Natural Resources
Conservation Service
Ecological site R038XA111AZ
Sandy Bottom
12-16
Last updated: 9/05/2019
Accessed: 04/22/2026
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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): 038X–Mogollon Transition South
AZ 38.1 – Lower Mogollon Transition
Elevations range from 3,000 to 4,500 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 MLRA 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
The Sandy Bottom ecological site occurs as sandy benches along creeks and drainageways and as swales. The site receives extra moisture due to flooding or from run-off of adjacent upland sites.
The soils mapped on this site are deep, and well drained to excessively well drained. They are stream alluvium formed from volcanic, granitic, and limestone sources.Table 1. Dominant plant species
Tree (1) Populus angustifolia
Shrub (1) Rhus trilobata
(2) Eriogonum wrightiiHerbaceous (1) Bouteloua curtipendula
(2) Panicum obtusumPhysiographic features
The Sandy Bottom ecological site occurs as sandy benches along creeks and drainageways and as swales. The site receives extra moisture due to flooding or from run-off of adjacent upland sites.
Table 2. Representative physiographic features
Landforms (1) Swale
Flooding duration Very brief (4 to 48 hours) to brief (2 to 7 days) Flooding frequency Occasional to frequent Elevation 3000 – 4500 ft Slope 0 – 3 % 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 percent in the northwest part of the area to 50/50 percent 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 BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
The Sandy Bottom ecological site receives extra moisture due to flooding or from run-off of adjacent upland sites.
Soil features
The soils mapped on the Sandy Bottom ecological site are deep, and well to excessively well drained. They are stream alluvium formed from volcanic, granitic, and limestone sources. Typical taxonomic units mapped on this site include: SSA-627 Mohave County Southern Part MU Fluvaquents-102; SSA-637 Yavapai County Western Part MU's Cordes Sandy Loam-Cx and LtB; SSA-639 Black Hills-Sedona area MU's Bodecker-400, 401, 415, 419, and 601; SSA-675 San Carlos Indian Reservation MU Bodecker-655; SSA-697 Mohave County Central Part MU's Cordes-22 and Riverwash-22.
Table 4. Representative soil features
Parent material (1) Alluvium – volcanic breccia
Surface texture (1) Sandy loam
(2) Extremely gravelly sandy loam
Family particle size (1) Loamy
Drainage class Well drained to excessively drained Permeability class Moderately rapid to very rapid Soil depth 40 – 60 in Surface fragment cover <=3" 0 – 65 % Calcium carbonate equivalent
(0-40in)0 – 5 % Soil reaction (1:1 water)
(0-40in)7.5 – 8 Subsurface fragment volume <=3"
(Depth not specified)0 – 75 % 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
Custom diagramStandard diagram
Figure 4. MLRA 38.1 (12-16"), Sandy Bottom
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 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe potential plant community is a mixture of trees, shrubs, and perennial grasses. Warm-season and cool-season grasses make up approximately equal percentages of the potential vegetation.
As the site deteriorates from disturbance perennial grasses decline and shrubby species, such as juniper, oak, willows and groundsel, increase or invade to dominate the site, usually with a resultant increase in erosion.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)Grass/Grasslike 480 840 1200 Tree 220 385 550 Shrub/Vine 80 140 200 Forb 48 84 120 Total 828 1449 2070 Figure 6. Plant community growth curve (percent production by month). AZ3811 , 38.1 12-16" p.z. all sites. Growth begins in the spring, most growth occurs in 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 0 1 7 15 20 22 20 10 5 0 0 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Dominant Perennial Grasses 170–500 sideoats grama BOCU Bouteloua curtipendula 70–140 – blue grama BOGR2 Bouteloua gracilis 14–70 – bullgrass MUEM Muhlenbergia emersleyi 35–70 – deergrass MURI2 Muhlenbergia rigens 35–70 – vine mesquite PAOB Panicum obtusum 14–70 – threeawn ARIST Aristida 14–70 – cane bluestem BOBA3 Bothriochloa barbinodis 14–70 – 2 Other perennial grasses 420–600 western wheatgrass PASM Pascopyrum smithii 60–75 – squirreltail ELELE Elymus elymoides ssp. elymoides 60–75 – wildrye ELYMU Elymus 55–70 – New Mexico feathergrass HENE5 Hesperostipa neomexicana 55–70 – muttongrass POFE Poa fendleriana 55–70 – spike dropseed SPCO4 Sporobolus contractus 45–70 – sand dropseed SPCR Sporobolus cryptandrus 50–70 – giant dropseed SPGI Sporobolus giganteus 45–70 – plains bristlegrass SEVU2 Setaria vulpiseta 50–60 – 3 Minor perennial and annual grasses 14–70 saltgrass DISTI Distichlis 3–18 – creeping muhly MURE Muhlenbergia repens 3–18 – tumblegrass SCPA Schedonnardus paniculatus 3–18 – Grass, annual 2GA Grass, annual 2–16 – Forb4 Forbs 28–140 Forb, annual 2FA Forb, annual 14–70 – Forb, perennial 2FP Forb, perennial 14–70 – Shrub/Vine5 Shrubs 70–210 boxelder ACNE2 Acer negundo 8–24 – netleaf hackberry CELAR Celtis laevigata var. reticulata 8–24 – skunkbush sumac RHTR Rhus trilobata 8–24 – plum PRUNU Prunus 8–24 – smooth sumac RHGL Rhus glabra 7–23 – currant RIBES Ribes 7–23 – grape VITIS Vitis 7–23 – bastardsage ERWR Eriogonum wrightii 7–23 – pale desert-thorn LYPA Lycium pallidum 7–23 – Tree6 Trees 280–480 narrowleaf cottonwood POAN3 Populus angustifolia 140–280 – Fremont cottonwood POFR2 Populus fremontii 24–30 – Arizona sycamore PLWR2 Platanus wrightii 20–30 – willow SALIX Salix 20–30 – Arizona walnut JUMA Juglans major 16–24 – Arizona white oak QUAR Quercus arizonica 16–24 – Emory oak QUEM Quercus emoryi 16–24 – Gambel oak QUGA Quercus gambelii 16–24 – Interpretations
Animal community
The Sandy Bottom ecological site is often overused as it has a long, green season, is readily accessible, and has natural water available. Special management is needed to obtain proper use of these areas. Area responds well to Prescribed Grazing practices. The natural water and excellent forage diversity, cover, and long, green seasons make this site good habitat for a variety of species.
Recreational uses
The Sandy Bottom ecological site occurs as sandy benches along creeks and drainages, and the aspect is tree-dominated with grassland openings, and occasional rock outcrop, all of which make it a good recreational area. The summers are warm and the winters are cold. Activities include wildlife observation, photography, hiking, hunting, and horseback riding.
Supporting information
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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