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Conservation Service
Ecological site F021XE239CA
Abies concolor var. lowiana-Pinus monticola/Achnatherum occidentale ssp. occidentale
Accessed: 07/13/2026
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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Associated sites
F021XE240CA Pinus contorta var. murrayana/Achnatherum
R021XE222CA Loamy Slope 30+ P.Z.
Similar sites
F021XE231CA Abies concolor var. lowiana/Symphoricarpos rotundifolius/Bromus marginatus
Western white pine is a trace or not present on this site.
Table 1. Dominant plant species
Tree (1) Abies concolor var. lowiana
(2) Pinus monticolaShrub Not specified
Herbaceous (1) Achnatherum occidentale ssp. occidentale
Physiographic features
This site occurs on mountain sideslopes on all aspects. Slopes range from 8 to 50 percent. Elevations range from 6800 to 8000 feet.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
Elevation 6800 – 8000 ft Slope 8 – 50 % Aspect Aspect is not a significant factor Climatic features
The climate of this site is subhumid, characterized by cool, dry summers and cold, moist winters. The area's precipitation comes mostly from winter Pacific cyclonic storms, with a very slight summer monsoonal season that is erratic but can be locally significant. Average annual precipitation ranges from 30 to 50 inches with most occurring during the winter months. Approximately half the precipitation falls as snow; half as rain. The mean annual temperature is approximately 41 degrees F. The frost-free period is 30 to 60 days.
Table 3 Representative climatic features
Frost-free period (average) 60 days Freeze-free period (average) 0 days Precipitation total (average) 50 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
There are no influencing water features associated with this site.
Soil features
The soils associated with this site are deep, well drained soils that formed in volcanic ash and colluvium over residuum from andesite or tuff. These soils have high amounts of vitric volcanic ash and glass throughout the profile which enhances the waterholding capacity. Soils are modified with 60 to 80 percent rock fragments, mainly gravels and cobbles. An argillic horizon occurs from 7 to 40 inches. Soil series associated with this site include Lotawaca.
Table 4. Representative soil features
Parent material (1) Colluvium – andesite
(2) Residuum – tuff
Surface texture (1) Ashy sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderately rapid Soil depth 40 – 60 in Surface fragment cover <=3" 25 – 40 % Surface fragment cover >3" 0 – 5 % Available water capacity
(0-40in)5 – 7 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)5.8 – 6.1 Subsurface fragment volume <=3"
(Depth not specified)10 – 30 % Subsurface fragment volume >3"
(Depth not specified)5 – 30 % Ecological dynamics
Major Successional Stages of Forestland Development:
Herbaceous: Vegetation is dominated by grasses and forbs under full sunlight. This stage is experienced after a major disturbance such as a crown fire or tree harvest. Skeleton forest (dead trees) remaining after fire or residual trees left after following harvest have little or no affect on the composition and production of the herbaceous vegetation.
Shrub-Herbaceous: Herbeceous vegetation and woody shrubs dominated the site. Various amounts of tree seedlings (less than 20 inches in height) may be present. Snowbrush ceanothus readily root-sprouts following wildfire and may dominate the community at this stage. Successional development of the community may be arrested by the complete dominance of snowbrush.
Sapling: In the absence of disturbance the tree seedlings develop into saplings (20 to 4.5 feet in height) with a range in canopy cover of about 5 to 10 percent. Vegetation consists of grasses, forbs, and shrubs in association with tree saplings.
Immature Forestland: The visual aspect and vegetal structure are dominated by white fir greater than 4.5 feet in height. The upper crown of dominant and co-dominant trees are cone or pyramidal shaped. Dominants are the tallest trees on the site; co-dominants are 65 to 85 percent of the height of dominant trees. Understory vegetation is moderately influenced by a tree overstory canopy of about 10 to 20 percent.
Mature Forestland: The visual aspect and vegetal structure are dominated by white fir and western white pine that have reached or are near maximal heights for this site. Dominant trees average greater than five inches in diameter at one-foot stump height. Tree canopy cover ranges from 30 to 40 percent. Understory vegetation is strongly influenced by tree competition, overstory shading, duff accumulation, etc. Few tree seedlings and/or saplings occur in the understory.
Over-Mature Forestland: In the absence of wildfire or other naturally occurring disturbances, the tree canopy on this site can become very dense. This stage is dominated by white fir that have reached maximal heights for this site. Upper crowns are typically irregularly flat-topped or rounded. Understory vegetation is sparse to absent due to tree competition. Tree canopy cover is at the maximum for this site and is commonly over 40 percent. Tree ages exceed 100 years.
Wildfire is recognized as a natural disturbance that strongly influenced the structure and composition of the climax vegetation of this forest site. At mid-elevations in the white fir zone, fires may have burned in a pattern of different severities, including patches where most of the trees survived, and patches where stands were completely destroyed. This type of fire regime creates a forest mosaic of stands with varied structures, species compositions, and seral stages. White fir is also a component of forest communities that evolved with less frequent, stand-replacing fires. White fir has thin-bark that is resin blistered and drooping, lower branches making this species moderately fire resistant. Young white fir is highly susceptible to fire. Western white pine is a fire-dependent, seral species. Mature trees have thick bark, moderate flammable foliage, and hanging lower limbs ranking this species as moderate in fire resistance. Young trees have thin bark and are easily killed by fire.
Fire Ecology:
Snowbrush ceanothus is promoted by fire, regenerating from seed stimulated by fire. Where its seeds are present in the soil, snowbrush ceanothus may dominate early seral growth following a medium or hot fire. Snowbrush ceanothus also sprouts vigorously from the root crown after fire. Resprouting may be an adaptation to recurring fires, allowing for rapid growth and recovery. When conifers overtop the shrubfields, snowbrush ceanothus may die out because of reduced light intensities in the forest understory.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 StateCommunity 1.1
Reference Plant CommunityThe reference plant community is dominated by white fir and western white pine. This site occurs above the zone of ponderosa pine to the upper montane zone. White fir becomes dominant particularly at lower elevations. Ponderosa pine and Washoe pine are often present at lower elevations. Understory shrubs include wax currant, snowberry and snowbrush ceanothus. Understory grasses include Wheeler bluegrass, mountain brome and Ross' sedge. White-veined wintergreen, tailcup lupine, and prickly hawkweed are common understory forbs.
Forest overstory.MATURE FORESTLAND: The visual aspect and vegetal structure are dominated by white fir and western white pine that have reached or are near maximal heights for this site. Dominant trees average greater than five inches in diameter at one-foot stump height. Tree canopy cover ranges from 30 to 40 percent. Understory vegetation is strongly influenced by tree competition, overstory shading, duff accumulation, etc. Few tree seedlings and/or saplings occur in the understory. Tree ages exceed 100 years.
Forest understory. Understory vegetative composition is about 40 percent grasses, 40 percent forbs and 30 percent shrubs and young trees when the average overstory canopy is medium (30 to 40 percent). Average understory production ranges from 400 to 800 pounds per acre with a medium canopy cover. Understory production includes the total annual production of all species within 4½ feet of the ground surface.
Figure 3. 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 140 210 280 Forb 140 210 280 Shrub/Vine 92 138 184 Tree 28 42 56 Total 400 600 800 Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Primary Perennial Grasses/Grasslikes 120–252 western needlegrass ACOCO Achnatherum occidentale ssp. occidentale 60–144 – Ross' sedge CARO5 Carex rossii 30–54 – Wheeler's bluegrass POWH2 Poa wheeleri 30–54 – 2 Secondary Perennial Grasses 15–30 California needlegrass ACOCC Achnatherum occidentale ssp. californicum 3–6 – mountain brome BRMA4 Bromus marginatus 3–6 – squirreltail ELEL5 Elymus elymoides 3–6 – blue wildrye ELGL Elymus glaucus 3–6 – spike trisetum TRSP2 Trisetum spicatum 3–6 – Forb3 Annual 6–12 Forb, annual 2FA Forb, annual 3–6 – tiny trumpet COLI2 Collomia linearis 3–6 – 4 Perennial 57–258 heartleaf arnica ARCO9 Arnica cordifolia 6–30 – tailcup lupine LUCAC3 Lupinus caudatus ssp. caudatus 6–30 – feathery false lily of the valley MARAR Maianthemum racemosum ssp. racemosum 6–30 – sweetcicely OSBE Osmorhiza berteroi 6–30 – slender penstemon PEGR4 Penstemon gracilentus 6–30 – tuber starwort PSJA2 Pseudostellaria jamesiana 6–30 – whiteveined wintergreen PYPI2 Pyrola picta 6–30 – white hawkweed HIAL2 Hieracium albiflorum 6–30 – prickly hawkweed HIHO Hieracium horridum 3–6 – ballhead waterleaf HYCA4 Hydrophyllum capitatum 3–6 – little prince's pine CHME Chimaphila menziesii 3–6 – Shrub/Vine5 Primary Shrubs 60–144 sticky currant RIVI3 Ribes viscosissimum 60–144 – 6 Secondary Shrubs 15–30 pinemat manzanita ARNE Arctostaphylos nevadensis 3–6 – mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 3–6 – snowbrush ceanothus CEVE Ceanothus velutinus 3–6 – wax currant RICE Ribes cereum 3–6 – roundleaf snowberry SYRO Symphoricarpos rotundifolius 3–6 – Tree7 Evergreen 18–54 western white pine PIMO3 Pinus monticola 6–30 – ponderosa pine PIPOP Pinus ponderosa var. ponderosa 3–6 – Sierra lodgepole pine PICOM Pinus contorta var. murrayana 3–6 – Table 7. Community 1.1 forest overstory composition
Common name Symbol Scientific name Nativity Height ft Canopy cover (%) Diameter in Basal area (square ft/acre) Treewestern white pine PIMO3 Pinus monticola Native – 0-35 – 0 Sierra lodgepole pine PICOM Pinus contorta var. murrayana Native – 0-2 – 0 ponderosa pine PIPOP Pinus ponderosa var. ponderosa Native – 0-2 – 0 Interpretations
Animal community
Livestock Interpretations:
This site is suited for cattle and sheep grazing during the spring, summer, and fall. Grazing management should be keyed to needlegrass production. Livestock will often concentrate on this site taking advantage of the shade and shelter offered by the tree overstory. Many areas are not used because of steep slopes and the lack of adequate water. Attentive grazing management is required due to steep slopes and erosion hazards. Harvesting trees under a sound management program can open up the tree canopy to allow increased production of understory species desirable for grazing.
Wildlife Interpretations:
These forests provide abundant browse and cover for large and small wildlife species. Mule deer, elk, and bear often use white fir habitats as either summer or winter range. Mule deer generally eat small amounts of white fir during the spring, fall, and winter, and sometimes larger amounts during the summer. The palatability of western white pine's foliage to large ungulates is generally rated as poor. However, the seeds of western white pine are an important part of the diet of small mammals. Spring browsing of white fir by deer can be particularly heavy when small white firs are the only green food available; all of the current or previous year's growth may be consumed. Porcupines also feed on the bark of white fir, and may destroy saplings. Rodents feed on the cambial tissue of white fir. During the winter, mice feed on the leaders of small white firs near snow level. In the spring, they feed on seedlings, sometimes destroying a large proportion of the current year's seedlings. Pocket gophers also feed on white fir seedlings in the winter and spring. White fir needles are an important part of the diet of blue grouse. White fir seeds are eaten by several species of small mammals and birds including grouse, chipmunks and mice, flying squirrels, chickadees, crossbills, and Clark's nutcracker. Hollow logs and snags of white fir can be important to various birds and animals for foraging in the interior wood. Because they contain resins, terpenes, and other substances that make the foliage irritating to the digestive tract, most conifers are not particularly palatable to grazing animals. White fir may be slightly palatable to goats. Immature foliage is also consumed by mule deer. White fir seeds are palatable to numerous species of small rodents.
White fir's evergreen foliage provides good hiding cover year-round and is usually continuous from the ground upward on trees less than 8 to 10 inches (20-25 cm) dbh. White fir stands of this nature provide excellent hiding cover for large wildlife species such as deer, elk, and black bear. If enough shrubs are present in the understory to provide adequate hiding cover, mature white fir forests are used by deer during fawning and by elk during calving.Hydrological functions
Runoff is medium to high. Potential for sheet and rill erosion is moderate to severe depending on slope.
Recreational uses
Steep slopes inhibit many forms of recreation. This site has potential for hiking, camping, cross-country skiing, and deer and upland game hunting. Off-road vehicles can destroy the fragile soil-vegetation complex causing severe erosion problems.
Wood products
Western white pine is highly valued as a timber species. The wood is used in the production of window and door sashes, paneling, dimension stock, matches and toothpicks. The wood is also used for carving.
White fir is a general, all-purpose, construction-grade wood used extensively for solid construction framing and plywood, and to a lesser extent, for pulpwood. It is also used for poles and pilings. White fir is also occasionally used for firewood.
PRODUCTIVITY CAPACITY:
This site has a low site quality for tree production. Site index ranges from about 25 to 30 for white fir (Schumacher, F.X. 1926) and 35 to 40 for western white pine (Haig I.T. 1932).
Firewood: About 45 to 55 cords per acre for stands averaging 30 to 40 feet in height and 70 years of age. There are about 205,000 British Thermal Units (BTUs) heat energy per cubic foot of white fir wood. Firewood is commonly measured in cords, or a stacked unit equivalent to 128 cubic feet. Solid wood volume in a cord varies, but usually ranges from 65 to 90 cubic feet of solid wood per cord. Assuming an average of 75 cubic feet of solid wood per cord, there are about 15 million BTUs of heat value in a cord of white fir.
Tree volume per acre: 3600 to 4500 cu ft/ac for stands averaging 30 to 40 feet in height and 70 years old.
MANAGEMENT GUIDES AND INTERPRETATIONS:
1. LIMITATIONS AND CONSIDERATIONS
a. Potential for sheet and rill erosion is moderate to severe depending on slope.
b. Moderate to severe equipment limitations on steeper slopes and on sites having extreme surface stoniness.
c. Proper spacing is the key to a well managed, multiple use, and multi-product forestland.
2. ESSENTIAL REQUIREMENTS
a. Adequately protect from wildfire.
b. Protect soils from accelerated erosion.
c. Apply proper grazing management.
3. SILVICULTURAL PRACTICES
Due to the low production of this site, silvicultural practices are not addressed.Other products
Native Americans uses for western white pine were several including chewingthe resin, weaving baskets from the bark, concocting a poultice for dressing wounds from the pitch, and collecting the cambium in the spring for food. Native American used the white fir needles for tea.
Other information
Western white pine and white fir are valuable ornamental trees. Cones of western white pine are collected for novelty items.
Supporting information
Type locality
Location 1: Modoc County, CA Township/Range/Section T44N R15E S3 UTM zone N UTM northing 728611 UTM easting 4611675 Latitude 41° 37′ 26″ Longitude 120° 15′ 20″ General legal description Northeast of Bald Mountain, Warner Mountains, Modoc National Forest, Modoc County, California. Other references
Fire Effects Information System (Online; http://www.fs.fed.us/database/feis/plants/).
Haig, I.T. 1932. Second-growth yield, stand, and volume tables for the western white pine type. USDA Technical Bulletin No. 323.
Miles, S.R. and C.B. Goudey. 1997. Ecological Subregions of California Section and Subsection Descriptions. United States Department of Agriculture Forest Service, Pacific Southwest Region R5-EM-TP-005. Subsection M261Gf-Warner Mountains.
Schumacher, F.X. 1926. Normal yield tables for white fir. California Agricultural Experiment Station Bulletin No. 407.
USDA-NRCS. 2000 National Forestry Manual - Part 537. Washington, D.C.
USDA-NRCS. 2004 National Forestry Handbook, Title 190. Washington, D. C.
USDA-NRCS Plants Database (Online; http://www.plants.usda.gov).
Contributors
P.NOVAK-ECHENIQUE
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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