Ecological site R030XA116AZ

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

This unit occurs within the Basin and Range Province and is characterized by broad basins, valleys, and old lakebeds. Widely spaced mountains trending north to south occur throughout the area. Isolated, short mountain ranges are separated by an aggraded desert plain. The mountains are fault blocks that have been tilted up. Long alluvial fans coalesce with dry lakebeds between some of the ranges.

LRU notes

AZ LRU 30-1 – Lower Mohave Desert

Elevations range from 400 to 2500 feet and precipitation averages 3 to 6 inches per year. Vegetation includes creosotebush, white bursage, Mormon tea, and brittlebush. The soil temperature regime is hyperthermic and the soil moisture regime is typic aridic.

Ecological site concept

This ecological site is found on uplands with deep, skeletal, calcareous soils. Cobble-sized fragments armor the soil surface and dominate the soil profile.

Associated sites

R030XA109AZ	Limy Upland 3-6" p.z. Deep Limy Upland, Deep, 3 to 6

R030XA109AZ

Limy Upland 3-6" p.z. Deep

Limy Upland, Deep, 3 to 6

Similar sites

R030XA109AZ	Limy Upland 3-6" p.z. Deep Limy Upland, Deep, 3 to 6

R030XA109AZ

Limy Upland 3-6" p.z. Deep

Limy Upland, Deep, 3 to 6

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 in an upland position on summits and shoulders of fan terraces. The site is identifiable by the numerous stones and cobbles on the soil surface.

Table 2. Representative physiographic features

Landforms	(1) Fan (2) Terrace
Flooding frequency	None
Ponding frequency	None
Elevation	152 – 610 m
Slope	2 – 15%
Aspect	Aspect is not a significant factor

Climatic features

The 30-1AZ Lower Mohave Desert Shrub land resource unit is characterized by a hot, dry climate. The average annual rainfall is 3 to 6 inches, but it can be extremely variable (e.g. from 0 to 11 inches). There can be long periods when little or no precipitation is received. Most of the precipitation for the year could arrive in just a couple of storms. The soil moisture regime is typic aridic and the soil temperature regime is hyperthermic. Winter precipitation from November through April occurs as gentle rains from storms coming out of the Pacific Ocean. Snow is very rare and only falls in the highest mountains. A seasonal drought occurs in May and June. Summer/fall precipitation from July through October comes from spotty, unreliable, and sometimes violent thunderstorms. The moisture originates in the Gulf of Mexico (and the Pacific Ocean in the fall) and flows into the state on the north end of the Mexican monsoon. Strong winds are common, especially during the spring.

Table 3. Representative climatic features

Frost-free period (average)	325 days
Freeze-free period (average)	365 days
Precipitation total (average)	152 mm

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

The soil of this ecological site is deep to very deep and is very cobbly throughout the soil profile. The soil surface ranges from very cobbly sandy loam to extremely cobbly sandy loam. The subsurface textures range from very gravelly sandy loam to very gravelly sand. The soil is derived from parent material of mixed igneous and metamorphic alluvium. The available water holding capacity is low to moderate. The permeability of the soil is moderately rapid to rapid. Hazard of erosion by water: slight to moderate; wind: slight.

A typical soil profile is:
A-0 to 2 inches; extremely cobbly sandy loam
Bk-2 to 12 inches; gravelly sandy loam
Bkq-12 to 60 inches; extremely gravelly sany loam

This ecological site has been correlated to map unit 697060, Huevi very gravelly sandy loam, Mohave County, AZ, Central Part SSA.

Table 4. Representative soil features

Surface texture	(1) Very cobbly sandy loam (2) Extremely cobbly sandy loam
Family particle size	(1) Sandy
Drainage class	Well drained
Permeability class	Moderately rapid
Soil depth	152 cm
Surface fragment cover <=3"	50 – 60%
Surface fragment cover >3"	65 – 95%
Available water capacity (0-101.6cm)	12.7 – 25.4 cm
Calcium carbonate equivalent (0-101.6cm)	10 – 30%
Electrical conductivity (0-101.6cm)	0 – 2 mmhos/cm
Sodium adsorption ratio (0-101.6cm)	0 – 2
Soil reaction (1:1 water) (0-101.6cm)	7.9 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	70 – 80%
Subsurface fragment volume >3" (Depth not specified)	0 – 15%

Ecological dynamics

Cobbly Limy Upland, 3"-6" p.z., Deep, is a widely dispersed desert shrub community. Natural disturbances are rare. After introduction of non-native annuals (forbs and/or grasses), the shift in total productivity with shift slightly toward seasonal herbaceous production following periods of rain. Livestock and wildlife use are limited on this site due low forage production and dispersed habitat. Dominant shrubs are creosote and white bursage. Assorted half-shrubs are widely scattered.

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

State 1
Historic Climax Plant Community

Community 1.1
Historic Climax Plant Community

The dominant aspect of this ecological site is a sparse stand of desert shrubs such as creosotebush, white brittlebush and white ratany. In years of above average annual precipitation annual grasses and forbs are abundant and showy. Change in the plant community is limited by low moisture and high temperatures. Fire is not a common occurance on this site due to the limited amount of biomass to serve as fuel generated on the site.

Figure 3. 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	275	297	314
Forb	58	81	99
Grass/Grasslike	4	15	20
Total	337	393	433

Table 6. Ground cover

Tree foliar cover	0%
Shrub/vine/liana foliar cover	0-2%
Grass/grasslike foliar cover	0%
Forb foliar cover	0-2%
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. Canopy structure (% cover)

Height Above Ground (m)	Tree	Shrub/Vine	Grass/ Grasslike	Forb
<0.15	–	–	–	4-6%
>0.15 <= 0.3	–	–	0-2%	–
>0.3 <= 0.6	–	4-6%	–	–
>0.6 <= 1.4	–	–	–	–
>1.4 <= 4	–	–	–	–
>4 <= 12	–	–	–	–
>12 <= 24	–	–	–	–
>24 <= 37	–	–	–	–
>37	–	–	–	–

Figure 4. Plant community growth curve (percent production by month). AZ3011, 30.1 3-6" p.z. all sites. Growth begins in late winter, most growth occurs in the spring..

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	7	30	32	13	7	3	5	2	1	0	0

Figure 5. Plant community growth curve (percent production by month). AZ3070, 30.23 6-9" p.z. big galleta. Growth begins in the spring, most growth occurs during the summer rainy season..

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	0	10	15	5	0	10	45	15	0	0	0

State 2
Historic Native Plant Community plus Introduced Annuals

Community 2.1
Non-native Annual Understory

This plant community resembles the historic native plant community, but exotic annuals have been introduced. Non-native species include red brome, Mediterranean grass (Schismus spp.), and filaree. The flourish of non-native annuals that occurs following rainfalls may preclude native annuals.

Transition T1A
State 1 to 2

Wind or mechanical transport of non-native seed or propagules.

Restoration pathway R2A
State 2 to 1

None known.

Additional community tables

Table 8. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (kg/hectare)	Foliar cover (%)
Grass/Grasslike
1				0–8
	big galleta	PLRI3	Pleuraphis rigida	0–8	–
2				4–8
	sixweeks fescue	VUOC	Vulpia octoflora	4–8	–
3				4–8
	Grass, annual	2GA	Grass, annual	4–8	–
Forb
4				4–20
	desert Indianwheat	PLOV	Plantago ovata	4–20	–
5				39–78
	Forb, annual	2FA	Forb, annual	39–78	–
6				4–8
	devil's spineflower	CHRI	Chorizanthe rigida	4–8	–
Shrub/Vine
7				157–196
	creosote bush	LATR2	Larrea tridentata	157–191	–
8				20–39
	white ratany	KRGR	Krameria grayi	20–39	–
9				39–78
	brittlebush	ENFA	Encelia farinosa	39–78	–
10				0–8
	burrobush	AMDU2	Ambrosia dumosa	0–8	–
11				0–11
	Shrub, other	2S	Shrub, other	0–11	–

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	12/22/2024
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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Natural ResourcesConservation Service

Ecological site R030XA116AZ

Cobbly Limy Upland 3-6" p.z. Deep

Last updated: 10/21/2024 Accessed: 12/22/2024

General information

Figure 1. Mapped extent

MLRA notes

LRU notes

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Ecosystem states

State 1 submodel, plant communities

State 2 submodel, plant communities

Natural Resources
Conservation Service

Last updated: 10/21/2024
Accessed: 12/22/2024