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Ecological site R030XB005NV

Arid Active Alluvial Fans

Last updated: 3/11/2025
Accessed: 04/03/2025

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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.

Basemap provided by ESRI. Sources: Esri, HERE, DeLorme, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), swisstopo, MapmyIndia, © OpenStreetMap contributors, and the GIS User Community.

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Figure 1. Mapped extent

Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.

MLRA notes

Major Land Resource Area (MLRA): 030X–Mojave Basin and Range

MLRA Description:
Major Land Resource Area (MLRA) 30, Mojave Desert, is found in southern California, southern Nevada, the extreme southwest corner of Utah and northwestern Arizona within the Basin and Range Province of the Intermontane Plateaus. The climate of the area is hot and dry with mostly hyperthermic and thermic soil temperature regimes and typic-aridic soil moisture regimes. Mean annual air temperatures are between 59-68 degrees F (15-20 C) with average summer maximum temperatures between 100-115 degrees F (38-46 C) and average winter minimum temperatures between 32-59 degrees F (0-15 C). This MLRA is within the arid climate zone however steep elevational gradients contribute to microclimates where semi-arid [mean annual precipitation is greater than 8 inches (200mm)] and hyper-arid [mean annual precipitation is less than 4 inches (100mm)] islands exist. Elevations range from below sea level to over 12,000 feet (3650 meters) in the higher mountain areas. Generally above 5,000 feet, soil temperature regimes can be mesic, cryic and frigid with soil moisture regimes being xeric or ustic. Orographic effects and low elevations can create hyper-arid conditions where the soil moisture regime is aridic-aridic. Due to the extreme elevational range found within this MLRA, land resource units (LRUs) were designated to group areas within the MLRA into similar land units.

LRU Description:
The arid climate zone (XB in ESD ID) LRU is found across the eastern half of California, much of the mid-elevations of Nevada, the southernmost portions of western Utah, and the mid-elevations of northwestern Arizona. Elevations range from 1800-5000 feet and precipitation ranges from 4-8 inches/year. Precipitation is bi-modal for most of the Mojave with precipitation occurring in winter and summer. Areas west of the 117 degree W meridian near Barstow, CA receive precipitation mainly during the winter months (Hereford et al. 2004). The soil temperature regimes are hyperthermic and thermic with a typic-aridic soil moisture regime. Vegetation includes creosote bush (Larrea tridentata), burrobush (Ambrosia dumosa), Mojave yucca (Yucca schidigera) Joshua tree (Yucca brevifolia), chollas, cactus, big galleta grass (Pleuraphis rigida) and several other warm season grasses. At the upper portions of the LRU, where the mean annual precipitation is between 6 to 8 inches (150-200 mm), plant production and diversity are greater and blackbrush (Coleogyne ramosissima) is a common dominant shrub.

Classification relationships

U.S. National Vegetation Classification (USNVC): 3 Desert and Semi-Desert, 3.A Warm Semi-Desert Scrub and Grassland, 3.A.1 Warm Semi-Desert Scrub and Grassland, D039 North America Warm Desert Scrub and Grassland, M088 Mojave-Sonoran Semi-Desert Scrub, G295 Sonoran-Mojave Creosotebush- White Bursage Desert Scrub Group, CEGL000956 Ambrosia dumosa – Larrea tridentata var. tridentata Dwarf-shrubland.

Ecological site concept

This site is extensive in the Mojave Desert and typically occurs on fan piedmonts, broad alluvial fans and fan remnants on all exposures. Slopes range from 2 to 30 percent, but slope gradients of 2 to 15 percent are typical. Elevations are 1200 to 4800 feet.

The soils associated with this site are typically shallow to moderately deep. The soils typically have a calcic horizon shallow to the surface. Soil depth to a layer restrictive to root development, such as a petrocalcic horizon, is greater than ten inches. Limy soils found within this site generally have low organic matter, high alkalinity and a coarse texture. This white bursage-creosotebush plant community is extensive throughout the Mojave Desert and consists of both long and short-lived perennial species.

This is a group concept and provisional STM that also covers the following ecological sites: R030XA058NV, R030XA071NV, R030XA073NV, R030XB156CA, R030XF028CA, R030XY110UT.

Associated sites

R030XB001NV	LIMY HILL 5-7 P.Z.
R030XB004NV	SANDY 5-7 P.Z.
R030XB019NV	Eroded Fan Remnant Pavette 4-6 P.Z.
R030XB039NV	LIMY FAN 5-7 P.Z.
R030XB079NV	GYPSIC SLOPE 3-5 P.Z.

Similar sites

R030XY110UT	Desert Loam (Creosotebush) Essentially the same ecological site concept as R030XB005NV.
R030XB039NV	LIMY FAN 5-7 P.Z. More productive site; PLRI3 dominant plant
R030XB205AZ	Sandy Loam Upland 6-10" p.z. Limy Subsurface, Gravelly Essentially the same ecological site concept as R030XB005NV.
R030XB075NV	GRAVELLY FAN 5-7 P.Z. More productive site; PLRI3 dominant plant
R030XB004NV	SANDY 5-7 P.Z. PLRI3-ACHY codominant grasses; sandy soils
R030XB019NV	Eroded Fan Remnant Pavette 4-6 P.Z. Less productive site; LATR2 dominant shrub
R030XB074NV	COBBLY LOAM 5-7 P.Z. MESP2 common shrub
R030XA121AZ	Limy Fan 3-6" p.z. Sandy Essentially the same ecological site concept as R030XB005NV.
R030XB156CA	Limy 5-7" p.z. (Low Production) Essentially the same ecological site concept as R030XB005NV.
R030XB211AZ	Limy Fan 6-9" p.z. Essentially the same ecological site concept as R030XB005NV.
R030XA105AZ	Limy Fan 3-6" p.z. Essentially the same ecological site concept as R030XB005NV.
R030XB017NV	LIMY HILL 3-5 P.Z. Less productive site; occurs on steep slopes
R030XB102NV	GRAVELLY LOAM 5-7 P.Z. KRLA2 major shrub
R030XB227AZ	Clay Loam Upland 6-9" p.z. Essentially the same ecological site concept as R030XB005NV.
R030XB001NV	LIMY HILL 5-7 P.Z. Less productive site; occurs on steep slopes
R030XA058NV	LIMY 5-7 P.Z. Essentially the same ecological site concept as R030XB005NV.
R030XB206AZ	Cobbly Limy Upland 6-9" p.z. Deep Essentially the same ecological site concept as R030XB005NV.
R030XB226AZ	Sandy Loam Upland 6-9" p.z. Fine Essentially the same ecological site concept as R030XB005NV.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Ambrosia dumosa (2) Larrea tridentata
Herbaceous	(1) Pleuraphis rigida

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Physiographic features

Table 2. Representative physiographic features

Landforms	(1) Fan piedmont (2) Alluvial fan (3) Fan remnant
Flooding duration	Extremely brief (0.1 to 4 hours) to brief (2 to 7 days)
Flooding frequency	None to very rare
Ponding frequency	None
Elevation	1,200 – 4,800 ft
Slope	2 – 30%
Aspect	Aspect is not a significant factor

Climatic features

The climate of the Mojave Desert has extreme fluctuations of daily temperatures, strong seasonal winds, and clear skies. The climate is arid and is characterized with cool, moist winters and hot, dry summers. Most of the rainfall falls between November and April. Summer convection storms from July to September may contribute up to 30 percent of the annual precipitation. The relative humidity is low, evaporation is high, the percentage of sunshine is high, and the daily and seasonal range in temperature is wide. Average annual precipitation is 5 to 8 inches. Mean annual air temperature is 56 to 65 degrees F. The average growing season is about 190 to 240 days.

Average annual precipitation in inches at the Searchlight Climate station is as follows:
Jan. 0.92, Feb. 0.96, Mar. 0.77, Apr. 0.40, May 0.20, Jun. 0.11, Jul. 0.91, Aug. 1.08, Sept. 0.61, Oct. 0.52, Nov. 0.43, Dec. 0.79.

Average annual snowfall in 1.3 inches occurring during Jan 0.7, Feb. 0. Mar. 0.1, Nov. 0.1 and Dec. 0.4.

Table 3. Representative climatic features

Frost-free period (average)	240 days
Freeze-free period (average)
Precipitation total (average)	8 in

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soils associated with this site are typically shallow to moderately deep. The soils typically have a calcic horizon shallow to the surface. Soil depth to a layer restrictive to root development, such as a petrocalcic horizon, is greater than ten inches. Limy soils found within this site generally have low organic matter, high alkalinity and a coarse texture. Available water capacity is typically very low to low and runoff is typically low to medium. Soil series associated with this site include: Anthony, Arada, Arrolime, Bard, Baseline, Bitter Spring, Blackmesa, Cave, Colorock, Crosgrain, Dalian, Filaree, Flattop, Gila, Glendale, Grapevine, Gypwash, Heleweiser, Hiller, Ireteba, Knob Hill, Mesabase, Monger, Mormon Mesa, Naye, Nickel, Riverbend, Sandpan, Seaman, Searchlight, Threelakes, Tonopah, Toquop, Upperline, Vace, Wechech, and Weiser.

Table 4. Representative soil features

Surface texture	(1) Very gravelly fine sandy loam (2) Very gravelly loamy sand (3) Very gravelly loam
Family particle size	(1) Loamy
Drainage class	Well drained to excessively drained
Permeability class	Moderate to moderately rapid
Soil depth	10 – 40 in
Surface fragment cover <=3"	5 – 90%
Surface fragment cover >3"	1 – 25%
Available water capacity (0-40in)	0.9 – 4.7 in
Calcium carbonate equivalent (0-40in)	20 – 60%
Electrical conductivity (0-40in)	8 mmhos/cm
Sodium adsorption ratio (0-40in)	30
Soil reaction (1:1 water) (0-40in)	7.9 – 9
Subsurface fragment volume <=3" (Depth not specified)	4 – 69%
Subsurface fragment volume >3" (Depth not specified)	15%

Ecological dynamics

This white bursage-creosotebush plant community is extensive throughout the Mojave Desert and consists of both long and short-lived perennial species. In stable, old communities, creosotebushes or clones may attain ages of several thousand years. Defoliation and death of creosotebush branches may occur as a result of long periods of intense moisture stress. Surface disturbance on this site may reduce plant cover, density and diversity and increase erosion. These changes can be very subtle or extremely obvious depending on the intensity and rate of use and an assortment of environmental factors (topography, rainfall, soil type). White bursage generally dominates more developed soils with the ability to hold moisture in the upper soil profile. The shallow roots of white bursage are able to effectively use moisture stored in the upper horizons when it is available and survive for extended periods of time when it is not (Hamerlynck et al. 2002). White bursage is not able to dominate the deep, weakly developed, coarse textured soils that store water deep in the profile, which is ideal for creosotebush. The spatial distribution of soils allows white bursage and creosotebush to share dominance on this ecological site. They will share dominance throughout the successional process, although the relative abundance is likely to change (Marshall 1994). Creosotebush commonly uses white bursage as a nurse plant, young creosotebushes are frequently found rooted beneath mature white bursage plants (Marshall 1995). White bursage is well adapted to the desert environment but prolonged periods of drought will result a reduction of biomass and possibly kill the plant. Under historically stable conditions, low available fuel and a longer fire return interval allowed the establishment of long-lived desert perennial communities.
Nutrient availability in the Mojave Desert is characterized by resource pulses. High temperatures and relatively small rainfall events allow nutrients to accumulate during extended dry periods when plant and microbial growth is restricted. When rainfall events do occur, they trigger biological activities including plant growth and nutrient uptake (Collins et al. 2008). Resource pulse availability is strongly correlated to the presence of microbiotic crusts in arid systems. Microbiotic crusts fix both carbon and nitrogen, and can be considered functional resource reserves. These reserves have lower activation thresholds in relation to water availability than plants, creating nonlinear ecosystem interactions (Collins et al. 2008). This relationship facilitates plant growth in arid environments and allows plants to utilize nutrients that would otherwise remain unavailable during small precipitation events.
The frost-free season can last for the better part of a year: however, vegetation is limited by nutrient availability. Nutrient concentrations in this shrub community are spatially variable. Nutrient resources are concentrated under the shrub canopy relative to the interspaces, called islands of fertility (Kieft et al. 1998). Fine, sandy alluvium on these sites provides material that the wind redistributes to mound-like coppice dunes beneath creosotebush canopies. Heights of coppice dunes increase as a function of creosotebush cover and are tallest on young alluvial surfaces. Moisture absorbed by and stored in the coppice dune enhances plant performance, in turn contributing to the plant’s effectiveness as a windbreak allowing for further deposition of eolian sands (McAuliffe et al 2007).
Destructive impacts such as land clearing can reduce long-lived creosotebush. The opportunistic perennials such as white bursage, rayless goldenhead (ACSP), white burrobush (HYSA), and wire lettuce species (STEPH) will increase. With a loss of perennial cover, non-native annual grasses and forbs such as red brome (BRRU2), Mediterranean grass (SCBA), and redstem filaree (ERCI6) will readily invade this site.

Fire Ecology:
Prior to Euro-American settlement, fire regimes in Mojave Desert shrub communities were characterized by relatively infrequent, stand-replacing fires. Mojave Desert communities are usually unaffected by fire due to low fuel loading, although a year of exceptionally heavy winter rains can generate fuels by producing a heavy stand of annual forbs and grasses. Plant species, native to the Mojave Desert, produce very little biomass, and communities generally have large interspaces, characteristics which are not conducive for carrying fire across the landscape. An altered fire regime can be detrimental to native plants that are not adapted to a frequent fire return interval. Fire can increase resource availability by reducing the amount of resources (moisture, nutrients) used by resident vegetation through mortality or injury (Zouhar et al. 2008). This increased resource availability can make the ecosystem more susceptible to invasions. Relative competitive ability post-fire controls the invasibility of a system. Often non-natives have superior competitive ability for resources such as water, nutrients and light. When fires do occur, the effect on the ecosystem may be extreme due to the harsh environment and the slow rate of recovery. White bursage and creosotebush possess limited sprouting ability, thus can be killed by fire. White bursage, however, can rapidly re-establish from off-site seed. Range ratany is top killed by fire and resprouts from the root crown post-fire. Nevada ephedra is top killed by fire, but commonly resprouts and may increase in cover. Damage to big galleta from fire varies. If big galleta is dry, damage may be severe. However, when plants are green, fire will tend to be less severe and damage may be minimal, with big galleta recovering quickly. The loss of native vegetation can be followed by invasion of non-native annual forbs and grasses.

State and transition model

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Figure 3. STM

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State 1
Reference State

The reference state is representative of the natural range of variability under pristine conditions. Community phase changes are primarily driven by changes in weather patterns and natural disturbances such as long-term drought and insect attacks. Wildfire is infrequent and patchy due to low fuel loading and widely spaced shrubs. Timing of disturbance combined with weather events determines plant community dynamics. The reference state has two community phases; one community phase dominated by mature shrubs and sparse herbaceous vegetation, the other community phase is dominated by native herbaceous vegetation with a recovering shrub component.

Community 1.1
Reference Plant Community

The reference community phase is dominated by white bursage and creosotebush. Perennial native grasses include big galleta, Indian ricegrass (ACHY) and desert needlegrass (ACSP12). Potential vegetative composition is about 10 percent perennial and annual grasses, 10 percent annual and perennial forbs and 80 percent shrubs. Approximate ground cover (basal and crown) is 15 to 25 percent. Under natural conditions the reference community is stable and long lived. Prolonged drought results in an overall reduction of the plant community.

Figure 4. 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	160	240	400
Grass/Grasslike	20	30	50
Forb	20	30	50
Total	200	300	500

Table 6. Soil surface cover

Tree basal cover	0%
Shrub/vine/liana basal cover	5-20%
Grass/grasslike basal cover	1-5%
Forb basal cover	1-25%
Non-vascular plants	0%
Biological crusts	1-15%
Litter	15-35%
Surface fragments >0.25" and <=3"	5-70%
Surface fragments >3"	0-5%
Bedrock	0-5%
Water	0%
Bare ground	5-50%

Figure 5. Plant community growth curve (percent production by month). NV3001, Mojave Desert, Creosotebush white bursage. Growth begins in spring if sufficient moisture is present from the previous winter. Dormancy occurs with hot summer temperatures and soil moisture is depleted. Some species will break summer dormancy if late summer convection storms bring adequate moisture..

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
0	5	25	35	25	0	0	5	5	0	0	0

Community 1.2
Plant Community 1.2

This community phase is characteristic of a post-disturbance plant community. Herbaceous biomass initially increases, sprouting shrubs recover quickly and provide favorable sites for the establishment of shrub seedlings. Plant community composition may vary depending on season of disturbance. This community phase is ‘at-risk’ of invasion by non-native species. Non-natives are able to take advantage of increased availability of critical resources following disturbance.

Pathway 1.1a
Community 1.1 to 1.2

Insect attack, low intensity, patchy wildfire and/or other localized disturbance.

Pathway 1.2a
Community 1.2 to 1.1

Absence from disturbance and natural regeneration over time.

State 2
Invaded State

The invaded state is characterized by the presence of non-native species. Compositionally, State 2 is similar to the reference state with a trace of non-natives in the understory. However, ecological resistance and resilience is reduced by the presence on non-native species, making it more difficult for this state to recover following a disturbance. Non-native annuals are highly flammable and promote wildfire where fires historically have been infrequent. State 2 has three community phases. One phase is similar to the reference community phase with a trace of non-natives in the understory. The second community phase is dominated by herbaceous vegetation, native and non-native. The last community phase has reduced perennial native vegetation and stable to increasing non-natives.

Community 2.1
Plant Community Phase 2.1

Figure 6. Limy 5-7 with trace of non-natives

This community phase is characterized by the presence of non-native species. Species composition and ecological processes (soil hydrology, nutrient cycling, and energy capture) is similar to the reference community phase. However, ecological resilience is reduced by the presence of non-natives. Non-natives are favored and will increase if disturbance regimes vary from the range of historic variation. This plant community responds differently following disturbance, when compared to non-invaded communities. Prolonged drought will result in an overall reduction of above ground biomass, including non-native annuals.

Community 2.2
Plant Community Phase 2.2

Figure 7. wildfire

This community phase is characteristic of a post-disturbance plant community and typically occurs following wildfire or other large disturbance that removes mature shrub canopy. Initially herbaceous biomass increases, which may or may not be dominated by non-native annuals. Sprouting shrubs quickly recover and serve as nurse plants for other shrub seedlings. Seedlings are dominated by white bursage and brittlebush species (ENCEL). This plant community is ‘at-risk’ of reoccurring wildfire. Increased herbaceous biomass, mainly non-native annuals, provide a continuous bed of fine fuels that promote the spread and decrease the spatial variability of wildfire.

Community 2.3
Plant Community Phase 2.3

This community phase typically occurs following reoccurring heavy surface disturbance and is characterized by a reduction in total shrub canopy. Non-native annuals persist and may increase with increased disturbance. Shrubs experience reduced vigor and reproductive capacity due to soil compaction and competition from non-natives. Decline in the cover of deep-rooted native perennial shrubs and bunchgrasses, results in reduced soil moisture and increased runoff.

Pathway 2.1a
Community 2.1 to 2.2

Plant Community Phase 2.1

Plant Community Phase 2.2

Low intensity, patchy wildfire, insect/disease attack or other localized disturbance.

Pathway 2.1b
Community 2.1 to 2.3

Reoccurring surface disturbance.

Pathway 2.2a
Community 2.2 to 2.1

Plant Community Phase 2.2

Plant Community Phase 2.1

Absence from disturbance and natural regeneration over time.

Pathway 2.3a
Community 2.3 to 2.2

Absence from disturbance, changes in management and natural regeneration over time.

State 3
Annual State

The non-native annual state is characterized by a significant reduction or loss of deep-rooted native perennials and a frequent disturbance return interval. Frequent and repeated disturbances, including wildfire favors the establishment of a non-native annual dominated state. Non-native annuals perform well under a frequent disturbance return interval due to their annual growth form, persistent seed bank and competitive ability. State 3 has two general community phases. One community phase is indicative of a post-fire community and is dominated by non-native annuals. The second community phase is characterized by the recovery of short-lived, native, woody perennials, such as white bursage, shadscale (ATCO) and brittlebush species.

Community 3.1
Plant Community Phase 3.1

This community phase is heavily dominated by non-native annuals. Non-native annuals benefit from fire and often outcompete natives for nutrients, water and light resources following fire or other disturbance. Ecological processes (infiltration, nutrient cycling and energy capture) are controlled by non-native species. Changes in these processes often cause changes in dynamic soil properties such as soil aggregate stability, which may affect water availability, resistance to erosion and eventually production.

Community 3.2
Plant Community Phase 3.2

This community phase is characterized by an overstory of short-lived native perennials (white bursage, shadscale, etc) and an understory of non-native annuals. The abundance of non-natives in the understory hinders the reestablishment of native shrubs by competing for water and nutrients. The continuous bed of fine fuels provided by non-native annuals increases the size and decreases the spatial variability of wildfires, preventing the recovery of long-lived native woody perennials. Prolonged drought reduces overall plant community production and cover.

Pathway 3.1a
Community 3.1 to 3.2

Absence of disturbance and natural regeneration over time.

Pathway 3.2a
Community 3.2 to 3.1

Wildfire and/or other localized disturbances.

Transition T1
State 1 to 2

Trigger: Introduction of non-native species Slow variables: Surface disturbance, changes in the kinds of animals and their grazing patterns, drought and/or changes in fire history that altered the recruitment rate of native species. Threshold: Non-native species cannot be easily removed from the system and have the potential to significantly alter disturbance regimes from their historic range of variation. Changes in the herbaceous understory, associated with the introduction of non-native annuals, reduce ecological resistance and resilience following a disturbance.

Transition T2
State 2 to 3

Trigger: Frequent and repeated wildfire Slow variables: Increased reproduction and cover of non-native invasive annuals. Threshold: Reduction in the deep-rooted perennial native herbaceous understory and severe reduction or loss of native shrubs leads to changes in soil hydrology; reducing infiltration and increasing runoff. Modified fire regime; including changes in the frequency, intensity, size and spatial variability of fires.

Additional community tables

Table 7. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Grass/Grasslike
1	Primary Perennial Grasses			1–24
	big galleta	PLRI3	Pleuraphis rigida	1–24	–
2	Secondary Perennial Grasses			1–24
	Indian ricegrass	ACHY	Achnatherum hymenoides	1–9	–
	desert needlegrass	ACSP12	Achnatherum speciosum	1–9	–
	threeawn	ARIST	Aristida	1–9	–
3	Annual			1–30
	sixweeks grama	BOBA2	Bouteloua barbata	1–9	–
Forb
4	Perennial			1–24
	threeawn	ARIST	Aristida	0–6	–
	desert globemallow	SPAM2	Sphaeralcea ambigua	1–6	–
5	Annual			1–60
	desert trumpet	ERIN4	Eriogonum inflatum	1–6	–
Shrub/Vine
6	Primary Shrubs			111–270
	burrobush	AMDU2	Ambrosia dumosa	75–150	–
	creosote bush	LATR2	Larrea tridentata	30–75	–
	littleleaf ratany	KRER	Krameria erecta	6–30	–
	Nevada jointfir	EPNE	Ephedra nevadensis	1–15	–
7	Secondary Shrubs			15–45
	shadscale saltbush	ATCO	Atriplex confertifolia	1–9	–
	brittlebush	ENCEL	Encelia	1–9	–
	winterfat	KRLA2	Krascheninnikovia lanata	1–9	–
	desert-thorn	LYCIU	Lycium	1–9	–
	Fremont's dalea	PSFR	Psorothamnus fremontii	1–9	–
	Mojave yucca	YUSC2	Yucca schidigera	1–9	–

Interpretations

Animal community

Livestock Interpretations:
This site is suitable for spring grazing by sheep and cattle where water is available. White bursage is an important browse species. Browsing pressure on white bursage is particularly heavy during years of low precipitation, when production of winter annuals is low. White bursage is of intermediate forage value. It is fair to good forage for horses and burros, and fair to poor for cattle and sheep. However, because there is often little other forage where white bursage grows, it is often highly valuable to browsing animals. Nutrient content of white bursage fluctuates seasonally, thereby causing browsing pressure to also fluctuate seasonally. Studies have shown crude protein to be the highest in the late winter, at 10 percent and declining the rest of the year to 4 to 7 percent (Hanley et al. 1977). Many animals bed in or under creosotebush. Domestic sheep dig shallow beds under creosotebush because it provides the only shade available in the desert scrub community. Creosotebush is unpalatable to livestock. The leaves of creosotebush contain antimicrobial phototoxins that provide a defense against a variety of damaging agents. Toxicity of these chemicals is enhanced by exposure to light (Downum et al. 1989). Consumption of creosotebush may be fatal to sheep. Big galleta is considered a valuable forage plant for cattle and domestic sheep. Its coarse, rigid culms make it able to withstand heavy grazing and trampling.

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, fine-tuned by the client through adaptive management throughout the year and from year to year.

Wildlife Interpretations:
A large compliment of wildlife species, including many bird, small mammal and reptile species depend on or at least partially utilize Mojave Warm Desert Scrub habitat.
This key habitat is critical to the survival of the federal and state threatened desert tortoise in Nevada. Desert tortoises often place their burrows directly under creosote bushes, taking advantage of the substrate stability created by the creosote roots. Similarly, large kit fox den complexes are often found in association with creosote habitat for the same reason. Desert reptiles, amphibians and other wildlife use creosotebush as a food source, a perch site and hibernate or estivate in burrows under it. The burrows provide a place to raise young and also allow wildlife to avoid predators and excessive daytime temperatures.
A host of additional heat-tolerant reptile species are also dependent on this habitat; lizards include the desert iguana, desert horned lizards, western whiptails, zebra-tailed lizards and side blotched lizards. Snakes include the spotted leafnosed snake, rosy boa, Western diamondback, Mojave and sidewinder rattlesnakes. The rocky slopes of many of southern Nevada’s mountain ranges within the Mojave/Sonoran Warm Desert Scrub are critical to the survival of the Nelson bighorn sheep subspecies.
Mammalian predators common to this site include the American badger, bobcat, coyote, kit fox and the occasional mountain lion (cougar); all of which utilize small mammals and other wildlife as a source of prey. Small mammals common to this site include antelope ground squirrels; Merriams, Panamint, and desert kangaroo rats; grasshopper and deer mice; black-tailed jackrabbits. Desert kangaroo rats and the desert pocket mouse depend on wind-blown sandy areas associated with this habitat type. Creosote seeds make up a large part of the desert pocket mouse’s diet. These small mammals, and others, are an important prey source for snakes as well as various bird species; including the burrowing owl and loggerhead shrike. Additional avian predators such as the American kestrel, great horned owls, and Ferruginous-legged and red-tail hawks are found throughout the area. Sparsely vegetated creosote and saltbush areas are home to the Le Conte’s thrasher. Other birds occurring on this site include common ravens, horned larks, rock wrens, great roadrunners, black-throated and sage sparrows and raptors.
White bursage is an important browse species for wildlife. Browsing pressure may be particularly heavy in years of low precipitation, when availability of winter annuals is limited. Mule deer browse range ratany year-long with seasonal peaks. Mule deer peak use is from February to April and from August to October. The intricately branched round shape of range ratany also provides valuable shelter for small mammals and birds.
Insects associated with this ecological site provide a significant foraging resource for bats. Typical bat species include: Allen’s big eared, big brown, California leaf-nosed, California myotis, fringed myotis, spotted, hoary, Townsend’s big eared, Western pipistrelle, Western small footed myotis, as well as, other bat species which are seasonally present. Bats utilize caves and crevices in rock formations, along with old mining shafts and tunnels for roost sites. Seasonal use of roost structures may depend on temperature and elevation. However, this site does not provide a significant source of roosting sites.
Drastic changes in the plant community composition, soil properties and disturbance regimes associated with this ecological site may affect the limited perennial water sources found in the Mojave desert. These water sources provide habitat for a variety fish species unique to the Mojave. The introduction of non-native fish species and the decreasing availability of perennial water have already impacted these fish.

Hydrological functions

Typically, runoff is low to medium and permeability is moderate to moderately rapid. Water flow patterns and rills are none to few in areas recently subject to intense summer rainfall and on steep slopes. Pedestals are rare with occurrence typically limited to areas within water flow patterns. Sparse shrub canopy and associated litter break provide some protection from raindrop impact and aid in infiltration.

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.

Other products

This site is located within the home territory of the Moapa Southern Paiute American Indians. Plants play a large role in many different types of Southern Paiute Indians ceremonial and non-ceremonial activites. Creosotebush has been highly valued for its medicinal properties by American Indians. It has been used to treat at least 14 illnesses, including colds. Twigs and leaves may be boiled as tea, steamed, pounded into a powder, pressed into a poultice, or heated into an infusion. White bursage is a host for sandfood (Pholisma sonorae), a parasitic plant with a sweet, succulent, subterranean flowerstalk. Sandfood was a valuable food supply for American Indians. A list of some traditional plants identified by Stoffle et al. (2011) that may be considered culturally sensitive can be found on this ecological site.

Other information

Creosotebush and white bursage may be used to rehabilitate disturbed environments in southwestern deserts. Once established, these species may improve sites for annuals and other perennials that grow under their canopies by trapping fine soil, organic matter, and symbiont propagules. Water infiltration and storage may also increase. Big galleta clumped growth form may help stabilize blowing sands.

Supporting information

Type locality

Location 1: Clark County, NV
Township/Range/Section	T25 R59 S17
UTM zone	N
UTM northing	3959211
UTM easting	644927
Latitude	35° 45′ 59″
Longitude	115° 23′ 48″
General legal description	Section 17, T25S, R59E MDBM. About 5 miles southwest of Jean, on west side of I15, Ivanpah Valley, Clark County, Nevada. This site also occurs in southern Lincoln County, Nevada.

Other references

Collins, S.L., R.L. Sinsabaugh, C. Crenshaw, L. Green, A. Porras-Alfaro, M. Stursova and L.H. Zeglin. 2008. Pulse dynamics and microbial processes in aridland ecosystems. J. of Ecology. 96: 413-420.

Downum, K.R., S. Villegas, E. Rodriguez and D.J. Keil. 1989. Plant Photosensitizers: A survey of their occurrence in arid and semiarid plant from North America. J. of Chemical Ecology. 15(1): 345-355.

Hamerlynck, E.P., J.R. McAuliffe, E.V. McDonald and S.D. Smith. 2002. Ecological responses of two Mojave Desert shrubs to soils horizon development and soil water dynamics. Ecology. 83.3: 768-779.

Hanley, Thomas A.; Brady, Ward W. 1977. Seasonal fluctuations in nutrient content of feral burro forages, lower Colorado River Valley, Arizona. Journal of Range Management. 30(5): 370-375.

Hereford, R., R.H. Webb and C. I. Longpre. 2004. Precipitation history of the Mojave Desert region, 1893-2001 (No. 117-03).

Kieft, T.L., C.S. White, S.R. Loftin, R. Aguilar, J.A. Craig and D. A. Skaar. 1998. Temporal Dynamics in Soil Carbon and Nitrogen Resources at a Grassland-Shrubland Ecotone. Ecology. 79.2: 671-683.

Kottek, M., Grieser, J., Beck, C., Rudolf, B., & Rubel, F. (2006). World map of the Köppen-Geiger climate classification updated. Meteorologische Zeitschrift, 15(3), 259-263.

Marshall, K.A. 1994. Ambrosia dumosa. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

Marshall, K.A. 1995. Larrea tridentata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/

McAuliffe, J.R., E.P. Hamerlynck, and M.C. Eppes. 2007. Landscape dynamics fostering the development and persistence of long-lived creosotebush (Larrea tridentata) clones in the Mojave Desert. J. of Arid Environments. 69:96-126.

Salem, B. B. (1989). Arid zone forestry: a guide for field technicians (No. 20). Food and Agriculture Organization (FAO).

Stoffle, R.W., K.A Van Vlack, H.Z. Johnson, P.T. Dukes, S.C. De Sola and K.L. Simmons. 2011. Tribally approved American Indian ethnographic analysis of the proposed Dry Lake solar energy zone. Solar Progtammatic Environmental Impact Statement. Bureau of Applied Research in Anthropology. U of Arizona. Available: http://solareis.anl.gov/documents/ethnographic/EthnographicAnalysis_AmargosaValley.pdf
USDA-NRCS Plants Database (Online; http://www.plants.usda.gov).

Zouhar, K., J.K. Smith, and S. Sutherland. 2008. Effect of Fire on Nonnative Invasive Plant and Invasibility of Wildland Ecosystems. USDA Forest Service Gen. Tech. Rep. RMRS-GTR-42-vol. 6.

Contributors

E. Hourihan/P. Novak-Echenique
RRK/BO'D
Dustin Detweiler

Approval

Kendra Moseley, 3/11/2025

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)	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 none to rare and may be evident in areas recently subject to intense summer rainfall and on steep slopes.
Presence of water flow patterns:
Water flow patterns none to rare and may be evident in areas recently subject to intense summer rainfall and on steeper slopes.
Number and height of erosional pedestals or terracettes:
Pedestals are none to rare with occurrence typically limited to areas within water flow patterns.
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare Ground up to 50% depending on amount of surface rock fragments; shrub canopy to 15%; basal area for perennial herbaceous plants up to 5%.
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 (<10 ft) 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 1 to 4 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 moderate medium and thin to strong very thick platy or singled grained. Soil surface colors are light and soils are typified by an ochric epipedon. Organic matter of the surface 2 to 3 inches is less than 1 percent. (lab characterization data)
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Sparse shrub canopy and associated litter provide some protection from raindrop impact. Perennial herbaceous plants slow runoff and increase infiltration.
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None. Platy or massive sub-surface horizons, subsoil calcic or 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:
Mojave Desert shrubs

Sub-dominant:
deep-rooted, warm-season, bunchgrasses > perennial forbs > deep-rooted, cool-season, bunchgrasses > annual forbs > shallow-rooted grasses

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 35% of total woody canopy; mature bunchgrasses commonly (±25%) have dead centers
Average percent litter cover (%) and depth ( in):
Between plant interspaces 15-25% and depth (<¼-inch)
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season ±300 lbs/ac. 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 on this site include red brome, filaree, annual mustards, and Mediterranean grass.
Perennial plant reproductive capability:
All functional groups should reproduce in average and above average growing season years. Little growth or reproduction occurs in extreme drought or extended drought periods.

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