Natural Resources
Conservation Service
Ecological site R030XB206AZ
Cobbly Limy Upland 6-9" p.z. Deep
Last updated: 10/21/2024
Accessed: 12/22/2024
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 30-2 – Middle Mohave Desert
Elevations range from 1500 to 3200 feet and precipitation averages 6 to 9 inches per year. Vegetation includes creosotebush, white bursage, yucca, prickly pear and cholla species, Mormon tea, flattop buckwheat, ratany, winterfat, bush muhly, threeawns, and big galleta. 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 deep, skeletal sandy loams with no root restricting layer. They are non-effervescent at the surface. Calcium carbonates increase with depth and soil is strongly effervescent at about 8 inches.
Associated sites
| R030XB214AZ |
Limy Upland 6-9" p.z. |
|---|---|
| R030XC306AZ |
Granitic Hills 10-13" p.z. Alkaline |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Ambrosia dumosa |
| Herbaceous |
(1) Pleuraphis rigida |
Physiographic features
This ecological site is found in an upland position on summits, shoulders and sideslopes of fan terraces and fan piedmonts. The soil surface of the ecological site is covered with gravel, cobbles and stones. Slopes range from 5 to 15 percent.
Table 2. Representative physiographic features
| Landforms |
(1)
Terrace
(2) Fan piedmont |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 579 – 914 m |
| Slope | 5 – 15% |
| Aspect | Aspect is not a significant factor |
Climatic features
The climate is arid and warm. Annual precipitation ranges from 6 to 9 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 59 to 70 degrees F. The average frost-free period ranges from 156 to 259 days.
Table 3. Representative climatic features
| Frost-free period (average) | 259 days |
|---|---|
| Freeze-free period (average) | 290 days |
| Precipitation total (average) | 229 mm |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
The soils of this ecological site are deep to very deep to any plant root restricting layer. Surface textures range from very gravelly sandy loam to very stony sandy loam. Subsurface textures range from very gravelly sandy loam to extremely cobbly loamy coarse sand. The available water capacity is low. Hazard of erosion by water is slight to moderate and by wind is slight. The soil surface may by non-effervescent, but the soil subsurface is slightly to strongly effevescent.
A typical soil profile is as follows:
A--0 to 2 inches; very gravelly sandy loam, 20 percent gravel, 10 percent cobble and 10 percent stones; noneffervescent; moderately alkaline (pH 8.2)
Bk1--2 to 8 inches; gravelly sandy loam, 20 percent gravel and 5 percent cobble; slightly effervescent with disseminated and segregated calcium carbonate as pendants on sand grains and rock fragments, 7 percent calcium carbonate equivalent; moderately alkaline (pH 8.2)
Bk2--8 to 30 inches; extremely cobbly loamy coarse sand, 35 percent gravel, 25 percent cobble and 10 percent stones; strongly effervescent with disseminated and segregated calcium carbonate as pendants on sand grains and rock fragments, 10 percent calcium carbonate equivalent; moderately alkaline (pH 8.4)
Bk3--30 to 62 inches; very gravelly coarse sand, dark yellowish brown (10YR 4/4) moist; single grained; 50 percent gravel and 5 percent cobble; strongly effervescent with disseminated and segregated calcium carbonate as pendants on sand grains and rock fragments, 7 percent calcium carbonate equivalent; moderately alkaline (pH 8.4)
2C--62 to 64 inches; coarse sand, 5 percent gravel; slightly effervescent with disseminated calcium carbonate, 2 percent calcium carbonate equivalent; moderately alkaline (pH 8.4)
Soil map units correlated to this ecological site include 623013, Blind Family and Shelly, Shivwits Area, Arizona SSA.
Table 4. Representative soil features
| Surface texture |
(1) Very gravelly sandy loam (2) Very stony sandy loam |
|---|---|
| Family particle size |
(1) Sandy |
| Drainage class | Somewhat excessively drained to excessively drained |
| Permeability class | Moderate to very rapid |
| Soil depth | 152 cm |
| Surface fragment cover <=3" | 20 – 50% |
| Surface fragment cover >3" | 0 – 50% |
| Calcium carbonate equivalent (0-101.6cm) |
0 – 25% |
| Electrical conductivity (0-101.6cm) |
0 – 2 mmhos/cm |
| Soil reaction (1:1 water) (0-101.6cm) |
7.4 – 8.6 |
| Subsurface fragment volume <=3" (Depth not specified) |
20 – 50% |
| Subsurface fragment volume >3" (Depth not specified) |
0 – 50% |
Ecological dynamics
This ecological site is a dispersed desert shrub dominated ecological site. Trees are widely scattered with a well-dispersed understory of large shrubs, small shrubs, and perennial grasses. 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 with shift slightly toward seasonal herbaceous production following periods of rain. Dominant shrubs are creosote and white bursage. Assorted half-shrubs are widely scattered.
State and transition model
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Ecosystem states
State 1 submodel, plant communities
State 1
Historic Climax Plant Community
Community 1.1
Historic Climax Plant Community
This ecological site is dominated by creosotebush and white bursage with an easthetically pleasing distribution of Joshua Trees. There are minor amounts of perennial grasses on this site. The cobbles and stones inhibit livestock movement. Degradation occurs only because of catastrophic events such as fire or man caused disturbances. The soil will always be protected by the gravels and cobbles. The site's total biomas production by weight (air-dried)is comprised of: grasses and grasslike plants - 5 to 10 percent, forbs 1 to 5 percent, shrubs 80 to 90 and trees 5 to 10 percent.
Figure 4. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Shrub/Vine | 99 | 235 | 351 |
| Tree | 6 | 17 | 39 |
| Grass/Grasslike | 6 | 20 | 39 |
| Forb | 2 | 8 | 19 |
| Total | 113 | 280 | 448 |
Table 6. Ground cover
| Tree foliar cover | 0-2% |
|---|---|
| Shrub/vine/liana foliar cover | 0-2% |
| Grass/grasslike foliar cover | 0-1% |
| Forb foliar cover | 0-1% |
| 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 (m) | Tree | Shrub/Vine | Grass/ Grasslike |
Forb |
|---|---|---|---|---|
| <0.15 | – | – | – | 0-1% |
| >0.15 <= 0.3 | – | – | 0-2% | – |
| >0.3 <= 0.6 | – | 4-7% | – | – |
| >0.6 <= 1.4 | – | – | – | – |
| >1.4 <= 4 | 0-2% | – | – | – |
| >4 <= 12 | – | – | – | – |
| >12 <= 24 | – | – | – | – |
| >24 <= 37 | – | – | – | – |
| >37 | – | – | – | – |
Figure 5. Plant community growth curve (percent production by month). AZ3022, 30.2 6-9" p.z. upland sites. Growth begins in the late winter, most growth occurs in the spring..
| 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 | 2 | 19 | 33 | 18 | 7 | 7 | 11 | 3 | 0 | 0 | 0 |
Figure 6. Plant community growth curve (percent production by month). AZ3030, 40-3AZ 7-10" p.z. big galleta. Growth begins in the spring, goes dormant in May through June, 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 | 10 | 10 | 0 | 0 | 15 | 55 | 10 | 0 | 0 | 0 |
State 2
Non-native Annuals
This plant community resembles the historic native plant community, but exotic annuals have been introduced. Non-native species include red brome, Mediterranean grass (Schismus spp.), and filaree. The flourish of non-native annuals that occurs following rainfalls may preclude native annuals.
Transition T1A
State 1 to 2
Introduction of non-native annual forb and grass seed.
Restoration pathway R2A
State 2 to 1
None known.
Additional community tables
Table 8. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 13–28 | |||||
| big galleta | PLRI3 | Pleuraphis rigida | 13–28 | – | ||
| 2 | 0–2 | |||||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 0–2 | – | ||
| 3 | 0–6 | |||||
| threeawn | ARIST | Aristida | 0–6 | – | ||
| 4 | 0–6 | |||||
| bush muhly | MUPO2 | Muhlenbergia porteri | 0–6 | – | ||
| 5 | 0–6 | |||||
| Indian ricegrass | ACHY | Achnatherum hymenoides | 0–6 | – | ||
| 6 | 2–6 | |||||
| Grass, annual | 2GA | Grass, annual | 2–6 | – | ||
|
Forb
|
||||||
| 7 | 0–2 | |||||
| desert globemallow | SPAM2 | Sphaeralcea ambigua | 0–2 | – | ||
| 8 | 2–6 | |||||
| Forb, annual | 2FA | Forb, annual | 2–6 | – | ||
| 9 | 2–9 | |||||
| Forb, perennial | 2FP | Forb, perennial | 2–9 | – | ||
|
Shrub/Vine
|
||||||
| 10 | 56–84 | |||||
| creosote bush | LATR2 | Larrea tridentata | 56–84 | – | ||
| 11 | 112–140 | |||||
| burrobush | AMDU2 | Ambrosia dumosa | 112–140 | – | ||
| 12 | 6–13 | |||||
| littleleaf ratany | KRER | Krameria erecta | 2–13 | – | ||
| white ratany | KRGR | Krameria grayi | 2–13 | – | ||
| 13 | 0–2 | |||||
| turpentinebroom | THMO | Thamnosma montana | 0–2 | – | ||
| 14 | 2–9 | |||||
| pricklypear | OPUNT | Opuntia | 2–9 | – | ||
| 15 | 2–6 | |||||
| spiny menodora | MESP2 | Menodora spinescens | 2–6 | – | ||
| 16 | 0–6 | |||||
| winterfat | KRLA2 | Krascheninnikovia lanata | 0–6 | – | ||
| 17 | 0–9 | |||||
| Nevada jointfir | EPNE | Ephedra nevadensis | 0–9 | – | ||
| 18 | 2–13 | |||||
| rayless goldenhead | ACSP | Acamptopappus sphaerocephalus | 0–11 | – | ||
| burrobrush | HYSA | Hymenoclea salsola | 0–11 | – | ||
| water jacket | LYAN | Lycium andersonii | 0–11 | – | ||
| Shrub (>.5m) | 2SHRUB | Shrub (>.5m) | 0–2 | – | ||
|
Tree
|
||||||
| 19 | 13–28 | |||||
| Joshua tree | YUBR | Yucca brevifolia | 13–28 | – | ||
Interpretations
Supporting information
Contributors
Harmon Hodgkinson
Harmon S. Hodgkinson
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 | 12/22/2024 |
| 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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