Natural Resources
Conservation Service
Ecological site R035XD413AZ
Sandy Loam Upland
7-11" p.z.
Calcareous
Last updated: 5/19/2025
Accessed: 04/23/2026
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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): 035X–Colorado Plateau
AZ CRA 35.4 – Colorado Plateau Cold Sagebrush – Grasslands
Elevations range from 4200 to 5100 feet and precipitation averages 7 to 11 inches. Vegetation includes winterfat, fourwing saltbush, buckwheat species, needlegrass, bottlebrush squirreltail, Indian ricegrass, black grama, blue grama, sideoats grama, gyp dropseed, and galleta. The soil temperature regime is mesic and the soil moisture regime is typic aridic. This unit occurs within the Colorado Plateau Physiographic Province and is characterized by a sequence of flat to gently dipping sedimentary rocks eroded into plateaus, valleys and deep canyons. Sedimentary rock classes dominate the plateau with volcanic fields occurring for the most part near its margin.Ecological site concept
This site occurs in an upland position on ridges, plateaus and mesas. It does not benefit greatly from run-in moisture. Elevation is 4,500 to 5,100 feet. Slope is 0 to 5 percent. Soils characterizing this site are very deep and well drained. They were formed in eolian sediments on ridges, fan terraces, plateaus and mesas. The sand content is greater than 35 percent. These soils may occur over calcareous sandstone or above gypsum accumulations at depths greater than 15 inches. The soil is calcareous at the surface. Reaction is moderately alkaline or strongly alkaline. The dominant aspect is desert grassland with scattered shrubs. In the original plant community, there is a mix of cool season and warm season grasses with shrubs and half shrubs. Common species are James’ galleta, sand dropseed, fourwing saltbush, and broom snakeweed. Plant species most likely to invade or increase on this site when it deteriorates are broom snakeweed and annuals.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Atriplex canescens
(2) Krascheninnikovia lanataHerbaceous (1) Pleuraphis jamesii
(2) Sporobolus cryptandrusPhysiographic features
This site occurs in an upland position on ridges, plateaus and mesas. It does not benefit greatly from run-in moisture. Wind erosion is a moderate hazard especially when the vegetative cover is removed.
Table 2. Representative physiographic features
Landforms (1) Ridge
(2) Mesa
(3) Structural bench
Flooding frequency None to occasional Ponding frequency None to rare Elevation 4500 – 5100 ft Slope 0 – 5 % Aspect Aspect is not a significant factor Climatic features
Winter-Summer moisture ratios are typically 70:30 on the west side of this LRU and shift to 60:40 on the east side. Late spring is usually the driest period, and early fall moisture can be sporadic. Summer rains fall June-September; moisture originates in the Gulf of Mexico and creates convective, usually brief, intense thunderstorms. Cool season moisture October-May tends to be frontal; it originates in the Pacific and the Gulf of California and falls in widespread storms with longer duration and lower intensity. Precipitation generally comes as snow December-February. Accumulations above 10 inches are not common, but can occur. Snow usually lasts 3-4 days, but can persist much longer. Summer daytime temperatures are commonly 95-100 F and, on occasion, exceed 105F. Winter air temperatures can regularly go below 15 F and have been recorded below -15 F.
Table 3 Representative climatic features
Frost-free period (average) 220 days Freeze-free period (average) 150 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
This site occurs in an upland position, not benefiting from excess run-in moisture.
Soil features
Soils characterizing this site are very deep and well drained. They were formed in eolian sediments on ridges, fan terraces, plateaus and mesas. The sand content is greater than 35 percent. These soils may occur over calcareous sandstone or above gypsum accumulations at depths greater than 15 inches. The soil is calcareous at the surface.
Typical taxonomic units include:
SSA625 Mohave County NE part MU 8 Brinkerhoff & Grieta, MU 42 Monue.Table 4. Representative soil features
Parent material (1) Eolian deposits – sandstone
Surface texture (1) Sandy loam
(2) Fine sandy loam
(3) Loamy fine sand
Family particle size (1) Loamy
Drainage class Well drained to somewhat excessively drained Permeability class Moderate to moderately rapid Soil depth 40 – 60 in Surface fragment cover <=3" 0 – 5 % Available water capacity
(0-40in)2.5 – 10 in Calcium carbonate equivalent
(0-40in)1 – 35 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)7.9 – 9 Subsurface fragment volume <=3"
(Depth not specified)5 – 30 % Ecological dynamics
For state and transition model see ecological site DX035X02EESG07, Arizona Strip - Typic Aridic - Sandstone or Sandy Loam Upland.
The plant communities found on an ecological site are naturally variable. Composition and production will vary with yearly conditions, location, aspect, and the natural variability of the soils. The historical climax plant community represents the natural potential plant communities found on relict or relatively undisturbed sites. Other plant communities described here represent plant communities that are known to occur when the site is disturbed by factors such as grazing, fire, or drought.
Production data provided in this site description is standardized to air-dry weight at the end of the summer growing season. The plant communities described in this site description are based on near normal rainfall years.
NRCS uses a Similarity Index to compare existing plant communities to the plant communities described here. Similarity Index is determined by comparing the production and composition of a plant community to the production and composition of a plant community described in this site description. To determine Similarity Index, compare the production (air-dry weight) of each species to that shown in the plant community description. For each species, count no more than the maximum amount shown for the species, and for each group, count no more than the maximum shown for the group. Divide the resulting total by the total normal year production shown in the plant community description. If rainfall has been significantly above or below normal, use the total production shown for above or below normal years. If field data is not collected at the end of the summer growing season, then the field data must be corrected to the end of the year production before comparing it to the site description. The growth curve can be used as a guide for estimating production at the end of the summer growing season.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 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThis site has a plant community made up primarily of mid and short grasses with a relatively small percentage of forbs and shrubs. The dominant aspect is desert grassland with scattered shrubs. In the original plant community there is a mix of cool season and warm season grasses with shrubs and half shrubs.
Plant species most likely to invade or increase on this site when it deteriorates are broom snakeweed and annuals.
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 270 326 383 Shrub/Vine 68 113 158 Forb 9 16 23 Total 347 455 564 Table 6. Ground cover
Tree foliar cover 0% Shrub/vine/liana foliar cover 0-10% Grass/grasslike foliar cover 10-20% 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 – – – 0-1% >0.5 <= 1 – – – – >1 <= 2 – 1-5% 10-20% – >2 <= 4.5 – – – – >4.5 <= 13 – – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 5. Plant community growth curve (percent production by month). AZ0002 , 35.4 7-11" p.z. sand dropseed. Some growth in spring, most growth in summer rainy season..
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 0 0 0 5 5 25 50 15 0 0 0 Figure 6. Plant community growth curve (percent production by month). AZ0004 , 35.4 7-11" p.z. fourwing saltbush. Some growth in spring, most growth in summer to early fall rainy season..
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 0 0 0 10 15 30 40 5 0 0 0 Figure 7. Plant community growth curve (percent production by month). AZ0005 , 35.4 7-11" p.z. Indian ricegrass. Most growth occurs in the spring, some growth occurs in the fall..
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 0 10 40 40 0 0 0 5 5 0 0 Figure 8. Plant community growth curve (percent production by month). AZ3541 , 35.4 7-11" p.z. all sites. Most growth occurs in the spring and during the summer rainy season..
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 9 20 15 5 16 25 6 2 1 0 Figure 9. Plant community growth curve (percent production by month). AZ3542 , 35.4 7-11" p.z. Needle and thread. Growth occurs mostly 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 0 15 60 20 5 0 0 0 0 0 0 Figure 10. Plant community growth curve (percent production by month). AZ0001 , 35.4 7-11. Growth begins in the spring, most growth occurs during the summer rainy season..
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 0 0 3 15 5 25 40 10 2 0 0 Additional community tables
Table 8. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Shrub/Vine0 65–150 broom snakeweed GUSA2 Gutierrezia sarothrae 23–45 – fourwing saltbush ATCA2 Atriplex canescens 23–45 – winterfat KRLA2 Krascheninnikovia lanata 14–23 – Greene's rabbitbrush CHGR6 Chrysothamnus greenei 5–9 – jointfir EPHED Ephedra 0–9 – rubber rabbitbrush ERNAG Ericameria nauseosa ssp. nauseosa var. glabrata 5–9 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 4–8 – 2 5–9 Shrub (>.5m) 2SHRUB Shrub (>.5m) 5–9 – Bigelow sage ARBI3 Artemisia bigelovii 0–5 – sand sagebrush ARFI2 Artemisia filifolia 0–5 – pale desert-thorn LYPA Lycium pallidum 0–5 – plains pricklypear OPPO Opuntia polyacantha 1–5 – banana yucca YUBA Yucca baccata 1–5 – Grass/Grasslike0 270–383 James' galleta PLJA Pleuraphis jamesii 90–135 – sand dropseed SPCR Sporobolus cryptandrus 23–68 – Indian ricegrass ACHY Achnatherum hymenoides 23–48 – Grass, annual 2GA Grass, annual 23–45 – needle and thread HECOC8 Hesperostipa comata ssp. comata 23–45 – sixweeks fescue VUOC Vulpia octoflora 0–23 – threeawn ARIST Aristida 5–23 – blue grama BOGR2 Bouteloua gracilis 14–23 – squirreltail ELELE Elymus elymoides ssp. elymoides 0–5 – Forb0 5–14 Forb, perennial 2FP Forb, perennial 5–14 – milkvetch ASTRA Astragalus 0–5 – mariposa lily CALOC Calochortus 0–5 – larkspur DELPH Delphinium 0–5 – pepperweed LEPID Lepidium 0–5 – phlox PHLOX Phlox 0–5 – ragwort SENEC Senecio 0–5 – globemallow SPHAE Sphaeralcea 0–5 – vetch VICIA Vicia 0–5 – 1 5–14 Forb, annual 2FA Forb, annual 5–14 – aster ASTER Aster 0–5 – mustard BRASS2 Brassica 0–5 – lambsquarters CHAL7 Chenopodium album 0–5 – crossflower CHTE2 Chorispora tenella 0–5 – flatcrown buckwheat ERDE6 Eriogonum deflexum 0–5 – fleabane ERIGE2 Erigeron 0–5 – stork's bill ERODI Erodium 0–5 – spurge EUPHO Euphorbia 0–5 – sunflower HELIA3 Helianthus 0–5 – lupine LUPIN Lupinus 0–5 – blazingstar MENTZ Mentzelia 0–5 – popcornflower PLAGI Plagiobothrys 0–5 – plantain PLANT Plantago 0–5 – Interpretations
Animal community
This site responds relatively quickly to good management. It adapts well to grazing systems which provide for an occasional rest. Proper stocking rates are important. This site is very susceptible to erosion, particularly overgrazed areas, old roads, cattle trails, and concentration areas.
This site provides a good ground cover and fair diversity for wildlife species. It lacks open permanent waters.
Species seen here include; pronghorns, black-tailed jackrabbits, coyotes, badgers, kangaroo rats, deer mice, and a variety of snakes and lizards.Recreational uses
This site occurs on rolling hills or alluvial fans with grasslands interspersed with shrubs.
Winters are cold and summers are quite warm. Spring and fall are the dry seasons and are typically cool and windy.
Recreational activities most likely to occur are hunting, cross-country riding, photography and wildlife observation.
Other information
Threatened and Endangered Species: Golden eagles and Prairie falcons occasionally use the site for feeding areas.
Supporting information
Type locality
Location 1: Mohave County, AZ Township/Range/Section T40N R5W S22 General legal description Pipe Valley Quad; about four miles west of Pipe Springs, AZ; Section 22, T40N, R5W, Mohave County. Contributors
Larry D. Ellicott
Steve BarkerApproval
Kendra Moseley, 5/19/2025
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 04/23/2026 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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