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Ecological site R030XD039CA

Coarse Gravelly Fans

Last updated: 10/21/2024
Accessed: 11/13/2024

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General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

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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 (primarily hyperthermic and thermic; however at higher elevations, generally above 5000 feet, mesic, cryic and frigid) and dry (aridic). Elevations range from below sea level to over 12,000 feet in the higher mountain areas found within the MLRA. Due to the extreme elevational range found within this MLRA, Land Resource Units (LRUs) were designated to group the MLRA into similar land units.

LRU Description:

This Land Resource Unit (designated by ‘XD’) is found on the eastern side of California. Elevations range from 400 to 2200 feet on average, but may be found up to 3600 feet on southern exposures. Precipitation ranges from 1 to 6 inches per year, but averages between 2-4 inches. This LRU is characterized primarily by the extreme aridity, hot temperatures, hyperthermic soil temperatures and low stature of widely spaced vegetation. Temperatures can reach over 110 degrees Fahrenheit for several weeks in July and August. Summer precipitation falls between July and September, ranging from 20-33% in the form of rain, and winter precipitation falls starting in November and ends between February and March, ranging from 56-70%, also mostly in the form of rain. Vegetation is primarily small, widely-spaced, low-producing creosote bush (Larrea tridentata), burrobush (Ambrosia dumosa), and brittlebush (Encelia farinosa).

Ecological Site Concept –

This ecological site occurs on fan aprons, alluvial fans, and fan remnants at elevations of 560 to 3610 feet. Soils are very deep, and typically have a high cover of surface gravels and cobbles, and have gravelly to extremely gravelly subsurface textures. This site typically has a very rare surface flooding regime. This ecological site occurs at the southern edge of the Mojave Desert (the Mojave Desert – Sonoran Desert or MLRA30 – 31 boundary). Thus, it represents a transition from a warm desert where winter precipitation is dominant, to a hot desert where summer precipitation is much more significant and frosts are rare.

Production reference value (RV) is 186 pounds per acre, and ranges from 120 to 318 pounds per acre depending on annual precipitation. The site is dominated by creosote bush (Larrea tridentata), and brittlebush (Encelia farinosa). A hyperthermic climate with low frost prevalence, deep gravelly soils, and a very rare surface flooding regime drives the vegetation community of this ecological site. Water rapidly permeates through coarse soils to deep soil layers in this hyperthermic climate. The deep-rooted, evergreen, creosote bush accesses deep water while extreme aridity at near surface depths, very rare flooding and low incidence of frost promotes dominance by the brittlebush.

The data in the following sections is from major (15% of map unit or greater) components only.

Classification relationships

Encelia farinosa Association of the Encelia farinosa shrubland alliance (Sawyer et al. 2009).

Associated sites

R030XD003CA	Hyperthermic Steep South Slopes This ecological site is found on adjacent south-facing mountain and hill slopes. Brittlebush (Encelia farinosa) is dominant.
R030XD006CA	Abandoned Fan This ecological site occurs on adjacent fan aprons. Creosote bush (Larrea tridentata) is dominant.
R030XD040CA	Hyperthermic Steep North Slopes This ecological site occurs on adjacent north-facing mountain slopes. Burrobush (Ambrosia dumosa) is dominant with a diverse secondary shrub community.
R030XY092NV	DESERT PATINA This ecological site occurs on adjacent flat fan remnants with a desert pavement surface. Vegetation is very sparse, and dominated by creosote bush (Larrea tridentata).
R030XY128CA	Broad, Gravelly, Hyperthermic Ephemeral Stream This ecological site occurs in medium-sized drainageways adjacent to this site. Desert lavender (Hyptis emoryi), creosote bush (Larrea tridentata) and burrobrush (Hymenoclea salsola) are dominant species.

Similar sites

R030XD041CA	Channeled Warm Alluvial Fans This ecological site occurs on soils with lower rock fragment cover on the soil surface and volume in the soil profile. Burrobush (Ambrosia dumosa) is co-dominant with creosote bush (Larrea tridenta).
R030XD003CA	Hyperthermic Steep South Slopes This ecological site occurs on mountain and hill slopes. Shrub diversity is lower, and brittlebush (Encelia farinosa) is strongly dominant.
R030XD006CA	Abandoned Fan This ecological site occurs on fan aprons receiving much less additional moisture. Creosote bush (Larrea tridentata) is dominant.
R030XD015CA	Hyper-Arid Fans This ecological site occurs on soils receiving less additional moisture. Brittlebush (Encelia farinosa) is trace if present, and burrobush (Ambrosia dumosa) is co-dominant with creosote bush (Larrea tridentata).

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Larrea tridentata (2) Encelia farinosa
Herbaceous	Not specified

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Physiographic features

This ecological site occurs on alluvial fans, fan aprons and fan remnants at elevations of 560 to 3610 feet, and slopes ranging from 2 to 15 percent. Flooding frequency (sheet flow) is none to very rare, and is extremely brief in duration. Runoff class is very low to low.

Table 2. Representative physiographic features

Landforms	(1) Alluvial fan (2) Fan apron (3) Fan remnant
Flooding duration	Extremely brief (0.1 to 4 hours)
Flooding frequency	Very rare
Ponding frequency	None
Elevation	560 – 3,610 ft
Slope	2 – 15%
Aspect	Aspect is not a significant factor

Climatic features

The climate of this ecological site is characterized by hot temperatures, aridity, and a bimodal precipitation pattern. Precipitation falls as rain, with 30 percent falling in summer between July and October, and 65 percent falling in winter between November and March. The mean annual precipitation is 3 to 5 inches and mean annual air temperature is 68 to 73 degrees F. The frost free period is 300 to 340 days.

Maximum and minimum monthly climate data for this ESD were generated by the Climate Summarizer
(http://www.nm.nrcs.usda.gov/technical/handbooks/nrph/Climate_Summarizer.xls) using data
from the following climate stations (results are unweighted averages):

42598, Eagle Mountain, CA (Period of record = 1933 to 2011) [1]

43855, Hayfield Reservoir, CA (Period of record = 1933 to 2011) [1]

049099, Twentynine Palms, California (Period of record = 1935 to 2011) [1]

The data from multiple weather were combined to most accurately reflect the climatic conditions of this ecological site.

Table 3. Representative climatic features

Frost-free period (average)	340 days
Freeze-free period (average)
Precipitation total (average)	5 in

Bar

Line

Figure 2. Monthly precipitation range

Bar

Line

Figure 3. Monthly average minimum and maximum temperature

Soil features

The soils associated with this ecological site are very deep, well to excessively drained, and formed in alluvium from granitoid, gneissic and igneous sources. Surface textures include loamy sand, fine sandy loam and very gravelly sandy loam with gravelly sand to extremely gravelly sand surbsurface textures, or gravelly and very gravelly sandy loam textures on stable fan remnants. Surface gravels (< 3 mm in diameter) range from 35 to 65 percent, and larger fragments range from 2 to 28 percent. Subsurface gravels by volume (for a depth of 0 to 59 inches) range from 3 to 50 percent and larger fragments by volume range from 0 to 25 percent.

This ecological site is associated with the Pintobasin soils (mixed, hyperthermic Typic Torripsamments); Carrizo soils (sandy-skeletal, mixed, hyperthermic Typic Torriorthents); and Rubylee (coarse-loamy, mixed, superactive, hyperthermic Typic Haplargids).

The Pintobasin and Carrizo soils are the soils most frequently associated with this ecological site. These soils are composed of stratified layers of very deep sands with little horizon development. The Carrizo soils have coarsetextures and are sandy-skeletal in the particle size control section while Pintobasin soils are sandy throughout. The Rubylee soils have an argillic horizon beginning at 3 inches below the surface. These soils typically have a desert pavement surface, but do not when associated with this ecological site.

This ecological site is correlated with the following map units and soil components in the Joshua Tree National Park Soil Survey:

1527;Pintobasin gravelly loamy fine sand, 4 to 15 percent slopes;Pintobasin;90
2111;Descent-Rubylee association, 8 to 50 percent slopes;Rubylee;very rarely flooded;40
1540;Carrizo-Russiroks complex, 2 to 8 percent slopes;Carrizo;very rarely flooded;35
1542;Carrizo complex, 4 to 15 percent slopes;Carrizo;very rarely flooded;70; Carrizo;steep;6; Pintobasin;1
2077;Oldale-Carrizo association, 2 to 8 percent slopes;Carrizo;very rarely flooded;15
1250;Ironlung-Rock outcrop complex, 30 to 75 percent slopes;Pintobasin;steep;1
1255;Goldenhills-Bulletproof-Fanhill-Whiterobe complex, 30 to 75 percent slopes;Rubylee;very rarely flooded;1

Table 4. Representative soil features

Parent material	(1) Alluvium – granite
Surface texture	(1) Very gravelly sandy loam (2) Sandy loam (3) Loamy sand
Family particle size	(1) Sandy
Drainage class	Well drained to excessively drained
Permeability class	Moderately rapid to rapid
Soil depth	59 in
Surface fragment cover <=3"	35 – 65%
Surface fragment cover >3"	2 – 28%
Available water capacity (0-40in)	1 – 3.6 in
Calcium carbonate equivalent (0-40in)	5%
Electrical conductivity (0-40in)	2 mmhos/cm
Sodium adsorption ratio (0-40in)	4
Soil reaction (1:1 water) (0-40in)	6.1 – 9
Subsurface fragment volume <=3" (Depth not specified)	3 – 50%
Subsurface fragment volume >3" (Depth not specified)	25%

Ecological dynamics

Abiotic Factors

The abiotic factors driving this site are very deep, coarse textured soils, hyperthermic soil temperatures, and a very rare surface flooding regime. This ecological site occurs on fan aprons, alluvial fans, and fan remnants, at elevations of 560 to 3610 feet. Soils are very deep, and have a high cover of surface gravels and cobbles, and gravelly to extremely gravelly subsurface textures. This site typically has a very rare surface flooding regime. This ecological site occurs at the southern edge of the Mojave Desert (the Mojave Desert -Lower Colorado Desert or MLRA30-31 boundary). Thus, it represents a transition from a warm desert where winter precipitation is dominant, to a hot desert where summer precipitation is much more significant, and frosts are rare. A hyperthermic climate with low frost prevalence, gravelly soils, and a very rare surface flooding regime drives the vegetation community of this ecological site. Very deep, coarse-textured soils and hyperthermic soil temperatures favor dominance by the deep-rooted creosote bush, while additional run-on and an arid climate with low frost pravelence supports dominance by brittlebush.

The soils associated with this ecological site are composed of stratified layers of gravelly to extremely gravelly sands. In the hyperthermic environment of this ecological site, water drains rapidly through these coarse gravelly soils, with minimal loss due to run-off and evaporation (Noy-Meir 1973, Austin et al. 2004). This results in greater water availability at deep depths, but little at near surface depths. Deep, free-draining soils promote dominance by the deep-rooted, long-lived evergreen creosote bush, which accesses deep water (McAuliffe 1994, Hamerlynk et al. 2002, Hamerlynk and McAuliffe 2008). Extreme aridity at near surface levels promotes dominance by brittlebush. Brittlebush is an extremely drought-tolerant, drought-deciduous shrub. Adaptations in degree of leaf pubescence and leaf size allow brittlebush to occupy sites ranging from relatively mesic coastal environments to extremely arid deserts (Ehleringer and Cook 1990, Sandquist and Ehleringer 1997, Housman et al. 2002, Sandquist and Ehleringer 2003). Throughout its range, brittlebush is most abundant on extremely arid topographical positions, such as steep south-facing slopes (McAuliffe and Devender 1998, Martre et al. 2002). While leaf and shoot-adaptations allow brittlebush to withstand hot temperatures and extreme aridity, freezing temperatures restrict brittlebush. Frosts cause branch die-back and mortality in adult brittlebush (Sandquist and Ehleringer 1996), and reduce seedling establishment (Bowers 1994). The rare occurrence of frost in this ecological site also promotes dominance by brittlebush. Very rare sheet flow provides additional moisture and provides soil disturbance, which provides opportunities for establishment of brittlebush.

Disturbance dynamics

The primary disturbances influencing this ecological site are drought, invasion by non-native annual plants, and fire, all of which interact. Drought is an important shaping force in Mojave Desert and Colorado Desert plant communities (Webb et al. 2003, Bowers 2005, Hereford et al. 2006, Miriti et al. 2007). Short-lived perennial shrubs and perennial grasses demonstrate the highest rates of mortality (Webb et al. 2003, Bowers 2005, Hereford et al. 2006, Miriti et al. 2007), and annual species remain dormant in the soil seedbank (Beatley 1969, 1974, 1976). Long-lived shrubs and trees are more likely to exhibit branch-pruning, and or limited recruitment during drought (e.g. Hereford et al. 2006, Miriti et al. 2007), leading to reduced cover and biomass in drought-afflicted communities.

Non-native annual species such as red brome (Bromus rubens), common Mediterranean grass (Schismus barbatus), redstem stork’s bill (Erodium cicutarium) and Asian mustard (Brassica tournefortii) have become naturalized throughout the Mojave and Colorado Deserts over the past century (Rickard and Beatley 1965, D'Antonio and Vitousek 1992, Brooks 1999, Reid et al. 2006, Norton et al. 2007). In lower elevations, where soil temperature regimes are hyperthermic and soil moisture is more limiting, Common Mediterranean grass is the dominant non-native grass (Brooks and Berry 2006). Like native annuals, nonnative annual cover and production is directly related to winter precipitation (Beatley 1969, Brooks and Berry 2006, Barrows et al. 2009).

Invasion by non-native annual grasses has increased the flammability of Mojave Desert vegetation communities by providing a continuous fine fuel layer between widely spaced shrubs (Brown and Minnich 1986, Brooks 1999, Brooks et al. 2004, Rao and Allen 2010, Rao et al. 2010). After fire, these communities appear to be more susceptible to invasion by exotic grasses, leading to a grass-fire cycle (D'Antonio and Vitousek 1992). In the Colorado Desert, brittlebush quickly becomes dominant after fire in creosote bush dominated communities, and severe or repeated fire may lead to an altered, brittlebush dominated state (Brown and Minnich 1986, Steers and Allen 2011).

State and transition model

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Standard diagram

Figure 4. R030XD039CA

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State 1
Historic State

State 1 represents the historic range of variability for this ecological site. This state no longer exists due to the ubiquitous naturalization of non-native species in the Mojave and Colorado Deserts. Periodic drought and rare fire were the natural disturbances influencing this ecological site. Fire would have been a very rare occurrence due to the lack of a continuous fine fuel layer between shrubs. Data for this State does not exist, but dynamics and composition would have been similar to State 2, except with only native species present. See State 2 narrative for more detailed information.

State 2
Reference State

State 2 represents the current range of variability for this site. Non-native annuals, including Mediterranean grass and Asian mustard, are naturalized in this plant community. Their abundance varies with precipitation, but they are at least sparsely present (as current year’s growth or present in the soil seedbank).

Community 2.1
Reference plant community

Figure 5. Community Phase 2.1

The reference plant community is maintained by periods of average climatic conditions and the absence of fire. It is dominated by creosote bush and brittlebush. Minor shrubs and cacti may include Schott’s dalea (Psorothamnus schottii), desert lavender (Hyptis emoryi), burrobush (Ambrosia dumosa), California barrel cactus (Ferocactus cylindraceus), teddybear cholla (Cylindropuntia bigelovii), and golden cholla (Cylindropuntia echinocarpa). The subshrub California fagonbush (Fagonia laevis) is typically present, as is the native perennial bunchgrass low woollygrass (Dasyochloa pulchella). Native annual forbs are seasonally present, and common species include Cryptantha (Cryptantha ssp.), pincushion flower (Chaenactis fremontii), and desert Indianwheat (Plantago ovata). Mediterranean grass and Asian mustard may be present at low levels.

Figure 6. 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	120	179	238
Forb	0	6	70
Grass/Grasslike	0	1	10
Total	120	186	318

Community 2.2
Drought Response

This community phase is characterized by declines in cover and production due to branch-pruning and lack of recruitment of long-lived species including creosote bush, mortality of short-lived species (burrobrush, California fagonbush), and lack of emergence of annual species. Cactus species have low mortality during drought, but recruitment is limited (Jordan and Nobel 1981). Creosote bush is an evergreen species capable of utilizing moisture at any time of the year. This ability buffers populations from the effects of drought that occur as the absence of the winter rains (the primary source of moisture for this ecological site). Further, creosote bush germinates in response to moisture during the warm season, so may still recruit if warm season rains occur during winter drought (Hereford et al. 2006). Creosote bush exhibits branch-pruning during severe drought, but mortality during drought in the Mojave Desert is very low (Webb et al. 2003, Hereford et al. 2006). In the Sonoran desert, mortality of creosote bush due to severe drought may be more pronounced, but still less than 5% (Bowers 2005). Brittlebush suffers very little mortality during modest drought, but up to 25% during more severe drought (Bowers, 2005). This community is at reduced risk of burning, and if it is ignited, will experience lower severity, smaller fires because of reductions in annual and perennial biomass (Minnich 2003). However, drought immediately after a period of heavy moisture, results in standing biomass of native fuels that may carry a fire one year post-production (Minnich 2003), and standing dead biomass of non-native annuals that may provide fuel for 2 -3 years post-fire (Minnich 2003; Rao et al. 2010).

Community 2.3
Fire regeneration community

This community phase is characterized by the loss of creosote bush from the plant community. Brittlebush rapidly colonizes burned areas, and reaches dominance before associated shrub species (Brown and Minnich 1986, Steers and Allen 2011). In burned creosote bush scrub in the Colorado Desert, brittlebush seedlings overwhelmingly dominated shrub succession within the first year after burning, and within 3 to 5 year dominated total cover (Brown and Minnich, 1986). By twelve years after fire, pre-burn cover and density is reached, and is dominated by brittlebush (Steers and Allen 2011). By twenty years, there is sparse cover of creosote bush and other secondary shrubs with brittlebush (Steers and Allen 2011). Short-lived shrubs capable of re-colonizing from off-site sources become more abundant, and include burrobush and California fagonbush. Desert lavender can resprout after fire, and will maintain or increase importance in the fire regeneration community. Native forbs and native and non-native annual grasses become more abundant. This is an at-risk community, as the dense brittlebush and annual community is more susceptible to repeat burning. If the fire return interval is less than 50 years, this community is likely to transition to state 3.

Pathway 2.1a
Community 2.1 to 2.2

This pathway occurs with prolonged or severe drought.

Pathway 2.1b
Community 2.1 to 2.3

This pathway occurs with moderate to severe fire.

Pathway 2.2a
Community 2.2 to 2.1

This pathway occurs with a return to average or above average precipitation.

Pathway 2.2b
Community 2.2 to 2.3

This pathway occurs with moderate to severe fire.

Pathway 2.3a
Community 2.3 to 2.1

This pathway occurs with time, and the absence of additional disturbance.

State 3
Repeated fire

This state develops when the fire return interval is less than 50 years. This state has been significantly altered from the natural range of variability found in States 1 and 2. Creosote bush is lost, and brittlebush, non-native and native annual grasses and forbs dominate the community.

Community 3.1
Brittlebush dominated community

This community is dominated by brittlebush. Native forbs and native and non-native annual grasses become more abundant.

Transition 1
State 1 to 2

This transition occurred with the naturalization of non-native species in this ecological site. Non-native species were introduced with settlement of the Southwest Desert region in the 1860s. Post-settlement cattle and sheep grazing, as well as dryland farming, helped to spread and facilitate their establishment (Brooks and Pyke 2000, Brooks et al. 2007).

Transition 2
State 2 to 3

This transition occurs when the fire return interval is less than 50 years.

Restoration pathway 1
State 3 to 2

Restoration of communities severely altered by repeat fire at the landscape scale is difficult. Methods may include aerial seeding of early native colonizers such as desert globemallow, burrobrush, threeawns (Aristida spp.), and desert marigold. Increased native cover may help to reduce non-native plant invasion, helps to stabilize soils, provides a source of food and cover for wildlife, including desert tortoise (Gopherus agassizii), and provides microsites that facilitate creosote bush establishment. However, the amount of seed required for success is often prohibitive. In this ecological site, brittlebush naturally colonizes rapidly, and large-scale planting of creosote bush and other secondary species would be required to restore this site to the reference state. Creosote bush can be successfully propagated and outplanted, especially if outplants receive supplemental water.

Additional community tables

Table 6. Community 2.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Shrub/Vine
1	Native shrubs			120–238
	brittlebush	ENFA	Encelia farinosa	18–190	4–15
	creosote bush	LATR2	Larrea tridentata	30–130	3–6
	burrobush	AMDU2	Ambrosia dumosa	0–50	0–4
	California barrel cactus	FECY	Ferocactus cylindraceus	0–30	0–1
	California fagonbush	FALA	Fagonia laevis	0–18	0–1
	teddybear cholla	CYBI9	Cylindropuntia bigelovii	0–6	0–1
	Wiggins' cholla	CYEC3	Cylindropuntia echinocarpa	0–4	0–1
	desert lavender	HYEM	Hyptis emoryi	0–3	0–1
	Schott's dalea	PSSC5	Psorothamnus schottii	0–3	0–1
Forb
2	Native forbs			0–70
	pincushion flower	CHFR	Chaenactis fremontii	0–30	0–2
	cryptantha	CRYPT	Cryptantha	0–6	0–9
	desert Indianwheat	PLOV	Plantago ovata	0–5	0–15
4	Non-native annual forbs			0–1
	Asian mustard	BRTO	Brassica tournefortii	0–1	0–1
Grass/Grasslike
3	Native grasses			0–1
	low woollygrass	DAPU7	Dasyochloa pulchella	0–1	0–1
5	Non-native annual grass			0–10
	Mediterranean grass	SCHIS	Schismus	0–10	0–1

Interpretations

Animal community

This ecological site is preferred habitat for the threatened desert tortoise (Gopherus agassizii agassizii). Creosote bush shrublands provides a home for an abundance of specialist insect species, for example, creosote bush flowers provide nutrition for over twenty species of bees, and the creosote bush grasshopper (Bootettix argentatus) feeds solely on creosote leaves (Pavlik 2008). This ecological site provides habitat for many reptiles and mammals. Brittlebush is used as forage by desert bighorn sheep and mule deer.

Recreational uses

This ecological site may be used for cross-country hiking and aesthetic enjoyment.

Other products

Creosote bush is an important medicinal plant for Native Americans. It has a very wide range of uses from treatment for consumption, bowl complaints, and menstrual cramps, to induce vomiting, relief for arthritis, rheumatism, aching bones and sprains, congestion and cold, as an antiseptic and disinfectant, dandruff, antispasmodic, to induce urination, gonorrhea, and to cancer treatment. (This list is not exhaustive). http://herb.umd.umich.edu/herb/search.pl?searchstring=Larrea+tridentata.

Creosote bush stems are used to make weapons, digging tools, and basket handles, and creosote gum is used for knife and awl handles. Creosote bush branches are used as thatch in dwelling construction. http://herb.umd.umich.edu/herb/search.pl?searchstring=Larrea+tridentata.

Brittlebush has medicinal uses for Native Americans, including as a poultice for pain and for toothaches. Brittlebush resin is used as chewing gum, to fasten arrow points to twigs, to waterproof water bottles, and is melted to make a varnish. Brittlebush twigs were used as kindling for quick fires. http://herb.umd.umich.edu/herb/search.pl?searchstring=Encelia+farinosa.

Brittlebush resin is burned as incense in churches in Mexico (Tesky 1993).

Supporting information

Inventory data references

The following NRCS plots were used to describe this site:

Community Phase 2.1:
FANHILL-1 (Type location)
011211-01
124972056B
I5-B
J5-G

Type locality

Location 1: Riverside County, CA
UTM zone	N
UTM northing	3750111
UTM easting	569110
General legal description	The type location is just inside the southern boundary of Joshua Tree National Park, approximately 0.14 mile north of Thousand Palms Canyon Road, approximately 3 miles from the intersection of Dillon Road and Thousand Palms Canyon Road.

Other references

Austin, A. T., L. Yahdjian, J. M. Stark, J. Belnap, A. Porporato, U. Norton, D. A. Ravetta, and S. M. Scheaeffer. 2004. Water pulses and biogeochemical cycles in arid and semiarid ecosystems. Oecologia 141:221-235.

Barrows, C. W., E. B. Allen, M. L. Brooks, and M. F. Allen. 2009. Effects of an invasive plant on a desert sand dune landscape. Biological Invasions 11:673-686.

Beatley, J. C. 1969. Dependence of desert rodents on winter annuals and precipitation. Ecology 50:721-724.

Beatley, J. C. 1974. Effects of rainfall and temperature on the distribution and behavior of Larrea tridentata (Creosote-bush) in the Mojave Desert of Nevada. Ecology 55:245-261.

Beatley, J. C. 1976. Rainfall and fluctuating plant populations in relation to distributions and numbers of desert rodents in southern Nevada. Oecologia 24:21-42.

Bowers, J. E. 1994. Natural conditions for seedling emergence of three woody species in the northern Sonoran Desert. Madroño 41:73-84.

Bowers, J. E. 2005. Effects of drought on shrub survival and longevity in the northern Sonoran Desert. Journal of the Torrey Botanical Society 132:421-431.

Brooks, M. L. 1999. Habitat invasibility and dominance by alien annual plants in the western Mojave Desert. Biological Invasions 1:325-337.

Brooks, M. L. and K. H. Berry. 2006. Dominance and environmental correlates of alien annual plants in the Mojave Desert, USA. Journal of Arid Environments 67:100-124.

Brooks, M. L., C. M. D'Antonio, D. M. Richardson, J. B. Grace, J. E. Keeley, J. M. DiTomaso, R. J. Hobbs, M. Pellant, and D. Pyke. 2004. Effects of invasive alien plants on fire regimes. Bioscience 54:677-689.

Brooks, M. L., T. C. Esque, and T. Duck. 2007. Creosotebush, blackbrush, and interior chaparral shrublands. RMRS-GTR-202.

Brooks, M. L. and D. A. Pyke. 2000. Invasive plants and fire in the deserts of North America. Pages 1-14 in Fire conference 2000: the first national congress on fire ecology, prevention, and management. Tall Timbers Research Station, Tallahassee, FL.

Brown, D. E. and R. A. Minnich. 1986. Fire and Changes in Creosote Bush Scrub of the Western Sonoran Desert, California. American Midland Naturalist 116:411-422.

D'Antonio, C. M. and P. M. Vitousek. 1992. Biological invasions by exotic grasses, the grass/fire cycle, and global change. Annual Review of Ecology and Systematics 23:63-87.

Ehleringer, J. R. and C. S. Cook. 1990. Characteristics of Encelia species differing in leaf reflectance and transpiration rate under common garden conditions. Oecologia 82:484-489.

Hamerlynk, E. P. and J. R. McAuliffe. 2008. Soil-dependent canopy die-back and plant mortality in two Mojave Desert shrubs. Journal of Arid Environments 72:1793-1802.

Hamerlynk, E. P., J. R. McAuliffe, E. V. McDonald, and S. D. Smith. 2002. Ecological responses of two Mojave desert shrubs to soil horizon development and soil water dynamics. Ecology 83:768-779.

Hereford, R., R. H. Webb, and C. I. Longpre. 2006. Precipitation history and ecosystem response to multidecadal precipitation variability in the Mojave Desert region, 1893-2001. Journal of Arid Environments 67:13-34.

Housman, D. C., M. V. Price, and R. A. Redak. 2002. Architecture of coastal and desert Encelia farinosa (Asteraceae): consequences of plastic and heritable variation in leaf characteristics. American Journal of Botany 89:1303-1310.

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Contributors

Alice Lee Miller
Marchel Munnecke

Approval

Kendra Moseley, 10/21/2024

Rangeland health reference sheet

Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.

Author(s)/participant(s)
Contact for lead author
Date	10/22/2024
Approved by	Kendra Moseley
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:

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