Natural Resources
Conservation Service
Ecological site R035XD401AZ
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7-11" p.z.
Last updated: 5/19/2025
Accessed: 05/06/2026
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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 on steep canyon walls and sides of plateaus and mesas. on escarpments on the Moenkopi Formation below the Shinarump Formation. It typically suffers from excessive runoff from the steep slopes. Elevation is 4,800 to 5,300 feet. Slope is 30 to 70 percent. Complex geology and topography have created a multitude of soil textures, depths and degrees of development. There are areas of exposed sandstone, shale and mudstone. The dominant aspect of this site is a cold desert shrub/grassland. Common species are sulphur-flower buckwheat, skunkbush sumac, needle and thread, and James’ galleta. Due to steep slopes access for livestock is severely limited.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Eriogonum umbellatum
Herbaceous (1) Hesperostipa comata ssp. comata
(2) Pleuraphis jamesiiPhysiographic features
This site occurs on steep canyon walls and sides of plateaus and mesas. It typically suffers from excessive runoff from the steep slopes.
Table 2. Representative physiographic features
Landforms (1) Canyon
(2) Valley side
Flooding frequency None Ponding frequency None Elevation 4800 – 5300 ft Slope 30 – 70 % 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
Runoff on this ecological site is typically very high due to steep slopes and shallow discontinuous soil cover. Due to its landscape position, this site is not typically influenced by streams or wetlands.
Soil features
The soils on this site occur as steep canyon walls, the sides of plateaus, mesas, hills and on escarpments. It typically suffers from excessive drainage. Complex geology and topography has created a multitude of soil textures, depths and developments. There are areas of exposed sandstone, shale and mudstone.
Typical taxonomic units in this site include:
SSA 623 Shivwits Area - MU 10 Berzatic family;
SSA 625 Mohave County NE Part - MU 64 a reference pedon for torriorthents.Table 4. Representative soil features
Parent material (1) Colluvium – sandstone and shale
Surface texture (1) Extremely cobbly loam
(2) Extremely cobbly sandy loam
(3) Very bouldery sandy loam
Family particle size (1) Loamy
Drainage class Well drained to somewhat excessively drained Permeability class Very slow to very rapid Soil depth 5 – 60 in Surface fragment cover <=3" 15 – 50 % Surface fragment cover >3" 5 – 20 % Available water capacity
(0-40in)0 – 7 in Calcium carbonate equivalent
(0-40in)5 – 20 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)7.4 – 9 Subsurface fragment volume <=3"
(Depth not specified)5 – 40 % Subsurface fragment volume >3"
(Depth not specified)5 – 10 % Ecological dynamics
For state and transition model see ecological group DX0335X02EESG16, Arizona Strip - Typic Aridic - Limestone Slopes.
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 CommunityThe dominant aspect of this site is a cold desert shrub/grassland. The site is on escarpments on the Moenkopi formation below the Shinarump formation. Due to steep slopes access for livestock is severely limited.
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 120 140 160 Grass/Grasslike 20 50 80 Forb 5 25 40 Tree 4 7 10 Total 149 222 290 Table 6. Ground cover
Tree foliar cover 0-0% Shrub/vine/liana foliar cover 0-10% 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 – – – – >0.5 <= 1 – – – 0-1% >1 <= 2 – – 0-1% – >2 <= 4.5 – 0-5% – – >4.5 <= 13 0-1% – – – >13 <= 40 – – – – >40 <= 80 – – – – >80 <= 120 – – – – >120 – – – – Figure 5. 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 6. 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 7. 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 8. 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 (%) Tree0 Trees 4–10 Utah juniper JUOS Juniperus osteosperma 2–10 – twoneedle pinyon PIED Pinus edulis 2–10 – Shrub/Vine0 120–150 sulphur-flower buckwheat ERUM Eriogonum umbellatum 20–30 – skunkbush sumac RHTR Rhus trilobata 10–30 – Apache plume FAPA Fallugia paradoxa 10–20 – mormon tea EPVI Ephedra viridis 10–20 – rubber rabbitbrush ERNAG Ericameria nauseosa ssp. nauseosa var. glabrata 10–20 – broom snakeweed GUSA2 Gutierrezia sarothrae 10–16 – Bigelow sage ARBI3 Artemisia bigelovii 2–10 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 4–8 – Mexican cliffrose PUME Purshia mexicana 0–6 – banana yucca YUBA Yucca baccata 0–2 – Utah serviceberry AMUT Amelanchier utahensis 0–2 – Nevada jointfir EPNE Ephedra nevadensis 0–2 – Torrey's jointfir EPTO Ephedra torreyana 0–2 – 4 Other Shrubs 0–10 Shrub (>.5m) 2SHRUB Shrub (>.5m) 0–10 – Wyoming big sagebrush ARTRW8 Artemisia tridentata ssp. wyomingensis 0–10 – fourwing saltbush ATCA2 Atriplex canescens 0–10 – Eastern Mojave buckwheat ERFA2 Eriogonum fasciculatum 0–10 – water jacket LYAN Lycium andersonii 0–10 – Sonoran scrub oak QUTU2 Quercus turbinella 0–10 – Mojave sage SAMO3 Salvia mohavensis 0–10 – twistspine pricklypear OPMA2 Opuntia macrorhiza 0–2 – Grass/Grasslike0 20–60 needle and thread HECOC8 Hesperostipa comata ssp. comata 10–30 – James' galleta PLJA Pleuraphis jamesii 10–16 – Indian ricegrass ACHY Achnatherum hymenoides 6–12 – desert needlegrass ACSP12 Achnatherum speciosum 0–2 – squirreltail ELELE Elymus elymoides ssp. elymoides 0–2 – 1 Other Perennial Grasses 0–4 Grass, perennial 2GP Grass, perennial 0–4 – threeawn ARIST Aristida 0–4 – sideoats grama BOCU Bouteloua curtipendula 0–4 – black grama BOER4 Bouteloua eriopoda 0–4 – prairie Junegrass KOMA Koeleria macrantha 0–4 – Forb0 8–32 princesplume STANL Stanleya 6–14 – white sagebrush ARLU Artemisia ludoviciana 0–4 – Brenda's yellow cryptantha CRFL5 Cryptantha flava 2–4 – flatcrown buckwheat ERDE6 Eriogonum deflexum 2–4 – desert trumpet ERIN4 Eriogonum inflatum 0–4 – whitestem blazingstar MEAL6 Mentzelia albicaulis 0–4 – 2 Other Perennial Forbs 2–4 Forb, perennial 2FP Forb, perennial 2–4 – brownfoot ACWR5 Acourtia wrightii 2–4 – buckwheat ERIOG Eriogonum 2–4 – fineleaf hymenopappus HYFI Hymenopappus filifolius 2–4 – beardtongue PENST Penstemon 2–4 – rock goldenrod PEPU7 Petradoria pumila 2–4 – spiny phlox PHHO Phlox hoodii 2–4 – 3 Other Annual Forbs 2–6 Forb, annual 2FA Forb, annual 2–6 – milkvetch ASTRA Astragalus 2–6 – borage BORAG Borago 2–6 – sacred thorn-apple DAWR2 Datura wrightii 2–6 – spurge EUPHO Euphorbia 2–6 – gilia GILIA Gilia 2–6 – desert tobacco NIOBO Nicotiana obtusifolia var. obtusifolia 2–6 – phacelia PHACE Phacelia 2–6 – primrose PRIMU Primula 2–6 – Interpretations
Animal community
This site is not suitable for grazing by livestock due to the steep topography and limited forage production. Access is severely limited by slope and a cover of cobbles and boulders. Erosion hazard is high because of sparse vegetation, steep slopes and rapid runoff.
There is relatively poor diversity within the plant community of this site. Because of the grass component, the site is dominated by grassland wildlife species. However, the site is transitory to almost all species due to lack of available water.
Recreational uses
Steepness of slope and ruggedness of the surface terrain limits recreation use to mainly hiking, wildlife viewing, and photography.
Winters are cold, however, relatively mild spring, fall and summer months are attractive to recreationists.
Wildlife most likely to be found on the site are; Black-tailed jackrabbit, cottontail rabbit, antelope squirrel, deer mouse, coyote, western rattlesnake, gopher snake, black-collared lizard, longnose leopard lizard, short-horned lizard, red tailed hawk, and ravens.Supporting information
Type locality
Location 1: Mohave County, AZ Township/Range/Section T33N R10W S2 General legal description Two possible locations: Coconino County - about 7 miles east of Colorado City - Section 5, T41N, R5W; Mohave County - Trail Canyon about 1 mile North of Parashant Canyon - Section 2, T33N, R10W. 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 05/06/2026 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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