Natural Resources
Conservation Service
Ecological site R040XC301AZ
Basalt Hills 3"-7" p.z.
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.
MLRA notes
Major Land Resource Area (MLRA): 040X–Sonoran Basin and Range
AZ 40.3 – Colorado Sonoran Desert
Elevations range from 300 to 1200 feet and precipitation averages 3 to 7 inches per year. Vegetation includes creosotebush, white bursage, brittlebush, Mormon tea, teddybear cholla, elephant tree, smoke tree, ocotillo, and big galleta. The soil temperature regime is hyperthermic 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 |
(1) Parkinsonia microphylla |
|---|---|
| Shrub |
(1) Encelia farinosa |
| Herbaceous |
(1) Muhlenbergia porteri |
Physiographic features
This range site occurs in an upland position. It does not benefit significantly from run-in moisture from adjacent areas, but it does suffer from excessive loss from run-off. It occurs on low hills and steep mountains.
Table 2. Representative physiographic features
| Landforms |
(1)
Hill
(2) Mountain |
|---|---|
| Elevation | 122 – 488 m |
| Slope | 25 – 70% |
Climatic features
Precipitation in this common resource area ranges from 3-7 inches yearly. Despite historical averages in rainfall amounts, as one moves from east to west in this resource area rains become more unpredictable and variable with Coefficients of Variation of annual rainfall equal to 44% at Gila Bend and 65% at Mohawk. Winter-Summer rainfall ratios are 40-60%. Summer rains fall July-September, originate in the Gulf of Mexico and are convective, usually brief intense thunderstorms. Summer thunderstorms usually form over the mountains in the afternoon and spread to the valleys and plains in the evening. The intensity of this precipitation is moderate to heavy, but rarely lasts more than half an hour. Many times these storms produce little more than gusty winds and light showers. Cool season moisture tends to be frontal, originate in the Pacific and Gulf of California and falls in widespread storms with long duration and low intensity. Snow is very rare and falls normally only in the higher mountains.
Mean temperature for the hottest month (Jul) is 93 F; the coldest month (Jan) is 53 F. Extreme temperatures of 125 F and 10 F have been recorded. Long periods of little or no effective moisture occur frequently.
The winter-spring precipitation is the most dependable on the site. Perennial grasses, though classed as warm season growers, grow actively year-round when moisture is available. Shrubs and trees generally respond to seasonal moisture. The two rainy periods bring about their respective production of either winter or summer annual grasses and forbs.
Table 3. Representative climatic features
| Frost-free period (average) | 363 days |
|---|---|
| Freeze-free period (average) | 0 days |
| Precipitation total (average) | 178 mm |
Figure 1. Monthly precipitation range
Figure 2. Monthly average minimum and maximum temperature
Influencing water features
Soil features
Soils are shallow to bedrock and plant rooting zone is restricted. Parent material is calcareous slope alluvium and residuum. The surface soil is 6-8 inches deep and ranges in texture from an extremely cobbly loam to very gravelly loam. Underlying layers and subsoil can absorb and hold most of the moisture the climate supplies. Soluble salt accumulations are low. pH ranges from 7.9-8.4. With good vegetation cover, infiltration rates are moderate. Stability against erosion processes is good. Plant-soil moisture relationships are good. Coarse fragments may be found throughout the soil and are more than 35% of the total soil volume.
Soils mapped on this site include: SSA-627 MU Hyder-63; SSA-649 MU's Cherioni-4 & Gachado-7; SSA-656 MU Cherioni-6.
Table 4. Representative soil features
| Surface texture |
(1) Gravelly loam (2) Very gravelly fine sandy loam (3) Very cobbly sandy loam |
|---|---|
| Family particle size |
(1) Loamy |
| Drainage class | Well drained |
| Permeability class | Moderately rapid |
| Soil depth | 10 – 51 cm |
| Surface fragment cover <=3" | 15 – 45% |
| Surface fragment cover >3" | 10 – 25% |
| Available water capacity (0-101.6cm) |
0.76 – 5.59 cm |
| Calcium carbonate equivalent (0-101.6cm) |
5 – 25% |
| Electrical conductivity (0-101.6cm) |
0 – 8 mmhos/cm |
| Sodium adsorption ratio (0-101.6cm) |
0 – 5 |
| Soil reaction (1:1 water) (0-101.6cm) |
7.9 – 8.4 |
| Subsurface fragment volume <=3" (Depth not specified) |
15 – 45% |
| Subsurface fragment volume >3" (Depth not specified) |
3 – 15% |
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 site is predominantly a shrub site. Perennial grasses make up a small percentage of the plant community. Annual grasses can make up a moderate percentage in years with good summer precipitation and forbs do the same in years with good winter precipitation. Perannial forbs and grasses, though classed as warm season growers, grow actively with winter moisture. Continued grazing use in winter and spring removes these plants. INcrease of brittlebush will occur when palatable species are removed.
Figure 3. 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 | 177 | 189 | 202 |
| Grass/Grasslike | 12 | 26 | 38 |
| Forb | 12 | 19 | 26 |
| Tree | 6 | 9 | 12 |
| Total | 207 | 243 | 278 |
Figure 4. Plant community growth curve (percent production by month). AZ4041, 40.3 3-7" p.z. all sites. Most growth occurs in the winter to early spring, plants are dormant May through October..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 5 | 20 | 40 | 25 | 0 | 0 | 0 | 0 | 0 | 0 | 5 | 5 |
Additional community tables
Table 6. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Grass/Grasslike
|
||||||
| 1 | Perennial Grasses | 11–22 | ||||
| big galleta | PLRI3 | Pleuraphis rigida | 2–4 | – | ||
| slim tridens | TRMU | Tridens muticus | 2–4 | – | ||
| threeawn | ARIST | Aristida | 1–2 | – | ||
| needle grama | BOAR | Bouteloua aristidoides | 1–2 | – | ||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 1–2 | – | ||
| nineawn pappusgrass | ENDE | Enneapogon desvauxii | 1–2 | – | ||
| littleseed muhly | MUMI | Muhlenbergia microsperma | 1–2 | – | ||
| bush muhly | MUPO2 | Muhlenbergia porteri | 1–2 | – | ||
| 2 | Annual Grasses | 6–11 | ||||
| sixweeks grama | BOBA2 | Bouteloua barbata | 1–3 | – | ||
| sixweeks fescue | VUOC | Vulpia octoflora | 1–3 | – | ||
| low woollygrass | DAPU7 | Dasyochloa pulchella | 1–2 | – | ||
| sixweeks threeawn | ARAD | Aristida adscensionis | 1–2 | – | ||
|
Forb
|
||||||
| 3 | Perennial Forbs | 11–22 | ||||
| pelotazo | ABIN | Abutilon incanum | 0–2 | – | ||
| trailing windmills | ALIN | Allionia incarnata | 0–2 | – | ||
| New Mexico silverbush | ARNE2 | Argythamnia neomexicana | 0–2 | – | ||
| desert marigold | BAMU | Baileya multiradiata | 0–2 | – | ||
| fleabane | ERIGE2 | Erigeron | 0–2 | – | ||
| Parry's false prairie-clover | MAPA7 | Marina parryi | 0–2 | – | ||
| wishbone-bush | MILAV | Mirabilis laevis var. villosa | 0–2 | – | ||
| Coues' cassia | SECO10 | Senna covesii | 0–2 | – | ||
| Coulter's globemallow | SPCO2 | Sphaeralcea coulteri | 0–2 | – | ||
| globemallow | SPHAE | Sphaeralcea | 0–2 | – | ||
| brownplume wirelettuce | STPA4 | Stephanomeria pauciflora | 0–2 | – | ||
| 4 | Annual Forbs | 2–11 | ||||
| common fiddleneck | AMMEI2 | Amsinckia menziesii var. intermedia | 0–1 | – | ||
| whitestem milkweed | ASAL | Asclepias albicans | 0–1 | – | ||
| spiderling | BOERH2 | Boerhavia | 0–1 | – | ||
| hoary bowlesia | BOIN3 | Bowlesia incana | 0–1 | – | ||
| devil's spineflower | CHRI | Chorizanthe rigida | 0–1 | – | ||
| cryptantha | CRYPT | Cryptantha | 0–1 | – | ||
| hairy prairie clover | DAMO | Dalea mollis | 0–1 | – | ||
| buckwheat | ERIOG | Eriogonum | 0–1 | – | ||
| California poppy | ESCAM | Eschscholzia californica ssp. mexicana | 0–1 | – | ||
| spurge | EUPHO | Euphorbia | 0–1 | – | ||
| pepperweed | LEPID | Lepidium | 0–1 | – | ||
| Coulter's lupine | LUSP2 | Lupinus sparsiflorus | 0–1 | – | ||
| tansyaster | MACHA | Machaeranthera | 0–1 | – | ||
| California evening primrose | OECA2 | Oenothera californica | 0–1 | – | ||
| evening primrose | OENOT | Oenothera | 0–1 | – | ||
| combseed | PECTO | Pectocarya | 0–1 | – | ||
| Emory's rockdaisy | PEEM | Perityle emoryi | 0–1 | – | ||
| phacelia | PHACE | Phacelia | 0–1 | – | ||
| desert Indianwheat | PLOV | Plantago ovata | 0–1 | – | ||
| sleepy silene | SIAN2 | Silene antirrhina | 0–1 | – | ||
| woolly tidestromia | TILA2 | Tidestromia lanuginosa | 0–1 | – | ||
|
Shrub/Vine
|
||||||
| 5 | Dominant Shrubs | 101–163 | ||||
| brittlebush | ENFA | Encelia farinosa | 90–126 | – | ||
| burrobush | AMDU2 | Ambrosia dumosa | 12–38 | – | ||
| 6 | Other Shrubs | 12–26 | ||||
| creosote bush | LATRT | Larrea tridentata var. tridentata | 2–4 | – | ||
| triangle bur ragweed | AMDE4 | Ambrosia deltoidea | 1–3 | – | ||
| littleleaf ratany | KRER | Krameria erecta | 1–3 | – | ||
| white ratany | KRGR | Krameria grayi | 1–3 | – | ||
| narrowleaf silverbush | ARLA12 | Argythamnia lanceolata | 1–2 | – | ||
| desert lavender | HYEM | Hyptis emoryi | 1–2 | – | ||
| desert-thorn | LYCIU | Lycium | 1–2 | – | ||
| desert ironwood | OLTE | Olneya tesota | 1–2 | – | ||
| woody crinklemat | TICAC | Tiquilia canescens var. canescens | 1–2 | – | ||
| 7 | Misc. Shrubs | 11–22 | ||||
| lacy tansyaster | MAPIP4 | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | 1–2 | – | ||
| bush arrowleaf | PLPL | Pleurocoronis pluriseta | 0–1 | – | ||
| Mexican bladdersage | SAME | Salazaria mexicana | 0–1 | – | ||
| American threefold | TRCA8 | Trixis californica | 0–1 | – | ||
| toothleaf goldeneye | VIDE3 | Viguiera dentata | 0–1 | – | ||
| San Felipe dogweed | ADPO | Adenophyllum porophylloides | 0–1 | – | ||
| sweetbush | BEJU | Bebbia juncea | 0–1 | – | ||
| Nevada jointfir | EPNE | Ephedra nevadensis | 0–1 | – | ||
| starry bedstraw | GAST | Galium stellatum | 0–1 | – | ||
| slender janusia | JAGR | Janusia gracilis | 0–1 | – | ||
| 8 | Succulents | 22–34 | ||||
| desert agave | AGDE | Agave deserti | 1–3 | – | ||
| buckhorn cholla | CYACA2 | Cylindropuntia acanthocarpa var. acanthocarpa | 2–3 | – | ||
| teddybear cholla | CYBI9 | Cylindropuntia bigelovii | 2–3 | – | ||
| Christmas cactus | CYLE8 | Cylindropuntia leptocaulis | 2–3 | – | ||
| ocotillo | FOSP2 | Fouquieria splendens | 2–3 | – | ||
| beavertail pricklypear | OPBA2 | Opuntia basilaris | 2–3 | – | ||
| globe cactus | MAMMI | Mammillaria | 1–2 | – | ||
| Engelmann's hedgehog cactus | ECEN | Echinocereus engelmannii | 1–2 | – | ||
| Emory's barrel cactus | FEEM | Ferocactus emoryi | 1–2 | – | ||
| candy barrelcactus | FEWI | Ferocactus wislizeni | 1–2 | – | ||
|
Tree
|
||||||
| 9 | Tree | 6–12 | ||||
| yellow paloverde | PAMI5 | Parkinsonia microphylla | 6–12 | – | ||
Interpretations
Animal community
The very cobbly surface and steep slopes limit use of this site. The site is more suited for use by stocker cattle in above average winters or summers than for yearlong use. Fencing, to restrict use of the site, and water development are important to improve livestock distribution. Stocker cattle work the rough slopes much better than cows with calves.
Natural water is limted to few, wet weather, potholes. Stock water developments are very important to wildlife on this site. The area is a feeding area for large desert mammale as the feed on it provides seasonal contrast to that of surrounding desert plains and bajadas. Cover, however, is usually poor. This, coupled with the lack of natural waters, limits the residency of large mammals.
Recreational uses
This site is located on steep, low hills and mountains. In years with above average winter moisture, brittlebush flower profusely and provide excellent contrast with the dark, basalt surface. Very few days in the fall, winter, or spring are too uncomfortable to enjoy outdoor activities. Jun-Aug afternoons, however, are warm enough to restrict activity. Horseback riding, wildlife observation, hunting, hiking and photography are the main activities suited to the site.
Other products
Masonary rock for fireplaces.
Supporting information
Contributors
Larry D. Ellicott
Steve Barker
Unknown
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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