Natural Resources
Conservation Service
Ecological site R040XA109AZ
Loamy Hills
10"-13" p.z.
Last updated: 5/29/2025
Accessed: 08/27/2026
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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 40.1 – Upper Sonoran Desert
Elevations range from 2000 to 3200 feet and precipitation averages 10 to 13 inches per year. Vegetation includes saguaro, palo verde, mesquite, creosotebush, triangle bursage, prickly pear, cholla, limberbush, wolfberry, bush muhly, threeawns, ocotillo, and globe mallow. 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 (1) Calliandra eriophylla
Herbaceous (1) Pleuraphis mutica
(2) Hilaria belangeriPhysiographic features
This site occurs as rolling hills and side slopes of low mountains. It is always in an upland position.
Table 2. Representative physiographic features
Landforms (1) Alluvial fan
(2) Terrace
Flooding frequency None Ponding frequency None Elevation 2000 – 3200 ft Slope 10 – 35 % Aspect Aspect is not a significant factor Climatic features
Precipitation in the sub resource area ranges from 10 to 13 inches in the southern part, along the Mexican border with elevations from about 1900 to 3200 feet. Precipitation in the northern part of the resource area ranges from 11 to 14 inches with elevations from about 1700 to 3500 feet. Winter-summer rainfall ratios range from 40%-60% in the southern portions of the land resource unit, to 50%-50% in the central portions, to 60%-40% in the northern part of the land resource unit. As one moves from east to west in this resource area rains become slightly more unpredictable and variable with Coefficients of Variation of annual rainfall equal to 29% at Tucson and 36% at Carefree. Summer rains fall July through Sept., originate in the Gulf of Mexico, and are convective, usually brief, intense thunderstorms. Cool season moisture tends to be frontal, originating in the Pacific and Gulf of California. This winter precipitation falls in widespread storms with long duration and low intensity. Snow is rare and seldom lasts more than an hour or two. May and June are the driest months of the year. Humidity is generally very low.
Winter temperatures are mild, with very few days recording freezing temperatures in the morning. Summer temperatures are warm to hot, with several days in June and July exceeding 105 degrees F.
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) 270 days Freeze-free period (average) 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, loamy soils. They may be gravelly. They are not limy and have fair to good plant-soil moisture relationships.
Soils mapped on this site include: in
SSA-637 Western Yavapai county MU Palo Verdes-PcE and
SSA-645 Aguila-Carefree area MU's Eba-42 & Pinaleno-43.Table 4. Representative soil features
Surface texture (1) Gravelly sandy loam
(2) Very gravelly loam
(3) Very gravelly clay loam
Family particle size (1) Loamy
Drainage class Moderately well drained to well drained Permeability class Slow to moderately slow Soil depth 60 – 80 in Surface fragment cover <=3" 5 – 65 % Surface fragment cover >3" 0 – 5 % Available water capacity
(0-40in)4 – 8 in Calcium carbonate equivalent
(0-40in)10 – 35 % Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)0 – 3 Soil reaction (1:1 water)
(0-40in)7.8 – 8.4 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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Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Historic Climax Plant CommunityCommunity 1.1
Historic Climax Plant CommunityThe native, potential plant community is perennial grasses with lesser amounts of perennial and annual forbs and desert shrub species.
As the site deteriorates from improper use, shrubby species and cactii increase to dominate it.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 420 450 480 Shrub/Vine 90 120 150 Forb 60 75 90 Total 570 645 720 Figure 5. Plant community growth curve (percent production by month). AZ4011 , 40.1 10-13" p.z. hill sites. Growth begins in the late winter, goes semi-dormant in the drought period of late May through early July, growth continues in the summer through early fall..
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 5 15 20 5 5 10 15 15 5 5 0 Figure 6. Plant community growth curve (percent production by month). AZ4032 , 40-3AZ 10-12" p.z. all sites. Growth begins in the spring, 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 0 10 15 20 30 20 5 0 0 0 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike0 Dominant Perennial Grasses 270–390 1 60–90 threeawn ARIST Aristida 10–15 – sideoats grama BOCU Bouteloua curtipendula 10–15 – black grama BOER4 Bouteloua eriopoda 10–15 – bush muhly MUPO2 Muhlenbergia porteri 10–15 – big galleta PLRI3 Pleuraphis rigida 10–15 – desert needlegrass ACSP12 Achnatherum speciosum 10–15 – 2 Misc Perennial Grasses 6–30 cane bluestem BOBA3 Bothriochloa barbinodis 2–8 – Arizona cottontop DICA8 Digitaria californica 2–8 – large-spike bristlegrass SEMA5 Setaria macrostachya 2–8 – slim tridens TRMU Tridens muticus 2–8 – 3 Annual Grasses 6–30 sixweeks threeawn ARAD Aristida adscensionis 1–3 – needle grama BOAR Bouteloua aristidoides 1–3 – sixweeks grama BOBA2 Bouteloua barbata 1–3 – Arizona brome BRAR4 Bromus arizonicus 1–3 – low woollygrass DAPU7 Dasyochloa pulchella 1–3 – Bigelow's bluegrass POBI Poa bigelovii 0–3 – Eastwood fescue VUMIC Vulpia microstachys var. ciliata 0–3 – sixweeks fescue VUOC Vulpia octoflora 0–3 – Arizona signalgrass URAR Urochloa arizonica 0–2 – muhly MUHLE Muhlenbergia 0–2 – littleseed muhly MUMI Muhlenbergia microsperma 0–2 – Forb4 Annual Forbs 30–60 desert Indianwheat PLOV Plantago ovata 4–10 – New Mexico thistle CINE Cirsium neomexicanum 4–10 – Coulter's lupine LUSP2 Lupinus sparsiflorus 4–8 – evening primrose OENOT Oenothera 0–5 – phacelia PHACE Phacelia 1–5 – cryptantha CRYPT Cryptantha 1–5 – American wild carrot DAPU3 Daucus pusillus 1–5 – California poppy ESCAM Eschscholzia californica ssp. mexicana 1–5 – gilia GILIA Gilia 1–5 – pepperweed LEPID Lepidium 2–5 – trefoil LOTUS Lotus 0–5 – trailing windmills ALIN Allionia incarnata 2–5 – ragweed AMBRO Ambrosia 2–5 – common fiddleneck AMMEI2 Amsinckia menziesii var. intermedia 1–5 – bristly fiddleneck AMTE3 Amsinckia tessellata 1–5 – milkvetch ASTRA Astragalus 2–5 – hoary bowlesia BOIN3 Bowlesia incana 0–5 – mariposa lily CALOC Calochortus 0–5 – woolly plantain PLPA2 Plantago patagonica 2–5 – New Mexico plumeseed RANE Rafinesquia neomexicana 1–5 – ragwort SENEC Senecio 2–5 – catchfly SILEN Silene 1–5 – Coulter's globemallow SPCO2 Sphaeralcea coulteri 2–5 – 5 Perennial Forbs 30–60 dwarf desertpeony ACNA2 Acourtia nana 1–2 – brownfoot ACWR5 Acourtia wrightii 1–2 – tuber anemone ANTU Anemone tuberosa 1–2 – California suncup CACA32 Camissonia californica 1–2 – bluedicks DICAC5 Dichelostemma capitatum ssp. capitatum 1–2 – desert trumpet ERIN4 Eriogonum inflatum 1–2 – Parry's false prairie-clover MAPA7 Marina parryi 1–2 – wishbone-bush MILAV Mirabilis laevis var. villosa 1–2 – Coues' cassia SECO10 Senna covesii 1–2 – desert globemallow SPAM2 Sphaeralcea ambigua 1–2 – globemallow SPHAE Sphaeralcea 1–2 – brownplume wirelettuce STPA4 Stephanomeria pauciflora 1–2 – Shrub/Vine6 Dominant Shrubs 60–90 Nevada jointfir EPNE Ephedra nevadensis 10–15 – Mexican bladdersage SAME Salazaria mexicana 10–15 – toothleaf goldeneye VIDE3 Viguiera dentata 10–15 – littleleaf ratany KRER Krameria erecta 10–15 – rough menodora MESC Menodora scabra 5–10 – slender janusia JAGR Janusia gracilis 5–10 – fairyduster CAER Calliandra eriophylla 5–10 – 7 Misc Shrubs 30–60 whitethorn acacia ACCO2 Acacia constricta 2–5 – catclaw acacia ACGR Acacia greggii 2–5 – rayless goldenhead ACSP Acamptopappus sphaerocephalus 2–5 – San Felipe dogweed ADPO Adenophyllum porophylloides 1–5 – shortleaf baccharis BABR Baccharis brachyphylla 2–5 – Goodding's tansyaster MAPIG2 Machaeranthera pinnatifida ssp. gooddingii var. gooddingii 2–5 – plains blackfoot MELE2 Melampodium leucanthum 1–5 – whitestem paperflower PSCO2 Psilostrophe cooperi 2–5 – Eastern Mojave buckwheat ERFA2 Eriogonum fasciculatum 2–5 – bastardsage ERWR Eriogonum wrightii 2–5 – threadleaf snakeweed GUMI Gutierrezia microcephala 1–4 – broom snakeweed GUSA2 Gutierrezia sarothrae 1–4 – desert-thorn LYCIU Lycium 1–4 – starry bedstraw GASTE2 Galium stellatum ssp. eremicum 1–3 – Lemmon's ragwort SELE8 Senecio lemmonii 1–3 – American threefold TRCA8 Trixis californica 1–3 – Chihuahuan brickellbush BRFL Brickellia floribunda 1–3 – rough brickellbush BRMIS Brickellia microphylla var. scabra 1–3 – crucifixion thorn CAHO3 Canotia holacantha 1–3 – brittlebush ENFA Encelia farinosa 1–3 – Wright's beebrush ALWR Aloysia wrightii 1–3 – 8 Succulents 6–30 saguaro CAGI10 Carnegiea gigantea 1–5 – ocotillo FOSP2 Fouquieria splendens 1–5 – banana yucca YUBA Yucca baccata 1–5 – cactus apple OPEN3 Opuntia engelmannii 1–3 – buckhorn cholla CYACA2 Cylindropuntia acanthocarpa var. acanthocarpa 1–3 – Engelmann's hedgehog cactus ECEN Echinocereus engelmannii 1–3 – candy barrelcactus FEWI Ferocactus wislizeni 1–3 – Tree9 Tree 5–10 yellow paloverde PAMI5 Parkinsonia microphylla 5–10 – Interpretations
Animal community
This site is accessible for and produces forage for use, yearlong, by all classes of livestock. Fencing and water developments my be needed to improve distribution and facilitate management.
For wildlife this site is an important one for smaller animals. As natural waters are lacking, stockwater developments are very important on the site. Numerous inclusions of drainageways provide adequate cover for larger animals such as mule deer.Recreational uses
This site is located on rolling hills and side slopes of desert mountains consisting of grassy hills with good desert wildflower production in years of good winter moisture.
Very few days in the fall, winter and spring are too uncomfortable to enjoy out-of-door activities. In June, July and August the afternoon heat restricts activity. The major activities are rockhounding, hunting, horseback riding, prospecting and photography.Wood products
None.
Other products
Mining occurs in places on the site.
Supporting information
Type locality
Location 1: Yavapai County, AZ Township/Range/Section T9N R4W S16 General legal description State Location: Section 16, T9N, R4W, Prescott F.O., JJ Coughlin Ranch. Other Field Office locations are Phoenix F.O. Section 12, T7N, R6W, Flying E Ranch on right-of-way of Wickenburh-Aguila Highway, Southside. Contributors
Larry D. Ellicott
UnknownApproval
Kendra Moseley, 5/29/2025
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 08/27/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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