Natural Resources
Conservation Service
Ecological site R041XB205AZ
Shallow Hills 8-12" p.z.
Last updated: 4/12/2021
Accessed: 12/03/2024
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): 041X–Madrean Archipelago
AZ 41.2 – Chihuahuan – Sonoran Desert Shrubs
Elevations range from 2600 to 4000 feet and precipitation ranges from 8 to 12 inches per year. Vegetation includes mesquite, palo verde, catclaw acacia, soaptree yucca, creosotebush, whitethorn, staghorn cholla, desert saltbush, Mormon tea, burroweed, snakeweed, tobosa, black grama, threeawns, bush muhly, dropseed, and burrograss. The soil temperature regime is thermic and the soil moisture regime is typic aridic. This unit occurs within the Basin and Range Physiographic Province and is characterized by numerous mountain ranges that rise abruptly from broad, plain-like valleys and basins. Igneous and metamorphic rock classes dominate the mountain ranges and sediments filling the basins represent combinations of fluvial, lacustrine, colluvial and alluvial deposits.
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
Not specified |
Physiographic features
This site occurs in the lowest elevations of the Madrean Basin and Range province in southeastern Arizona. It occurs on steep hill-slopes with a rough appearance. Boulders and rock outcrops tend to hide the range site.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Mountain |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 2,600 – 4,000 ft |
| Slope | 15 – 65% |
| Aspect | N, E, S |
Climatic features
Precipitation ranges from 8-12 inches annually. More than half falls during Jul-Sep in brief, but often heavy, thunderstorms. The rest of the moisture comes as light rain or snow that falls slowly for a day or more, but rarely lasts more than a day. May and June are normally the driest months. Humidity is generally very low.
Temperatures are mild throughout most of the year. Freezing temperatures are common at night Dec-Feb; brief 0 F may be observed some nights. During June, July & August, some days may exceed 100 F.
In years of average or greater winter precipitation, annual grasses and forbs occur abundantly in the interspaces.
Table 3. Representative climatic features
| Frost-free period (average) | 240 days |
|---|---|
| Freeze-free period (average) | |
| Precipitation total (average) |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
Soils are shallow and very shallow; developed in place on granite and related rocks. They are very gravelly and cobbly both in the profile and on the surface. They have moderately rapid infiltration rates with low water-holding capacity. Plant-soil moisture relationship are good due to runoff from the adjacent rock outcrops.
Soil series mapped to date on this site include: SSA-662 Safford area MU's ClF Cellar and SSA-666 Cochise County Northwest part MU 86 Wikiup family & Anklam.
Table 4. Representative soil features
| Parent material |
(1)
Slope alluvium
–
granite
|
|---|---|
| Surface texture |
(1) Very gravelly sandy loam (2) Very cobbly sandy loam (3) Gravelly sandy loam |
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately rapid to moderate |
| Soil depth | 5 – 20 in |
| Surface fragment cover <=3" | 30 – 60% |
| Surface fragment cover >3" | 5 – 25% |
| Available water capacity (0-40in) |
0.6 – 3.2 in |
| Calcium carbonate equivalent (0-40in) |
5% |
| Electrical conductivity (0-40in) |
2 mmhos/cm |
| Sodium adsorption ratio (0-40in) |
2 |
| Soil reaction (1:1 water) (0-40in) |
7.4 – 8 |
| Subsurface fragment volume <=3" (Depth not specified) |
35 – 65% |
| Subsurface fragment volume >3" (Depth not specified) |
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 Climax Plant Community
Community 1.1
Historic Climax Plant Community
This range site has a plant community dominated by grass. The small trees and shrubs give it a slight brushy aspect. As this site deteriorates, oak, burroweed, broom snakeweed and other woody or weedy species increase or invade. Washes on or below the site carry heavy sediment loads when this site deteriorates. However, in excellent condition, the erosion is very slight.
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 | 490 | 525 | 560 |
| Shrub/Vine | 35 | 70 | 105 |
| Total | 525 | 595 | 665 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | 53–79 | |||||
| blue grama | BOGR2 | Bouteloua gracilis | 53–79 | – | ||
| hairy grama | BOHI2 | Bouteloua hirsuta | 53–79 | – | ||
| 2 | 66–110 | |||||
| tobosagrass | PLMU3 | Pleuraphis mutica | 110–154 | – | ||
| crinkleawn grass | TRACH2 | Trachypogon | 53 | – | ||
| slim tridens | TRMU | Tridens muticus | 53 | – | ||
| threeawn | ARIST | Aristida | 53 | – | ||
| cane bluestem | BOBA3 | Bothriochloa barbinodis | 53 | – | ||
| sprucetop grama | BOCH | Bouteloua chondrosioides | 53 | – | ||
| sideoats grama | BOCU | Bouteloua curtipendula | 53 | – | ||
| black grama | BOER4 | Bouteloua eriopoda | 53 | – | ||
| slender grama | BORE2 | Bouteloua repens | 53 | – | ||
| plains lovegrass | ERIN | Eragrostis intermedia | 53 | – | ||
| curly-mesquite | HIBE | Hilaria belangeri | 53 | – | ||
| bush muhly | MUPO2 | Muhlenbergia porteri | 53 | – | ||
| 3 | 27 | |||||
| threeawn | ARIST | Aristida | 27 | – | ||
| Rothrock's grama | BORO2 | Bouteloua rothrockii | 27 | – | ||
| Arizona cottontop | DICA8 | Digitaria californica | 27 | – | ||
| woolyspike balsamscale | ELBA | Elionurus barbiculmis | 27 | – | ||
| tanglehead | HECO10 | Heteropogon contortus | 27 | – | ||
| green sprangletop | LEDU | Leptochloa dubia | 27 | – | ||
| common wolfstail | LYPH | Lycurus phleoides | 27 | – | ||
| bullgrass | MUEM | Muhlenbergia emersleyi | 27 | – | ||
| Texas bluestem | SCCI2 | Schizachyrium cirratum | 27 | – | ||
| plains bristlegrass | SEVU2 | Setaria vulpiseta | 27 | – | ||
|
Shrub/Vine
|
||||||
| 4 | 7 | |||||
| whitethorn acacia | ACCO2 | Acacia constricta | 7 | – | ||
| agave | AGAVE | Agave | 7 | – | ||
| fairyduster | CAER | Calliandra eriophylla | 7 | – | ||
| ratany | KRAME | Krameria | 7 | – | ||
| sensitive plant | MIMOS | Mimosa | 7 | – | ||
| pricklypear | OPUNT | Opuntia | 7 | – | ||
| soaptree yucca | YUEL | Yucca elata | 7 | – | ||
| 5 | 4 | |||||
| threeawn | ARIST | Aristida | 22 | – | ||
| Rothrock's grama | BORO2 | Bouteloua rothrockii | 22 | – | ||
| curly-mesquite | HIBE | Hilaria belangeri | 22 | – | ||
| burrograss | SCBR2 | Scleropogon brevifolius | 22 | – | ||
| dropseed | SPORO | Sporobolus | 22 | – | ||
| catclaw acacia | ACGR | Acacia greggii | 4 | – | ||
| cassia | CASSI | Cassia | 4 | – | ||
| common sotol | DAWH2 | Dasylirion wheeleri | 4 | – | ||
| longleaf jointfir | EPTR | Ephedra trifurca | 4 | – | ||
| coralbean | ERFL7 | Erythrina flabelliformis | 4 | – | ||
| bastardsage | ERWR | Eriogonum wrightii | 4 | – | ||
| ocotillo | FOSP2 | Fouquieria splendens | 4 | – | ||
| Thurber's cotton | GOTH | Gossypium thurberi | 4 | – | ||
| winterfat | KRLA2 | Krascheninnikovia lanata | 4 | – | ||
| Emory oak | QUEM | Quercus emoryi | 4 | – | ||
| skunkbush sumac | RHTR | Rhus trilobata | 4 | – | ||
| jojoba | SICH | Simmondsia chinensis | 4 | – | ||
Interpretations
Animal community
Cattle use the accessible parts of the site readily, and due to the unusually narrow lanes of accessibility, small rills erode along their trails and the soil is frequently removed to bedrock.
Limited numbers of springs, seeps and permanent streams occur on this site. Runoff from nearby rocks is a source of water when trapped in depressions.
Rock outcrops and boulders break up the site and are not considered part of the site, but provide cover for wildlife. Mast from oak, browse from shrubs and forba provide food for several species of wildlife. Cover for escape, nesting, and resting is easily found for small mammals and birds, as well as larger mammals.
Recreational uses
Huge round boulders form rock piles on the site and give the area a rugged appearance. The wide variety of plants provides good aesthetic appeal. Plants such as ocotillo, yucca and coral-bean lend color to the site. Although a few winter days aer cold and some summer days are hot, most of the year is very comfortable. Activities include wildlife observations, horseback riding, hunting, hiking, photography, nature studies, picnicking and camping.
Supporting information
Type locality
| Location 1: Cochise County, AZ | |
|---|---|
| Township/Range/Section | T15S R20E S20 |
| General legal description | USGS Quadrangle—Galleta Flat East; about 1,100 feet west and 1,300 feet south of the northeast corner of section 20, Township 15 south, Range 20 east |
Contributors
Dan Robinett
Larry D. Ellicott
Steve Barker
Unknown
Approval
Curtis Talbot, 4/12/2021
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 | 09/06/2022 |
| Approved by | Curtis Talbot |
| 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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