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Conservation Service
Ecological site R023XY015NV
STONY LOAM 12-14 P.Z.
Last updated: 4/10/2025
Accessed: 09/16/2026
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Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
Ecological site concept
Currently there is only a draft of the initial concept for this ecological site. The initial concept for this site places it within the Loamy 10-20 PZ Mountain Big Sagebrush and Bluebunch Wheatgrass Ecological Site Group. To view the General STM and other information available for this ESG please go to https://edit.jornada.nmsu.edu/catalogs/esg/023X/R023XY905NV
This site is less productive than the modal site with only 900 lbs/ac in normal years. Slopes on this site typically range from 4 to 15 percent. Soils in this site have a loam surface layer modified with high volumes of stones and cobbles. Unlike the group modal site, the dominant shrub on this site is antelope bitterbrush with mountain big sagebrush making up only a small component of the plant community. This site is similar to the modal with a five state model.Associated sites
R023XY007NV LOAMY 14-16 P.Z.
R023XY017NV CLAYPAN 14-16 P.Z.
R023XY031NV CLAYPAN 10-14 P.Z.
R023XY041NV LOAMY 12-14 P.Z.
R023XY066NV ASHY LOAM 14-16 P.Z.
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PUTR2 often prevalent, but ARTRV dominant shrub; PSSPS-FEID codominant
R023XY016NV SOUTH SLOPE 12-16 P.Z.
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R023XY066NV ASHY LOAM 14-16 P.Z.
FEID-ACHNA codominant
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Purshia tridentata
(2) Artemisia tridentata ssp. vaseyanaHerbaceous (1) Pseudoroegneria spicata ssp. spicata
Physiographic features
This site occurs on summits and backslopes of plateaus, hills, and mountains on all aspects. Slopes range from 4 to 50 percent, but slope gradients of 4 to 15 percent are typical. Elevations are 5000 to 7900 feet.
Table 2. Representative physiographic features
Landforms (1) Mountain
(2) Hill
(3) Plateau
Elevation 5000 – 7900 ft Slope 4 – 50 % Aspect Aspect is not a significant factor Climatic features
The climate associated with this site is semiarid and characterized by cool, moist winters and warm, dry summers. Average annual precipitation is 12 to 14 inches. Mean annual air temperature is 42 to 45 degrees F. The average growing season is about 70 to 90 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).
Average annual precipitation is 16 to over 20 inches. Mean annual air temperature is 41 to 44 degrees F. The average growing season is about 50 to 70 days.
Mean annual precipitaion at the Bear Creek, Nevada SNOTEL station (170501020301) is 37.69 inches.
monthly mean precipitation is:
January 3.84; February 3.75; March 4.38; April 4.9;
May 3.99; June 2.82; July .95; August 1.66;
September 1.22; October 2.12;
November 3.67; December 4.38.Table 3 Representative climatic features
Frost-free period (average) 80 days Freeze-free period (average) Precipitation total (average) 10 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 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
These soils associated with this site have formed in residuum and colluvium derived from volcanic parent materials. The soils are shallow to moderately deep, well drained, and have moderate to moderately slow permeability. The soils in this site have a loam surface layer modified with high volumes of stones and cobbles. The surface cover of large rock fragments (cobbles and stones) is typically 20 percent. Subsoils are heavy clays that are normally slightly acid. Fractured bedrock is usually found at 16 to 22 inches. The subsoil hinders rooting to some degree but a significant number of roots enter fractures within the bedrock or underlying material. The soil series associated with this site include: Hart Camp, Madeline, and Sumine.
Table 4. Representative soil features
Surface texture (1) Very stony loam
(2) Gravelly loam
(3) Very cobbly loam
Family particle size (1) Clayey
Drainage class Well drained Permeability class Moderately slow to moderate Soil depth 10 – 40 in Surface fragment cover <=3" 15 – 25 % Surface fragment cover >3" 0 – 20 % Available water capacity
(0-40in)2.2 – 3.4 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)Not specified 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)9 – 25 % Subsurface fragment volume >3"
(Depth not specified)0 – 9 % Ecological dynamics
Where management results in abusive grazing use by livestock and/or feral horses, shrub abundance and canopy increase as perennial grasses and forbs decrease. Excessive cattle use in late summer and fall will adversely affect bitterbrush production and seedling survival. Western and Utah juniper commonly invades this site in absence of fire.
Fire Ecology:
Presettlement fire return intervals for antelope bitterbrush communities range from 15 to 25 years. Season of burning and environmental conditions have a large impact on antelope bitterbrush ability to survive fire and sprout. Antelope bitterbrush 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. Mountain big sagebrush is highly susceptible to injury from fire. It is often top-killed by fire and will not resprout. Burning bluebunch wheatgrass may remove most of the aboveground biomass but does not usually result in plant mortality. Bluebunch wheatgrass is generally favored by burning. Burning stimulates flowering and seed production. However, season of burning affects mortality. Western needlegrass is moderately damaged by fire. The recovery time is between 3 and 5 years. 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. Early season burning is more damaging to this needlegrass than late season burning. Idaho fescue grows in a dense, fine-leaved tuft. Fires tend to burn within the accumulated fine leaves at the base of the plant and may produce temperatures sufficient to kill some of the root crown. Mature Idaho fescue plants are commonly reported to be severely damaged by fire in all seasons.State and transition model
Custom diagramStandard diagramMore interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Reference Plant CommunityCommunity 1.1
Reference Plant CommunityThe reference plant community is dominated by bluebunch wheatgrass, antelope bitterbrush and mountain big sagebrush. Thurber's or western needlegrass, and Idaho fescue are other important species associated with this site. Potential vegetative composition is about 55% grasses, 10% forbs and 35% shrubs and trees. Approximate ground cover (basal and crown) is about 30 to 45 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 330 495 605 Shrub/Vine 200 292 349 Forb 60 90 110 Tree 10 23 36 Total 600 900 1100 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Primary Perennial Grasses 333–585 bluebunch wheatgrass PSSPS Pseudoroegneria spicata ssp. spicata 270–360 – Idaho fescue FEID Festuca idahoensis 18–90 – western needlegrass ACOCO Achnatherum occidentale ssp. occidentale 23–68 – Thurber's needlegrass ACTH7 Achnatherum thurberianum 22–67 – 2 Secondary Perennial Grasses 18–90 Indian ricegrass ACHY Achnatherum hymenoides 5–27 – squirreltail ELEL5 Elymus elymoides 5–27 – needle and thread HECO26 Hesperostipa comata 5–27 – prairie Junegrass KOMA Koeleria macrantha 5–27 – basin wildrye LECI4 Leymus cinereus 5–27 – bluegrass POA Poa 5–27 – muttongrass POFEF Poa fendleriana ssp. fendleriana 5–27 – Sandberg bluegrass POSE Poa secunda 5–27 – Forb3 Perennial 45–135 balsamroot BALSA Balsamorhiza 5–27 – tapertip hawksbeard CRAC2 Crepis acuminata 5–27 – lupine LUPIN Lupinus 5–27 – beardtongue PENST Penstemon 5–27 – clover TRIFO Trifolium 5–27 – Shrub/Vine4 Primary Shrubs 180–315 antelope bitterbrush PUTR2 Purshia tridentata 135–225 – mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 45–90 – 5 Secondary Shrubs 18–90 Utah serviceberry AMUT Amelanchier utahensis 9–27 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 9–27 – wild crab apple PERA4 Peraphyllum ramosissimum 9–27 – currant RIBES Ribes 9–27 – mountain snowberry SYOR2 Symphoricarpos oreophilus 9–27 – Tree6 Evergreen 10–36 western juniper JUOC Juniperus occidentalis 5–18 – Utah juniper JUOS Juniperus osteosperma 5–18 – Interpretations
Animal community
Livestock Interpretations:
This site is suitable for livestock grazing. Grazing management should be keyed to perennial grass production. Bluebunch wheatgrass is considered one of the most important forage grass species on western rangelands for livestock. Although bluebunch wheatgrass can be a crucial source of forage, it is not necessarily the most highly preferred species. Western needlegrass has a spreading and deeply penetrating root system, which makes it resistant to trampling. 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. Idaho fescue provides important forge for many types of domestic livestock. The foliage cures well and is preferred by livestock in late fall and winter. 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. 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.
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:
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. Mountain big sagebrush is highly preferred and nutritious winter forage for mule deer and elk. 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. Bluebunch wheatgrass is considered one of the most important forage grass species on western rangelands for wildlife. Bluebunch wheatgrass does not generally provide sufficient cover for ungulates, however, mule deer are frequently found in bluebunch-dominated grasslands. Western needlegrass provides valuable forage for many species of wildlife. Thurber needlegrass is valuable forage for wildlife. Idaho fescue provides important forge for several wildlife species. It is reported to be good forage for pronghorn, and deer in ranges of northern Nevada.Hydrological functions
There are typically no rills or pedestals. There may be a few, widely spaced and shallow, rills on steeper slopes (over 20% gradient). Frost heaving of shallow rooted plants should not be considered a "normal" condition. Water flow patterns are typically non-existent but may rarely occur on steeper slopes in areas recently subjected to intense summer convection storms or rapid snowmelt. Gullies are non-existent in areas of this site that occur on stable landforms. Perennial herbaceous plants (especially deep-rooted bunchgrasses [i.e., bluebunch wheatgrass] slow runoff and increase infiltration. Shrub canopy and associated litter break raindrop impact and provide opportunity for snow catch and accumulation on site.
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 offers rewarding opportunities to photographers and for nature study. This site is used for camping and hiking and has potential for upland and big game hunting.
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.
Supporting information
Type locality
Location 1: Lassen County, CA Township/Range/Section T36N R16E S2 UTM zone N UTM northing 742209 UTM easting 4544434 Latitude 41° 0′ 54″ Longitude 120° 7′ 10″ General legal description Approximately 2.5 miles southeast of Windy Flat, Old Tuledad Road, Lassen County, California. This site also occurs in Washoe and Humboldt Counties, Nevada. Location 2: Washoe County, NV Township/Range/Section T45N R21E S10 UTM zone N UTM northing 283259 UTM easting 4634862 Latitude 41° 50′ 9″ Longitude 119° 36′ 37″ General legal description NE 1/4 NE 1/4, Approximately 1.25 miles south of Nevada Route 34A (summits and shoulders of plateaus south of Last Chance Ranch), USF&WS Sheldon Antelope Refuge, Washoe County, Nevada. This site also occurs in Humboldt 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
BH/SW/GKB
T Stringham (UNR under contract with BLM)Approval
Kendra Moseley, 4/10/2025
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Gary Brackley Contact for lead author State Rangeland Management Specialist Date 06/20/2006 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
Typically none. There may be a few, widely spaced and shallow, rills on steeper slopes (over 20% gradient). -
Presence of water flow patterns:
Water flow patterns are typically non-existent but may rarely occur on steeper slopes in areas recently subjected to intense summer convection storms or rapid snowmelt. -
Number and height of erosional pedestals or terracettes:
Pedestals are typically non-existent. 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 ± 25%; surface rock fragments ±40%; shrub canopy 20 to 30%; foliar cover of perennial herbaceous plants ± 40%. -
Number of gullies and erosion associated with gullies:
Gullies are non-existent in areas of this site that occur on stable landforms. -
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) 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 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 very thin to medium platy. Soil surface colors are dark and the soils are typified by a mollic epipedon. Organic matter of the surface 2 to 4 inches is typically 1 to 3 percent. 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., bluebunch wheatgrass] 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 (antelope bitterbrush & mountain big sagebrush) > associated shrubs = deep-rooted, cool season, perennial forbs. (By above ground production)Sub-dominant:
Fibrous, shallow-rooted, cool season, perennial and annual forbs = shallow-rooted, cool season, perennial grasses. (By above ground production)Other:
Additional:
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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 25% of total woody canopy; some of the mature bunchgrasses (<10%) have dead centers. -
Average percent litter cover (%) and depth ( in):
Between plant interspaces (± 25%) and litter depth 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 (through June) ± 900 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:
Rabbitbrush spp. and western juniper are increaser on this site. Cheatgrass, annual mustards, knapweeds, medusahead, and thistles are invaders on this site. -
Perennial plant reproductive capability:
All functional groups should reproduce in average (or normal) and above average growing season years.
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