Natural Resources
Conservation Service
Ecological site DX035X03G602
Clay Loam Upland
13-17" p.z.
(PIED, JUOS)
Last updated: 5/20/2025
Accessed: 04/24/2026
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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
This ecological site occurs in Common Resource Area 35.6 - the Colorado Plateau Pinyon-Juniper-Sagebrush
The Common Resource Area occurs within the Colorado Plateau Physiographic Province. Elevations range from 5800 to 7300 feet and precipitation averages 13 to 17 inches per year. Vegetation includes pinyon, juniper, big sagebrush, cliffrose, Mormon tea, muttongrass, prairie junegrass, squirreltail, western wheatgrass, and blue grama. The soil temperature regime is mesic and the soil moisture regime is aridic ustic. 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
The soils grouped on this site are deep to very deep with clay loam surface textures. Subsoil textures are clay loam and clay. This ecological site is located on summits, footslopes, shoulders and fan terraces of hills, mesas and plateaus. It also occurs on alluvial fans and stream terraces. Slopes range from 1 to 10 percent.
Table 1. Dominant plant species
Tree (1) Juniperus osteosperma
(2) Pinus edulisShrub (1) Artemisia tridentata ssp. wyomingensis
Herbaceous (1) Pascopyrum smithii
Legacy ID
F035XF602AZ
Physiographic features
This site is located on summits, footslopes, shoulders and fan terraces of hills, mesas and plateaus. It also occurs on on alluvial fans on valley sides and stream terraces on valley floors. The soil is deep to very deep to any plant root restricting layer. Slope of the ecological site ranges from 1 to 10 percent.
Table 2. Representative physiographic features
Landforms (1) Mesa
(2) Plateau
(3) Terrace
Flooding frequency None Ponding frequency None Elevation 5800 – 7300 ft Slope 1 – 15 % Aspect Aspect is not a significant factor Climatic features
The climate of this Common Resource Area is semiarid with warm summers and cool winters. The mean annual precipitation ranges from 13 – 17 inches, but it is very erratic, often varying substantially from year to year. The majority of the precipitation comes from October through April. This precipitation comes as gentle rain or snow from frontal storms coming out of the Pacific Ocean. Snow is common from November through February. Generally no more than a few inches of snow accumulates, melting within a few days, but may last a week or more. The remaining precipitation comes from July through September as spotty, unreliable and sometimes violent thunderstorms. The moisture for this precipitation originates in the Gulf of Mexico (and the Pacific Ocean in the fall) and flows into the area on the north end of the Mexican monsoon. Late May through late June is generally a dry period. The mean annual air temperature ranges from 47 to 49 degrees Fahrenheit (F). The frost-free period (air temperature > 32 degrees F) ranges from 113 to 144 days (@ 50 percent probability). Strong winds are common, especially in the spring.
Table 3 Representative climatic features
Frost-free period (average) 140 days Freeze-free period (average) 160 days Precipitation total (average) 20 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
The soil moisture on this ecological site comes from precipitation. The site does not benefit significantly from run-on moisture. The clay loam to clay surface texture of the soil allows the site to capture the gentle winter storms and the light summer storms if the site has good vegetative cover. Rapid snowmelt and strong summer thunderstorms will produce runoff, reducing the amount of effective rainfall available for plant production on this site.
Soil features
The soils are deep to very deep with clay loam surface textures. Subsoil textures are clay loam and clay. Parent materials derive mainly from shale alluvium, but also colluvium and residuum from shale, siltstone and sandstone.
Soil survey map unit components correlated with this ecological site include:
SSA-715 Fort Defiance Area AZ/NM 129-VenzuniTable 4. Representative soil features
Parent material (1) Alluvium – shale
Surface texture (1) Clay loam
Family particle size (1) Clayey
Drainage class Moderately well drained to well drained Permeability class Moderate to very slow Soil depth 40 – 60 in Surface fragment cover <=3" 0 – 5 % Surface fragment cover >3" 0 – 5 % Available water capacity
(0-40in)5 – 9.3 in Calcium carbonate equivalent
(0-40in)0 – 10 % Electrical conductivity
(0-40in)0 – 4 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 5 Soil reaction (1:1 water)
(0-40in)7.4 – 8.4 Ecological dynamics
An ecological site is not a precise assemblage of species for which the proportions are the same from place to place or from year to year. In all plant communities, variability is apparent in productivity and occurrence of individual species. Spatial boundaries of the communities; however, can be recognized by characteristic patterns of species composition, association, and community structure. The historic climax plant community for this ecological site has been described by sampling relict or relatively undisturbed sites and/or reviewing historic records. The historic climax plant community is the plant community that evolved over time with the soil forming process and long term changes in climatic conditions of the area. It is the plant community that was best adapted to the unique combination of environmental factors associated with the site.
Natural disturbances, such as drought, fire, grazing of native fauna, and insects, are inherent in the development and maintenance of these plant communities. The effects of these disturbances are part of the range of characteristics of the ecological site. Fluctuations in plant community structure and function caused by the effects of natural disturbances help establish the boundaries and characteristics of an ecological site. They are accounted for as part of the range of characteristics of the ecological site. Recognizable plant community phases are identified in the reference state of the ecological site. Some sites may have a small range of variation, while others have a large range. Some plant community phases may exist for long periods of time, while others may only occur for a couple of years after a disturbance.
Deterioration of the plant community, hydrology, or soil site stability on an ecological site can result in crossing a threshold or potentially irreversible boundary to another state, or equilibrium. This can occur as a result of the loss of soil surface through erosion, the loss of the stability of the site due to disturbances that cause active erosion on the site, increases in the amounts and/or patterns or runoff from rainstorms, changes in availability of surface and subsurface water, significant changes in plant structural and functional types, or the introduction of non-native species. When these thresholds are crossed, the potential of the ecological site to return to the historic climax plant community can be lost, or restoration will require significant inputs . There may be multiple states possible for an ecological site, determined by the type and or severity of disturbance.
The known states and transition pathways for this ecological site are described in the state and transition model. Within each state, there may be one or more known plant community phases. These community phases describe the different plant community that can be recognized and mapped across this ecological site. The state and transition model is intended to help land users recognize the current plant community on the ecological site, and the management options for improving the plant community to the desired plant community.
Plant production information in this site description is standardized to the annual production on an air-dry weight basis in near normal rainfall years.
State and transition model
Custom diagramStandard diagram
Figure 4. State and Transition Model - F05XF602AZ
More interactive model formats are also available. View Interactive Models
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
Reference StateThis is a forest site and is dominated by juniper and pinyon trees with a canopy of 30 to 50 percent. The plant community composition for production is mostly trees (40%), grasses (30%), shrubs (25%) and forbs (5%).
Community 1.1
Pinyon/Juniper - Big sagebrush - Western wheatgrass
The dominant aspect of the site is a Colorado pinyon and Utah juniper woodland with understory of cool season grasses and large shrubs. Major grasses include western wheatgrass, blue grama, squirreltail and muttongrass. Dominant shrubs are Wyoming big sagebrush, Stansbury cliffrose, and antelope bitterbrush.
Figure 5. 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)Tree 200 250 350 Grass/Grasslike 150 225 300 Shrub/Vine 100 175 250 Forb 25 50 75 Total 475 700 975 Community 1.2
Pinyon/Juniper Overstory & Mixed ShrubsThis plant community is characterized by a woodland overstory with mixed shrubs and scattered perennial grasses and forbs. Dominant shrubs are cliffrose, rabbitbrush, big sagebrush, black sagebrush, yucca, snakeweed and antelope bitterbrush. Dominant grasses include muttongrass, blue grama, prairie junegrass and western wheatgrass may or not be present.
Pathway 1.2a
Community 1.2 to 1.1Prescribed grazing, favorable climate/moisture, tree thinning – woodcutting or insect infestation (bark beetle)
State 2
Eroded StateCommunity 2.1
PInyon/Juniper with Sparse UnderstoryThis plant community is characterized by an eroded surface with a woodland overstory of pinyon and juniper and a sparse understory of shrubs, very few grasses and forbs. There is high bare ground in this plant community due to a loss of perennial and shrub cover. The soil surface is eroded and increased rills and sheet flow on steeper slopes. This has potential for compacted soils due to low rock fragments and trailing/hoof actions for continuous livestock use.
Restoration pathway R2A
State 2 to 1Unknown, possible mechanical treatment along with range seeding, prescribed grazing/ no grazing
Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Dominant Grasses 70–140 western wheatgrass PASM Pascopyrum smithii 70–140 – 2 Codominate Grasses 70–140 Indian ricegrass ACHY Achnatherum hymenoides 21–42 – blue grama BOGR2 Bouteloua gracilis 21–42 – squirreltail ELEL5 Elymus elymoides 21–42 – muttongrass POFE Poa fendleriana 21–42 – 3 Miscellaneous Grasses 7–35 Grass, annual 2GA Grass, annual 0–14 – Grass, perennial 2GP Grass, perennial 0–14 – prairie Junegrass KOMA Koeleria macrantha 0–14 – spike muhly MUWR Muhlenbergia wrightii 0–14 – sideoats grama BOCU Bouteloua curtipendula 0–7 – White Mountain sedge CAGE Carex geophila 0–7 – Forb4 Common Forbs 7–35 pingue rubberweed HYRI Hymenoxys richardsonii 1–14 – tansyaster MACHA Machaeranthera 1–14 – globemallow SPHAE Sphaeralcea 1–14 – 5 Other Forbs 7–35 Forb, annual 2FA Forb, annual 0–7 – Forb, perennial 2FP Forb, perennial 0–7 – rose heath CHER2 Chaetopappa ericoides 0–7 – trailing fleabane ERFL Erigeron flagellaris 0–7 – buckwheat ERIOG Eriogonum 0–7 – scarlet gilia IPAG Ipomopsis aggregata 0–7 – flatspine stickseed LAOC3 Lappula occidentalis 0–7 – Wright's deervetch LOWR Lotus wrightii 0–7 – beardtongue PENST Penstemon 0–7 – woolly plantain PLPA2 Plantago patagonica 0–7 – Shrub/Vine6 Dominant Shrubs 105–175 Wyoming big sagebrush ARTRW8 Artemisia tridentata ssp. wyomingensis 35–105 – Stansbury cliffrose PUST Purshia stansburiana 7–35 – antelope bitterbrush PUTR2 Purshia tridentata 7–35 – 7 Other Shrubs 35–70 Utah serviceberry AMUT Amelanchier utahensis 0–14 – black sagebrush ARNO4 Artemisia nova 0–14 – perennial cornflower CEMO Centaurea montana 0–14 – snakeweed GUTIE Gutierrezia 0–14 – mormon tea EPVI Ephedra viridis 0–14 – rubber rabbitbrush ERNA10 Ericameria nauseosa 0–7 – plains pricklypear OPPO Opuntia polyacantha 0–7 – banana yucca YUBA Yucca baccata 0–7 – longflower rabbitbrush CHDE2 Chrysothamnus depressus 0–7 – Greene's rabbitbrush CHGR6 Chrysothamnus greenei 0–7 – Whipple cholla CYWH Cylindropuntia whipplei 0–7 – Shrub (>.5m) 2SHRUB Shrub (>.5m) 0–7 – Tree9 Trees 210–280 Utah juniper JUOS Juniperus osteosperma 70–140 – twoneedle pinyon PIED Pinus edulis 70–140 – Gambel oak QUGA Quercus gambelii 0–35 – Table 7. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Other references
Updates and revisions for this ESD were conducted as part of a 2007-2012 Interagency Technical Assistance Agreement between the Bureau of Indian Affairs–Navajo Region and the NRCS-Arizona.
Contributors
Dan Carroll
Ken Gishi
Kenneth GishiApproval
Kendra Moseley, 5/20/2025
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 04/24/2026 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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