Natural Resources
Conservation Service
Ecological site F022AY126NV
Pinus albicaulis-Pinus flexilis/Poa-Carex
Accessed: 04/21/2026
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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Table 1. Dominant plant species
Tree (1) Pinus albicaulis
(2) Pinus flexilisShrub Not specified
Herbaceous (1) Poa
(2) CarexPhysiographic features
This woodland community occurs on smooth to concave sideslopes of mountains. The site is typically found on northerly aspects at lower elevations and on all aspects at higher elevations. Slopes range from 8 to over 75 percent but are typically more than 30 percent. Elevations are generally over 8,000 feet.
Table 2. Representative physiographic features
Landforms (1) Mountain
(2) Mountain slope
Elevation 8000 – 12000 ft Slope 8 – 75 % Aspect N, NE, NW Climatic features
">Influencing water features
There are no influencing water features associated with this site.
Soil features
Table 3. Representative soil features
Surface texture (1) Very gravelly loamy coarse sand
(2) Very gravelly sandy loam
Drainage class Well drained to somewhat excessively drained Permeability class Moderately rapid to rapid Soil depth 20 – 60 in Surface fragment cover <=3" 25 – 55 % Surface fragment cover >3" 5 – 20 % Available water capacity
(0-40in)0.6 – 3.6 in Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)4.5 – 6.5 Subsurface fragment volume <=3"
(Depth not specified)16 – 41 % Subsurface fragment volume >3"
(Depth not specified)2 – 26 % Ecological dynamics
Whitebark pine grows in cold, snowy, and generally moist climates. On semiarid ranges it is most common on cold, moist sites, whereas it is most common on warm, dry sites on moist ranges. Whitebark pine is common on ridges and near timberline, where trees are exposed to strong, desiccating winds. Hurricane-force wind velocities (> 73 mi/h (117 km/h)) occur every year on most whitebark pine sites and are especially common on ridgetops.
Climax communities of whitebark pine are relatively open and favorable to establishment of this moderately shade-tolerant species. Clark's nutcrackers, by caching seed in forested sites, maintain climax communities of whitebark pine. Nutcrackers are attracted to open sites for seed caching and are efficient in seeding burned areas.
Limber pine is a slow growing, long-lived species, sometimes taking several hundred years to reach maturity. Mature trees may exceed 1000 years of age. Limber pine stands are broadly even-aged, though populations also occur in uneven-aged stands and on very harsh sites as widely spaced, isolated individuals. Trees often have an irregular or multi-stem growth form, and rarely reach over 50 feet. At high elevations they sometimes form krummholz.
Fire Ecology:
Young trees are usually killed by any fire that scorches their stems. Mature trees with thicker bark can survive. The vulnerability of this species to fire is reduced by the open stand structure, sparse fuels, and sparse undergrowth of limber pine communities.
Wildfires are less frequent in limber pine communities than in other conifer habitats because of limited productivity and fuel accumulation associated with poor soil development, short growing seasons, and late snowmelt.
Whitebark pine wood is highly flammable even when green, and the dry, windswept upper slopes where whitebark pine grows are predisposed to lightning strikes. Whitebark pine and mixed-conifer communities with a whitebark component experience fire frequently; however, fire is usually unable to spread widely due to discontinuous canopies and sparse understory fuels. Fire severity is low where surface fuels are sparse, and the resulting underburn kills mostly small trees and fire-susceptible overstory species, leaving live, mature whitebark pine. Mature whitebark pine survive low-severity surface fire. Moderate-severity surface fire kills the majority of mature trees. Severe surface and crown fires kill even the largest whitebark pine. Whitebark pine will continue to decline if fire is not allowed to periodically set back the successional clock. Secondary succession, accelerated by white pine blister rust and bark beetle outbreaks, results in rapid replacement of whitebark pine by shade-tolerant, fire-sensitive species such as subalpine fir and mountain hemlock. Without burning, genetically valuable seed produced by blister-rust resistant whitebark pine is wasted: no new openings are created where Clark's nutcracker can cache seed and seedlings can establish.State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Reference Plant CommunityCommunity 1.1
Reference Plant CommunityThe reference plant community is the interpretative plant community for this site. The historic climax plant community is characterized by an overstory canopy cover of 40 percent. This site is dominated by whitebark pine and limber pine. Lodgepole pine is often a minor constituent of the overstory. Mountain brome, Letterman's, pine and western needlegrasses, bluegrasses, sedges and lupine are the principal understory plants.
Forest overstory.Overstory tree canopy composition is about 50 to 65 percent whitebark pine with about 35 to 45 percent limber pine and less than 15 percent lodgepole pine.<br /> <br /> Major Successional Stages of Woodland Development:<br /> <br /> HERBACEOUS: Vegetation is dominated by grasses and forbs under full sunlight. This stage is experienced after a major disturbance such as wildfire. Skeleton forest (dead trees) remaining after fire or other disturbances has little or no affect on the composition and production of the herbaceous vegetation.<br /> <br /> TREE SEEDLING-HERBACEOUS: Herbaceous vegetation and tree seedlings dominate the site. Various amounts of tree seedlings (less than 20 inches in height) may be present up to the point where they are obviously a component of the vegetal structure. Lodgepole pine is often a major tree species within this stage following wildfire.<br /> <br /> SAPLING: In the absence of disturbance, tree seedlings develop into saplings (20 inches to 4.5 feet in height) with a canopy cover generally less than 10 percent. Vegetation consists of grasses and forbs in association with tree saplings.<br /> <br /> IMMATURE WOODLAND: Whitebark pine and limber pine greater than 4½ feet in height form a major constituent of the visual aspect and vegetal structure of the plant community. The upper crown of dominant and codominant trees are pyramidal-shaped. Young whitebark pine and limber pine plants are prevalent in the understory. Understory vegetation is moderately influenced by a tree overstory canopy of about 15 to 30 percent.<br /> <br /> MATURE WOODLAND: The visual aspect and vegetal structure are dominated by whitebark pine and limber pine that have reached or are near maximal heights for the site. Dominant trees average greater than five inches in diameter at one-foot stump height. Tree canopy cover is typically about 30 to 45 percent. Understory vegetation is strongly influenced by tree competition. Infrequent, yet periodic wildfire is a natural factor influencing the development and maintenance of these mature woodlands. This stage of woodland development is assumed to be representative of this woodland site in a pristine environment.<br /> <br /> OVER-MATURE WOODLAND: This stage is dominated by whitebark pine and limber pine that have reached maximal heights for the site. Dominant and codominant trees average greater than six inches in diameter at the 4½ foot height (DBH). Understory vegetation is sparse due to tree competition, overstory shading, duff accumulation, etc. Tree canopy cover is commonly greater than 40 percent.<br /> <br /> <br />
Forest understory. Understory vegetative composition is about 50 percent grasses, 5 percent forbs, and 45 percent shrubs and young trees when the average overstory canopy is medium. Average understory production ranges from 50 to 150 pounds per acre. Understory production includes the total annual production of all species within 4 1/2 feet of the ground surface.
Additional community tables
Table 4. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
Wildlife Interpretations:
Whitebark pine is a valuable source of food and cover for wildlife. Bears, rodents, and birds consume the seeds The trunks provide nesting sites for cavity nesters including northern flickers and mountain bluebirds. Blue grouse use the branches for roosting and escape cover. Whitebark pine provides ecologically critical linkage between Clark's nutcracker and lower-elevation, Clark's nutcracker-dependant pines. Bear consumption of whitebark pine seed peaks just before hibernation in late October and early November. Bears feeding on whitebark pine seeds tend to feed on nothing else, and a good supply of seeds increases bear fecundity. Wildlife and livestock use whitebark pine/shrub communities for shade and bedding cover.
The large, wingless seeds of limber pine have high energy content. Pine seeds provide critical food for rodents and birds, which cache the seeds for later use. Other small mammals and birds benefit from these caches. Bears also feed from caches. Sites with limber pine provide key winter range for deer and elk. Bighorn sheep use open stands on ridges.
Livestock Interpretations:
Difficult access and low forage production result in low forage value of whitebark-limber pine stands for livestock.Hydrological functions
Whitebark pine's role in protecting watersheds may be its most undervalued critical function. Whitebark pine sites are highly valuable watersheds. The open canopies of whitebark pine communities are thought to slow snowmelt and retain more snowpack than the closed canopies of late-succession communities.
Recreational uses
The main recreation is hiking in this area.
Wood products
Mainly due to the species' inaccessibility, whitebark pine wood is not considered commercially valuable. Large-diameter whitebark pine in mixed stands were harvested in the past. Whitebark pine is classified as a soft-wood pine, and its wood has bending, compression, and shearing properties similar to eastern (P. strobus) and western white pine.
The wood of limber pine has little commercial value. Its potential for timber and fuelwood production is low, because the trees are slow growing with irregular form. Limber pine has been used locally for mine props and railroad ties.
PRODUCTIVE CAPACITY
Very low quality site for tree production. At present, site productivity and site index information is not available for either whitebark pine or limber pine.
Productivity Class: 0
CMAI*:<0.9 to 1.4 ft3/ac/yr; <0.06 to 0.09 m3/ha/yr.
*CMAI: is the culmination of mean annual increment or highest average growth rate of the stand in the units specified.
MANAGEMENT GUIDES AND INTERPRETATIONS
1. LIMITATIONS AND CONSIDERATIONS
a. Significant restrictions or limitations for forest land use or management due to steep slopes.
2. ESSENTIAL REQUIREMENTS
a. Protect soils from accelerated erosion.
b. Apply proper grazing management
3. SILVICULTURAL PRACTICES
a. Harvest cut selectively or in small patches (size dependent upon site conditions) to enhance forage production.
1) Thinning and improvement cutting- Removal of poorly formed, diseased and low vigor trees for firewood.
2) Harvest cutting- Selectively harvest surplus trees to achieve desired spacing. Do not select only "high grade" trees for harvest.
3) Slash disposal- broadcasting slash improves reestablishment of native understory species and establishment of seeded grasses and forbs after tree harvest.
b. Prescription burning program to maintain desired canopy cover and manage site reproduction.
c. Mechanical tree removal on suitable sites to enhance forage production and manage site reproduction.
d. Pest control-porcupines can cause extensive damage and populations should be controlled.
e. Fire hazard- Fire usually not a problem in well-managed, mature stands.
Other products
Whitebark pine seeds are a traditional Native American food.
Limber pine is used in the nursery trade for landscaping.Other information
Throughout much of its range, whitebark pine communities have experienced tremendous change over the past century from the affects of fire suppression, mountain pine beetle and blister rust. Fire suppression has contributed to change in habitat structure and functions. Blister rust, an introduced pathogen, is increasing whitebark pine mortality in these woodlands. fire suppression can lead to tree islands coalescing and the conversion of parklands into a more closed forest habitat. Parkland conditions can displace alpine conditions through tree invasions. Livestock use and heavy horse or foot traffic can lead to trampling and soil compaction. Slow growth in this habitat prevents rapid recovery.
Supporting information
Type locality
Location 1: Mono County, CA Latitude 38° 26′ 11″ Longitude 119° 34′ 1″ General legal description Toiyabe National Forest. Sierra Nevada Range, Virginia Lakes area, Mono County, California. This site also occurs in Alpine County, California. Other references
Fire Effects Information System[Online], http://www.fs.fed.us/database/feis
Plants Database [Online], http://www.plants.usda.gov
Lanner, Ronald M.. 1984. Trees of the Great Basin, A Natural History. Reno University of Nevada Press.
USDA-NRCS. 1980. National Forestry Manual - Part 537. Washington, D.C.
Contributors
Angela Mushrush
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
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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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