Natural Resources
Conservation Service
Ecological site R030XC321AZ
Sandy Loam Upland 10-13" p.z. Fine
Last updated: 10/21/2024
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): 030X–Mojave Basin and Range
This unit occurs within the Basin and Range Province and is characterized by broad basins, valleys, and old lakebeds. Widely spaced mountains trending north to south occur throughout the area. Isolated, short mountain ranges are separated by an aggraded desert plain. The mountains are fault blocks that have been tilted up. Long alluvial fans coalesce with dry lakebeds between some of the ranges.
LRU notes
AZ LRU 30-3 – Upper Mohave Desert
Elevations range from 2800 to 4500 feet and precipitation averages 9 to 12 inches per year. Vegetation includes Joshua tree, blackbrush, creosotebush, ratany, bush muhly, big galleta, black grama, desert needlegrass, and Indian ricegrass. The soil temperature regime is thermic and the soil moisture regime is typic aridic.
Ecological site concept
This ecological site is located on gently sloping uplands. Soils are non-calcareous, moderately deep to deep. Textures range from sandy loam to gravelly loamy sand, and/or fine sandy loam.
Associated sites
| R030XC305AZ |
Coarse Sandy Loam 10-13" p.z. |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
(1) Pleuraphis rigida |
Physiographic features
This ecological site is found in an upland position on shoulders, summits and sideslopes of fan terraces.
Table 2. Representative physiographic features
| Landforms |
(1)
Terrace
(2) Fan |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 2,400 – 4,000 ft |
| Slope | 1 – 12% |
| Aspect | Aspect is not a significant factor |
Climatic features
The climate is arid and warm. Annual precipitation ranges from 10 to 13 inches. About 65 percent of the rainfall comes from October through May as gentle rain from Pacific storms which may last for a couple of days. The rest of the rainfall comes during the summer monsoon season from July through September as spotty, brief, intense thunderstorms. Snow rarely falls, and only remains on the ground a few hours at most. Annual air temperature ranges from 46 to 76 degrees F. The average frost-free period ranges from 121 to 231 days.
Table 3. Representative climatic features
| Frost-free period (average) | 231 days |
|---|---|
| Freeze-free period (average) | 269 days |
| Precipitation total (average) | 13 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
The soil of this ecological site is deep to very deep with surface textures of sandy loam, gravelly sandy loam and gravelly loam. Subsoil textures are sandy clay loam, coarse sandy loam, gravelly sandy loam, gravelly sandy clay loam, very gravelly sandy loam, sandy loam, extremely gravelly sand, and gravelly loamy sand. The soil parent material is alluvium from granite and igneous rocks. Geologic formation varies. Soil available water capacity is moderate to high. The soil's erosion hazard from water is slight to moderate and from wind is slight. The soil is non-sodic, non-saline with pH of 7.4-8.0 (mildly to moderately alkaline). The soil moisture regime is typic aridic and temperature regime is thermic.
A typical soil profile is:
A-0 to 4 inches; gravelly loamy sand
BA-4 to 10 inches; gravelly sandy loam
2Bt1-10 to 26 inches; gravelly sandy clay
2Bt2-26 to 40 inches; gravelly sandy clay loam
3Bkn-40 to 60 inches; very gravelly sand
Soil taxonomic classifications include Fine, mixed, superactive, thermic Typic Haplargids; Fine-loamy, mixed, superactive, thermic Ustic Haplargids; Fine-loamy, mixed, superactive, thermic Typic Haplargids; Fine, mixed, superactive, thermic Ustic Haplargids.
Soil mapping units correlated to this ecological site are 627125, Vekol family, Mohave County, AZ, Southern Part and 697057, 627090, 697165, Courtland family, Dutchflat, Whitehouse soils, Mohave County, AZ, Central Part.
Table 4. Representative soil features
| Parent material |
(1)
Alluvium
–
granite
|
|---|---|
| Surface texture |
(1) Gravelly sandy loam (2) Gravelly loam (3) Sandy loam |
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately slow to moderate |
| Soil depth | 60 in |
| Surface fragment cover <=3" | 20 – 45% |
| Surface fragment cover >3" | Not specified |
| Available water capacity (0-40in) |
5 – 7 in |
| Calcium carbonate equivalent (0-40in) |
2 – 10% |
| Electrical conductivity (0-40in) |
Not specified |
| Sodium adsorption ratio (0-40in) |
Not specified |
| Soil reaction (1:1 water) (0-40in) |
7.4 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
20 – 70% |
| Subsurface fragment volume >3" (Depth not specified) |
5% |
Ecological dynamics
Sandy Loam Upland, Fine, 10"-13" p.z., is a grass-shrubland ecological site. Shrubs are well-dispersed across the site. Annual forbs and grasses flourish following rainfall. Natural disturbances are rare. After introduction of non-native annuals (forbs and/or grasses), the shift in total productivity is shift increased seasonal herbaceous production following periods of rain. Continuous, yearlong, livestock grazing will remove the perennial grass dominance.
State and transition model
More interactive model formats are also available.
View Interactive Models
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State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Historic Climax Plant Community
Community 1.1
Historic Climax Plant Community
The dominant aspect of this plant community is a desert grassland with shrubs. Major grasses are big galleta, bush muhly and black grama. Shrubs include fourwing saltbush, range ratany (Krameria erecta), Anderson wolfberry Lycium Andesonii), rayless goldenhead and buckhorn cholla.
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 | 56 | 165 | 417 |
| Shrub/Vine | 38 | 115 | 313 |
| Forb | 6 | 20 | 70 |
| Total | 100 | 300 | 800 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 0-2% |
| Grass/grasslike foliar cover | 1-3% |
| Forb foliar cover | 0% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0% |
Table 7. Canopy structure (% cover)
| Height Above Ground (ft) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.5 | – | – | – | 0-2% |
| >0.5 <= 1 | – | – | – | – |
| >1 <= 2 | – | – | 8-12% | – |
| >2 <= 4.5 | – | 8-12% | – | – |
| >4.5 <= 13 | – | – | – | – |
| >13 <= 40 | – | – | – | – |
| >40 <= 80 | – | – | – | – |
| >80 <= 120 | – | – | – | – |
| >120 | – | – | – | – |
Figure 5. Plant community growth curve (percent production by month). AZ3024, 30.3 10-13" p.z. upland sites. Growth begins in the spring and continues through 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 | 1 | 8 | 18 | 18 | 11 | 14 | 20 | 8 | 2 | 0 | 0 |
State 2
Historic Native Plant Community plus Introduced Annuals
Community 2.1
Non-native Annuals
This plant community resembles the historic native plant community, but exotic annuals have been introduced. Non-native species include wild oat, red brome, Mediterranean grass (Schismus spp.), and filaree. The flourish of non-native annuals that occurs following rainfalls may preclude native annuals.
State 3
Shrubland
Community 3.1
Shrubs and Annuals
Perennial grass canopy cover is reduced and largely absent. Shrub density and cover has increased. Native and non-native annual forbs and grasses dominate the plant community following rainfall. Remnant perennial grasses will not be able to re-colonize; removal of grazing pressure will allow existing perennial grasses to regain vigor.
Transition T1A
State 1 to 2
Introduction of non-native annual forb and grass seed.
Transition T1B
State 1 to 3
Yearlong continuous livestock grazing. Introduction of non-native annual forb and grass seed.
Transition T2A
State 2 to 3
Yearlong continuous livestock grazing.
Restoration pathway R3A
State 3 to 2
Prescribed grazing/no grazing. Range seeding may accelerate establishment of perennial grasses and desirable shrubs.
Additional community tables
Table 8. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 45–75 | |||||
| big galleta | PLRI3 | Pleuraphis rigida | 45–75 | – | ||
| 2 | 15–30 | |||||
| black grama | BOER4 | Bouteloua eriopoda | 15–30 | – | ||
| 3 | 15–30 | |||||
| bush muhly | MUPO2 | Muhlenbergia porteri | 15–30 | – | ||
| 4 | 3–6 | |||||
| Parish's threeawn | ARPUP5 | Aristida purpurea var. parishii | 3–6 | – | ||
| 5 | 0–6 | |||||
| sand dropseed | SPCR | Sporobolus cryptandrus | 0–6 | – | ||
| 6 | 3–15 | |||||
| spike dropseed | SPCO4 | Sporobolus contractus | 3–15 | – | ||
| 7 | 0–6 | |||||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 0–6 | – | ||
| 8 | 3–15 | |||||
| Grass, perennial | 2GP | Grass, perennial | 3–15 | – | ||
| 9 | 3–15 | |||||
| Grass, annual | 2GA | Grass, annual | 3–15 | – | ||
|
Forb
|
||||||
| 10 | 3–15 | |||||
| desert globemallow | SPAM2 | Sphaeralcea ambigua | 3–15 | – | ||
| 11 | 3–9 | |||||
| Forb, perennial | 2FP | Forb, perennial | 3–9 | – | ||
| 12 | 3–12 | |||||
| Forb, annual | 2FA | Forb, annual | 3–12 | – | ||
|
Shrub/Vine
|
||||||
| 13 | 3–15 | |||||
| fourwing saltbush | ATCA2 | Atriplex canescens | 3–15 | – | ||
| 14 | 0–6 | |||||
| Eastern Mojave buckwheat | ERFAP | Eriogonum fasciculatum var. polifolium | 0–6 | – | ||
| 15 | 3–9 | |||||
| Mexican bladdersage | SAME | Salazaria mexicana | 3–9 | – | ||
| 16 | 3–15 | |||||
| rayless goldenhead | ACSP | Acamptopappus sphaerocephalus | 3–15 | – | ||
| 17 | 3–6 | |||||
| Nevada jointfir | EPNE | Ephedra nevadensis | 3–6 | – | ||
| 18 | 0–15 | |||||
| broom snakeweed | GUSA2 | Gutierrezia sarothrae | 0–15 | – | ||
| 19 | 3–9 | |||||
| burrobrush | HYSA | Hymenoclea salsola | 3–9 | – | ||
| 20 | 3–15 | |||||
| littleleaf ratany | KRER | Krameria erecta | 3–15 | – | ||
| 21 | 3–15 | |||||
| water jacket | LYAN | Lycium andersonii | 3–15 | – | ||
| 22 | 3–9 | |||||
| banana yucca | YUBA | Yucca baccata | 3–9 | – | ||
| 23 | 3–15 | |||||
| banana yucca | YUBA | Yucca baccata | 3–15 | – | ||
| 24 | 0–3 | |||||
| beavertail pricklypear | OPBA2 | Opuntia basilaris | 0–3 | – | ||
| 25 | 3–9 | |||||
| branched pencil cholla | CYRA9 | Cylindropuntia ramosissima | 3–9 | – | ||
| 26 | 3–15 | |||||
| Shrub, other | 2S | Shrub, other | 3–15 | – | ||
Interpretations
Supporting information
Contributors
Harmon Hodgkinson
Harmon S. Hodgkinson
Karlynn Huling
Larry D. Ellicott
Stephen Cassady
Approval
Kendra Moseley, 10/21/2024
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 | 10/22/2024 |
| Approved by | Kendra Moseley |
| 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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