Ecological site R040XD005CA

R040XD200CA	Rarely Flooded Fans This site is a little more stable with less active flow patterns and the presence of brittlebrush.

Tree	Not specified
Shrub	(1) Larrea tridentata (2) Ambrosia dumosa
Herbaceous	(1) Plantago ovata (2) Cryptantha

Landforms	(1) Alluvial fan
Flooding duration	Extremely brief (0.1 to 4 hours) to very brief (4 to 48 hours)
Flooding frequency	Rare to occasional
Elevation	500 – 2600 ft
Slope	4 – 30 %
Aspect	Aspect is not a significant factor

Frost-free period (average)	360 days
Freeze-free period (average)	360 days
Precipitation total (average)	10 in

Surface texture	(1) Extremely gravelly sandy loam (2) Sand
Family particle size	(1) Sandy
Drainage class	Well drained to excessively drained
Permeability class	Moderate to moderately rapid
Soil depth	40 – 72 in
Surface fragment cover <=3"	29 – 70 %
Surface fragment cover >3"	0 – 10 %
Available water capacity (0-40in)	1.77 – 2.95 in
Calcium carbonate equivalent (0-40in)	7 – 25 %
Electrical conductivity (0-40in)	0 – 2 mmhos/cm
Sodium adsorption ratio (0-40in)	0 – 5
Soil reaction (1:1 water) (0-40in)	7.4 – 8.6
Subsurface fragment volume <=3" (Depth not specified)	9 – 10 %
Subsurface fragment volume >3" (Depth not specified)	2 – 3 %

Ecological dynamics

This creosotebush (Larrea tridentata) site is widespread throughout the Sonoran Desert and consists of both long-lived and short-lived perennial species. In stable, old communities, creosotebushes or clones may attain ages of several thousand years. Defoliation and death of branches of creosotebush may occur as a result of long periods of intense moisture stress. Surface disturbance may reduce plant cover, density and diversity of this site. These changes can be very subtle or extremely obvious depending on the intensity of use, rate of use, and an assortment of environmental factors (topography, rainfall, soil type). After surface disturbance, white bursage (Ambrosia dumosa) may initially increase and an invasion of non-native annual grasses and forbs such as schismus (Schismus arabicus) and red-stem filaree (Erodium cicutarium) may occur.
White burrobush (Hymenoclea salsola) is the primary perennial pioneer species. Fire effects: Creosotebush is very flammable and is poorly adapted to fire, due to its limited sprouting ability. Factors such as season of burning, fuel quantity, fire intensity and age of existing shrubs will affect the ability of creosotebush to resprout. White bursage can also be killed by fire, however, it can rapidly reestablish from off-site seed.

State and transition model

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Creosotebush-white bursage

2. Introduced Grasses and Forbs

State 1 submodel, plant communities

1.1. Creosotebush-white bursage

State 1
Creosotebush-white bursage

Community 1.1
Creosotebush-white bursage

Figure 3. Limy Fan 2-4

The interpretative plant community is the historic climax community prior to European colonization. This community is dominated by creosotebush and white bursage in almost equal numbers. The site appears like a Limy 2-4 with a more developed bursage component and slightly higher production. The site is shallowly dissected by channels which bring increased run-off and are responsible for the higher production in comparison to a Limy 2-4 site. These channels, while bringing in more moisture to the site, are not developed enough to sustain trees. California barrel cactus (Ferocactus cylindraceus) and buckhorn cholla (Cylindropuntia acanthocarpa) are present in small quantities. Wolfberry (Lycium andersonii) is also a minor component which is restricted to the channel areas. Annual forbs and grasses are seasonally present. The potential plant community is 90% shrubs, 5% forbs, and 5% grasses. The total vegetation cover of the site is 25%. Biological crusts compose up to 20% of the ground cover of the site.

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	74	97	120
Forb	1	2	3
Grass/Grasslike	0	1	2
Total	75	100	125

Table 6. Ground cover

Tree foliar cover	0%
Shrub/vine/liana foliar cover	20-20%
Grass/grasslike foliar cover	0-0%
Forb foliar cover	0-10%
Non-vascular plants	0%
Biological crusts	0%
Litter	0%
Surface fragments >0.25" and <=3"	0%
Surface fragments >3"	0%
Bedrock	0%
Water	0%
Bare ground	0%

Table 7. Soil surface cover

Tree basal cover	0%
Shrub/vine/liana basal cover	10-20%
Grass/grasslike basal cover	0-0%
Forb basal cover	0-10%
Non-vascular plants	0%
Biological crusts	20-20%
Litter	10-10%
Surface fragments >0.25" and <=3"	60-60%
Surface fragments >3"	0%
Bedrock	0%
Water	0%
Bare ground	10-10%

Table 8. Canopy structure (% cover)

Height Above Ground (ft)	Tree	Shrub/Vine	Grass/ Grasslike	Forb
<0.5	–	–	0-1%	1-2%
>0.5 <= 1	–	15-20%	–	–
>1 <= 2	–	20-25%	–	–
>2 <= 4.5	–	40-45%	–	–
>4.5 <= 13	–	1-3%	–	–
>13 <= 40	–	–	–	–
>40 <= 80	–	–	–	–
>80 <= 120	–	–	–	–
>120	–	–	–	–

State 2
Introduced Grasses and Forbs

Non-native annual grasses and forbs such as schismus (Schismus arabicus) and red-stem filaree (Erodium cicutarium) are predominant..

Transition T1A
State 1 to 2

After surface disturbance, white bursage (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=AMDU2" target="_blank" title="Open in plants.usda.gov">Ambrosia dumosa</a>) may initially increase and an invasion of non-native annual grasses and forbs such as schismus (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=SCAR" target="_blank" title="Open in plants.usda.gov">Schismus arabicus</a>) and red-stem filaree (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=ERCI6" target="_blank" title="Open in plants.usda.gov">Erodium cicutarium</a>) may occur.

Restoration pathway R2A
State 2 to 1

Over time with minimal disturbance creosote bush and white bursage will re-establish. White burrobush (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=HYSA" target="_blank" title="Open in plants.usda.gov">Hymenoclea salsola</a>) is the primary perennial pioneer species.

Additional community tables

Table 9. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Shrub/Vine
1	Native Shrubs			74–120
	creosote bush	LATR2	Larrea tridentata	35–57	–
	burrobush	AMDU2	Ambrosia dumosa	33–54	–
	water jacket	LYAN	Lycium andersonii	1–3	–
	white ratany	KRGR	Krameria grayi	1–2	–
	California barrel cactus	FECY	Ferocactus cylindraceus	0–1	–
Grass/Grasslike
2	Perennial grass			0–1
	big galleta	PLRI3	Pleuraphis rigida	0–1	–
4	Annual Grass			0–1
	sixweeks grama	BOBA2	Bouteloua barbata	0–1	–
Forb
3	Native Forbs			1–3
	desert Indianwheat	PLOV	Plantago ovata	1–3	–

Location 1: San Bernardino County, CA
UTM zone	N
UTM northing	3814211
UTM easting	724520
Latitude	34° 26′ 42″
Longitude	114° 33′ 22″
General legal description	This site occurs within the Chemehuevi Wash OHV area. The type locality is about 3 miles south of the Lake Havasu rd. on the Heritage Trail (dirt).

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	06/28/2026
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

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

Dominant:

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
Perennial plant reproductive capability:

Download reference sheet

Natural ResourcesConservation Service

Ecological site R040XD005CA

Hyper-Arid Active Alluvial Fans 2-4" p.z.

Last updated: 3/04/2025 Accessed: 06/28/2026

Search

General information

MLRA notes

Classification relationships

Ecological site concept

Similar sites

Table 1. Dominant plant species

Natural Resources
Conservation Service

Hyper-Arid Active Alluvial Fans
2-4" p.z.

Last updated: 3/04/2025
Accessed: 06/28/2026