Natural Resources
Conservation Service
Ecological site R039XA130AZ
Loamy Bottom
17-22" p.z.
Last updated: 9/05/2019
Accessed: 09/20/2026
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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.Associated sites
R039XA131AZ Loamy Bottom 17-22" p.z. Subirrigated
R039XA137AZ Loamy Upland 17-22" p.z. Subirrigated
R039XA138AZ Clay Loam Upland 17-22 p.z.
Similar sites
R039XA129AZ Clay Bottom 17-22"
Table 1. Dominant plant species
Tree (1) Pinus ponderosa
Shrub (1) Ericameria nauseosa ssp. nauseosa var. glabrata
Herbaceous (1) Muhlenbergia wrightii
(2) Poa compressaPhysiographic features
This site occurs on valley floors as narrow to broad drainageways. The site does benefit from run-in moisture from adjacent areas.
Table 2. Representative physiographic features
Landforms (1) Alluvial flat
(2) Drainageway
Flooding duration Very brief (4 to 48 hours) to brief (2 to 7 days) Flooding frequency None to occasional Ponding duration Brief (2 to 7 days) to long (7 to 30 days) Ponding frequency Occasional to frequent Elevation 6000 – 8000 ft Slope 0 – 2 % Ponding depth 0 – 1 in Water table depth 14 – 40 in 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
This site experiences occasional to frequent ponding, the duration ranging from brief to long. It experiences non to occasional flooding, the duration ranging from very brief to brief.
Soil features
The soils in this site are very deep. Surface textures include loam to about 3 inches thick. Subsurface textures include gravelly clay loam, very gravelly clay and sandy clay. Hazard of erosion is moderate. Typical taxonomic units include: from SSA-695 Kaibab NF area MU's 3-Crossplain Family.
Table 4. Representative soil features
Surface texture (1) Loam
Family particle size (1) Clayey
Drainage class Poorly drained to somewhat poorly drained Permeability class Moderately slow to slow Soil depth 60 – 70 in Surface fragment cover <=3" 0 – 35 % Available water capacity
(0-40in)0.14 – 0.21 in Calcium carbonate equivalent
(0-40in)0 – 1 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 2 Soil reaction (1:1 water)
(0-40in)7.4 – 7.8 Subsurface fragment volume <=3"
(Depth not specified)0 – 35 % 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: spike muhly, canada bluegrass, scattered ponderosa pine, and scattered rubber rabbitbrushThis state is grass dominant with scattered trees and shrubs.
Community 1.1
Historic Climax Plant CommunityThe historic climax plant community of this site is dominated by a variety of grasses and forbs.
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 720 740 760 Forb 40 60 80 Shrub/Vine 0 8 16 Tree 0 4 8 Total 760 812 864 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: rubber rabbitbrushThis state shows a decrease in grass and an increase in rubber rabbitbrush.
Transition T1A
State 1 to 2Excessive disturbance such as periodic fire, ground disturbing recreation, and continuous, season-long grazing will cause a threshold to be crossed to a rubber rabbitbrush state.
Restoration pathway R2A
State 2 to 1An increase in soil organic carbon and a decrease in bare ground will help restore the system.
Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Tree0 0–6 ponderosa pine PIPO Pinus ponderosa 0–6 – Shrub/Vine0 0–30 rubber rabbitbrush ERNAG Ericameria nauseosa ssp. nauseosa var. glabrata 0–13 – pingue rubberweed HYRI Hymenoxys richardsonii 0–13 – Woods' rose ROWOW Rosa woodsii var. woodsii 0–6 – 3 6–25 aster ASTER Aster 6–13 – cinquefoil POTEN Potentilla 0–6 – sandwort ARENA Arenaria 0–6 – Grass/Grasslike0 150–375 spike muhly MUWR Muhlenbergia wrightii 98–195 – deergrass MURI2 Muhlenbergia rigens 32–65 – mountain muhly MUMO Muhlenbergia montana 0–32 – pine dropseed BLTR Blepharoneuron tricholepis 0–32 – Ross' sedge CARO5 Carex rossii 6–20 – rush JUNCU Juncus 6–20 – Grass, annual 2GA Grass, annual 6–13 – little bluestem SCSC Schizachyrium scoparium 0–6 – nodding brome BRAN Bromus anomalus 0–6 – 1 115–240 Canada bluegrass POCO Poa compressa 98–162 – slender wheatgrass ELTRT Elymus trachycaulus ssp. trachycaulus 6–20 – western wheatgrass PASM Pascopyrum smithii 6–20 – squirreltail ELELE Elymus elymoides ssp. elymoides 6–13 – Arizona fescue FEAR2 Festuca arizonica 0–6 – prairie Junegrass KOMA Koeleria macrantha 0–6 – Fendler's threeawn ARPUF Aristida purpurea var. fendleriana 0–6 – muttongrass POFE Poa fendleriana 0–6 – 2 10–65 mat muhly MURI Muhlenbergia richardsonis 0–32 – blue grama BOGR2 Bouteloua gracilis 8–20 – tufted hairgrass DECE Deschampsia cespitosa 0–13 – Forb0 25–105 iris IRIS Iris 6–13 – Lewis flax LILE3 Linum lewisii 6–13 – western yarrow ACMIO Achillea millefolium var. occidentalis 6–13 – pussytoes ANTEN Antennaria 6–13 – white sagebrush ARLU Artemisia ludoviciana 0–6 – milkvetch ASTRA Astragalus 0–6 – thistle CIRSI Cirsium 0–6 – horsetail EQUIS Equisetum 0–6 – redroot buckwheat ERRA3 Eriogonum racemosum 0–6 – strawberry FRAGA Fragaria 0–6 – lupine LUPIN Lupinus 0–6 – dock RUMEX Rumex 0–6 – Interpretations
Animal community
This site is suitable for all classes of livestock for spring through fall grazing use. The site will produce substantial amounts of high quality forage in average precipitation years. This site responds relatively quickly to good management. It adapts well to grazing systems which provide for an occasional rest. Proper stocking rates are important. This site is very susceptible to erosion, particularly overgrazed areas, old roads, cattle trails, and concentration areas.
This site offers a fair diversity in the vegetative complex for wildlife. In higher condition classes the site is most suitable to grassland wildlife species. As retrogression occurs the woody species increase and wildlife species utilizing the site may change.Hydrological functions
This site acts as a buffer strip between the uplands and wash channels. therefore it is important to keep this site well vegetated to protect water quality.
Recreational uses
This site has a variety of summer flowers. It has excellent aesthetic appeal because of the open grassland appearance.
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: Coconino County, AZ Township/Range/Section T21N R5E S20 General legal description Garland Prairie 7 1/2 Min. Quad, Camp Navajo, SE1/4 NE1/4 Sec 20 T21N R5E, Coconino County, AZ. Contributors
Larry D. Ellicott
Stephen CassadyApproval
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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