Natural Resources
Conservation Service

Ecological site F038XA131AZ

Sandy Loam Upland
12-16" p.z.
Limy, Fine, Gravelly (JUOS)

Last updated: 5/07/2020
Accessed: 09/22/2026

Home / esd CATALOG / MLRA 038X / ecological site F038XA131AZ

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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.

MLRA notes

Major Land Resource Area (MLRA): 038X–Mogollon Transition South

AZ 38.1 – Lower Mogollon Transition

Elevations range from 3000 to 4500 feet and precipitation averages 12 to 16 inches per year. Vegetation includes canotia, one-seed juniper, mesquite, catclaw acacia, jojoba, turbinella oak, ratany, shrubby buckwheat, algerita, skunkbush, tobosa, vine mesquite, bottlebrush squirreltail, grama species, curly mesquite, desert needlegrass and New Mexico feathergrass. The soil temperature regime is thermic and the soil moisture regime is ustic aridic. This unit occurs within the Transition Zone Physiographic Province and is characterized by canyons and structural troughs or valleys. Igneous, metamorphic and sedimentary rock classes occur on rough mountainous terrain in association with less extensive sediment filled valleys exhibiting little integrated drainage.

Ecological site concept

This site resides in alluvium derived from sedimentary geology. It occurs on fan remnants.

Table 1. Dominant plant species

Tree	(1) Juniperus osteosperma
Shrub	(1) Quercus turbinella (2) Purshia stansburiana
Herbaceous	(1) Bouteloua gracilis

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Physiographic features

This site occurs on fan remnants.Slope is 2 to 15 percent. Elevation ranges from 1524 to 1707 meters (5000-5600 ft.).

Table 2. Representative physiographic features

Landforms	(1) Fan (2) Alluvial fan
Elevation	5000 – 5600 ft
Slope	2 – 15 %
Aspect	Aspect is not a significant factor

Climatic features

Precipitation in this common resource area averages 12 to 16 inches annually. The winter-summer rainfall ratio ranges from about 60/40% in the northwest part of the area to 50/50% in the southeast part. Summer rains fall July through September; are from high-intensity, convective thunderstorms. This moisture originates primarily from the Gulf of Mexico, but can come from the remnants of Pacific hurricanes in September. Winter moisture is frontal, originates in the north Pacific, and falls as rain or snow in widespread storms of low intensity and long duration. Snowfall ranges from a trace to 10 inches per year and can occur from November through March. Snow seldom persists for more than a day except on north aspects. May and June are the driest months of the year. Humidity is generally low all year. Average annual air temperatures range from 59 to 70 degrees F (thermic temperature regime). Daytime temperatures in the summer are commonly in the high 90’s. Freezing temperatures are common from October through April, usually during the night or early morning hours. The actual precipitation, available moisture and temperature vary, depending on, region, elevation, rain shadow effect and aspect.

Table 3 Representative climatic features

Frost-free period (average)	230 days
Freeze-free period (average)	290 days
Precipitation total (average)	20 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly average minimum and maximum temperature

Soil features

Site occurs on fan remnants and have an accumulation of calcium carbonate in the B horizon. PH ranges from 7.9 to 8.4.
Soils mapped on this site include: from SSA-697 Mohave County Central Part MU Mextank-87.

Table 4. Representative soil features

Parent material	(1) Alluvium – limestone
Surface texture	(1) Very gravelly sandy loam
Family particle size	(1) Loamy
Drainage class	Moderately well drained to well drained
Permeability class	Moderately slow to moderate
Soil depth	60 – 80 in
Surface fragment cover <=3"	0 – 45 %
Available water capacity (0-40in)	2.5 – 5 in
Calcium carbonate equivalent (0-40in)	5 – 20 %
Subsurface fragment volume <=3" (Depth not specified)	0 – 80 %

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

More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Tree State

2. Shrub State

State 1
Tree State

This site has an overstory comprised of pinyon pine (30%) and juniper (70%). The tree canopy cover is generally 40-55%, but can be higher. The understory is comprised of aproximately 60% shrubs, 30% grasses and 5% each small trees and forbs. Understory species include sideoats grama, muttongrass, blue grama, penstemon, Stansbury cliffrose, turbinella oak and desert ceanothus.

Non-native plant species may be present in minor amounts. Once non-native plants are introduced into the plant community, it is very difficult to eliminate these plants from the site.

State 2
Shrub State

n this community the understory is affected by disturbace that reduces the grass component and shrubs increase and become more dominant. Shrub species that can increase are broom snakeweed, mormon tea, big sage and banana yucca.

Non-native plant species may be present in minor amounts. Once non-native plants are introduced into the plant community, it is very difficult to eliminate these plants from the site.

Transition T1
State 1 to 2

Disturbance that reduces perennial grasses, unmanaged grazing, drought, fire suppression.

Restoration pathway R1
State 2 to 1

Brush removal and possibly tree removal in conjunction with grazing management.

Additional community tables

Supporting information

Type locality

Location 1: Mohave County, AZ
Township/Range/Section	T22N R11W S30
General legal description	Type location is about 2,000 feet south and 850 feet east of the northwest corner of sec. 30, T. 22 N., R. 11 W.

Contributors

Karlynn Huling
Larry D. Ellicott

Approval

Scott Woodall, 5/07/2020

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	09/22/2026
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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:
Perennial plant reproductive capability:

Download reference sheet

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