Natural Resources
Conservation Service
Ecological site R040XB220AZ
Granitic Upland 7"-10" p.z.
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): 040X–Sonoran Basin and Range
AZ 40.2 – Middle Sonoran Desert
Elevations range from 1200 to 2000 feet and precipitation averages 7 to 10 inches per year. Vegetation includes saguaro, palo verde, creosotebush, triangle bursage, brittlebush, prickly pear, cholla, desert saltbush, wolfberry bush muhly, threeawns, 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) Ambrosia deltoidea |
Herbaceous |
(1) Pleuraphis rigida |
Physiographic features
This site occurs on pediments, undulating uplands in and around the low desert mountains. Slopes range from 1% to 15%. Elevations are from 1000 to 2500 feet.
Table 2. Representative physiographic features
Landforms |
(1)
Pediment
|
---|---|
Flooding frequency | None |
Ponding frequency | None |
Elevation | 1,000 – 2,500 ft |
Slope | 15% |
Aspect | Aspect is not a significant factor |
Climatic features
Precipitation in the sub-resource area ranges from 7 to 10 inches. Elevations range from 900 to 2050 feet. Winter-summer rainfall ratios range from 40% to 60% in the southern part along the international boundary, to 60% to 40% in the central and northern parts of the sub-resource area. 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 38% at Florence and 46% at Aguila. Summer rains fall July- September, originate in the Gulf of Mexico, and are convective, usually brief, intense thunderstorms. Summer precipitation is extremely erratic and undependable in this area. Cool season moisture tends to be frontal, originates in the Pacific and Gulf of California, and falls in widespread storms with long duration and low intensity. This is the dependable moisture supply for vegetation in the area. Snow is very rare and usually melts on contact. May-June is the driest time of the year. Humidity is very low.
Winter temperatures are very mild with very few days recording freezing for short periods of time. Summertime temperatures are hot to very hot with many days in June-July exceeding 105 degrees F. Frost-free days range from 280 at stations in major river valleys with cold air drainage to 320 to 350 days at upland stations.
Both the spring and the summer growing seasons are equally important for perennial grass, forb and shrub growth. Cool and warm season annual forbs and grasses can be common in their respective seasons with above average rainfall. Perennial forage species can remain green throughout the year with available moisture.
Table 3. Representative climatic features
Frost-free period (average) | 350 days |
---|---|
Freeze-free period (average) | 0 days |
Precipitation total (average) | 10 in |
Figure 2. Monthly precipitation range
Figure 3. Monthly average minimum and maximum temperature
Influencing water features
Soil features
These are shallow and very shallow soils formed on acid and intermediate igneous parent materials and on sandstone, quartzite, arkose and gneiss. They are coarse textured, non-calcareous and have well developed gravel covers. Bedrock is usually slightly weathered into grus material at the soil juncture, and may be slightly calcareous. Rock outcrops make up a small percentage of soil units. Plant-soil moisture relationships are poor. This site is mapped in 7 Soil Survey areas in Southwestern Arizona on CRA D40-2.
Soils mapped on this site include: SSA-645 Aguila-Carefree area MU Vaiva-123; SSA-651 Central Maricopa county MU Gachado-GA; SSA-653 Gila Bend-Ajo area MU's Gachado XGrSL-40 and Quilotosa-53; SSA-658 Gila River Indian Reservation MU's Quilotosa-26 and Vaiva-26; SSA-659 Western Pinal county MU Vaiva-46; SSA-661 Eastern Pinal-Southern Gila counties MU's Ajolito-285 and Suncity-605; SSA-703 Tohono O'odham area Quilotosa-50. Parent material kind includes resiuum also. Parent material origin includes rhyolite and gneiss.
Table 4. Representative soil features
Surface texture |
(1) Gravelly sandy loam (2) Very gravelly loam |
---|---|
Family particle size |
(1) Loamy |
Drainage class | Well drained |
Permeability class | Moderately slow to moderately rapid |
Soil depth | 4 – 20 in |
Surface fragment cover <=3" | 35 – 65% |
Surface fragment cover >3" | 1 – 10% |
Available water capacity (0-40in) |
0.2 – 1.6 in |
Calcium carbonate equivalent (0-40in) |
1 – 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) |
35 – 65% |
Subsurface fragment volume >3" (Depth not specified) |
1 – 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 fire, grazing, 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 amount shown for the group. Divide the resulting total by the total normal year production shown in the plant community description. If the 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
Historical Climax Plant Community
Community 1.1
Historical Climax Plant Community
The potential plant community on this site is a mixture of desert trees, shrubs, cacti and perennial forbs and grasses. Annuals are of minor importance in the plant community. The aspect is shrubland. With poorly managed grazing, perennial forage species like; desert trumpet, slender janusia, flattop buckwheat and bush muhly disappear from the plant community. Trees tend to be shrubby on this site due to soils shallow to bedrock. This site lacks the cobble and stone cover of adjacent hillslopes. Gravel size and cover may be lacking on moderate slopes to prevent water erosion. Plant populations for major species range from 40 to 100 trees per acre for paloverde and ironwood, 500 to 800 plants per acre for triangle bursage and white brittlebush, 1 to 10 saguaros per acre and 5 to 20 ocotillo plants per acre. Perennial plant basal cover on this site is very low from 1/2 to 1 percent.
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) |
---|---|---|---|
Shrub/Vine | 188 | – | 225 |
Tree | 188 | – | 225 |
Forb | 13 | – | 38 |
Grass/Grasslike | 13 | – | 25 |
Total | 402 | – | 513 |
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 | 2–10 | |||||
bush muhly | MUPO2 | Muhlenbergia porteri | 0–3 | – | ||
big galleta | PLRI3 | Pleuraphis rigida | 0–1 | – | ||
slim tridens | TRMU | Tridens muticus | 0–1 | – | ||
purple threeawn | ARPU9 | Aristida purpurea | 0–1 | – | ||
Wright's threeawn | ARPUW | Aristida purpurea var. wrightii | 0–1 | – | ||
spidergrass | ARTE3 | Aristida ternipes | 0–1 | – | ||
spidergrass | ARTEG | Aristida ternipes var. gentilis | 0–1 | – | ||
low woollygrass | DAPU7 | Dasyochloa pulchella | 0–1 | – | ||
nineawn pappusgrass | ENDE | Enneapogon desvauxii | 0–1 | – | ||
2 | 2–10 | |||||
Rothrock's grama | BORO2 | Bouteloua rothrockii | 0–3 | – | ||
delicate muhly | MUFR | Muhlenbergia fragilis | 0–1 | – | ||
littleseed muhly | MUMI | Muhlenbergia microsperma | 0–1 | – | ||
Bigelow's bluegrass | POBI | Poa bigelovii | 0–1 | – | ||
sixweeks fescue | VUOC | Vulpia octoflora | 0–1 | – | ||
sixweeks threeawn | ARAD | Aristida adscensionis | 0–1 | – | ||
prairie threeawn | AROL | Aristida oligantha | 0–1 | – | ||
needle grama | BOAR | Bouteloua aristidoides | 0–1 | – | ||
sixweeks grama | BOBA2 | Bouteloua barbata | 0–1 | – | ||
Forb
|
||||||
3 | 10–25 | |||||
desert trumpet | ERIN4 | Eriogonum inflatum | 0–5 | – | ||
desert globemallow | SPAM2 | Sphaeralcea ambigua | 0–5 | – | ||
Coues' cassia | SECO10 | Senna covesii | 0–3 | – | ||
shrubby deervetch | LORI3 | Lotus rigidus | 0–2 | – | ||
Parry's false prairie-clover | MAPA7 | Marina parryi | 0–2 | – | ||
slender poreleaf | POGR5 | Porophyllum gracile | 0–1 | – | ||
poreleaf dogweed | ADPO2 | Adenophyllum porophyllum | 0–1 | – | ||
narrowleaf silverbush | ARLA12 | Argythamnia lanceolata | 0–1 | – | ||
New Mexico silverbush | ARNE2 | Argythamnia neomexicana | 0–1 | – | ||
whitemargin sandmat | CHAL11 | Chamaesyce albomarginata | 0–1 | – | ||
brownplume wirelettuce | STPA4 | Stephanomeria pauciflora | 0–1 | – | ||
California fagonbush | FALA | Fagonia laevis | 0–1 | – | ||
paleface | HIDE | Hibiscus denudatus | 0–1 | – | ||
4 | 2–10 | |||||
combseed | PECTO | Pectocarya | 0–5 | – | ||
desert Indianwheat | PLOV | Plantago ovata | 0–5 | – | ||
broadleaved pepperweed | LELA2 | Lepidium latifolium | 0–5 | – | ||
flax | LINUM | Linum | 0–1 | – | ||
foothill deervetch | LOHU2 | Lotus humistratus | 0–1 | – | ||
desert deervetch | LOMI | Lotus micranthus | 0–1 | – | ||
coastal bird's-foot trefoil | LOSAB | Lotus salsuginosus var. brevivexillus | 0–1 | – | ||
Arizona lupine | LUAR4 | Lupinus arizonicus | 0–1 | – | ||
Coulter's lupine | LUSP2 | Lupinus sparsiflorus | 0–1 | – | ||
lacy tansyaster | MAPIP4 | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | 0–1 | – | ||
bristly nama | NAHI | Nama hispidum | 0–1 | – | ||
glandular threadplant | NEGL | Nemacladus glanduliferus | 0–1 | – | ||
desert tobacco | NIOBO | Nicotiana obtusifolia var. obtusifolia | 0–1 | – | ||
cloak fern | NOTHO | Notholaena | 0–1 | – | ||
Florida pellitory | PAFL3 | Parietaria floridana | 0–1 | – | ||
brownfoot | ACWR5 | Acourtia wrightii | 0–1 | – | ||
weakleaf bur ragweed | AMCO3 | Ambrosia confertiflora | 0–1 | – | ||
common fiddleneck | AMMEI2 | Amsinckia menziesii var. intermedia | 0–1 | – | ||
bristly fiddleneck | AMTE3 | Amsinckia tessellata | 0–1 | – | ||
milkvetch | ASTRA | Astragalus | 0–1 | – | ||
desert marigold | BAMU | Baileya multiradiata | 0–1 | – | ||
Coulter's spiderling | BOCO2 | Boerhavia coulteri | 0–1 | – | ||
hoary bowlesia | BOIN3 | Bowlesia incana | 0–1 | – | ||
exserted Indian paintbrush | CAEXE | Castilleja exserta ssp. exserta | 0–1 | – | ||
yellow tackstem | CAPA7 | Calycoseris parryi | 0–1 | – | ||
white tackstem | CAWR | Calycoseris wrightii | 0–1 | – | ||
pincushion | CHAEN | Chaenactis | 0–1 | – | ||
brittle spineflower | CHBR | Chorizanthe brevicornu | 0–1 | – | ||
lipfern | CHEIL | Cheilanthes | 0–1 | – | ||
devil's spineflower | CHRI | Chorizanthe rigida | 0–1 | – | ||
hairy prairie clover | DAMO | Dalea mollis | 0–1 | – | ||
American wild carrot | DAPU3 | Daucus pusillus | 0–1 | – | ||
Parish's larkspur | DEPAP3 | Delphinium parishii ssp. parishii | 0–1 | – | ||
western tansymustard | DEPI | Descurainia pinnata | 0–1 | – | ||
tall mountain larkspur | DESC | Delphinium scaposum | 0–1 | – | ||
flatcrown buckwheat | ERDE6 | Eriogonum deflexum | 0–1 | – | ||
miniature woollystar | ERDI2 | Eriastrum diffusum | 0–1 | – | ||
buckwheat | ERIOG | Eriogonum | 0–1 | – | ||
woolly sunflower | ERIOP2 | Eriophyllum | 0–1 | – | ||
Texas stork's bill | ERTE13 | Erodium texanum | 0–1 | – | ||
California poppy | ESCAM | Eschscholzia californica ssp. mexicana | 0–1 | – | ||
gilia | GILIA | Gilia | 0–1 | – | ||
Gordon's bladderpod | LEGO | Lesquerella gordonii | 0–1 | – | ||
velvet turtleback | PSRA | Psathyrotes ramosissima | 0–1 | – | ||
New Mexico plumeseed | RANE | Rafinesquia neomexicana | 0–1 | – | ||
chia | SACO6 | Salvia columbariae | 0–1 | – | ||
sleepy silene | SIAN2 | Silene antirrhina | 0–1 | – | ||
Coulter's globemallow | SPCO2 | Sphaeralcea coulteri | 0–1 | – | ||
woollyhead neststraw | STMI2 | Stylocline micropoides | 0–1 | – | ||
woolly tidestromia | TILA2 | Tidestromia lanuginosa | 0–1 | – | ||
cliffbrake | PELLA | Pellaea | 0–1 | – | ||
phacelia | PHACE | Phacelia | 0–1 | – | ||
Shrub/Vine
|
||||||
5 | 10–25 | |||||
Eastern Mojave buckwheat | ERFA2 | Eriogonum fasciculatum | 0–10 | – | ||
slender janusia | JAGR | Janusia gracilis | 0–5 | – | ||
littleleaf ratany | KRER | Krameria erecta | 0–5 | – | ||
fairyduster | CAER | Calliandra eriophylla | 0–5 | – | ||
rough menodora | MESC | Menodora scabra | 0–2 | – | ||
burrobush | AMDU2 | Ambrosia dumosa | 0–2 | – | ||
American threefold | TRCA8 | Trixis californica | 0–1 | – | ||
6 | 75–100 | |||||
triangle bur ragweed | AMDE4 | Ambrosia deltoidea | 30–50 | – | ||
brittlebush | ENFA | Encelia farinosa | 10–20 | – | ||
white ratany | KRGR | Krameria grayi | 2–10 | – | ||
Tucson bur ragweed | AMCO4 | Ambrosia cordifolia | 2–10 | – | ||
7 | 10–25 | |||||
ocotillo | FOSP2 | Fouquieria splendens | 0–3 | – | ||
water jacket | LYAN | Lycium andersonii | 0–3 | – | ||
Arizona desert-thorn | LYEX | Lycium exsertum | 0–3 | – | ||
desert wolfberry | LYMA | Lycium macrodon | 0–3 | – | ||
Hall's shrubby-spurge | TEHA | Tetracoccus hallii | 0–2 | – | ||
sangre de cristo | JACA2 | Jatropha cardiophylla | 0–2 | – | ||
Nevada jointfir | EPNE | Ephedra nevadensis | 0–2 | – | ||
longleaf jointfir | EPTR | Ephedra trifurca | 0–2 | – | ||
creosote bush | LATR2 | Larrea tridentata | 0–2 | – | ||
Arizona nettlespurge | JACI | Jatropha cinerea | 0–1 | – | ||
desert lavender | HYEM | Hyptis emoryi | 0–1 | – | ||
turpentinebroom | THMO | Thamnosma montana | 0–1 | – | ||
Parish's goldeneye | VIPA14 | Viguiera parishii | 0–1 | – | ||
arrow poision plant | SEBI9 | Sebastiania bilocularis | 0–1 | – | ||
catclaw acacia | ACGR | Acacia greggii | 0–1 | – | ||
9 | Succulents | 10–25 | ||||
beavertail pricklypear | OPBA2 | Opuntia basilaris | 0–2 | – | ||
Leconte's barrel cactus | FECYL | Ferocactus cylindraceus var. lecontei | 0–2 | – | ||
Emory's barrel cactus | FEEM | Ferocactus emoryi | 0–2 | – | ||
candy barrelcactus | FEWI | Ferocactus wislizeni | 0–2 | – | ||
senita cactus | PASC14 | Pachycereus schottii | 0–1 | – | ||
organpipe cactus | STTH3 | Stenocereus thurberi | 0–1 | – | ||
Engelmann's hedgehog cactus | ECEN | Echinocereus engelmannii | 0–1 | – | ||
Tree
|
||||||
8 | 50–75 | |||||
desert ironwood | OLTE | Olneya tesota | 20–35 | – | ||
yellow paloverde | PAMI5 | Parkinsonia microphylla | 20–35 | – |
Interpretations
Animal community
Areas of this site are associated with steep, rough, hillsites. It will be overused unless grazing systems allow enough rest for recovery or fencing is used to isolate it from the adjacent mountains. This site produces no herbaceous forage and very little useable browse for livestock. Water will be available in bedrock canyons for short periods of time after heavy rainfall.
Water developments are very important to wildlife species on this site. Some free water may remain, after rains, for a few weeks in the rock lined drainages that bisect this site. Large mammals use the site seasonally unless permanent water supplies are available. Food, cover, diversity and some topography make this site home to a variety of desert animals. Desert tortoises den in rock crevices along drainage ways through areas of this site.
Other information
T&E: Antilocapra Americana sonoriensis
(Sonoran pronghorn)
Leptonycteris curasoae yerbebuena
(Lesser long-nosed bat)
Supporting information
Type locality
Location 1: Maricopa County, AZ | |
---|---|
Township/Range/Section | T7S R2E S4 |
General legal description | Buckeye FO - AK Ranch - Paloverde Mountains |
Location 2: Maricopa County, AZ | |
Township/Range/Section | T5S R5E S4 |
General legal description | Chandler FO - Gila River Indian Community |
Location 3: Maricopa County, AZ | |
Township/Range/Section | T3N R4W S1 |
General legal description | Phoenix FO - Douglas Ranch - White Tank Mtns. |
Location 4: Pima County, AZ | |
Township/Range/Section | T14S R3W S23 |
General legal description | Sells FO - Hickiwan Dist. |
Location 5: Pima County, AZ | |
Township/Range/Section | T8S R3E S10 |
General legal description | Sells FO - Little Table Mtns., SE 1/4 sec. 10 |
Location 6: Pima County, AZ | |
Township/Range/Section | T12S R6W S29 |
General legal description | Tucson FO - Cameron Ranch at Ajo |
Contributors
Dan Robinett
Larry D. Ellicott
Steve Barker
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) | Dave Womack, Byron Lambeth, Dan Robinett, Emilio Carrillo |
---|---|
Contact for lead author | NRCS Tucson Area Office |
Date | 03/02/2005 |
Approved by | S. Cassady |
Approval date | |
Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rills are common and continuous in absence of high gravel cover. They commonly occur along bedding planes and joints in the bedrock parent material. -
Presence of water flow patterns:
Discontinuous, 10-15 feet in length. Will see shorter flow paths with high surface coarse fragments. -
Number and height of erosional pedestals or terracettes:
Shrubs have symmetical ounds caused by the actions of splash, rosion and rodent activity. There are no pedestals on rock or gravel fragments and no terracettes are present. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
10-60% (low values due to high rock and gravel cover)
-
Number of gullies and erosion associated with gullies:
None -
Extent of wind scoured, blowouts and/or depositional areas:
None -
Amount of litter movement (describe size and distance expected to travel):
Most litter size classes stay in lace due to high rock and gravel cover. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
No slake test done. Expect ratings of 1-3 in perennial plant interspaces, 4-5 under shrub canopies. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Weak granular to subangular blocky; color is 7.5-10YR5/4 dry, 7.5-10YR4/4 Moist; thickness to 4 inches. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Canopy 15-20%: 50% shrubs, 23% trees, 25% succulents and 1-2% perennial grass. Cover is well dispersed throughout site. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
None -
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 shrubs > trees > winter annuals > shrubs > summer annuals > perennial forbs > perennial grasses > succulentsSub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
2050% tree & shrub canopy mortality, 75-90% mortality on perennial grasses. -
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
150 lbs/ac unfavorable precipitation; 250 lbs/ac normal precipitation; 350 lbs/ac favorable precipitation. -
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:
Sahara mustard -
Perennial plant reproductive capability:
Not impaired for shrubs; drought impaired for perennial grasses and forbs.
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