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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.
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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 Not specified
Shrub (1) Ambrosia deltoidea
Herbaceous (1) Muhlenbergia porteri
(2) Pleuraphis rigidaPhysiographic features
This site occurs on hillslopes and ridgetops. Slopes are from 15 to 45%. Elevations range from 1200 to 2600 feet.
Table 2. Representative physiographic features
Landforms (1) Hill
(2) Ridge
Elevation 1200 – 2600 ft Slope 15 – 45 % 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 BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
These are deep and moderately deep soils formed in old alluvium from mixed origins. They are loamy and non-calcareous to moderate (20 inches) depths. Soil surfaces are well protected with gravel and rock covers. Plant-soil moisture relationships are fair to good.
Soils mapped on this site include: SSA-645 Aguila-Carefree area MU's Ebon > 15% slope-49 & Pinamt-49.Table 4. Representative soil features
Surface texture (1) Very gravelly loam
(2) Extremely gravelly clay loam
Family particle size (1) Clayey
Drainage class Well drained Permeability class Slow Soil depth 60 in Surface fragment cover <=3" 35 – 65 % Surface fragment cover >3" 1 – 10 % Available water capacity
(0-40in)3 – 6 in Calcium carbonate equivalent
(0-40in)1 – 15 % 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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Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Historical Climax Plant CommunityCommunity 1.1
Historical Climax Plant CommunityThe potential plant community on this site is a diverse mixture of perennial and annual grasses and forbs, shrubs, desert trees and cacti. The aspect is shrubland.
With continuous, heavy grazing and/or drought, perennial grasses and forbs quickly disappear from the plant community. Trees are shrubby in nature on this site and canopy cover does not exceed 5%. Soils are well protected by covers of gravels, cobbles and rocks. Cryptogam cover is low due to the small percentage of bare soil areas. Red brome, a cool season, introduced, annual grass is well entrenched on areas of this site. It competes with native annual species and acts to increase the frequency of fires on this site which can remove the native trees, shrubs and cacti. Plant populations for major species are; 5 to 20 trees per acre, 500 to 1000 triangle bursage per acre and 100 to 200 cholla per acre.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 203 – 293 Grass/Grasslike 45 – 113 Forb 45 – 90 Total 293 – 496 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 20–45 bush muhly MUPO2 Muhlenbergia porteri 5–15 – purple threeawn ARPU9 Aristida purpurea 0–5 – Parish's threeawn ARPUP5 Aristida purpurea var. parishii 0–3 – Wright's threeawn ARPUW Aristida purpurea var. wrightii 0–3 – spidergrass ARTE3 Aristida ternipes 0–3 – spidergrass ARTEG Aristida ternipes var. gentilis 0–3 – big galleta PLRI3 Pleuraphis rigida 0–3 – slender grama BORE2 Bouteloua repens 0–2 – tanglehead HECO10 Heteropogon contortus 0–2 – slim tridens TRMU Tridens muticus 0–2 – tobosagrass PLMU3 Pleuraphis mutica 0–1 – low woollygrass DAPU7 Dasyochloa pulchella 0–1 – Arizona cottontop DICA8 Digitaria californica 0–1 – nineawn pappusgrass ENDE Enneapogon desvauxii 0–1 – plains bristlegrass SEVU2 Setaria vulpiseta 0–1 – 2 5–65 Eastwood fescue VUMIC Vulpia microstachys var. ciliata 0–10 – Pacific fescue VUMIP Vulpia microstachys var. pauciflora 0–10 – sixweeks fescue VUOC Vulpia octoflora 0–10 – sixweeks threeawn ARAD Aristida adscensionis 0–5 – prairie threeawn AROL Aristida oligantha 0–5 – needle grama BOAR Bouteloua aristidoides 0–5 – sixweeks grama BOBA2 Bouteloua barbata 0–5 – Rothrock's grama BORO2 Bouteloua rothrockii 0–5 – Arizona brome BRAR4 Bromus arizonicus 0–1 – tufted lovegrass ERPEP2 Eragrostis pectinacea var. pectinacea 0–1 – Mexican sprangletop LEFUU Leptochloa fusca ssp. uninervia 0–1 – mucronate sprangletop LEPA6 Leptochloa panicea 0–1 – delicate muhly MUFR Muhlenbergia fragilis 0–1 – littleseed muhly MUMI Muhlenbergia microsperma 0–1 – Bigelow's bluegrass POBI Poa bigelovii 0–1 – Arizona signalgrass URAR Urochloa arizonica 0–1 – 3 0–10 mesquite mistletoe PHCA8 Phoradendron californicum 0–8 – bigseed alfalfa dodder CUIN Cuscuta indecora 0–2 – 4 5–10 Alga 2ALGA Alga 1–5 – Lichen 2LICHN Lichen 1–3 – Moss 2MOSS Moss 1–2 – Fungus 2FUNGI Fungus 1–2 – Forb5 20–45 desert globemallow SPAM2 Sphaeralcea ambigua 0–5 – Emory's globemallow SPEM Sphaeralcea emoryi 0–5 – Louisiana vetch VILUL2 Vicia ludoviciana ssp. ludoviciana 0–2 – woollyhead neststraw STMI2 Stylocline micropoides 0–1 – Coulter's globemallow SPCO2 Sphaeralcea coulteri 0–1 – Nuttall's povertyweed MONU Monolepis nuttalliana 0–1 – evening primrose OENOT Oenothera 0–1 – Florida pellitory PAFL3 Parietaria floridana 0–1 – beardtongue PENST Penstemon 0–1 – phacelia PHACE Phacelia 0–1 – desert Indianwheat PLOV Plantago ovata 0–1 – slender poreleaf POGR5 Porophyllum gracile 0–1 – chia SACO6 Salvia columbariae 0–1 – poreleaf dogweed ADPO2 Adenophyllum porophyllum 0–1 – trailing windmills ALIN Allionia incarnata 0–1 – carelessweed AMPA Amaranthus palmeri 0–1 – bluestar AMSON Amsonia 0–1 – tuber anemone ANTU Anemone tuberosa 0–1 – narrowleaf silverbush ARLA12 Argythamnia lanceolata 0–1 – New Mexico silverbush ARNE2 Argythamnia neomexicana 0–1 – smallflowered milkvetch ASNU4 Astragalus nuttallianus 0–1 – desert marigold BAMU Baileya multiradiata 0–1 – spiderling BOERH2 Boerhavia 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 – whitemargin sandmat CHAL11 Chamaesyce albomarginata 0–1 – hyssopleaf sandmat CHHY3 Chamaesyce hyssopifolia 0–1 – New Mexico thistle CINE Cirsium neomexicanum 0–1 – American wild carrot DAPU3 Daucus pusillus 0–1 – wedgeleaf draba DRCU Draba cuneifolia 0–1 – whisperingbells EMPE Emmenanthe penduliflora 0–1 – spreading fleabane ERDI4 Erigeron divergens 0–1 – buckwheat ERIOG Eriogonum 0–1 – Texas stork's bill ERTE13 Erodium texanum 0–1 – dainty desert hideseed EUMI2 Eucrypta micrantha 0–1 – California fagonbush FALA Fagonia laevis 0–1 – gilia GILIA Gilia 0–1 – Arizona poppy KAGR Kallstroemia grandiflora 0–1 – Gordon's bladderpod LEGO Lesquerella gordonii 0–1 – Bigelow's linanthus LIBI2 Linanthus bigelovii 0–1 – foothill deervetch LOHU2 Lotus humistratus 0–1 – desert deervetch LOMI Lotus micranthus 0–1 – coastal bird's-foot trefoil LOSA Lotus salsuginosus 0–1 – slender goldenweed MAGR10 Machaeranthera gracilis 0–1 – desertdandelion MALAC3 Malacothrix 0–1 – Parry's false prairie-clover MAPA7 Marina parryi 0–1 – lacy tansyaster MAPIP4 Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida 0–1 – rough menodora MESC Menodora scabra 0–1 – Shrub/Vine6 90–150 triangle bur ragweed AMDE4 Ambrosia deltoidea 90–150 – 7 20–65 water jacket LYAN Lycium andersonii 0–5 – Berlandier's wolfberry LYBE Lycium berlandieri 0–5 – Arizona desert-thorn LYEX Lycium exsertum 0–5 – desert wolfberry LYMA Lycium macrodon 0–5 – yellow paloverde PAMI5 Parkinsonia microphylla 0–5 – desert ironwood OLTE Olneya tesota 0–3 – ocotillo FOSP2 Fouquieria splendens 0–3 – sangre de cristo JACA2 Jatropha cardiophylla 0–3 – creosote bush LATR2 Larrea tridentata 0–2 – starry bedstraw GAST Galium stellatum 0–2 – velvet mesquite PRVE Prosopis velutina 0–2 – lotebush ZIOB Ziziphus obtusifolia 0–1 – catclaw acacia ACGR Acacia greggii 0–1 – Tucson bur ragweed AMCO4 Ambrosia cordifolia 0–1 – burrobush AMDU2 Ambrosia dumosa 0–1 – Coulter's brickellbush BRCO Brickellia coulteri 0–1 – 8 20–45 jojoba SICH Simmondsia chinensis 0–10 – spiny hackberry CEEH Celtis ehrenbergiana 0–3 – littleleaf ratany KRER Krameria erecta 0–3 – white ratany KRGR Krameria grayi 0–2 – Mexican bladdersage SAME Salazaria mexicana 0–2 – fairyduster CAER Calliandra eriophylla 0–2 – brittlebush ENFA Encelia farinosa 0–2 – Nevada jointfir EPNE Ephedra nevadensis 0–1 – Eastern Mojave buckwheat ERFA2 Eriogonum fasciculatum 0–1 – American threefold TRCA8 Trixis californica 0–1 – Parish's goldeneye VIPA14 Viguiera parishii 0–1 – Indian mallow ABUTI Abutilon 0–1 – whitethorn acacia ACCO2 Acacia constricta 0–1 – 9 45–90 beavertail pricklypear OPBA2 Opuntia basilaris 0–10 – woollyjoint pricklypear OPTO2 Opuntia tomentosa 0–5 – Leconte's barrel cactus FECYL Ferocactus cylindraceus var. lecontei 0–2 – candy barrelcactus FEWI Ferocactus wislizeni 0–2 – globe cactus MAMMI Mammillaria 0–1 – senita cactus PASC14 Pachycereus schottii 0–1 – organpipe cactus STTH3 Stenocereus thurberi 0–1 – Engelmann's hedgehog cactus ECEN Echinocereus engelmannii 0–1 – rainbow cactus ECPE Echinocereus pectinatus 0–1 – Interpretations
Animal community
Steep slopes and very gravelly to cobbly surfaces limit grazing distribution epecially during the hot summer months. Stocker cattle will use areas of this site fairly well during the fall, winter and spring. In years with above average winter rainfall the production of annual forbs and grasses can be significant and will allow for additional carrying capacity in the March-May growing season. The plant community may be deficient in energy in the summer through winter seasons.
Water developments can be very important to wildlife species on this site. Cover and diversity are somewhat lacking for the larger desert mammals but the diverse topography makes up for that. The site is also home to a variety of small mammal, reptile and bird species.Other information
T&E: Leptonycteris curasoae yerbe beuna
(Lesser long-nosed bat)
Supporting information
Type locality
Location 1: Maricopa County, AZ Township/Range/Section T6N R2W S33 General legal description Phoenix FO - Desert Hills CAttle Co. Location 2: Maricopa County, AZ Township/Range/Section T3N R6E S21 General legal description Chandler FO - McDowell Mountains Contributors
Dan Robinett
Dan Robinett, J. Norris
Larry D. Ellicott
Stephen Cassady
Steve BarkerRangeland 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, Shai Schendel, Scott Stratton, Dan Robinett, Emilio Carrillo Contact for lead author NRCS Tucson Area Office Date 12/14/2005 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
-
Number and extent of rills:
Fairly common, 8-10 feet apart well vegetated by annuals in El Nino years, all rills have gently sloping banks. -
Presence of water flow patterns:
Uncommon; verland flow location difficult to determine due to high gravel cover. -
Number and height of erosional pedestals or terracettes:
Pedestals are uncommon only observed near naturally eroding rills; terracettes only formed by high densities of rock fragments. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
5-10%, gravel cover 85-90% -
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 place. Fine classes may move 5-10 feet before being intercepted by plants of rock fragments. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Expect values of 1-3 in canopy interspaces, and 4-6 under plant canopies. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Weak thin platy to weak granular; thickness to 1 inch. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Canopy 20-25%: 50% shrubs (40% jojoba), 35-40% trees, 3-5% half shrubs, and 0-1% succulents. Cver 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:
shrubs > trees = half shrubs > succulents. In El Nino years, annual forbs and grasses can be greater than all groups.Sub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
10% of perennial grass plants have been lost in recent prolonged drought; 18, 68, 23, 10, 39 and 24% canopy cover mortality of cresote, mormon tea, paloverde, flattop buckwheat, range ratany and triangle bursage, respectively. -
Average percent litter cover (%) and depth ( in):
El Nino years -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
300 lbs/ac unfavorable precipitation, 450 lbs/ac normal precipitation, 600 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, filaree, Mediterranean grass, red brome(at higher elevations of MLRA). -
Perennial plant reproductive capability:
Not impaired for shrubs; drouht impaired for perennial grasses and forbs.
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