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Ecological site R035XC306AZ

Clayey Upland
10-14" p.z.

Last updated: 5/20/2025
Accessed: 04/24/2026

Home / esd CATALOG / MLRA 035X / ecological site R035XC306AZ

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General information

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 35.3 – the Colorado Plateau Sagebrush – Grasslands

Elevations range from 4800 to 6700 feet, and precipitation averages 10 to 14 inches. Vegetation includes Wyoming big sagebrush, Utah juniper, Colorado pinyon - cliffrose, Mormon tea, fourwing saltbush, blackbrush, Indian ricegrass, needle and thread, western wheatgrass, Galleta, black grama, blue grama, and sand dropseed. The soil temperature regime is mesic, and the soil moisture regime is ustic 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 ecological site occurs in an upland position on mesas, fans, and plateaus. Slopes range from 0 to 15 percent.
The soil of this site is moderately deep to very deep to any plant root restricting layer. The surface texture of the soil includes clay, cobbly clay, and silty clay. Subsurface horizon textures are predominantly clay to clay loam but occasionally are loam.
The surface soils on this site are shrink swell clays that create large cracks in the surface when the soil is dry.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Artemisia tridentata
Herbaceous	(1) Bouteloua gracilis

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Physiographic features

This ecological site occurs in an upland position on mesas, fans, and plateaus. Slopes range from 0 to 15 percent. The soil of this site is deep to very deep to any plant root restricting layer. Soil cracking is noticable on the soil surface when the soil is dry due to the shrink-swell nature of the soil.

Table 2. Representative physiographic features

Landforms	(1) Mesa (2) Plateau (3) Fan
Flooding frequency	None
Ponding frequency	None
Elevation	4800 – 5800 ft
Slope	0 – 15 %
Aspect	Aspect is not a significant factor

Climatic features

Winter summer moisture ratios range from 70:30 to 60:40. Late spring is usually the driest period, and early fall moisture can be sporadic. Summer rains fall from June through September; moisture originates in the Gulf of Mexico and creates convective, usually brief, intense thunderstorms. Cool season moisture from October through 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 from December through February. Accumulations above 12 inches are not common but can occur. Snow usually lasts for 3-4 days but can persist much longer. Summer daytime temperatures are commonly 95 - 100 F and on occasion exceed 105 F. Winter air temperatures can regularly go below 10 F and have been recorded below - 20 F.

Table 3 Representative climatic features

Frost-free period (average)	170 days
Freeze-free period (average)	190 days
Precipitation total (average)	10 in

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Figure 2. Monthly precipitation range

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Figure 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. <br />
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The cracking clay soil allows the site to capture most of the the prcipitation events when the site is dry, and water can be captured by the cracks in the surface of the soil. If the soil is wet, and the cracks have swelled shut, then the the infiltration is very slow, and most of the rainfall will run off.

Soil features

The surface soils on this site are shrink swell clays that create large cracks in the surface when the soil is dry. The soil of this site is moderately deep to very deep to any plant root restricting layer. The surface texture of the soil includes clay, cobbly clay, and silty clay. Subsurface horizon textures are predominantly clay to clay loam but occasionally are loam. The soil reaction ranges from slightly to moderately alkaline (7.4 to 9.0) and is non to slightly effervescent throughout the soil profile. Permeability is slow to very slow.

Soil survey map unit components correlated to this ecological site include:

SSA 625 Mohave County Area NE part 9-Campanile, 43-Campanile/Padilla;

SSA 715 Fort Defiance Area 18-Chafin, 128-Venadito.

Table 4. Representative soil features

Parent material	(1) Alluvium – sandstone and shale
Surface texture	(1) Clay (2) Cobbly
Family particle size	(1) Clayey
Drainage class	Well drained
Permeability class	Moderately slow to slow
Soil depth	40 – 80 in
Surface fragment cover >3"	0 – 10 %
Available water capacity (0-40in)	8.4 – 9.6 in
Calcium carbonate equivalent (0-40in)	0 – 5 %
Electrical conductivity (0-40in)	0 – 2 mmhos/cm
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	7.4 – 9

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 diagram

Standard diagram

Figure 4. 352 ClayeyUpland S&T

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 text

State 1
Reference State

This state, which includes the Historic Climax Plant Community is a grassland site with scattered shrubs and trees. Plant species most likely to invade or increase on the site are big sagebrush, broom snakeweed, juniper and annuals.

Community 1.1
Native Grassland (HCPC)

Figure 5. 35.3 Clayey Upland

This plant community is dominated by a mixture of both cool and warm season grasses with scattered shrubs, scattered pinyon and juniper and some forbs. Dominant grasses include; blue grama, black grama, sideoats grama, squirreltail and Indian ricegrass. Shrubs include big sagebrush, fourwing saltbush and Mormon tea.

Figure 6. 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	400	600	800
Shrub/Vine	100	160	250
Tree	0	40	75
Forb	10	25	35
Total	510	825	1160

Figure 7. Plant community growth curve (percent production by month). AZ3531 , 35.3 10-14" p.z. all 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	3	17	18	10	19	20	10	1	1	0

State 2
Natives/Introduced State

This site is a grassland with increased shrubs, scattered trees and non-native annual species.

Community 2.1
Shrub/ Grasses

This plant community is similar to the Historic Climax Plant Community (1.1) as a grass dominated site with an increase in shrubs and a few trees. Non-native annuals such as cheatgrass and Russian thistle occur throughout the site.

State 3
Invaded State

This site has a juniper overstory with shrubs dominating the understory and non-native annual species.

Community 3.1
Juniper-Shrub Community

This site has become invaded with Utah juniper, pinyon, big sagebrush and non-native annual species. Perennial grasses have decreased on the site, but are still present. There is an increase in bareground and erosion on the site.

Transition T1A
State 1 to 2

Fire exclusion/Lack of natural fire, favorable precipitation for trees/shrubs, Unmanaged grazing.

Transition T2A
State 2 to 3

Heavy ground disturbance, unmanaged grazing, exclusion of fire.

Restoration pathway R3A
State 3 to 2

Favorable precipitation, managed grazing, fire, range seeding.

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)
Grass/Grasslike
1	Warm Season Perennial Grasses			200–500
	blue grama	BOGR2	Bouteloua gracilis	100–225	–
	sideoats grama	BOCU	Bouteloua curtipendula	75–150	–
	black grama	BOER4	Bouteloua eriopoda	50–150	–
	James' galleta	PLJA	Pleuraphis jamesii	25–75	–
2	Cool Season Perennial Grasses			150–450
	squirreltail	ELELE	Elymus elymoides ssp. elymoides	75–150	–
	needle and thread	HECOC8	Hesperostipa comata ssp. comata	50–125	–
	western wheatgrass	PASM	Pascopyrum smithii	50–125	–
	Indian ricegrass	ACHY	Achnatherum hymenoides	50–125	–
3	Other Grasses			40–100
	threeawn	ARIST	Aristida	10–35	–
	ring muhly	MUTO2	Muhlenbergia torreyi	10–35	–
	spike muhly	MUWR	Muhlenbergia wrightii	10–35	–
	sand dropseed	SPCR	Sporobolus cryptandrus	10–35	–
	Grass, perennial	2GP	Grass, perennial	0–15	–
	Grass, annual	2GA	Grass, annual	0–10	–
Forb
4	Forbs			10–35
	sideoats grama	BOCU	Bouteloua curtipendula	75–150	–
	Forb, annual	2FA	Forb, annual	0–20	–
	Forb, perennial	2FP	Forb, perennial	0–20	–
	globemallow	SPHAE	Sphaeralcea	0–20	–
Shrub/Vine
5	Shrubs			100–250
	black grama	BOER4	Bouteloua eriopoda	75–150	–
	Wyoming big sagebrush	ARTRW8	Artemisia tridentata ssp. wyomingensis	40–125	–
	fourwing saltbush	ATCA2	Atriplex canescens	40–125	–
	jointfir	EPHED	Ephedra	40–125	–
	broom snakeweed	GUSA2	Gutierrezia sarothrae	5–10	–
Tree
6	Trees			0–75
	blue grama	BOGR2	Bouteloua gracilis	112–225	–
	Utah juniper	JUOS	Juniperus osteosperma	0–75	–
	twoneedle pinyon	PIED	Pinus edulis	0–75	–

Table 7. Community 2.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 8. Community 3.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Interpretations

Animal community

This site is suitable for grazing throughout most of the year with shrubs providing forage during the period when snow covers palatable grasses.

Habitat diversity on this site is fair when moderate amounts of shrubs and trees are present. Permanent waters are lacking as are diverse tree species and growth forms. Typical animals on the site include rabbits, mule deer, antelope, various song birds, and raptors.

Recreational uses

The land form of this site is old basalt flows or eroded clay bottoms or swales. This site is a grassland interspersed with shrubs and a few trees. Winters are cold and spring tends to be windy. Late spring, summer, and fall provide attractive recreation weather. Sport hunting is the main activity of this site. Other recreation activities, such as cross country riding, photography, and wildlife observation are incidental.

Wood products

No wood products are produced from this site.

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

Byron Lambeth
Ken Gishi
Larry D. Ellicott
Stephen Cassady
Unknown

Approval

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)	Steve Cassady, Kyle Spencer, Tobiah Salvail
Contact for lead author	State Rangeland Management Specialist, NRCS-Arizona State Office, Phoenix,AZ
Date	04/29/2008
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
None
Presence of water flow patterns:
None
Number and height of erosional pedestals or terracettes:
No pedestals, but turf building is common under long-lived perennial grasses and shrubs.
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground is <50%.
Number of gullies and erosion associated with gullies:
None
Extent of wind scoured, blowouts and/or depositional areas:
None
Amount of litter movement (describe size and distance expected to travel):
Litter does not move appreciably except during the largest storm events.
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface of this site normally seals, developing a very strong cap very resistant to erosion.
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
The surface of soils associated with this site are moderate thin platy structure parting to strong very fine angular blocky; extremely hared, very firm, very sticky, and very plastic. Color is reddish brown (2.5YR 4/4) dry and dark reddish brown (2.5YR 3/4) moist.
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Randomly scattered plants consisting of about 75 percent grasses, 20 percent shrubs and 5 percent forbs promote infiltration and reduce runoff. The average distance to the nearest perennial plant (fetch) ranges from 4 to 8 inches with the majority ranging from 1 to 10 inches but occasionally as far as 20 inches.
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
No compaction layer, although a harder clay layer is encountered about 15 inches below the soil surface.
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:
Grasses (65-80%) >> shrubs (15-30%) > forbs (1-5%)

Sub-dominant:

Other:

Additional:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
In “normal” precipitation years mortality should be no more than 10 percent. During periods of prolonged drought mortality may be much higher, especially on half-shrubs and 80 to 90 percent death on Wyoming big sagebrush has been observed.
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Average annual production on this site is expected to be 700-800 lbs/ac in a year of average precipitation.
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:
Russian thistle (Salsola kali), cheatgrass (Bromus tectorum), and lambsquarter (Chenopodium album) are commonly found in small amounts on the site (< 2 percent). During years of above average winter and spring moisture the composition of these may increase slightly. Severe disturbance may cause an increase in one or all of these plants creating a potential for a shortened fire frequency on the site which could result in crossing a threshold to a state with increased introduced annual plants and fewer native shrubs.
Perennial plant reproductive capability:
All plants native to this site are adapted to the climate and are capable of producing seeds, stolons, and/or rhizomes except during the most severe droughts.

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