Natural Resources
Conservation Service
Ecological site R030XB205AZ
Sandy Loam Upland
6-10" p.z.
Limy Subsurface, Gravelly
Last updated: 10/21/2024
Accessed: 08/12/2026
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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 30-2 – 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 gently sloping uplands. Soils are non-calcareous at the surface, effervescence increases with depth. Textures are gravelly sandy loams.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Larrea tridentata
(2) Ambrosia dumosaHerbaceous (1) Pleuraphis rigida
Physiographic features
This ecological site is found in an upland position on summits, shoulders and concave areas of fan terraces. Slopes range from 1 to 10 percent.
Table 2. Representative physiographic features
Landforms (1) Terrace
Flooding frequency None Ponding frequency None Elevation 1500 – 3000 ft Slope 1 – 15 % Aspect Aspect is not a significant factor Climatic features
The climate is arid and warm. Annual precipitation ranges from 6 to 10 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 BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
The soil of this site is deep to very deep. Surface textures range from gravelly loamy sand to sandy loam. Subsurface textures range from very gravelly loamy sand to sandy loam. The soil is slightly effervescent at the surface becoming strongly to violently effervescent in the subsurface.
Table 4. Representative soil features
Surface texture (1) Gravelly loamy sand
(2) Gravelly sandy loam
(3) Sandy loam
Family particle size (1) Sandy
Drainage class Somewhat excessively drained Permeability class Moderately rapid to rapid Soil depth 60 in Surface fragment cover <=3" 0 – 10 % Surface fragment cover >3" Not specified Calcium carbonate equivalent
(0-40in)0 – 40 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Soil reaction (1:1 water)
(0-40in)7.8 – 9 Subsurface fragment volume <=3"
(Depth not specified)3 – 30 % Subsurface fragment volume >3"
(Depth not specified)Not specified Ecological dynamics
The plant community on this site is shrub dominated with a very sparse understory of perennial grasses and perennial forbs. Natural disturbance rarely occurs on this site. Limited available forage restrict livestock impacts on this site. Annual forbs flourish in springs, particularly following wet winters; the green forage produced is desired by livestock but is largely unused once matured. Non-native annuals are well adapted on this 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 textEcosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe dominant aspect of this ecological site is a desert shrub. This site is dominated by creosotebush and white bursage with sparse amounts of big galleta occurring in the small drainages.
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 136 250 362 Grass/Grasslike 12 36 61 Forb 2 11 20 Tree 0 3 7 Total 150 300 450 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 0-0% Grass/grasslike foliar cover 0-0% Forb foliar cover 0-0% 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 – – 0-1% – >1 <= 2 – – – – >2 <= 4.5 – 8-12% – – >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
Non-native AnnualsCommunity 2.1
Non-native AnnualsThis 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 2Introduction of non-native annual forb and grass seed,
Restoration pathway R2A
State 2 to 1None known.
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 11–22 big galleta PLRI3 Pleuraphis rigida 11–22 – 2 0–7 Indian ricegrass ACHY Achnatherum hymenoides 0–7 – 3 0–9 sand dropseed SPCR Sporobolus cryptandrus 0–9 – 4 2–11 Grass, annual 2GA Grass, annual 2–11 – Forb5 0–2 desert globemallow SPAM2 Sphaeralcea ambigua 0–2 – 6 2–7 Forb, annual 2FA Forb, annual 2–7 – Shrub/Vine7 90–112 creosote bush LATR2 Larrea tridentata 90–112 – 8 45–79 burrobush AMDU2 Ambrosia dumosa 45–79 – 9 2–11 rayless goldenhead ACSP Acamptopappus sphaerocephalus 2–11 – 10 0–4 water jacket LYAN Lycium andersonii 0–4 – 11 0–2 Nevada jointfir EPNE Ephedra nevadensis 0–2 – 12 2–4 littleleaf ratany KRER Krameria erecta 0–4 – white ratany KRGR Krameria grayi 0–4 – littleleaf ratany KRER Krameria erecta 0–4 – white ratany KRGR Krameria grayi 0–4 – 13 0–4 pricklypear OPUNT Opuntia 0–4 – 14 0–2 Mojave yucca YUSC2 Yucca schidigera 0–2 – 15 0–2 ocotillo FOSP2 Fouquieria splendens 0–2 – 16 2–11 Shrub (>.5m) 2SHRUB Shrub (>.5m) 2–11 – Tree17 0–4 Joshua tree YUBR Yucca brevifolia 0–4 – Table 9. Community 2.1 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 08/12/2026 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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