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Ecological site R030XB105NV

BOULDERY LIMESTONE SLOPE 5-7 P.Z.

Last updated: 2/26/2025
Accessed: 08/28/2026

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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.

Ecological site concept

This site occurs on northerly-facing sideslopes of mountains with limestone geology. Slopes range from 30 to over 75 percent, but slope gradients of 50 to 75 percent are most typical. Elevations are 3200 to 4000 feet. The soil associated with this site are shallow and derived from limestone parent material. Stone and boulder-sized rock fragments are common.

Please refer to group concept R030XB068NV to view the provisional STM.

Associated sites

R030XA002NV	LIMESTONE HILL 5-7 P.Z.
R030XA006NV	SHALLOW LIMESTONE SLOPE 5-7 P.Z.
R030XB106NV	GRAVELLY SLOPE 5-7 P.Z.

R030XA002NV

LIMESTONE HILL 5-7 P.Z.

R030XA006NV

SHALLOW LIMESTONE SLOPE 5-7 P.Z.

R030XB106NV

GRAVELLY SLOPE 5-7 P.Z.

Similar sites

R030XB091NV	MOUNTAIN RIDGE Greater shrub diversity; MOUT rare to absent
R030XB106NV	GRAVELLY SLOPE 5-7 P.Z. ATCO codominant shrub
R030XA002NV	LIMESTONE HILL 5-7 P.Z. ATCO dominant shrub
R030XB123NV	LIMESTONE SLOPE 5-7 P.Z. MOUT minor spp., if present
R030XB101NV	TABLELAND 5-7 P.Z. Occurs on mesa tops; slopes < 8 percent
R030XA006NV	SHALLOW LIMESTONE SLOPE 5-7 P.Z. CORA & ATCO dominant shrubs

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Krascheninnikovia lanata (2) Mortonia utahensis
Herbaceous	(1) Achnatherum speciosum

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Physiographic features

Table 2. Representative physiographic features

Landforms	(1) Mountain slope
Elevation	3200 – 4000 ft
Slope	30 – 75 %

Climatic features

The climate is hot and arid, with mild winters and very hot summers. Precipitation is greatest in the winter with a lesser secondary peak in summer, typical of the Mojave Desert. Average annual precipitation is 5 to 7 inches. Mean annual air temperature is 60 to 69 degrees F. The average growing season is about 180 to 240 days.

Table 3 Representative climatic features

Frost-free period (average)	240 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

Ecological dynamics

Please refer to group concept R030XB068NV to view the provisional STM.

This plant community is found on very steep limestone mountain sideslopes where the soils are very shallow and unstable. This growing environment supports vegetation that can extract moisture and nutrients from fissures in bedrock material and that requires little soil development. Natural disturbances such as landslides and wildfire help to maintain this plant community. Following wildfire, snakeweed, desertrue, and ephedra greatly increase. Species likely to invade this site are annual forbs and grasses.

Fire Ecology:
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. Torrey’s ephedra has medium fire tolerance and is similar to Nevada ephedra. Desert needlegrass has persistent dead leaf bases, which make it susceptible to burning. Fire removes the accumulation; a rapid, cool fire will not burn deep into the root crown and surviving tufts will resprout. 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 the least harmful. Bush muhly regenerates following fire from soil-stored seed. Fire probably top-kills bush muhly. Burning causes at least short-term decline of bush muhly. Recovery time is thought to vary considerably and is probably dependent on postfire weather and competition.

State and transition model

More interactive model formats are also available. View Interactive Models
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

This is a reference plant community dominated primarily by winterfat, Utah mortonia, Mojave sage, arid needlegrass, and bush muhly.
Potential vegetative composition is about 20% grasses, 5% annual and perennial forbs, and 75% shrubs. Approximate ground cover (basal and crown) is 5 to 10 percent.

Figure 3. Annual production by plant type (representative values) or group (midpoint values)

Table 4. Annual production by plant type

Plant type	Low (lb/acre)	Representative value (lb/acre)	High (lb/acre)
Shrub/Vine	150	225	375
Grass/Grasslike	40	60	100
Forb	10	15	25
Total	200	300	500

Additional community tables

Table 5. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Primary Perennial Grasses			36–114
	Mormon needlegrass	ACAR14	Achnatherum aridum	15–45	–
	desert needlegrass	ACSP12	Achnatherum speciosum	15–45	–
	bush muhly	MUPO2	Muhlenbergia porteri	6–24	–
2	Secondary Perennial Grasses			6–30
	Indian ricegrass	ACHY	Achnatherum hymenoides	2–9	–
	threeawn	ARIST	Aristida	2–9	–
	low woollygrass	DAPU7	Dasyochloa pulchella	2–9	–
	big galleta	PLRI3	Pleuraphis rigida	2–9	–
	slim tridens	TRMU	Tridens muticus	2–9	–
3	Annual Grasses			1–9
Forb
4	Perennial forbs			6–24
5	Annual forbs			1–15
Shrub/Vine
6	Primary shrubs			69–167
	winterfat	KRLA2	Krascheninnikovia lanata	30–60	–
	Utah mortonia	MOUT	Mortonia utahensis	15–45	–
	Mojave sage	SAMO3	Salvia mohavensis	8–32	–
	pungent brickellbush	BRAR2	Brickellia arguta	8–15	–
	Torrey's jointfir	EPTO	Ephedra torreyana	8–15	–
7	Secondary shrubs			20–40
	fourwing saltbush	ATCA2	Atriplex canescens	3–9	–
	beavertail pricklypear	OPBA2	Opuntia basilaris	3–9	–
	Fremont's dalea	PSFR	Psorothamnus fremontii	3–9	–
	Joshua tree	YUBR	Yucca brevifolia	3–9	–
	Mojave yucca	YUSC2	Yucca schidigera	3–9	–

Interpretations

Animal community

Livestock Interpretations:
This site has limited value for livestock grazing, due to the low forage production, steep slopes and stony surfaces. Desert needlegrass produces considerable basal foliage and is good forage while young. Young desert needlegrass is palatable to all classes of livestock. Mature herbage is moderately grazed by horses and cattle but rarely grazed by sheep. Arid needlegrass is preferred by horses year round, desired by sheep, desired by cattle and preferred in the spring and deer and antelope desire it in the spring and is undesired the rest of the year. Bush muhly is readily eaten by livestock throughout the year when available; however, it is usually not abundant enough to provide much forage. It is grazed heavily in winter when other species become scarce. Because of its branching habit, it is extremely susceptible to heavy grazing. Bush muhly is damaged when continuously grazed to a stubble height of less than 4 inches (10 cm). Winterfat is an important forage plant for livestock in salt-desert shrub rangeland and subalkaline flats. Winterfat palatability is rated as good for sheep, good to fair for horses, and fair for cattle. Abusive grazing practices have reduced or eliminated winterfat on some areas even though it is fairly resistant to browsing. Grazing season has more influence on winterfat than grazing intensity. Early winter grazing may actually be beneficial. Torrey’s ephedra is important winter forage for cattle and sheep. Torrey’s ephedra is moderately palatable to all domestic livestock especially as winter browse.

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:
Winterfat is an important forage plant for wildlife in salt-desert shrub rangeland and subalkaline flats. Animals that browse winterfat include mule deer, Rocky Mountain elk, desert bighorn sheep, and pronghorn antelope. Torrey’s ephedra is an important browse species for big game. Torrey’s ephedra is moderately palatable to many big game species, especially as winter browse. Desert bighorn sheep and feral horses and burros will graze desert needlegrass. The palatability of bush muhly for wildlife species is rated fair to poor.

Other information

Desert needlegrass may be used for groundcover in areas of light disturbance, but it is susceptible to excessive trampling.

Supporting information

Type locality

Location 1: Clark County, NV
Township/Range/Section	T24S R57E S26
General legal description	Low elevation mountain sideslopes three to four miles northeast of Sandy, Clark 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

BLS/GKB

Approval

Sarah Quistberg, 2/26/2025

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)
Contact for lead author
Date	08/28/2026
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-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:
Perennial plant reproductive capability:

Download reference sheet

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