Natural Resources
Conservation Service
Ecological site F041XA128AZ
Mountains (PIPO)
25"-30" p.z.
Last updated: 4/09/2021
Accessed: 09/14/2026
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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
MLRA notes
Major Land Resource Area (MLRA): 041X–Madrean Archipelago
AZ 41.1 – Mexican Oak-Pine Forest and Oak Savannah
Elevations range from 4500 to 10,700 feet and precipitation ranges from 16 to 30 inches. Vegetation includes Emory oak, Mexican blue oak, Arizona white oak, one-seed juniper, alligator juniper, sacahuista, California bricklebush, skunkbush sumac, Arizona rosewood, wait-a-bit mimosa, sideoats grama, blue grama, purple grama, wooly bunchgrass, plains lovegrass, squirreltail, and pinyon ricegrass. The soil temperature regime ranges from thermic to mesic and the soil moisture regime ranges from aridic ustic to typic ustic. 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) Pinus ponderosa
Shrub Not specified
Herbaceous (1) Muhlenbergia
Physiographic features
This site occurs on hillslopes, toeslopes and ridgetops. Slope aspect is site differentiating at elevations near land resource subarea boundaries.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
(2) Ridge
Flooding frequency None Ponding frequency None Elevation 6500 – 8900 ft Slope 5 – 60 % Climatic features
Precipitation in this zone of the common resource area ranges from 16-20 inches per year with elevations from 4700-5500 feet. Approximately 40% of this moisture comes as gentle rain or snow during the winter-spring (Oct-Apr) season; originates in the north Pacific and Gulf of California and comes as frontal storms with long duration and low intensity. The remaining 60% falls in the summer season (May-Sep); originates in the Gulf of Mexico and are convective, usually brief, intense thunderstorms. Snow is common Dec-Mar, averaging 5-15 inches per year, but rarely lasts more than a week. May and June are the driest months. Humidity is low.
Temperatures are mild. Freezing temperatures are common at night from Oct-May, but daytime temperatures are almost always over 40 F. Below 0 F temperatures can occur Dec-Feb. Daytime summer highs rarely exceed 95 F.
Species like plains lovegrass, bottlebrush squirreltail, Arizona white oak and Emory oak begin growth in late March to April. Warm season grasses begin growth in July or August with receipt of the first summer rains.Table 3 Representative climatic features
Frost-free period (average) 200 days Freeze-free period (average) Precipitation total (average) 20 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
Soil features
These are shallow to moderately deep soils formed on a variety of parent materials and are non-calcareous. They have a thin (1-6 inches) dark colored layer of rotting pine needles (duff) over a light colored allulvial (leached) horizon. Subsoils range in texture from very gravelly sandy loam to clay loam. Bedrock ranges from hard to slightly weathered (5-10 inches) at the soil juncture. Soil reaction is acidic. Surfaces are fairly well protected by covers of boulders, rocks, cobbles and/or gravels. Plant-soil moisture relationships are good. Numerous areas of rock outcrop occur intermingled with soil areas.
Soils mapped on this unit include: SSA-667 Santa Cruz area MU FcF Fanno acid; SSA-669 Pima county Eastern part MU 76 Far & Spudrock; SSA-671 Cochise county Douglas-Tombstone part MU 64 Far & Huachuca.Table 4. Representative soil features
Parent material (1) Alluvium – granite
(2) Colluvium – gneiss
Surface texture (1) Gravelly fine sandy loam
(2) Very flaggy sandy loam
Family particle size (1) Loamy
Drainage class Moderately well drained to well drained Permeability class Moderate to moderately rapid Soil depth 10 – 40 in Surface fragment cover <=3" 10 – 30 % Available water capacity
(0-40in)0 – 2.5 in Subsurface fragment volume <=3"
(Depth not specified)35 – 45 % Ecological dynamics
The historic native state includes the native plant communities that occur on the site, including the historic climax plant community. This state includes other plant communities that naturally occupy the site following fire, drought, flooding, herbivores, and other natural disturbances. The historic climax plant community represents the natural climax community that eventually reoccupies the site with proper management.
State and transition model
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More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textState 1 submodel, plant communities
State 1
Community 1.1
TestingState 2
Transition T
State 1 to 2Additional community tables
Table 5. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
This site produces a moderate amount of forage ofr livestock. If grazing occurs in late spring through summer, it should be done in pasture rotation to allow regrowth. Grazing in the winter may limit use of the site in winters with heavy snows. Mountain lion predation can be severe on calves in the spring and summer on this site.
This site is home to a variety of wildlife species. Two species of turkey and tree squirrels exist in this habitat. Moderate numbers of Coues whitetail deer occur on this site. Black bear use the site extensively and need large unfragmented areas in association with pine-fir above and dense oak woodland below, to survive. The site is home to two threatened species; the Mexican spotted owl and the American peregrine falcon. Free water occurs infrequently on the site as springs, seeps or streamflow. Snag are very important for a variety of bird and small mammal species and their predators. Small water catchments (overtank aprons) usually provide year-round water at these elevations and average precipitation.Wood products
These woodlands are in site productivity class 4R. Ponderosa and Arizona pine can live 300-500 years. Trees mature at 150 years. Number of trees per acre in mature stands range from 50-100. Basal area at maturity ranges from 150-250 square feet per acre. Volume of mature stands range from 20-30 thousand board feet. Average age to reach diameter breast height is 10-12 years. There are 5-6 sawlogs in dominant trees at maturity.
Ponderosa and Arizona pine have the ability to release regardless of age. Proper spacing on this site for these two species is D+12 (diameter +12) in feet. This results in maximum productivity. Trees produce good seed crops every 3-5 years. Down and dead fuel loads in mature stands with a natural fire regime average 0-2 tons per acre. In stands protected from fire for long periods, down and dead fuel loads can be over 20 tons per acre.
Equipment use is limited due to over 20% slopes. Washouts are common on unsurfaced roads due to steep slopes and shallow soils. Stonyness is severen in the area due to stony and cobbly soils and rock outcrops. Watertable flooding is slight.
Erosion potential is severe in cleared areas, as well as roads and trails, due to shallow-erodible soils, steep slopes and high R factors.
Compaction potential is slight to moderate. Workability for roads is severe due to shallow soils and hard bedrock. Rutting potential is severe. Revegetation potential is good due to excellent climate.
Harvest cutting: In second growth stands, think doghair thickets to release trees to pole size. In 20 years, pulpwood harvest to thin to a D+8 spacing. In 50 years, harvest sawlogs to leave a D+12 spacing. Lop and scatter debris from thinning and broadcast burn. Pile debris from pulp and sawlog harvest and burn in fall. Avoid clearcuts. Harvest which maintains uneven age stands and mosaics of openings, thickets, with areas of pole size and mature trees will maximize other values like wildlife, forage, recreation, and allow for reasonable site productivity and harvest of wood products. Harvest should be limited to slopes of 20% or less.
Use prescribed burning in October-November to remove debris from thinning or harvest operations. Burning will reduce pine beetles living in the debris and will reduce fire hazards in the May-August wildfire season as long as tree scorch is minimized. Prescribed burning in late spring can be used to thin unnaturally thick stands and needs to be followed up with a second fire in the fall to consume standing and dead-down fuels resulting from the initial fire. Once second growth stands have been thinned and burned, naturally occuring wildfires should be allowed to burn.
Use pruning, thinning and harvest to control dwarf mistletoe and pine beetles.
Revegetation: Pine cones should be collected in September-October. 250 closed pinecones equals one bushel. 100 lbs fres cones equal 2-7 lbs of seed. There are 12,000 seeds per pound. Stratify seeds at 41 F for 30-60 days and plant in containers in the spring. Plant seedlings in the field in summer.
Pine species need fire to prepare a mineral soil seedbed for natural regeneration.
Plant competition is slight for pine seedlings after a fire.
Windthrow hazard is moderate to severe on ridgetops and windward slopes after fire or harvest cutting in immature stands.Other products
Pine cones for decorative purposes.
Mushrooms and fungus for food.
Berries for jam, jellies.
Wildflowers for decorative uses.Other information
Threatened or endangered plants and animals:
New Mexican Ridgenose rattlesnake (Crotalus willardi obscurus); American Peregrine falcon (Falco peregrinus anatum); Mexican spotted owl (Strix occidentalis lucida); Mexican grey wolf (Canis lupus baileyi); Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis); Ocelot (Felis pardalis); Thick-billed parrot (Rhynchospitta pachyrhycha)Supporting information
Contributors
Karlynn Huling
Larry D. EllicottApproval
Curtis Talbot, 4/09/2021
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 09/14/2026 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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