Natural Resources
Conservation Service
Ecological site R030XC315AZ
Sandy Loam Upland
10-13" p.z.
Fine, Gravelly
Last updated: 10/21/2024
Accessed: 08/17/2026
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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 gravelly loamy sand to gravelly loamy sand.
Associated sites
R030XC315AZ Sandy Loam Upland 10-13" p.z. Fine, Gravelly
R030XC331AZ Sandy Loam Slopes 10-13" p.z. Limy, Skeletal
R030XC334AZ Clay Loam Upland 10-13" p.z.
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous (1) Bouteloua eriopoda
(2) Pleuraphis rigidaPhysiographic features
This ecological site is found in an upland positon on ridges, shoulders and sideslopes of fan terraces.
Table 2. Representative physiographic features
Landforms (1) Terrace
(2) Fan
Flooding frequency None Ponding frequency None Elevation 3300 – 4000 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 a surface texture of gravelly loamy sand. Subsoil textures are sandy clay loam, sandy clay, gravelly sandy clay and gravelly loamy sand. The available water capacity is high. The soil's erosion hazard from water is high and from wind is moderate. Runoff from the soil is slow. The soil is non-saline, non-sodic with pH of 7.0-7.6 (neutral to mildly alkaline). The soil moisture regime is typic aridic and temperature regime is thermic.
A typical soil profile is:
A-0 to 4 inches; gravelly loamy sand
BA-4 to 10 inches; gravelly sandy loam
2Bt1-10 to 26 inches; gravelly sandy clay
2Bt2-26 to 40 inches; gravelly sandy clay loam
3Bkn-40 to 60 inches; very gravelly sand
The taxonomic classification of the soil is Fine, mixed, superactive, thermic Typic Haplargids.
This ecological site has been correlated to map unit 627130, Whitehouse family soil, Mohave County, AZ, SSA.Table 4. Representative soil features
Surface texture (1) Gravelly sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Slow Soil depth 60 – 0 in Surface fragment cover <=3" 20 – 45 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)5 – 8 in Calcium carbonate equivalent
(0-40in)0 – 1 % Electrical conductivity
(0-40in)Not specified 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)20 – 45 % Subsurface fragment volume >3"
(Depth not specified)0 – 5 % Ecological dynamics
Sandy Loam Upland, Fine, Gravelly, 10"-13" p.z., is a shrub-grassland 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 shrub-grass mix. Major grasses include black grama, big galleta and bush muhly. Dominant shrubs in about equal amounts are range ratany (Krameria erecta), Anderson wolfberry (Lycium Andersonii), rayless goldenhead, broom snakeweed, banana yucca and turpentinebush. Scattered Utah Juniper can occur on 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)Grass/Grasslike 59 190 471 Shrub/Vine 33 115 299 Forb 7 30 86 Tree 1 15 44 Total 100 350 900 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 – – – 1-3% >0.5 <= 1 – – 4-6% – >1 <= 2 – – – – >2 <= 4.5 – 9-11% – – >4.5 <= 13 0-1% – – – >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 AnnualsPerennial grass canopy cover is reduced and largely absent. Shrub density and cover has increased. Native and non-native annual forbs and grasses dominate the plant community following rainfall. Remnant perennial grasses will not be able to re-colonize; removal of grazing pressure will allow existing perennial grasses to regain vigor.
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 35–70 black grama BOER4 Bouteloua eriopoda 35–70 – 2 35–70 big galleta PLRI3 Pleuraphis rigida 35–70 – 3 4–18 Parish's threeawn ARPUP5 Aristida purpurea var. parishii 4–18 – 4 4–18 bush muhly MUPO2 Muhlenbergia porteri 4–18 – 5 0–7 low woollygrass DAPU7 Dasyochloa pulchella 0–7 – 6 0–7 desert needlegrass ACSP12 Achnatherum speciosum 0–7 – 7 4–18 Grass, perennial 2GP Grass, perennial 4–18 – Forb8 4–10 desert globemallow SPAM2 Sphaeralcea ambigua 4–10 – 9 7–14 Forb, perennial 2FP Forb, perennial 7–14 – 10 4–10 Forb, annual 2FA Forb, annual 4–10 – Shrub/Vine11 4–18 littleleaf ratany KRER Krameria erecta 4–18 – 12 4–18 water jacket LYAN Lycium andersonii 4–18 – 13 4–18 rayless goldenhead ACSP Acamptopappus sphaerocephalus 4–18 – 14 4–18 broom snakeweed GUSA2 Gutierrezia sarothrae 4–18 – 15 4–18 banana yucca YUBA Yucca baccata 4–18 – 16 4–18 turpentine bush ERLA12 Ericameria laricifolia 4–18 – 17 0–7 buckhorn cholla CYACM Cylindropuntia acanthocarpa var. major 0–7 – 18 4–10 crucifixion thorn CAHO3 Canotia holacantha 4–10 – 19 4–18 Shrub, other 2S Shrub, other 4–18 – Tree20 4–18 Utah juniper JUOS Juniperus osteosperma 4–18 – 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
Karlynn Huling
Larry D. Ellicott
Stephen CassadyApproval
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 08/17/2026 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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