Natural Resources
Conservation Service
Ecological site R030XC011NV
GRAVELLY INSET FAN 7-9 P.Z.
Last updated: 2/25/2025
Accessed: 03/18/2025
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 inset fans and stream terraces of upper piedmont slopes. Slope gradients of 2 to 8 percent are most typical. Elevations are 5350 to 6400 feet. The soils associated with this site are moderately deep to deep and derived from mixed rock sources.
Please refer to group concept R030XB098NV to view the provisional STM.
Associated sites
| R030XB051NV |
UPLAND WASH |
|---|---|
| R030XC007NV |
SHALLOW GRAVELLY LOAM 7-9 P.Z. |
Similar sites
| R030XB051NV |
UPLAND WASH PLRI3 dominant grass |
|---|---|
| R030XC007NV |
SHALLOW GRAVELLY LOAM 7-9 P.Z. PRFA, SAMO3 absent |
| R030XC018NV |
SHALLOW GRAVELLY SLOPE 11-13 P.Z. PRFA minor species, SAMO3 absent |
| R030XB090NV |
GRAVELLY FAN 7-9 P.Z. BOER4 dominant grass |
| R030XB108NV |
GRAVELLY INSET FAN 7-9 P.Z. PLRI3 dominant grass |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Coleogyne ramosissima |
| Herbaceous |
(1) Achnatherum speciosum |
Physiographic features
This site occurs on inset fans and stream terraces of upper piedmont slopes. Slope gradients of 2 to 8 percent are most typical. Elevations are 5350 to 6400 feet.
Table 2. Representative physiographic features
| Landforms |
(1)
Inset fan
(2) Stream terrace |
|---|---|
| Flooding duration | Very brief (4 to 48 hours) |
| Flooding frequency | Rare |
| Elevation | 1,631 – 1,951 m |
| Slope | 2 – 8% |
| Aspect | Aspect is not a significant factor |
Climatic features
The primary air masses affecting the Spring Mountains are cold maritime polar air from the Gulf of Alaska and warmer, moist maritime subtropical air from lower latitudes. Occasionally there are invasions of cold continental polar air from northern Canada or the Rocky Mountains. Precipitation in the area results primarily from the passage of cyclones with associated fronts during fall, winter and spring; from closed cyclones in late winter and spring; and from the flow of moist tropical air from the southeast to the southwest quadrant in the summer.
Average annual precipitation is 7 to 9(10) inches. Mean annual air temperature is 54 to 65 degrees F. The average growing season is about 140 to 210 days.
Table 3. Representative climatic features
| Frost-free period (average) | 210 days |
|---|---|
| Freeze-free period (average) | |
| Precipitation total (average) | 229 mm |
Figure 1. Monthly average minimum and maximum temperature
Influencing water features
This site is subject to flood flows during spring runoff and during convective summer storms.
Soil features
The soils associated with this site are moderately deep to deep and derived from mixed rock sources. Water intake rates are moderately rapid, available water capacity is low, runoff is low and soils are well drained to somewhat excessively drained. The soils are subject to periodic (often intense) flood flows that occur primarily during summer convection storm activity. The soils are classified as Aridic Calcixerolls and Typic Haplocalcids.
Table 4. Representative soil features
| Surface texture |
(1) Very gravelly sandy loam (2) Extremely cobbly fine sandy loam |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained to somewhat excessively drained |
| Permeability class | Moderately rapid |
| Soil depth | 183 cm |
| Surface fragment cover <=3" | 40 – 45% |
| Surface fragment cover >3" | 5 – 35% |
| Available water capacity (0-101.6cm) |
4.32 – 6.35 cm |
| Electrical conductivity (0-101.6cm) |
0 – 8 mmhos/cm |
| Sodium adsorption ratio (0-101.6cm) |
0 – 13 |
| Soil reaction (1:1 water) (0-101.6cm) |
7.9 – 9 |
| Subsurface fragment volume <=3" (Depth not specified) |
24 – 66% |
| Subsurface fragment volume >3" (Depth not specified) |
2 – 17% |
Ecological dynamics
Please refer to group concept R030XB098NV to view the provisional STM.
With severe disturbance such as flash flood flows or wildfire, snakeweed, Mojave buckwheat and burrobrush significantly increase. Species likely to invade this site are introduced annuals such as red brome and filaree.
Fire Ecology:
Blackbrush communities historical fire return intervals appear to have been on the order of centuries, allowing late seral blackbrush stands to reestablish. Low amounts of fine fuels in interspaces probably limited fire spread to only extreme fire conditions, during which high winds, low relative humidity, and low fuel moisture led to high intensity stand-replacing crown fires. The fuel complex in blackbrush appears to be more conducive to burning now than in the past. Non-native annual grasses currently occur in most blackbrush stands resulting in large stand-replacing fires. Blackbrush stands are considered to be one of the most flammable native plant assemblages in the Mojave Desert and fire will start and spread easily due to the dense, close spacing nature and resinous foliage of blackbrush. Blackbrush is slow to reestablish and may take 60 or more years to reestablish. Desert peach sprouts from rhizomes and/or lignotubers following fire, and becomes abundant on burned sites. Postfire seedling establishment is rare based on the limited postfire regeneration studies available. Desert peach is typically only top-killed by fire. Neither aboveground stem survival nor complete shrub kill is reported following fire. Fire effects on Stansbury cliffrose are variable. Fire may kill or severely damage plants. Late-season fire also increases the risk of mortality. Stansbury cliffrose is a weak sprouter that is generally killed by severe fire. 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. Most perennial grasses have root crowns that can survive wildfire. Muttongrass is unharmed to slightly harmed by light-severity fall fires. Muttongrass appears to be harmed by and slow to recover from severe fire.
State and transition model
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View Interactive Models
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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 blackbrush. Other important species associated with this site include desert needlegrass, muttongrass, and desert peach, and Mojave sage. Potential vegetative composition is about 20% grasses, 5% annual and perennial forbs and 75% shrubs. Approximate ground cover (basal and crown) is 25 to 40 percent.
Figure 2. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Shrub/Vine | 336 | 504 | 673 |
| Grass/Grasslike | 90 | 135 | 179 |
| Forb | 22 | 34 | 45 |
| Total | 448 | 673 | 897 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Primary Perennial Grasses | 47–155 | ||||
| desert needlegrass | ACSP12 | Achnatherum speciosum | 34–101 | – | ||
| muttongrass | POFE | Poa fendleriana | 13–54 | – | ||
| 2 | Secondary Perennial Grasses | 1–54 | ||||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 3–20 | – | ||
| threeawn | ARIST | Aristida | 3–20 | – | ||
| bush muhly | MUPO2 | Muhlenbergia porteri | 3–20 | – | ||
|
Forb
|
||||||
| 3 | Perennial Forbs | 13–54 | ||||
| 4 | Annual Forbs | 1–54 | ||||
|
Shrub/Vine
|
||||||
| 5 | Primary Shrubs | 284–572 | ||||
| blackbrush | CORA | Coleogyne ramosissima | 202–303 | – | ||
| desert almond | PRFA | Prunus fasciculata | 67–135 | – | ||
| Stansbury cliffrose | PUST | Purshia stansburiana | 1–67 | – | ||
| Mojave sage | SAMO3 | Salvia mohavensis | 13–67 | – | ||
| 6 | Secondary Shrubs | 67–101 | ||||
| Shockley's goldenhead | ACSH | Acamptopappus shockleyi | 7–13 | – | ||
| woolly fruit bur ragweed | AMER | Ambrosia eriocentra | 7–13 | – | ||
| big sagebrush | ARTR2 | Artemisia tridentata | 7–13 | – | ||
| fourwing saltbush | ATCA2 | Atriplex canescens | 7–13 | – | ||
| Virgin River brittlebush | ENVI | Encelia virginensis | 7–13 | – | ||
| jointfir | EPHED | Ephedra | 7–13 | – | ||
| narrowleaf yerba santa | ERAN2 | Eriodictyon angustifolium | 7–13 | – | ||
| Eastern Mojave buckwheat | ERFAP | Eriogonum fasciculatum var. polifolium | 7–13 | – | ||
| Apache plume | FAPA | Fallugia paradoxa | 7–13 | – | ||
| threadleaf snakeweed | GUMI | Gutierrezia microcephala | 7–13 | – | ||
| burrobrush | HYSA | Hymenoclea salsola | 7–13 | – | ||
| spiny menodora | MESP2 | Menodora spinescens | 7–13 | – | ||
| Fremont's dalea | PSFR | Psorothamnus fremontii | 7–13 | – | ||
| Sonoran scrub oak | QUTU2 | Quercus turbinella | 7–13 | – | ||
| skunkbush sumac | RHTR | Rhus trilobata | 7–13 | – | ||
| banana yucca | YUBA | Yucca baccata | 7–13 | – | ||
| Joshua tree | YUBR | Yucca brevifolia | 7–13 | – | ||
|
Tree
|
||||||
| 7 | Trees | 3–13 | ||||
| Utah juniper | JUOS | Juniperus osteosperma | 3–13 | – | ||
Interpretations
Animal community
Livestock Interpretations:
This site is suited to grazing by livestock during the late spring, summer and early fall. Grazing management should be keyed to perennial grasses or palatable shrubs production. Blackbrush is not preferred as forage by domestic livestock, but does provide some forage during the spring, summer and fall. Heavy grazing by livestock decreased the per acre stem count of desert peach. Stansbury cliffrose is an important browse species for livestock, especially in the winter. Young desert needlegrass is palatable to all classes of livestock. Mature herbage is moderately grazed by horses and cattle, but rarely grazed by sheep. Muttongrass is excellent forage for domestic livestock especially in the early spring. Muttongrass begins growth in late winter and early spring, which makes it available before many other forage plants.
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:
Blackbrush is a valuable browse species for bighorn sheep. It may also comprise up to 25% of the mule deer winter diet. Blackbrush provides cover for upland game birds, nongame birds and small mammals. Use of desert peach by mule deer varies largely by location; as low as 1-5% of diet on some sites and up to 57% on other sites. Mule deer consume new desert peach growth in the early spring and frequent desert peach habitat. Numerous small mammals gather and consume desert peach fruits and seeds and/or browse desert peach stemsWhite-tailed antelope squirrels, Great Basin pocket mice, deer mice, and Panamint kangaroo rats utilize desert peach fruits and seeds. Black-tailed jackrabbits seasonally utilize desert peach as forage. Stansbury cliffrose is an important browse species for mule deer, pronghorn, game birds, and songbirds. Wild ungulates use it heavily in winter. Young desert needlegrass is palatable to many species of wildlife. Desert needlegrass produces considerable basal foliage and is good forage while young. Desert bighorn sheep graze desert needlegrass. Deer and elk make heavy use of muttongrass, especially in early spring when other green forage is scarce. Depending upon availability of other nutritious forage, deer may use muttongrass in all seasons. Muttongrass cures well and is an important fall and winter deer food in some areas.
Hydrological functions
Runoff is low. Permeability is moderately rapid.
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 hiking and has potential for upland and big game hunting.
Other products
Indian ricegrass was traditionally eaten by some Native American peoples. The Paiutes used seed as a reserve food source.
Other information
Blackbrush contributes to desert fertility by 1) protecting the soil against wind erosion through retarding the movement of soil and increasing the accumulation of fine soil particles around its base; 2) protecting understory vegetation from the effects of high temperatures, thereby helping to retain surface nitrogen and adding organic matter to the soil; and 3) serving as a nitrogen reservoir through the storage of nitrogen in roots, leaves, and stems.
Indian ricegrass is well-suited for surface erosion control and desert revegetation although it is not highly effective in controlling sand movement.
Supporting information
Type locality
| Location 1: Clark County, NV | |
|---|---|
| Township/Range/Section | T21S R58E S4 |
| General legal description | About ½ mile east of Willow Spring site along the paved loop road within Red Rock National Conservation Area, 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
TJ WOLFE
Approval
Sarah Quistberg, 2/25/2025
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) | PATTI NOVAK-ECHENIQUE |
|---|---|
| Contact for lead author | State Rangeland Management Specialist |
| Date | 07/20/2012 |
| Approved by | Sarah Quistberg |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rills are none to rare. Rock fragments armor the soil surface. -
Presence of water flow patterns:
Water flow patterns are none to rare. Rock fragments armor the soil surface. -
Number and height of erosional pedestals or terracettes:
Pedestals are none to 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 ± 10-20%. -
Number of gullies and erosion associated with gullies:
Gullies are none to rare 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) 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 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. Areas of this site occurring on soils that have a physical crust will probably have stability values less than 3. (To be field tested.) -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface structure is thick platy. Soil surface colors are light and soils are typified by an ochric epipedon. Organic matter of the surface 2 to 3 inches is typically 1.5 to 2 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., basin wildrye]) 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. Subangular blocky or massive sub-surface 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:
Tall shrubs (spiny hopsage & Wyoming big sagebrush)Sub-dominant:
deep-rooted, cool season, perennial bunchgrasses > shallow-rooted, cool season, perennial bunchgrasses > associated shrubs > deep-rooted, cool season, perennial forbs = fibrous, shallow-rooted, cool season, perennial forbs = annual 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 25% of total woody canopy; some of the mature bunchgrasses (<20%) have dead centers. -
Average percent litter cover (%) and depth ( in):
Within plant interspaces (± 15%) 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 (end of May) ± 800 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:
Increasers include rabbitbrush. Invaders include cheatgrass, halogeton, Russian thistle, bassia, and annual mustards. -
Perennial plant reproductive capability:
All functional groups should reproduce in average (or normal) and above average growing season years.
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