Natural Resources
Conservation Service
Ecological site R030XB224AZ
Gypsum Fan 6-9" p.z.
Last updated: 10/21/2024
Accessed: 11/21/2024
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.
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 found on gently sloping uplands. The calcareous soils are non-skeletal, deep, and have visible gypsum crystals at depths within the profile. Soil texture is sandy loam throughout.
Associated sites
R030XB208AZ |
Gypsum Hills 6-9" p.z. |
---|---|
R030XB222AZ |
Gypsum Hills 6-9" p.z. Alkaline |
R030XB225AZ |
Loamy Wash 6-9" p.z. Gypsic |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
(1) Ambrosia dumosa |
Herbaceous |
(1) Pleuraphis rigida |
Physiographic features
This ecological site is found in an upland position on summits of fan terraces.
Table 2. Representative physiographic features
Landforms |
(1)
Terrace
(2) Fan |
---|---|
Flooding duration | Extremely brief (0.1 to 4 hours) |
Flooding frequency | None to rare |
Ponding frequency | None |
Elevation | 1,600 – 3,200 ft |
Slope | 3 – 20% |
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) | 259 days |
---|---|
Freeze-free period (average) | 290 days |
Precipitation total (average) | 9 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
The soil of this ecological site is deep to very deep. It is highly gypsiferous, being formed from mixed alluvium from gypsiferous sedimentary layers of the Kaibab and Moenkopi formations. The surface texture of the soil is generally very gravelly fine sandy loam. Subsurface textures include fine sandy loam, sand, very cobbly sandy loam and loam. The soil permeability is moderately rapid to rapid. It is naturally a very erosive soil with a hazard of erosion by water of moderate to very severe and by wind of moderate. It is a non-saline, non-sodic soil with a PH of 7.6 to 8.2 (slightly to moderately alkaline).
A typical profile is:
0 to 2 inches; very gravelly fine sandy loam
2 to 12 inches; calcareous loam
12 to 29 inches; gypsiferous sandy loam that has 40 to 80 percent crystalline gypsum as sand-size particles
29 to 32 inches; crystalline gypsum
32 to 40 inches; gypsiferous sandy loam that has 50 percent crystalline gypsum
40 to 60 inches; very cobbly sandy loam that has 80 percent gypsum
This ecological site has been correlated to map unit 623067, Ruesch soil, Shivwits Area, AZ, SSA.
Table 4. Representative soil features
Parent material |
(1)
Alluvium
–
rock gypsum
|
---|---|
Surface texture |
(1) Very gravelly fine sandy loam |
Family particle size |
(1) Loamy |
Drainage class | Somewhat excessively drained |
Permeability class | Moderately rapid |
Soil depth | 60 in |
Surface fragment cover <=3" | 40 – 50% |
Surface fragment cover >3" | Not specified |
Available water capacity (0-40in) |
4 – 7 in |
Calcium carbonate equivalent (0-40in) |
6 – 23% |
Electrical conductivity (0-40in) |
2 – 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) |
5% |
Subsurface fragment volume >3" (Depth not specified) |
Not specified |
Ecological dynamics
This ecological site is dominated by dispersed desert shrubs. Perennial grasses and forbs are present in natural depressions. Annual forbs and grasses flourish following rainfall. Natural disturbances are rare; however, the gypsiferous soils are vulnerable to water erosion after soil disturbance. 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. Dominant shrubs are creosote and white bursage. Assorted half-shrubs are widely scattered.
State and transition model
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State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Historic Climax Plant Community
Community 1.1
Historic Climax Plant Community
The dominant aspect is mixed desert shrub with scattered perennial grasses. Dominant shrubs are white bursage, Nevada Mormon Tea, white ratany and Fremont dalea. The dominant grass is big galleta. Broom snakeweed will increase with severe disturbance, Russian thistle and red brome will invade.
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 | 92 | 215 | 368 |
Grass/Grasslike | 6 | 25 | 62 |
Forb | 2 | 10 | 20 |
Total | 100 | 250 | 450 |
Table 6. Ground cover
Tree foliar cover | 0% |
---|---|
Shrub/vine/liana foliar cover | 1-3% |
Grass/grasslike foliar cover | 0% |
Forb foliar cover | 0% |
Non-vascular plants | 0% |
Biological crusts | 1-3% |
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 | – | – | – | – |
>0.5 <= 1 | – | – | 0-2% | – |
>1 <= 2 | – | – | – | – |
>2 <= 4.5 | – | 9-11% | – | – |
>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 |
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 red brome, Mediterranean grass (Schismus spp.), and filaree. The flourish of non-native annuals that occurs following rainfalls may preclude native annuals.
State 3
Eroded
Community 3.1
Large Shrubs
The understory of the plant community is diminished. Active water erosion is indicated by extensive water flow patterns and pedestalling of cobbles and perennial plant bases. In extremely eroded conditions, rills are connected and gullies are present. Non-native annuals will flourish in protected areas after wet winters.
Transition T1A
State 1 to 2
Introduction of non-natvie annual forb and grass seed.
Transition T1B
State 1 to 3
Mechanical soil disturbance such as trailing from off-road vehicles, unplanned road or trail development, or trailing by livestock. Off-site accelerated run-on from trails, roads, adjacent farm fields, or dam building.
Restoration pathway R2A
State 2 to 1
None known.
Transition T2A
State 2 to 3
Mechanical soil disturbance such as trailing from off-road vehicles, unplanned road or trail development, or trailing by livestock. Off-site accelerated run-on from trails, roads, adjacent farm fields, or dam building.
Restoration pathway R3A
State 3 to 2
Unknown, possible removal of off-road vehicles, prescribed grazing/no grazing.
Additional community tables
Table 8. Community 1.1 plant community composition
Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
---|---|---|---|---|---|---|
Grass/Grasslike
|
||||||
1 | 12–25 | |||||
big galleta | PLRI3 | Pleuraphis rigida | 12–25 | – | ||
2 | 2–5 | |||||
low woollygrass | DAPU7 | Dasyochloa pulchella | 2–5 | – | ||
3 | 2–8 | |||||
Grass, annual | 2GA | Grass, annual | 0–4 | – | ||
Grass, perennial | 2GP | Grass, perennial | 0–4 | – | ||
threeawn | ARIST | Aristida | 0–4 | – | ||
bush muhly | MUPO2 | Muhlenbergia porteri | 0–4 | – | ||
burrograss | SCBR2 | Scleropogon brevifolius | 0–4 | – | ||
sand dropseed | SPCR | Sporobolus cryptandrus | 0–4 | – | ||
gyp dropseed | SPNE | Sporobolus nealleyi | 0–4 | – | ||
sixweeks fescue | VUOC | Vulpia octoflora | 0–4 | – | ||
Forb
|
||||||
4 | 2–5 | |||||
Forb, perennial | 2FP | Forb, perennial | 0–2 | – | ||
desert marigold | BAMU | Baileya multiradiata | 0–2 | – | ||
desert trumpet | ERIN4 | Eriogonum inflatum | 0–2 | – | ||
desert globemallow | SPAM2 | Sphaeralcea ambigua | 0–2 | – | ||
5 | 2–5 | |||||
Forb, annual | 2FA | Forb, annual | 0–2 | – | ||
buckwheat | ERIOG | Eriogonum | 0–2 | – | ||
phacelia | PHACE | Phacelia | 0–2 | – | ||
Shrub/Vine
|
||||||
6 | 50–75 | |||||
burrobush | AMDU2 | Ambrosia dumosa | 50–75 | – | ||
7 | 25–50 | |||||
Nevada jointfir | EPNE | Ephedra nevadensis | 25–50 | – | ||
8 | 25–50 | |||||
white ratany | KRGR | Krameria grayi | 25–50 | – | ||
9 | 12–38 | |||||
Fremont's dalea | PSFR | Psorothamnus fremontii | 12–38 | – | ||
10 | 12–25 | |||||
creosote bush | LATR2 | Larrea tridentata | 12–25 | – | ||
11 | 12–25 | |||||
water jacket | LYAN | Lycium andersonii | 12–25 | – | ||
12 | 8–20 | |||||
banana yucca | YUBA | Yucca baccata | 8–20 | – | ||
13 | 5–12 | |||||
winterfat | KRLA2 | Krascheninnikovia lanata | 5–12 | – | ||
14 | 2–5 | |||||
rayless goldenhead | ACSP | Acamptopappus sphaerocephalus | 2–5 | – | ||
15 | 2–5 | |||||
pricklypear | OPUNT | Opuntia | 2–5 | – | ||
16 | 0–2 | |||||
burrobrush | HYSA | Hymenoclea salsola | 0–2 | – | ||
17 | 0–5 | |||||
Shrub, other | 2S | Shrub, other | 0–2 | – | ||
fourwing saltbush | ATCA2 | Atriplex canescens | 0–2 | – | ||
echinocactus | ECHIN2 | Echinocactus | 0–2 | – | ||
button brittlebush | ENFR | Encelia frutescens | 0–2 | – | ||
broom snakeweed | GUSA2 | Gutierrezia sarothrae | 0–2 | – | ||
pricklypear | OPUNT | Opuntia | 0–2 | – |
Interpretations
Animal community
Wildlife species found on this ecological site include coyote, jackrabbit, desert cottontail, striped skunk, antelope squirrel, pocket gopher, gopher snake, Mohave rattlesnake, western rattlesnake, raven, pocket mouse, and kangaroo rat.
Supporting information
Contributors
Larry D. Ellicott
Stephen Cassady
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 | 10/21/2024 |
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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