Natural Resources
Conservation Service
Ecological site R030XC306AZ
Granitic Hills
10-13" p.z.
Alkaline
Last updated: 10/21/2024
Accessed: 08/10/2026
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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 steeply sloping (15%-65%) uplands. Soils are very shallow to shallow over granitic or schist bedrock.
Associated sites
R030XC311AZ Limy Upland 10-13" p.z.
Limy Upland, 10 to 13
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Eriogonum fasciculatum
(2) Ambrosia dumosaHerbaceous (1) Achnatherum speciosum
(2) Bouteloua eriopodaPhysiographic features
This ecological site is located in an upland postion on backslopes and summits of mountains and hills.
Table 2. Representative physiographic features
Landforms (1) Mountain
(2) Hill
Flooding frequency None Ponding frequency None Elevation 3600 – 5800 ft Slope 25 – 70 % 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 shallow to very shallow. Sol surface textures are extremely stony sandy loam, extremely cobbly sandy loam, extremely stony coarse sandy loam and very gravelly coarse sandy loam. Subsoil textures are very gravelly sandy loam, extremely cobbly loam, very gravelly clay, very gravelly clay loam, extremely stony coarse sandy loam, and very gravelly coarse sandy loam. Soil parent materials are colluvium and alluvium from igneous and metamorphic rocks. Soil available water capacity is very low. The soils's erosion hazard by water is slight to very severe and by wind is slight. The soil is non-saline, non-sodic with mild to moderate alkalinity (pH 7.6-8.0). The soil moisture regime is typic aridic and temperature regime is thermic. Granite bedrock is found at a depth of 8-13 inches.
A typical soil profile is:
A-0- to 2 inches; extremely cobbly sandy loam
Bt1-2 to 5 inches; extremely gravelly sandy loam
Bt2-5 to 8 inches; very gavelly sandy clay loam
Bt3-8 to 10 inches; very gravelly sandy clay loam
2Cr-10 to 60 inches;weathered bedrock
Taxanomioc classification of soils correlated to this ecological site include Loamy-skeletal, mixed, superactive, thermic, shallow Typic Haplargids, Loamy-skeletal, mixed, nonacid, thermic Lithic Toriorthents.
Map units correlated to this ecological site include 697035, Nodman soil;697066 and 697068, Hulda soil, Mohave County, AZ, Central Part SSA and 623057, Nipton soil, Shivwits Area, AZ, Part of Mohave County, AZ SSA.
Table 4. Representative soil features
Surface texture (1) Extremely stony sandy loam
(2) Extremely cobbly sandy loam
(3) Very gravelly sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderately slow to moderately rapid Soil depth 60 – 0 in Surface fragment cover <=3" 45 – 70 % Surface fragment cover >3" 55 – 65 % Available water capacity
(0-40in)2.5 – 4 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)0 – 2 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)45 – 80 % Subsurface fragment volume >3"
(Depth not specified)15 – 50 % Ecological dynamics
Granitic/Schist Hills, Alkaline, 10"-13" p.z., is a shrub dominated ecological site. Sparse perennial grasses and forbs are occasionally encountered. Annual forbs and grasses flourish following rainfall. Natural disturbances are rare. After introduction of non-native annuals (forbs and/or grasses), they flourish following wet winters. Dominant shrubs are flattop buckwheat, creosote and white bursage. Assorted half-shrubs are widely scattered.
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 site is a desert shrub-grass mix. It is dominated by flattop buckwheat, white bursage, Nevada and green mormon tea, range and white ratany and desert needlegrass and black grama grasses. The site has some local areas abundant with blackbrush.
The site has good soil moisture-plant relationship even though the soils are shallow.
With severe disturbance, turpentinebush, broom snakeweed and threeawn will increase; red brome and other undesirable annuals 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 156 265 417 Grass/Grasslike 141 225 348 Forb 3 10 35 Total 300 500 800 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 – – – 0-2% >0.5 <= 1 – – 9-11% – >1 <= 2 – 18-22% – – >2 <= 4.5 – – – – >4.5 <= 13 – – – – >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.
Transition T1A
State 1 to 2Introduction of non-native annual forb and grass seed.
Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 50–75 desert needlegrass ACSP12 Achnatherum speciosum 50–75 – 2 5–25 bush muhly MUPO2 Muhlenbergia porteri 5–25 – 3 25–50 black grama BOER4 Bouteloua eriopoda 25–50 – 4 5–25 big galleta PLRI3 Pleuraphis rigida 5–25 – 5 5–15 threeawn ARIST Aristida 5–15 – 6 0–25 sideoats grama BOCU Bouteloua curtipendula 0–25 – 7 5–25 Grass, perennial 2GP Grass, perennial 0–10 – low woollygrass DAPU7 Dasyochloa pulchella 0–10 – sand dropseed SPCR Sporobolus cryptandrus 0–10 – slim tridens TRMU Tridens muticus 0–10 – 8 15–25 Grass, annual 2GA Grass, annual 15–25 – Forb9 0–5 desert globemallow SPAM2 Sphaeralcea ambigua 0–5 – desert globemallow SPAM2 Sphaeralcea ambigua 0–5 – 10 5–25 Forb, perennial 2FP Forb, perennial 5–25 – 11 0–10 Forb, annual 2FA Forb, annual 0–10 – Shrub/Vine12 125–150 burrobush AMDU2 Ambrosia dumosa 75–100 – Eastern Mojave buckwheat ERFAP Eriogonum fasciculatum var. polifolium 75–100 – 13 25–50 Nevada jointfir EPNE Ephedra nevadensis 25–40 – mormon tea EPVI Ephedra viridis 25–40 – 14 0–10 broom snakeweed GUSA2 Gutierrezia sarothrae 0–10 – 15 5–25 littleleaf ratany KRER Krameria erecta 5–20 – white ratany KRGR Krameria grayi 5–20 – 16 0–5 banana yucca YUBA Yucca baccata 0–5 – 17 0–10 catclaw acacia ACGR Acacia greggii 0–10 – 18 5–25 button brittlebush ENFR Encelia frutescens 5–25 – 19 0–15 creosote bush LATR2 Larrea tridentata 0–15 – 20 25–75 Shrub, other 2S Shrub, other 0–25 – rayless goldenhead ACSP Acamptopappus sphaerocephalus 0–25 – blackbrush CORA Coleogyne ramosissima 0–25 – purple coneflower ECHIN Echinacea 0–25 – turpentine bush ERLA12 Ericameria laricifolia 0–25 – barrel cactus FEROC Ferocactus 0–25 – burrobrush HYSA Hymenoclea salsola 0–25 – water jacket LYAN Lycium andersonii 0–25 – pricklypear OPUNT Opuntia 0–25 – desert almond PRFA Prunus fasciculata 0–25 – Mexican bladdersage SAME Salazaria mexicana 0–25 – 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. EllicottApproval
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 08/10/2026 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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