Natural Resources
Conservation Service
Ecological site R039XA105AZ
Shallow Loamy
17-22" p.z.
Last updated: 9/05/2019
Accessed: 10/03/2026
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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): 039X–Mogollon Transition North
AZ 39.1 Mogollon Plateau Coniferous Forests
Elevations range from 7000 to 12,500 feet and precipitation averages 20 to 35 inches per year. Vegetation includes ponderosa pine, Gambel oak, Arizona walnut, sycamore, Douglas fir, blue spruce, Arizona fescue, sheep fescue, mountain muhly, muttongrass, junegrass, pine dropseed, and dryland sedges. The soil temperature regime ranges from mesic to frigid and the soil moisture regime ranges from typic ustic to udic 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.Table 1. Dominant plant species
Tree (1) Pinus ponderosa
(2) Pinus edulisShrub (1) Ceanothus fendleri
(2) Rosa woodsiiHerbaceous (1) Muhlenbergia montana
(2) Bouteloua gracilisPhysiographic features
This site occurs in an upland position on open rocky slopes and ridgetops. It neither benefits from run-in moisture nor suffers excessively from run-off.
Table 2. Representative physiographic features
Landforms (1) Ridge
Elevation 6500 – 8000 ft Slope 5 – 40 % Aspect Aspect is not a significant factor Climatic features
About 40% of the moisture in this Common Resource Area (CRA), or Land Resource Unit (LRU) comes as rain from June to September. The remainder comes from October to May as snow or light rain. Extreme temperatures of 97 and -37 degrees Fahrenheit have been recorded. Some moisture is usually received every month.
Table 3 Representative climatic features
Frost-free period (average) 170 days Freeze-free period (average) 120 days Precipitation total (average) 20 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
The soils on this site are very shallow (5-10") and shallow (10-20"), they formed in alluvium derived mainly from hard tuff. Surface textures include fine sandy loam, cobbly sandy loam, cobbly loam, sandy loam or loam and are about five inches thick. Subsurface textures include loam, sandy clay loam or clay loam with over 50 percent rock fragments. Plant-soil moisture relationships are poor and the content of soluble salts is low.
Typical taxonomic units include: SSA 635 Apache County central part - MU's BsE and BuC Bushvalley loam and cobbly sandy loam (warm phase).Table 4. Representative soil features
Parent material (1) Alluvium – welded tuff
Surface texture (1) Fine sandy loam
(2) Cobbly sandy loam
(3) Cobbly loam
Family particle size (1) Loamy
Drainage class Moderately well drained to well drained Permeability class Slow to moderately slow Soil depth 5 – 20 in Surface fragment cover <=3" 45 – 80 % Soil reaction (1:1 water)
(0-40in)6.5 – 7 Subsurface fragment volume <=3"
(Depth not specified)50 – 60 % Ecological dynamics
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
Grass Dominant Plant Community: pine dropseed, mountain muhly, blue gramaGrass Dominant Community. This ecological site is dominated by warm-season grasses such as pine dropseed, mountain muhly, and blue grama. There are some scattered ponderosa pine along with pinyon and juniper.
Community 1.1
Historic Climax Plant CommunityThis site has a plant community made up primarily of mid grasses with lesser amounts of forbs, shrubs and trees. In the potential plant community there is a mixture of both cool and warm season grasses.
Plant species most likely to increase as retrogression occurs on the site, are Arizona fescue, bottlebrush squirreltail and alligator juniper. Kentucky bluegrass invades the site as deterioration occurs.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 750 800 850 Tree 120 150 180 Forb 50 75 100 Shrub/Vine 10 30 50 Total 930 1055 1180 Figure 5. Plant community growth curve (percent production by month). AZ3911 , 39.1 17-22" p.z. all sites. 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 5 10 10 10 20 20 20 5 0 0 State 2
Shrub Dominant Plant Community with increased alligator juniperTransition T1
State 1 to 2Continuous, season-long herbivory which decreases the growth and colonization of some plant species.
Restoration pathway R1
State 2 to 1Prescribed grazing where decreaser species such as pine dropseed and mountain muhly may colonize, establish healthy root systems, and hold the soil in place.
Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Tree0 100–200 ponderosa pine PIPO Pinus ponderosa 0–50 – twoneedle pinyon PIED Pinus edulis 10–30 – alligator juniper JUDE2 Juniperus deppeana 20–30 – Utah juniper JUOS Juniperus osteosperma 10–20 – oneseed juniper JUMO Juniperus monosperma 5–10 – Shrub/Vine0 10–50 Fendler's ceanothus CEFE Ceanothus fendleri 10–50 – Woods' rose ROWOW Rosa woodsii var. woodsii 10–50 – Grass/Grasslike0 750–850 mountain muhly MUMO Muhlenbergia montana 150–250 – blue grama BOGR2 Bouteloua gracilis 50–150 – sedge CAREX Carex 0–100 – pine dropseed BLTR Blepharoneuron tricholepis 50–100 – Arizona fescue FEAR2 Festuca arizonica 20–80 – Idaho fescue FEID Festuca idahoensis 20–80 – Canada bluegrass POCO Poa compressa 25–75 – muttongrass POFE Poa fendleriana 25–75 – squirreltail ELELE Elymus elymoides ssp. elymoides 30–50 – spike muhly MUWR Muhlenbergia wrightii 0–30 – sheep fescue FEOV Festuca ovina 10–20 – threeawn ARIST Aristida 0–20 – Forb0 50–100 globemallow SPHAE Sphaeralcea 5–10 – Forb, annual 2FA Forb, annual 5–10 – geranium GERAN Geranium 5–10 – sunflower HELIA3 Helianthus 5–10 – pea LATHY Lathyrus 5–10 – lupine LUPIN Lupinus 5–10 – cinquefoil POTEN Potentilla 3–8 – scarlet gilia IPAGF Ipomopsis aggregata ssp. formosissima 3–8 – yarrow ACHIL Achillea 3–8 – milkvetch ASTRA Astragalus 3–8 – Indian paintbrush CASTI2 Castilleja 3–8 – Interpretations
Animal community
This site is well suited for all classes of livestock. It is used primarily for late spring, summer and early fall grazing. Prescribed Grazing systems are essential to maintain the plant community balance on the site. Steeper slopes occurring within the site will require special management practices to encourage utilization.
This site has relatively poor habitat diversity in the native plant community. It is primarily adapted to grassland wildlife species except at the edge of timber where it is utilized by many species. Large game animals are migratory onto the site primarily for summer use.Recreational uses
This site has a variety of summer flowers. It has excellent aesthetic appeal because of the open grassland appearance, which is adjacent to a distinct timber edge..
Summers are cool and pleasant but winters are harsh and cold.
Hunting, camping, hiking, cross country skiing, photography and wildlife observation are favorite activities.
Supporting information
Type locality
Location 1: Apache County, AZ Township/Range/Section T5N R30E S2 General legal description About 1/4 mile North West of Alpine, AZ. Contributors
Larry D. Ellicott
Steve BarkerApproval
Scott Woodall, 9/05/2019
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 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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