Natural Resources
Conservation Service
Ecological site R030XC334AZ
Clay Loam Upland
10-13" p.z.
Last updated: 10/21/2024
Accessed: 04/19/2026
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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 30-3 – Upper Mohave Desert
Elevations range from 2800 to 4500 feet and precipitation averages 9 to 12 inches per year. Vegetation includes Joshua tree, blackbrush, creosotebush, ratany, bush muhly, big galleta, black grama, desert needlegrass, and Indian ricegrass. The soil temperature regime is thermic and the soil moisture regime is typic aridic.Ecological site concept
This ecological site is located on gently sloping uplands. Soils are non-calcareous, moderately deep to deep. Textures range from from sandy clay to cobbly clay loam.
Associated sites
R030XC331AZ Sandy Loam Slopes 10-13" p.z. Limy, Skeletal
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Eriogonum fasciculatum
(2) Salazaria mexicanaHerbaceous (1) Pleuraphis rigida
Physiographic features
This ecological site occurs in an upland position on shoulders, ridges and footslopes of fan terraces.
Table 2. Representative physiographic features
Landforms (1) Terrace
(2) Fan
Flooding frequency None Ponding frequency None Elevation 2700 – 4200 ft Slope 2 – 15 % Aspect Aspect is not a significant factor Climatic features
The climate is arid and warm. Annual precipitation ranges from 10 to 13 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 46 to 76 degrees F. The average frost-free period ranges from 121 to 231 days.
Table 3 Representative climatic features
Frost-free period (average) 230 days Freeze-free period (average) 270 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
The soil of this ecological site is deep with surface textures of very gravelly sandy loam, gravelly loamy sand and sandy loam. Subsoil textures are very gravelly clay, very gravelly sandy clay, very gravelly loam, clay loam, clay, and cobbly clay loam. The parent material is alluvium from varied geologic formations. Soil available water capacity is high. The soil's erosion hazard for water is slight to moderate and for wind is slight to severe. Runoff from this soil is slow. The soil is non-saline and non-sodic. The soil moisture regime is typic aridic and temperature regime is thermic.
A typical soil profile is:
A-0 to 1 inch; very gravelly sandy loam
Bt-1 to 8 inches; very gravelly clay
Bt-8 to 32 inches; very gravelly clay
Bt3-32 to 52 inches; very gravelly sandy clay
2Bkb-52 to 60 inches; very gravelly loam
The taxanomic classification of soils correlated to this ecological site include Clayey-skeletal, mixed, superactive, thermic Typic Calciargids.
Soil map units correlated to this ecological site include 697096, Eba family soil, Mohave County, AZ, Central Part SSA.Table 4. Representative soil features
Surface texture (1) Very gravelly sandy loam
(2) Gravelly loamy sand
(3) Sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Slow Soil depth 60 – 0 in Surface fragment cover <=3" 45 – 70 % Surface fragment cover >3" 0 – 15 % Available water capacity
(0-40in)3 – 6 in Calcium carbonate equivalent
(0-40in)0 – 25 % Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)6.6 – 8.4 Subsurface fragment volume <=3"
(Depth not specified)45 – 70 % Subsurface fragment volume >3"
(Depth not specified)0 – 25 % Ecological dynamics
Clay Loam Upland, 10"-13" p.z., is a grass-shrubland ecological site. Shrubs are well-dispersed across the site. Annual forbs and grasses flourish following rainfall. Natural disturbances are rare. After introduction of non-native annuals (forbs and/or grasses), the shift in total productivity is shift increased seasonal herbaceous production following periods of rain. Continuous, yearlong, livestock grazing will remove the perennial grass dominance.
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 textEcosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe dominant aspect of this plant community is a desert grassland - shrub mix. Major grasses are big galleta, black grama and fluffgrass.
Shrubs include flattop buckwheat, Mexican bladdersage, range ratany, banana yucca and rayless goldenhead. In some areas, Joshua tree and California Juniper are present in minor amounts.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)Grass/Grasslike 49 155 347 Shrub/Vine 50 150 347 Forb 1 15 34 Tree 0 5 22 Total 100 325 750 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 0-0% Grass/grasslike foliar cover 0-0% Forb foliar cover 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/
GrasslikeForb <0.5 – – – 0-2% >0.5 <= 1 – – 9-11% – >1 <= 2 – – – – >2 <= 4.5 – 13-17% – – >4.5 <= 13 0-2% – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 5. Plant community growth curve (percent production by month). AZ3024 , 30.3 10-13" p.z. upland sites. Growth begins in the spring and continues through the summer..
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 1 8 18 18 11 14 20 8 2 0 0 State 2
Historic Native Plant Community plus Introduced AnnualsCommunity 2.1
Non-native AnnualsThis plant community resembles the historic native plant community, but exotic annuals have been introduced. Non-native species include wild oat, red brome, Mediterranean grass (Schismus spp.), and filaree. The flourish of non-native annuals that occurs following rainfalls may preclude native annuals.
State 3
ShrublandCommunity 3.1
Shrubs and AnnualsYears of continuous livestock grazing (same season, yearlong) will remove perennial grasses and reduce desirable shrubs. Native and non-native annuals flourish in the bare interspaces.
Transition T1A
State 1 to 2Introduction of non-native annual forb and grass seed.
Transition T1B
State 1 to 3Yearlong continuous livestock grazing. Introduction of non-native annual forb and grass seed.
Transition T2A
State 2 to 3Yearlong continuous livestock grazing.
Restoration pathway R3A
State 3 to 2Prescribed grazing/no grazing. Range seeding may accelerate establishment of perennial grasses and desirable shrubs.
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 65–98 big galleta PLRI3 Pleuraphis rigida 65–98 – 2 3–10 bush muhly MUPO2 Muhlenbergia porteri 3–10 – 3 3–16 black grama BOER4 Bouteloua eriopoda 3–16 – 4 3–16 low woollygrass DAPU7 Dasyochloa pulchella 3–16 – 5 0–6 Parish's threeawn ARPUP5 Aristida purpurea var. parishii 0–6 – 6 0–3 sand dropseed SPCR Sporobolus cryptandrus 0–3 – 7 0–6 desert needlegrass ACSP12 Achnatherum speciosum 0–6 – 8 3–16 Grass, perennial 2GP Grass, perennial 3–6 – Forb9 0–3 desert trumpet ERIN4 Eriogonum inflatum 0–3 – 10 0–3 desert marigold BAMU Baileya multiradiata 0–3 – 11 3–10 Forb, perennial 2FP Forb, perennial 0–6 – 12 0–6 Forb, annual 2FA Forb, annual 0–6 – Shrub/Vine13 32–49 Eastern Mojave buckwheat ERFAP Eriogonum fasciculatum var. polifolium 32–49 – 14 3–16 banana yucca YUBA Yucca baccata 3–16 – 15 0–10 Nevada jointfir EPNE Ephedra nevadensis 0–10 – 16 3–16 rayless goldenhead ACSP Acamptopappus sphaerocephalus 3–16 – 17 0–16 crucifixion thorn CAHO3 Canotia holacantha 0–16 – 18 3–16 littleleaf ratany KRER Krameria erecta 3–16 – 19 3–16 broom snakeweed GUSA2 Gutierrezia sarothrae 3–16 – 20 0–10 water jacket LYAN Lycium andersonii 0–10 – 21 0–10 creosote bush LATR2 Larrea tridentata 0–10 – 22 16–32 Mexican bladdersage SAME Salazaria mexicana 16–32 – 23 3–6 catclaw acacia ACGR Acacia greggii 3–6 – 24 0–6 buckhorn cholla CYACM Cylindropuntia acanthocarpa var. major 0–6 – 25 0–3 whitestem paperflower PSCO2 Psilostrophe cooperi 0–3 – 26 3–16 Shrub, other 2S Shrub, other 3–16 – Tree27 0–3 California juniper JUCA7 Juniperus californica 0–3 – 28 0–6 Joshua tree YUBR Yucca brevifolia 0–6 – Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Contributors
Harmon Hodgkinson
Harmon S. Hodgkinson
Larry D. Ellicott
Steve BarkerApproval
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 04/19/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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