Natural Resources
Conservation Service

Ecological site R030XB222AZ

Gypsum Hills
6-9" p.z.
Alkaline

Last updated: 10/21/2024
Accessed: 08/17/2026

Home / esd CATALOG / MLRA 030X / ecological site R030XB222AZ

USC

Metric

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.

Click to explore map

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 30-2 – Middle Mohave Desert

Elevations range from 1500 to 3200 feet and precipitation averages 6 to 9 inches per year. Vegetation includes creosotebush, white bursage, yucca, prickly pear and cholla species, Mormon tea, flattop buckwheat, ratany, winterfat, bush muhly, threeawns, and big galleta. The soil temperature regime is thermic and the soil moisture regime is typic aridic.

Ecological site concept

This ecological site is located on steeply sloping uplands (slopes 15%-65%). Soils are very shallow to shallow, derived from Moenkopi gypsum. Underlying parent material is hard gypsite.

Associated sites

R030XB224AZ	Gypsum Fan 6-9" p.z.

R030XB224AZ

Gypsum Fan 6-9" p.z.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Atriplex confertifolia (2) Ephedra nevadensis
Herbaceous	Not specified

Download full description

Physiographic features

This ecological site occurs on rounded, eroding hills and escarpments. The soils are derived from Moenkopi gypsum.

Table 2. Representative physiographic features

Landforms	(1) Hill (2) Escarpment
Flooding frequency	None
Ponding frequency	None
Elevation	1600 – 3400 ft
Slope	15 – 40 %
Aspect	Aspect is not a significant factor

Climatic features

The climate is arid and warm. Annual precipitation ranges from 6 to 9 inches. About 65 percent of the rainfall comes from October through May as gentle rain from Pacific storms which may last for a couple of days. The rest of the rainfall comes during the summer monsoon season from July through September as spotty, brief, intense thunderstorms. Snow rarely falls, and only remains on the ground a few hours at most. Annual air temperature ranges from 59 to 70 degrees F. The average frost-free period ranges from 156 to 259 days.

Table 3 Representative climatic features

Frost-free period (average)	260 days
Freeze-free period (average)	290 days
Precipitation total (average)	10 in

Bar

Line

Figure 2. Monthly precipitation range

Bar

Line

Figure 3. Monthly average minimum and maximum temperature

Soil features

The soil of this ecological site is very shallow to shallow to hard gypsite. The soil is gypsiferous throughout the profile. The hazard of water erosion is severe and hazard of wind erosion is moderately high.

A typical soil profile is:
A--0 to 2 inches; pink (7.5YR 7/4) fine sandy loam, brown (7.5YR 5/4) moist; moderate medium platy structure; soft, very friable, nonsticky and nonplastic; very few very fine roots; many fine and very fine vesicular pores; 2 percent gypsum; strongly effervescent, 33 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 2 inches thick)

Cy--2 to 6 inches; pale yellow (5Y 7/3) fine and medium sand sized dispersed crystalline gypsite with white (N 8/) 1 to 2 cm bands of harder more consolidated crystalline gypsite and 10 to 20 percent loamy material, pale olive and white (5Y 6/3 and N 8/) moist; slightly hard and hard, friable and firm, nonsticky and nonplastic; many fine and very fine irregular pores; 32 percent gypsum; slightly effervescent, 30 percent calcium carbonate equivalent; slightly alkaline (pH 7.8); abrupt smooth boundary. (3 to 10 inches thick)

Cr1--6 to 10 inches; white, pink and light brownish gray (N 8/, 5YR 8/4, 2.5YR 6/2) stratified weathered gypsiferous materials (crystalline gypsite, siltstone and mudstone); very hard, very firm; 40 percent gypsum; noneffervescent; abrupt boundary. (0 to 10 inches thick)

Cr2--10 to 60 inches; hard gypsite.

The soil taxanomic classification is: Loamy, gypsic, thermic, shallow Typic Torriorthents

Soils correlated to this ecological site include map unit 623028 and 623029, Gypill soil, Shivwits Area SSA.

Table 4. Representative soil features

Parent material	(1) Alluvium – mudstone (2) Colluvium – siltstone
Surface texture	(1) Fine sandy loam
Family particle size	(1) Loamy
Drainage class	Moderately well drained to well drained
Permeability class	Moderately slow to moderate
Soil depth	4 – 15 in
Surface fragment cover <=3"	Not specified
Available water capacity (0-40in)	0 – 2.5 in
Calcium carbonate equivalent (0-40in)	5 – 35 %
Electrical conductivity (0-40in)	0 – 4 mmhos/cm
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	7.4 – 8.4
Subsurface fragment volume <=3" (Depth not specified)	0 – 25 %

Ecological dynamics

Gypsum Hills, 6"-9" p.z., Alkaline, is a sparse saltbush dominated ecological site. Annual forbs and grasses flourish following rainfall. Natural disturbances are rare. After introduction of non-native annuals (forbs and/or grasses), seasonal herbaceous production increases following periods of rain. Dominant shrubs are shadscale and Mormon tea. Creosote and white bursage are very sparse. Perennial grasses and forbs are largely absent from this ecological site.

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 site is desert shrub. The dominant shrubs are shadscale and Mormon tea with an occasional creosotebush and white ratany. Grasses are uncommon on this site.

With severe disturbance plants that will increase include shadscale, plants that will invade include red brome.

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	25	68	130
Forb	0	7	20
Total	25	75	150

Table 6. Ground cover

Tree foliar cover	0%
Shrub/vine/liana foliar cover	0-0%
Grass/grasslike foliar cover	0%
Forb foliar cover	0-0%
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 (ft)	Tree	Shrub/Vine	Grass/ Grasslike	Forb
<0.5	–	–	–	0-1%
>0.5 <= 1	–	–	–	–
>1 <= 2	–	–	–	–
>2 <= 4.5	–	4-6%	–	–
>4.5 <= 13	–	–	–	–
>13 <= 40	–	–	–	–
>40 <= 80	–	–	–	–
>80 <= 120	–	–	–	–
>120	–	–	–	–

Figure 5. Plant community growth curve (percent production by month). AZ3022 , 30.2 6-9" p.z. upland sites. Growth begins in the 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	2	19	33	18	7	7	11	3	0	0	0

Figure 6. Plant community growth curve (percent production by month). AZ3038 , 35.5 6-9" p.z. Nevada Mormon tea. Growth occurs mostly in the spring and early summer using stored winter 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	0	15	25	20	15	15	10	0	0	0	0

Figure 7. Plant community growth curve (percent production by month). AZ3075 , 30.23 6-9" p.z. white ratany. Most growth occurs in the spring, some growth occurs in the summer. Flowers 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	0	5	20	35	5	10	15	10	0	0	0

State 2
Historic Native Plant Community plus Introduced Annuals

Community 2.1
Non-native Annuals

This plant community resembles the historic native plant community, but exotic annuals have been introduced. Non-native species include Asian mustard (Brassica tournefortii), red brome, Mediterranean grass (Schismus spp.), and filaree. Red brome may come to dominate annual grasses.

Transition T1A
State 1 to 2

Introduction of non-native annual grass and forb seed.

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 ()	Foliar cover (%)
Forb
1				1–2
	desert trumpet	ERIN4	Eriogonum inflatum	1–2	–
2				0–8
	Forb, perennial	2FP	Forb, perennial	0–8	–
3				1–2
	Forb, annual	2FA	Forb, annual	1–2	–
Shrub/Vine
4				30–45
	shadscale saltbush	ATCO	Atriplex confertifolia	30–45	–
5				8–15
	Nevada jointfir	EPNE	Ephedra nevadensis	8–15	–
6				4–8
	creosote bush	LATR2	Larrea tridentata	4–8	–
7				1–2
	white ratany	KRGR	Krameria grayi	1–2	–
8				1–4
	Subshrub (<.5m)	2SUBS	Subshrub (<.5m)	1–4	–

Table 9. Community 2.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

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	08/17/2026
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