocks (17 to 43 million years old) are common on the eastern side of the area. Also, some scattered outcrops of Mesozoic sedimentary and volcanic rocks and tuffaceous sedimentary rocks are in the mountains within the interior of this MLRA.

Climate
The average annual precipitation is 5 to 10 inches (125 to 255 millimeters) in most of the area but is as much as 19 inches (485 millimeters) on high mountain slopes. Most of the rainfall occurs as high-intensity, convective thunderstorms during the growing season. The amount of precipitation is very low from summer to midautumn. The precipitation in winter occurs mainly as snow. The average annual temperature is 43 to 54 degrees F (6 to 12 degrees C). The freeze-free period averages 155 days and ranges from 110 to 195 days, decreasing in length with elevation.

Water
The amount of precipitation is very low, and water for irrigation is obtained principally from diversions on the four large rivers in the area and from water stored in the Lahontan, Rye Patch, and Weber Reservoirs. Pyramid Lake and Walker Lakes are terminal lakes for the Truckee and Walker Rivers, respectively. Much of the annual flow of both rivers is diverted for irrigation, causing lake levels to fall and levels of dissolved salts to increase causing problems for the native Lahontan cutthroat trout.

Soils
The dominant soil orders are Aridisols and Entisols. The soils in the area are predominantly a mesic temperature regime, aridic moisture regime, and have a mixed mineralogy. They are generally well drained, loamy or sandy, commonly skeletal, and shallow to very deep. Accumulation of salts, tufa deposits, and eolian sediments with soluble salts over lacustrine deposits influence most of the soils in the basin landforms of this MLRA. Soils on bedrock-controlled landforms are typically comprised of volcanic or tuffaceous sedimentary colluvium over residuum.

Biological Resources
This area supports extensive areas of salt-desert shrub vegetation. Shadscale and Bailey’s greasewood are widespread, occurring both individually and together. Grasses are generally sparse, although Indian ricegrass is prominent, especially on the sandy soils. Fourwing saltbush, winterfat, spiny hopsage, wolfberry, ephedra, dalea, and bud sagebrush are common shrubs. Basin wildrye, creeping wildrye, alkali sacaton, saltgrass, black greasewood, rubber rabbitbrush, and big saltbush are important plants on saline bottom lands and terraces. A few marsh areas support cattail, bulrushes, sedges, and rushes. Big sagebrush, along with scattered Utah juniper and singleleaf pinyon, is associated with Thurber needlegrass, desert needlegrass, Sandberg bluegrass, and squirreltail on the higher elevation piedmont slopes and mountains.

Ecological site concept

The Shallow Calcareous Loam 10-12 P.Z. site occurs on summits and sideslopes of hills and mountains on all aspects. Slopes range from 4 to over 75 percent, but slope gradients of 15 to 50 percent are typical. Elevations are 4400 to 7200 feet. The soils are shallow and very shallow and well drained. Surface soils typically have high amounts of gravels and cobbles. Subsoils typically are skeletal and have an argillic horizon.

Associated sites

R027XY031NV	SHALLOW CALCAREOUS LOAM 8-10 P.Z. ACHY dominant grass; less productive site

R027XY031NV

SHALLOW CALCAREOUS LOAM 8-10 P.Z.

ACHY dominant grass; less productive site

Similar sites

R027XY061NV	SHALLOW CALCAREOUS SLOPE 8-10 P.Z. ACSP12-ACHY codominant grasses
R027XY083NV	MOUNTAIN RIDGE ARAR8 dominant shrub
R027XY079NV	GRAVELLY CLAYPAN 8-10 P.Z. ARARL3 dominant shrub; ACTH7 dominant grass
R027XY020NV	SHALLOW CLAYPAN 8-10 P.Z. ARARL3 dominant shrub; ACSP12 dominant grass

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Artemisia nova
Herbaceous	(1) Achnatherum thurberianum

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Physiographic features

Table 2. Representative physiographic features

Landforms	(1) Hill (2) Mountain slope
Runoff class	Very high
Elevation	4400 – 7200 ft
Slope	4 – 75 %
Water table depth	72 – 0 in
Aspect	Aspect is not a significant factor

Climatic features

The climate associated with this site is semiarid, characterized by cool, moist winters and warm, dry summers. Average annual precipitation is 10 to 12 (14) inches. Mean annual air temperature is 43 to 50 degrees F. The average growing season is about 90 to 110 days.

Table 3 Representative climatic features

Frost-free period (average)	110 days
Freeze-free period (average)
Precipitation total (average)	10 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soils associated with this site are shallow and very shallow and well drained. Surface soils typically have high amounts of gravels and cobbles. Subsoils typically are skeletal and have an argillic horizon. Rock fragments in the profile occupy plant growing space and reduce the potential soil moisture holding capacity. The available water capacity is very low to low, soil permeability is slow to moderate, and surface runoff is medium to high. The soil moisture regime is aridic bordering on xeric and the soil temperature regime is mesic. The soil series associated with this site include: Atlow, Hooplite, Jung, and Puffer.

The representative soil series is Hooplite, a loamy-skeletal, mixed, superactive, mesic Lithic Xeric Haplargids. An ochric epipedon occurs from the soil surface to 10 cm or an argillic horizon occurs from 10 to 20 cm.

Table 4. Representative soil features

Parent material	(1) Residuum – rhyolite (2) Colluvium – rhyolite
Surface texture	(1) Very gravelly loam (2) Very cobbly loam
Family particle size	(1) Clayey
Drainage class	Well drained
Permeability class	Slow to moderate
Soil depth	8 – 19 in
Surface fragment cover <=3"	20 – 40 %
Surface fragment cover >3"	2 – 25 %
Available water capacity (0-40in)	0.7 – 4.1 in
Calcium carbonate equivalent (0-40in)	0 – 15 %
Electrical conductivity (0-40in)	0 – 2 mmhos/cm
Sodium adsorption ratio (0-40in)	0 – 12
Soil reaction (1:1 water) (0-40in)	7 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	15 – 45 %
Subsurface fragment volume >3" (Depth not specified)	5 – 20 %

Ecological dynamics

Where management results in abusive grazing use by cattle or feral horses, Sandberg's bluegrass and bottlebrush squirreltail increase in the understory as black sagebrush and rabbitbrush increase and become the dominant vegetation. Grazing by sheep will reduce black sagebrush, Thurber's needlegrass, and Sandberg's bluegrass in the plant community. Cheatgrass, Russian thistle, and halogeton are species most likely to invade this site. Following wildfire, shadscale and spiny hopsage (with rabbitbush, horsebrush, and snakeweed) often replace black sagebrush.

Fire Ecology:
Black sagebrush communities generally lack enough fine fuels to carry a fire. In addition to low fine fuel loading, wide shrub spacing makes fire infrequent or difficult to prescribe in black sagebrush types. Black sagebrush is highly susceptible to fire-caused mortality; plants are readily killed by all fire intensities. Following burning, reestablishment occurs through off-site sources. Winterfat is either killed or top-killed by fire, depending on fire severity. Severe fire can kill the perennating buds located several inches above the ground surface and thus kills the plant. In addition, severe fire usually destroys seed on the plant. Low-severity fire scorches or only partially consumes the aboveground portions of winterfat and thus does not cause high mortality. Fires in spiny hopsage sites generally occur in late summer when plants are dormant, and sprouting generally does not occur until the following spring. Spiny hopsage is considered to be somewhat fire tolerant and often survives fires that kill sagebrush. Mature spiny hopsage generally sprout after being burned. Spiny hopsage is reported to be least susceptible to fire during summer dormancy. Thurber’s 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. Indian ricegrass can be killed by fire, depending on severity and season of burn. Indian ricegrass reestablishes on burned sites through seed dispersed from adjacent unburned areas. Sandberg bluegrass is generally unharmed by fire. It produces little litter, and its small bunch size and sparse litter reduces the amount of heat transferred to perennating buds in the soil. Its rapid maturation in the spring also reduces fire damage, since it is dormant when most fires occur.

State and transition model

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Standard diagram

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Ecosystem states

1. Reference State

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Reference State

Community 1.1
Reference Plant Community

The reference plant community is dominated by black sagebrush and Indian ricegrass. Potential vegetative composition is about 50% grasses, 5% forbs and 45% shrubs. Approximate ground cover (basal and crown) is 20 to 30 percent.

Figure 3. 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	100	175	250
Shrub/Vine	90	157	225
Forb	10	18	25
Total	200	350	500

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Primary Perennial Grasses			147–245
	Thurber's needlegrass	ACTH7	Achnatherum thurberianum	105–140	–
	Indian ricegrass	ACHY	Achnatherum hymenoides	35–70	–
	Sandberg bluegrass	POSE	Poa secunda	7–35	–
2	Secondary Perennial Grasses			18–53
	squirreltail	ELEL5	Elymus elymoides	2–18	–
	needle and thread	HECO26	Hesperostipa comata	2–18	–
	James' galleta	PLJA	Pleuraphis jamesii	2–18	–
Forb
3	Perennial			7–35
	milkvetch	ASTRA	Astragalus	2–18	–
	buckwheat	ERIOG	Eriogonum	2–18	–
	phlox	PHLOX	Phlox	2–18	–
	globemallow	SPHAE	Sphaeralcea	2–18	–
Shrub/Vine
4	Primary Perennial Shrubs			89–193
	black sagebrush	ARNO4	Artemisia nova	75–123	–
	spiny hopsage	GRSP	Grayia spinosa	7–35	–
	winterfat	KRLA2	Krascheninnikovia lanata	7–35	–
5	Secondary Perennial Shrubs			18–53
	shadscale saltbush	ATCO	Atriplex confertifolia	2–18	–
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	2–18	–
	Nevada jointfir	EPNE	Ephedra nevadensis	2–18	–
	bud sagebrush	PIDE4	Picrothamnus desertorum	2–18	–
	littleleaf horsebrush	TEGL	Tetradymia glabrata	2–18	–

Interpretations

Animal community

Livestock Interpretations:
This site is suited to livestock grazing. Grazing management should be keyed perennial grass and palatable shrub production. 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. Indian ricegrass is highly palatable to all classes of livestock in both green and cured condition. It supplies a source of green feed before most other native grasses have produced much new growth. Bluegrass is a widespread forage grass. It is one of the earliest grasses in the spring and is sought by domestic livestock and several wildlife species. Sandberg 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.
In winter, at lower elevations, black sagebrush is heavily utilized by domestic sheep. Winterfat is an important forage plant for livestock, especially during winter when forage is scarce. Abusive grazing practices have reduced or eliminated winterfat on some areas even though it is fairly resistant to browsing. Effects depend on severity and season of grazing. Spiny hopsage provides a palatable and nutritious food source for livestock, particularly during late winter through spring. Domestic sheep browse the succulent new growth of spiny hopsage in late winter and early spring.

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:
Black sagebrush is a significant browse species within the Intermountain region. It is especially important on low elevation winter ranges in the southern Great Basin, where extended snow free periods allow animal’s access to plants throughout most of the winter. In these areas it is heavily utilized by pronghorn and mule deer. Sagebrush-grassland communities provide critical sage-grouse breeding and nesting habitats. 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. Winterfat is an important forage plant for Wildlife, especially during winter when forage is scarce. Winterfat seeds are eaten by rodents. Winterfat is a staple food for black-tailed jackrabbit. Mule deer and pronghorn antelope browse winterfat. Winterfat is used for cover by rodents. It is potential nesting cover for upland game birds, especially when grasses grow up through its crown. Spiny hopsage provides a palatable and nutritious food source for big game animals. Spiny hopsage is used as forage to at least some extent by domestic goats, deer, pronghorn, and rabbits. Thurber needlegrass is valuable forage for wildlife. Indian ricegrass is eaten by pronghorn in moderate amounts whenever available. In Nevada, it is consumed by desert bighorns. A number of heteromyid rodents inhabiting desert rangelands show preference for seed of Indian ricegrass. Indian ricegrass is an important component of jackrabbit diets in spring and summer. In Nevada, Indian ricegrass may even dominate jackrabbit diets during the spring through early summer months. Indian ricegrass seed provides food for many species of birds. Doves, for example, eat large amounts of shattered Indian ricegrass seed lying on the ground.

Hydrological functions

Runoff is high to very high. Permeability is slow to moderate. Hydrologic soil groups include C and D. Rills are none to rare. Water flow patterns are few and can be expected in areas subjected to summer convection storms or rapid snowmelt. Pedestals are rare. Occurrence is usually limited to areas of water flow patterns. Perennial herbaceous plants (especially deep-rooted bunchgrasses [i.e., Thurber's needlegrass] slow runoff and increase infiltration. Shrub canopy and associated litter break raindrop impact.

Recreational uses

Aesthetic value is derived from the diverse floral and faunal composition and the colorful flowering of wild flowers and shrubs during the spring and early summer. This site is used for camping and hiking and has potential for upland and big game hunting.

Other products

Some Native American peoples traditionally ground parched seeds of spiny hopsage to make pinole flour. Indian ricegrass was traditionally eaten by some Native Americans. The Paiutes used seed as a reserve food source.

Other information

Black sagebrush is an excellent species to establish on sites where management objectives include restoration or improvement of domestic sheep, pronghorn, or mule deer winter range. Winterfat adapts well to most site conditions, and its extensive root system stabilizes soil. However, winterfat is intolerant of flooding, excess water, and acidic soils. Spiny hopsage has moderate potential for erosion control and low to high potential for long-term revegetation projects. It can improve forage, control wind erosion, and increase soil stability on gentle to moderate slopes. Spiny hopsage is suitable for highway plantings on dry sites in Nevada.

Supporting information

Inventory data references

NASIS soil component data.

Type locality

Location 1: Churchill County, NV
Township/Range/Section	T19N R37E S27
UTM zone	N
UTM northing	4370649
UTM easting	431017
Latitude	39° 28′ 57″
Longitude	117° 48′ 7″
General legal description	About 6 miles north of Cold Creek HMS just east of USHwy 50, Edwards Creek Valley area, Churchill County, Nevada. This site also occurs in Lyon, Mineral, Pershing, and Storey Counties, Nevada.
Location 2: Mineral County, NV
Township/Range/Section	T13N R33E S5
General legal description	About 2 miles east of Nevada Scheelite Mine, Monte Cristo Mountains, Mineral County, Nevada. This site also occurs in Lyon, Pershing, and Storey Counties, Nevada.

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

DK/GD
TK Stringham

Approval

Kendra Moseley, 6/03/2024

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)	Patti Novak-Echenique
Contact for lead author	State Rangeland Management Specialist
Date	09/21/2009
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Rills are none to rare.
Presence of water flow patterns:
Water flow patterns are few and 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 usually 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 ± 40% depending on amount of surface rock fragments.
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 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 remain in place except during large rainfall 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 6 on most soil textures found on this site. (To be field tested.)
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface structure is typically thin to thick platy. Soil surface colors are light brownish grays and soils are typified by an ochric epipedon. Organic carbon of the surface 2 to 3 inches is typically 1 to 1.5 percent dropping off quickly below. Organic matter content can be more or less depending on micro-topography.
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Perennial herbaceous plants (especially deep-rooted bunchgrasses [i.e., Thurber needlegrass] slow runoff and increase infiltration. Shrub canopy and associated litter break raindrop impact.
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Compacted layers are none. Subangular blocky, platy, or massive sub-surface horizons, subsoil argillic horizons or duripans 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 > low shrubs (black sagebrush)

Sub-dominant:
associated shrubs = shallow-rooted, cool season, grasses > deep-rooted, cool season, perennial forbs = fibrous, shallow-rooted, cool season, perennial and annual forbs

Other:

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 25% of total woody canopy; some of the mature bunchgrasses (<20%) have dead centers.
Average percent litter cover (%) and depth ( in):
Under canopy and between plant interspaces (20-30%) and depth of litter is <½ inch.
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season (end of May) ± 350 lbs/ac; Spring moisture significantly affects total production. Favorable years ± 500 lbs/ac and unfavorable years ± 200 lbs/ac.
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:
Potential invaders include singleleaf pinyon, Utah juniper, halogeton, Russian thistle, annual mustards, and cheatgrass.
Perennial plant reproductive capability:
All functional groups should reproduce in average (or normal) and above average growing season years. Little growth or reproduction occurs in drought years.

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