Natural Resources
Conservation Service
Ecological site F035XA121AZ
Shallow Loam 10-14" p.z. Cobbly (JUOS)
Accessed: 11/21/2024
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.
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
AZ CRA 35.1 - Colorado Plateau Mixed Grass Plains
Elevations range from 5100 to 6000 feet and precipitation averages 10 to 14 inches per year. Vegetation includes Stipa species, Indian ricegrass, galleta, and blue grama, fourwing saltbush, winterfat, and cliffrose. 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.
Table 1. Dominant plant species
| Tree |
(1) Juniperus osteosperma |
|---|---|
| Shrub |
(1) Purshia stansburiana |
| Herbaceous |
(1) Bouteloua gracilis |
Physiographic features
Site occurs on footslopes and summits of low hills. Depth is from very shallow to shallow. Surface textures from extremely cobble loam to very gravelly loam. Subsurface textures from very cobbly loam to very cobbly clay loam. pH from 7.4 to 8.4 and hazard of erosion is slight from water and wind.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Mesa (3) Plateau |
|---|---|
| Flooding duration | Extremely brief (0.1 to 4 hours) to very brief (4 to 48 hours) |
| Flooding frequency | None to rare |
| Ponding duration | Very brief (4 to 48 hours) |
| Ponding frequency | None |
| Elevation | 5,200 – 5,500 ft |
| Slope | 1 – 12% |
| Aspect | Aspect is not a significant factor |
Climatic features
50-60% of moisture falls as rain Jul-Sep and is the most effective moisture for plant growth. The remaining moisture comes as snow during the winter.
Mean temperature for the hottest month (Jul) is 72 F; for the coldest month (Jan) is 32 F. Extreme temperatures of 105 F and -28F have been recorded. Long periods with little or no effective moisture are relatively common.
Table 3. Representative climatic features
| Frost-free period (average) | 160 days |
|---|---|
| Freeze-free period (average) | 180 days |
| Precipitation total (average) | 13 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
Soils are very shallow to shallow. Surface textures are Extremely cobbly loam to very gravelly loam. Subsurface textures from very cobbly loam to very cobbly clay loam. pH from 7.4 to 8.4 with Limestone bedrock at 17 to 28 inches and lime content at 40% plus.
Typical taxonomic units include:
SSA-699 Hualapai/Havasupai Area MU's 53 Curhollow and Winona.
Table 4. Representative soil features
| Parent material |
(1)
Residuum
–
limestone
|
|---|---|
| Surface texture |
(1) Extremely cobbly loam (2) Very cobbly loam |
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderate |
| Soil depth | 5 – 20 in |
| Surface fragment cover <=3" | 5 – 15% |
| Surface fragment cover >3" | 10 – 20% |
| Available water capacity (0-40in) |
1 – 2 in |
| Calcium carbonate equivalent (0-40in) |
15 – 35% |
| Electrical conductivity (0-40in) |
2 mmhos/cm |
| Soil reaction (1:1 water) (0-40in) |
7.4 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
2 – 15% |
| Subsurface fragment volume >3" (Depth not specified) |
5 – 10% |
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
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Ecosystem states
State 1 submodel, plant communities
State 1
Historic Natural Plant Community
Community 1.1
Historic Natural Plant Community
Woodland community with an overstory of Utah juniper and Colorado pinyon. Understory species include blue grama, black grama, needleandthread, globemallow, astragalus, Stansbury cliffrose, and running prickly pear.
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 | 110 | 145 | 180 |
| Shrub/Vine | 60 | 80 | 100 |
| Forb | 30 | 40 | 50 |
| Tree | 15 | 20 | 25 |
| Total | 215 | 285 | 355 |
Table 6. Canopy structure (% cover)
| Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.5 | – | – | – | – |
| >0.5 <= 1 | – | – | 0-40% | – |
| >1 <= 2 | – | 2-10% | – | 0-5% |
| >2 <= 4.5 | 0-5% | – | 0-20% | – |
| >4.5 <= 13 | – | 5-20% | – | – |
| >13 <= 40 | 25-35% | – | – | – |
| >40 <= 80 | – | – | – | – |
| >80 <= 120 | – | – | – | – |
| >120 | – | – | – | – |
Additional community tables
Table 7. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Tree
|
||||||
| 1 | 12–16 | |||||
| Utah juniper | JUOS | Juniperus osteosperma | 12–16 | – | ||
| twoneedle pinyon | PIED | Pinus edulis | 12–16 | – | ||
|
Shrub/Vine
|
||||||
| 2 | 30–50 | |||||
| Mexican cliffrose | PUME | Purshia mexicana | 20–40 | – | ||
| banana yucca | YUBA | Yucca baccata | 16–20 | – | ||
| Fremont's mahonia | MAFR3 | Mahonia fremontii | 16–20 | – | ||
| tulip pricklypear | OPPH | Opuntia phaeacantha | 16–20 | – | ||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 12–16 | – | ||
| mormon tea | EPVI | Ephedra viridis | 12–16 | – | ||
| spiny greasebush | GLSPS | Glossopetalon spinescens var. spinescens | 12–16 | – | ||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 12–16 | – | ||
|
Grass/Grasslike
|
||||||
| 3 | 150–250 | |||||
| blue grama | BOGR2 | Bouteloua gracilis | 100–140 | – | ||
| squirreltail | ELELE | Elymus elymoides ssp. elymoides | 16–20 | – | ||
| black grama | BOER4 | Bouteloua eriopoda | 16–20 | – | ||
| sand dropseed | SPCR | Sporobolus cryptandrus | 16–20 | – | ||
| needle and thread | HECOC8 | Hesperostipa comata ssp. comata | 12–16 | – | ||
| Grass-like, perennial | 2GLP | Grass-like, perennial | 12–16 | – | ||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 12–16 | – | ||
| sideoats grama | BOCU | Bouteloua curtipendula | 12–16 | – | ||
|
Forb
|
||||||
| 4 | 10–20 | |||||
| milkvetch | ASTRA | Astragalus | 5–8 | – | ||
| globemallow | SPHAE | Sphaeralcea | 5–8 | – | ||
| Forb, perennial | 2FP | Forb, perennial | 4–6 | – | ||
Interpretations
Animal community
This site is suitable for grazing during any period of the year by cows and calves, stocker cattle, sheep and horses. Prescribed grazing systems can benefit this site by allowing rest periods for the cool season species.
The potential plant community provides a variety of food and cover plants for wildlife. When the vegetation complex retrogresses then unpalatable shrub species increase and the site becomes less usable as a foraging area for some species. Grazing practices that encourage cool season grass species are beneficial to antelope, cottontails and rodents. Shrubs that provide both food and cover should be maintained.
Wildlife factors of Food, Cover, Topography are good but water is scarce in natural springs and potholes.
Recreational uses
Site is located on gently sloping plains and mesa tops which lend themselves to activities such as horseback riding, wildlife observation and hunting.
This site has a variety of spring and summer flowers which are particularly noticeable after good moisture periods. It has good aesthetic appeal when not severely disturbed.
Winters are cold, however, relatively mild spring, fall and summer months are attractive to recreationists.
Wood products
Site Index = 35 - 40
Fuelwood (Cords/Ac) = 4 - 6
Fence Posts (7 foot) /Ac = 15 - 20
Christmas Trees/Ac = 5 - 10
CMAI* per year = 3sq ft/ac
Productivity Class = 1
*CMAI is the "Culmination of Mean Annual Increment" or highest average growth rate of the stand in the units specified.
Other information
Woodland Uses and Management Interpretations
Equipment & Operability Considerations -
Suitable Equipment for:
Harvesting: All kinds
Site Prep: All kinds
Tree Planting: Best to do by hand(shallow soil)
Precommercial Thinning: All kinds
Equipment Limitation:
Slope: None
Unsurfaced Roads: None
Stoniness/rock outcrop: Slight
Water table/flooding: None
Erosion Potential is slight for all uses.
Soil Management:
Compaction potential: Good
Rutting potential: Rutting may occur when wet
Revegetation potential:
Poor - due to shallow, droughty soil
Supporting information
Type locality
| Location 1: Mohave County, AZ | |
|---|---|
| Township/Range/Section | T25N R10W S9 |
| General legal description | Nelson Quad - 4 miles northeast of Peach Springs, north of Highway 66 on the Hualapai Indian Reservation, Arizona |
Contributors
Harmon Hodgkinson
Karlynn Huling
Larry D. Ellicott
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
-
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:
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