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Ecological site R027XY019NV

STONY SLOPE 4-8 P.Z.

Last updated: 6/03/2024
Accessed: 11/21/2024

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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 Stony Slope 4-8 P.Z. site occurs on lower mountain slopes, hills, and piedmont slopes on all aspects. Slopes range from 4 to 75 percent, but slope gradients of 15 to 50 percent are most typical. Elevations are 4000 to 7200 feet. The soils are predominantly very shallow to shallow and well drained that formed in residuum and colluvium derived from volcanic rocks. The soil surface is very stony and is typically moderately coarse in texture.

Associated sites

R027XY015NV	STONY LOAM 4-8 P.Z. More productive site; gentler slopes

R027XY015NV

STONY LOAM 4-8 P.Z.

More productive site; gentler slopes

Similar sites

R027XY013NV	LOAMY 4-8 P.Z. ATCO dominant shrub; SABA14 minor shrub, if present
R027XY018NV	GRAVELLY LOAM 4-8 P.Z. PIDE4 major shrub; more productive site
R027XY027NV	BARREN GRAVELLY SLOPE 4-8 P.Z. ATCO dominant shrub; SABA14 minor shrub, if present
R027XY037NV	LOAMY SLOPE 5-8 P.Z. ATCO dominant shrub; SABA14 minor shrub, if present
R027XY017NV	SOUTH SLOPE 4-8 P.Z. ACSP12 dominant grass

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Atriplex confertifolia (2) Sarcobatus baileyi
Herbaceous	(1) Achnatherum hymenoides

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Physiographic features

Table 2. Representative physiographic features

Landforms	(1) Fan piedmont (2) Hill (3) Mountain slope
Runoff class	High to very high
Elevation	4,000 – 7,200 ft
Slope	4 – 75%
Water table depth	72 in
Aspect	Aspect is not a significant factor

Climatic features

The climate associated with this site is arid, characterized by cool, moist winters and hot, dry summers. Average annual precipitation is 4 to 8 inches. Mean annual air temperature is 48 to 54 degrees F. The average growing season is about 100 to 130 days.

Table 3. Representative climatic features

Frost-free period (average)	130 days
Freeze-free period (average)
Precipitation total (average)	8 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soils in this site are predominantly very shallow to shallow and well drained that formed in residuum and colluvium derived from volcanic rocks. The soil surface is very stony and is typically moderately coarse in texture. Available water capacity is very low. Runoff is very high. Permeability is moderate to moderately slow. Sheet and rill erosion potential ranges from slight to high as slope increases. Soil stability values should be 2 to 4 on most soil textures found on this site. Areas of this site occurring on soils that have a physical crust will probably have stability values less than 3. Soils having thin surface sand sheet will have lower stability values. The soils that are associated with this site are Theon and Trocken.

Table 4. Representative soil features

Parent material	(1) Colluvium – volcanic rock (2) Residuum – volcanic rock
Surface texture	(1) Very cobbly loam (2) Very gravelly loam (3) Very stony loam
Family particle size	(1) Loamy
Drainage class	Well drained
Permeability class	Moderate to moderately slow
Soil depth	8 – 72 in
Surface fragment cover <=3"	25 – 52%
Surface fragment cover >3"	1 – 23%
Available water capacity (0-40in)	0.7 – 3.7 in
Calcium carbonate equivalent (0-40in)	10%
Electrical conductivity (0-40in)	2 mmhos/cm
Sodium adsorption ratio (0-40in)	12
Soil reaction (1:1 water) (0-40in)	6.6 – 9
Subsurface fragment volume <=3" (Depth not specified)	7 – 72%
Subsurface fragment volume >3" (Depth not specified)	5 – 26%

Ecological dynamics

As ecological condition declines, shadscale, littleleaf horsebrush and Bailey's greasewood increase as Indian ricegrass decreases. After wildfire, galleta and cheatgrass can dominate the plant community. The species most likely to invade this site are cheatgrass, galleta, Douglas' rabbitbrush, horsebrush, burrobrush, snakeweed, halogeton, Russian thistle and annual mustards.

Fire Ecology:
The mean fire return interval for shadscale-greasewood communities range from 35 to 100 years. Shadscale communities are usually unaffected by fire because of low fuel loads, although a year of exceptionally heavy winter rains can generate fuels by producing a heavy stand of annual forbs and grasses. Increased presence of non-native annual grasses, such as cheatgrass, can alter fire regimes by increasing fire frequency under wet to near-normal summer moisture conditions. When fire does occur, the effect on the ecosystem may be extreme. Bailey's greasewood may be killed by severe fires, but it commonly sprouts soon after low to moderate-severity fire.
Indian ricegrass can be killed by fire, depending on severity and season of burn. Budsage is killed by fire. Budsage communities rarely burn due to insufficient fire loads. 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. Needlegrasses are damaged by burning due to the dense plant material that can burn slowly and long, charring to the growing points. Late summer and early fall fires are least harmful. Bottlebrush squirreltail's small size, coarse stems, and sparse leafy material aid in its tolerance of fire. Postfire regeneration occurs from surviving root crowns and from on- and off-site seed sources. Frequency of disturbance greatly influences postfire response of bottlebrush squirreltail. Undisturbed plants within a 6 to 9 year age class generally contain large amounts of dead material, increasing bottlebrush squirreltail's susceptibility to fire.

State and transition model

Custom diagram

Standard diagram

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Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Reference Plant Community

State 1 submodel, plant communities

1.1. Reference Plant Community

State 1
Reference Plant Community

Community 1.1
Reference Plant Community

The reference plant community is dominated by Bailey's greasewood, shadscale, and Indian ricegrass. Potential vegetative composition is about 25% grasses, 5% forbs and 70% shrubs. Approximate ground cover (basal and crown) is less than 15 percent. Bare ground is approximately 35 to >50%, surface rock fragments are approximately 40 to >60%, shrub canopy 5 to <15%, basal area for perennial herbaceous plants <1%. Dead branches within individual shrubs are common and standing dead shrub canopy material may be as much as 40% of total woody canopy. Some of the mature bunchgrasses commonly have dead centers. Fine litter between plant interspaces is approximately trace to 1% cover and the depth of litter is approximately one-fourth inch.

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)
Shrub/Vine	35	122	210
Grass/Grasslike	12	44	75
Forb	3	9	15
Total	50	175	300

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			17–49
	Indian ricegrass	ACHY	Achnatherum hymenoides	9–26	–
	desert needlegrass	ACSP12	Achnatherum speciosum	4–14	–
	squirreltail	ELEL5	Elymus elymoides	4–9	–
2	Secondary Perennial Grasses			4–14
	needle and thread	HECO26	Hesperostipa comata	1–5	–
	James' galleta	PLJA	Pleuraphis jamesii	1–5	–
	Sandberg bluegrass	POSE	Poa secunda	1–5	–
	sand dropseed	SPCR	Sporobolus cryptandrus	1–5	–
Forb
3	Perennial			4–18
	globemallow	SPHAE	Sphaeralcea	1–7	–
	princesplume	STANL	Stanleya	1–7	–
Shrub/Vine
4	Primary Perennial Shrubs			56–128
	shadscale saltbush	ATCO	Atriplex confertifolia	26–61	–
	bud sagebrush	PIDE4	Picrothamnus desertorum	4–14	–
	Forb, perennial	2FP	Forb, perennial	2–8	–
	globemallow	SPHAE	Sphaeralcea	1–7	–
	princesplume	STANL	Stanleya	1–7	–
5	Secondary Perennial Shrubs			9–26
	yellow rabbitbrush	CHVI8	Chrysothamnus viscidiflorus	1–5	–
	Nevada jointfir	EPNE	Ephedra nevadensis	1–5	–
	spiny hopsage	GRSP	Grayia spinosa	1–5	–
	winterfat	KRLA2	Krascheninnikovia lanata	1–5	–
	Shockley's desert-thorn	LYSH	Lycium shockleyi	1–5	–

Interpretations

Animal community

Livestock Interpretations:
This site is marginally suited for livestock grazing due to steep slopes and low forage production. Grazing management should be keyed to Indian ricegrass, desert needlegrass, and bottlebrush squirreltail production. 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. Desert needlegrass provides a palatable and nutritious feed for livestock and wildlife during the spring and early summer. Bottlebrush squirreltail is very palatable winter forage for domestic sheep of Intermountain ranges. Domestic sheep relish the green foliage. Overall, bottlebrush squirreltail is considered moderately palatable to livestock. Shadscale is a valuable browse species, providing a source of palatable, nutritious forage for a wide variety of livestock. Shadscale provides good browse for domestic sheep. Shadscale leaves and seeds are an important component of domestic sheep and cattle winter diets.
Bailey’s greasewood is an important winter browse plant for domestic sheep and cattle. It also receives light to moderate use by domestic sheep and cattle during spring and summer months. Greasewood contains soluble sodium and potassium oxalates that may cause poisoning and death in domestic sheep and cattle if large amounts are consumed in a short time. Budsage is palatable and nutritious forage for domestic sheep in the winter and spring although it is known to cause mouth sores in lambs. Budsage can be poisonous or fatal to calves when eaten in quantity. Budsage, while desired by cattle in spring, is poisonous to cattle when consumed alone.

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:
Shadscale is a valuable browse species, providing a source of palatable, nutritious forage for a wide variety of wildlife particularly during spring and summer before the hardening of spiny twigs. It supplies browse, seed, and cover for birds, small mammals, rabbits, deer, and pronghorn antelope. Bailey’s greasewood is an important winter browse plant for big game animals and a food source for many other wildlife species. It also receives light to moderate use by mule deer and pronghorn during spring and summer months. Budsage is palatable, nutritious forage for upland game birds, small game and big game in winter. Budsage is rated as "regularly, frequently, or moderately taken" by mule deer in Nevada in winter and is utilized by bighorn sheep in summer, but the importance of budsage in the diet of bighorns is not known. Bud sage comprises 18 – 35% of a Pronghorn’s diet during the spring where it is available. Chukar will utilize the leaves and seeds of bud sage. Budsage is highly susceptible to effects of browsing. It decreases under browsing due to year-long palatability of its buds and is particularly susceptible to browsing in the spring when it is physiologically most active. 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. Desert needlegrass is palatable to wildlife and is grazed during the spring.
Bottlebrush squirreltail is a dietary component of several wildlife species. Bottlebrush squirreltail may provide forage for mule deer and pronghorn.

Hydrological functions

Rills are rare on this site. A few can be expected on steeper slopes in areas subjected to summer convection storms or rapid spring snowmelt. Water flow patterns are often numerous in areas subjected to summer convection storms. Flow patterns are short and stable. Pedestals are rare with occurrence typically limited to area within water flow patterns. Frost heaving of shallow rooted plants should not be considered as normal condition. Gullies are rare in areas of this site that occur on stable landforms. Where this site occurs on inset fans, gullies and head cuts associated with ephemeral channel entrenchment are common. Gullies and head cuts should be healing or stable. Fine litter (foliage from grasses and annual and perennial forbs) are expected to move the distance of slope length during intense summer convection storms or rapid snowmelt events. Persistent litter (large woody material) will remain in place except during catastrophic events. Very sparse shrub canopy have little value in breaking raindrop impact. Medium to fine textured surface soils have moderate to rapid runoff and medium to slow infiltration rates. Very high amounts of surface rock fragments and steep slopes increase runoff potential yet stabilize soil.

Recreational uses

This site offers rewarding opportunities to photographers and for nature study. This site has potential for off-road vehicle use and hiking.

Other products

Shadscale seeds were used by Native Americans of Arizona, Utah and Nevada for bread and mush.
Indian ricegrass was traditionally eaten by some Native American peoples. The Paiutes used seed as a reserve food source. The leaves, seeds and stems of greasewood are edible.

Other information

Re-vegetation of shadscale communities is inherently difficult. Dry soil surfaces resulting from low humidity, high irradiation, and moderate to strong winds are major obstacles in re-vegetation projects.Indian ricegrass is well-suited for surface erosion control and desert revegetation although it is not highly effective in controlling sand movement. Bottlebrush squirreltail is tolerant of disturbance and is a suitable species for revegetation.

Supporting information

Inventory data references

NASIS soil component data.

Type locality

Location 1: Churchill County, NV
Township/Range/Section	T23N R26E S19
General legal description	About 5 miles northeast of Nightengale Interchange off I 80, Fireball Ridge area, Churchill County, Nevada. This site also occurs in Lyon, Mineral, Pershing and Storey county, 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

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)	GK BRACKLEY
Contact for lead author	State Rangeland Management Specialist
Date	06/20/2006
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 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 often numerous in areas subjected to summer convection storms. Flow patterns short and stable.
Number and height of erosional pedestals or terracettes:
Pedestals are rare with occurrence typically limited to area within water flow patterns. Frost heaving of shallow rooted plants should not be considered as normal condition.
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare Ground ± 35 to > 50%; surface rock cover ±40 to > 60%; shrub canopy 5 to < 15%; basal area for perennial herbaceous plants < 1%.
Number of gullies and erosion associated with gullies:
Gullies are rare in areas of this site that occur on stable landforms. Where this site occurs on inset fans gullies and head cuts associated with ephemeral channel entrenchment are common. Gullies and head cuts should be healing or stable.
Extent of wind scoured, blowouts and/or depositional areas:
None to Slight
Amount of litter movement (describe size and distance expected to travel):
Fine litter (foliage from grasses and annual & perennial forbs) is expected to move the distance of slope length during intense summer convection storms or rapid snowmelt events. Persistent litter (large woody material) will remain 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 2 to 4 on most soil textures found on this site. Areas of this site occurring on soils that have a physical crust will probably have stability values less than 3. (This will be field tested.)
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface structure is typically fine to very fine granular. Soil surface colors are light and the soils are typified by an ochric epipedon. Organic carbon of the surface 2 to 3 inches is typically less than to 1 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:
Very sparse shrub canopy little value in breaking raindrop impact. Medium to fine textured surface soils have moderate to rapid runoff and medium to slow infiltration rates. Very high amounts of surface rock fragments and steep slopes increase runoff potential yet stabilize soil.
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. Platy or massive sub-surface horizons, subsoil argillic horizons or hardpans shallow to the surface 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: Low-statured salt desert shrubs (shadscale & Bailey's greasewood). ( By above ground production)

Sub-dominant:
Associated shrubs > Deep-rooted, cool season, perennial bunchgrasses > shallow-rooted, cool season, perennial bunchgrasses > deep-rooted, cool season, perennial forbs > fibrous, shallow-rooted, cool season, annual and perennial forbs. ( By above ground production)

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Dead branches within individual shrubs are common and standing dead shrub canopy material may be as much as 40% of total woody canopy; mature bunchgrasses commonly have dead centers.
Average percent litter cover (%) and depth ( in):
Fine litter between plant interspaces (± T-1%) and depth of litter is ± ¼ inch.
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season (February thru April [May]) ± 175 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, galleta, horsebrush, burrobrush, snakeweed, halogeton, Russian thistle, and annual mustards are invaders on this site. Douglas' rabbitbrush is an increaser on this site.
Perennial plant reproductive capability:
All functional groups should reproduce in above average growing season years.

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