Natural Resources
Conservation Service
Ecological site F021XE236CA
Pinus washoensis-Abies concolor var. lowiana/Symphoricarpos rotundifolius/Bromus marginatus
Accessed: 08/16/2026
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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Classification relationships
Holland, R.F. 1986. Preliminary descriptions of the terrestrial natural communities of California. Unpublished report. State of California, The Resources Agency, Department of Fish and Game, Natural Heritage Division, Sacramento, CA. Element Code: 85220 - Washoe Pine - Fir Forest
Sawyer, J.O. and T. Keeler-Wolf 1995. A manual of California vegetation. Washoe Pine Series.
Smith, S. and B. Davidson. 2003. User's Manual Terrestrial Ecological Unit Inventory (TEUI) Land Type Associations, Modoc National Forest. Code: WFmv White Fir-Washoe/Mt. Snowberry/Starwort AssociationAssociated sites
R021XE216CA Aspen Thicket
R021XE222CA Loamy Slope 30+ P.Z.
R021XE229CA Ashy Slope 30+ P.Z.
Table 1. Dominant plant species
Tree (1) Pinus washoensis
(2) Abies concolor var. lowianaShrub (1) Symphoricarpos rotundifolius
Herbaceous (1) Bromus marginatus
Physiographic features
This site occurs on toeslopes of mountains and plateaus. Slopes range from 4 to 50 but slope gradients from 8 to 30 percent are most typical. Elevations range from 5400 to 8000. Mean annual precipitation is approximately 25 inches and the mean annual temperature is approximately 40 degrees F.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
Elevation 5400 – 8000 ft Slope 4 – 50 % Aspect Aspect is not a significant factor Climatic features
The climate of this site is subhumid, characterized by warm, 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 20 to 30 inches with most occurring during the winter months. Approximately half the precipitation falls as snow; half as rain.
Table 3 Representative climatic features
Frost-free period (average) 80 days Freeze-free period (average) 0 days Precipitation total (average) 30 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 moderately deep to very deep. They are formed in volcanic ash and colluvium over residuum derived from glassy tuff. These soils have high amounts of vitric volcanic ash and glass throughout the profile which enhances the waterholding capacity. These soils are modified with 40 to 65 percent rock fragments, mainly gravel or cobbles. Soil series associated with this site include Lyonman and Longval. Lyonman has a mollic epipedon to 18 inches and an argillic horizon from 13 to 31 inches. Longval has a mollic epipedon to 32 inches.
Table 4. Representative soil features
Parent material (1) Colluvium – tuff
Surface texture (1) Ashy sandy loam
(2) Ashy fine sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate to moderately rapid Soil depth 22 – 60 in Surface fragment cover <=3" 0 – 5 % Surface fragment cover >3" Not specified Available water capacity
(0-40in)4 – 5 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)5.6 – 7.3 Subsurface fragment volume <=3"
(Depth not specified)20 – 60 % Subsurface fragment volume >3"
(Depth not specified)1 – 35 % 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 crown fire. Skeleton forest (dead trees) remaining after fire or residual trees left following harvest have little or no affect on the composition and production of the herbaceous vegetation.
SHRUB-HERBACEOUS: Herbaceous vegetation and woody shrubs 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 major component of the vegetal structure.
SAPLING: In the absence of disturbance the tree seedlings develop into saplings (20 inches 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 Washoe pine greater than 4.5 feet in height. The young ponderosa pine are still very susceptible to fire at this stage. Seedlings and saplings of ponderosa pine are common in the understory. Dominants are the tallest trees on the site; co-dominants are 65 to 85 percent of the highest of dominant trees. Understory vegetation is moderately influenced by a tree overstory canopy of about 15 to 25 percent.
MATURE FORESTLAND: This stage is dominated by Washoe pine that have reached or are near maximal heights for the site. Tree canopy cover ranges from 30 to 35 percent. Understory vegetation is strongly influenced by tree competition, overstory shading, duff accumulation, etc. Infrequent, yet periodic, wildfire is presumed to be a natural factor influencing the understory of mature ponderosa pine forests. Washoe pine trees, at this stage of growth, are relatively resistant to cool, slow burning, wildfires through the understory because of their thick, insulating bark. Ground fires in these forests affect understory vegetal structure and composition leaving an open grass-forb community with scattered mountain big sagebrush and associated mountain browse species. This stage of community development is assumed to be representative of this site in the pristine environment.
OVER-MATURE FORESTLAND: This stage is dominated by Washoe pine that have reached maximal heights (150+ ft) for the site. Understory vegetation is reduced due to tree competition, overstory shading, duff accumulation, etc. Few seedlings or saplings of Washoe pine are found in the understory.
Prior to European settlement, eastern-slope yellow pine communities generally consisted of either monotypic stands or mixtures of Washoe, ponderosa and Jeffrey pines. Structurally, eastside pine forests consisted of widely scattered large trees from 80 to 100 feet in height. Low-severity fires were frequent, and stand-replacing fires were occasional. Canopy closures probably ranged from about 30 percent on dry sites to 80 percent on moister sites. Susceptibility to fire in mid-elevation Washoe pine stands has increased since 1850 due to high fuel loads and increased stocking of white fir. Juniper and shrub cover have replaced the typical shrub/grass understory at low elevations as a result of fire suppression and historical livestock grazing. Literature concerning fire effects specific to Washoe pine is lacking, however, yellow pines are moderately resistant to fire due to the thick, corky bark and the tall, erect trunk free of lower limbs. Washoe pine exhibits low seed production and has low reproductive capacity.
Fire Ecology:
Mountain brome is likely to be top-killed by fire, although the coarse stems and broad leaves may be more fire-resistant than fine-leaved bunchgrasses. Mountain brome is most susceptible to fire damage when it is actively growing in spring and early summer. Sedge is top-killed by fire, with rhizomes protected by insulating soil. The rhizomes of sedge species may be killed by high-severity fires that remove most of the soil organic layer. Reestablishment after fire occurs by seed establishment and/or rhizomatous spread.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 characterized as an open park-like appearance with an overstory of yellow pines and relatively few understory trees. Washoe pine is the dominant tree, with ponderosa pine, lodgepole pine, western white pine, western juniper, and white fir comprising up to 10 percent of the overstory. Mature trees will exceed 100 feet in height and have trunks 3 to 5 feet in diameter. An overstory canopy cover of 30 to 35 percent is assumed to be representative of tree dominance on this site. The understory is dominated by perennial grasses and forbs with scattered shrubs, such as roundleaf snowberry, mountain brome, Ross'sedge, Wheeler's bluegrass and several species of perennial forbs.
Forest overstory.Mature Forestland: <br /> The visual aspect and vegetal structure are dominated by large Washoe pine trees that have reached or are near maximal heights (80-150 feet) for the site. Tree canopy cover ranges from 30 to 35 percent. This stage of community development is assumed to be representative of this site in the pristine environment.
Forest understory. Understory vegetation is approximately 50 percent grasses and grass-like plants, 10 percent forbs and 40 percent shrubs and young trees. Average understory production ranges from 200 to 650 pounds per acre with a medium canopy cover. Understory production includes the total annual production of all species withing 4.5 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 100 213 325 Shrub/Vine 70 149 228 Forb 20 42 65 Tree 10 21 32 Total 200 425 650 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 129–306 mountain brome BRMA4 Bromus marginatus 43–102 – Ross' sedge CARO5 Carex rossii 43–102 – Wheeler's bluegrass POWH2 Poa wheeleri 43–102 – Forb2 Perennial 28–56 wavyleaf Indian paintbrush CAAP4 Castilleja applegatei 2–4 – California rayless fleabane ERIN2 Erigeron inornatus 2–4 – common woolly sunflower ERLA6 Eriophyllum lanatum 2–4 – prickly hawkweed HIHO Hieracium horridum 2–4 – ballhead waterleaf HYCA4 Hydrophyllum capitatum 2–4 – granite prickly phlox LIPU11 Linanthus pungens 2–4 – tailcup lupine LUCAC3 Lupinus caudatus ssp. caudatus 2–4 – sweetcicely OSBE Osmorhiza berteroi 2–4 – Brown's peony PABR Paeonia brownii 2–4 – spreading phlox PHDI3 Phlox diffusa 2–4 – whiteveined wintergreen PYPI2 Pyrola picta 2–4 – lambstongue ragwort SEINM Senecio integerrimus var. major 2–4 – Menzies' campion SIME Silene menziesii 2–4 – woolly mule-ears WYMO Wyethia mollis 2–4 – Shrub/Vine3 Primary Shrubs 43–102 roundleaf snowberry SYRO Symphoricarpos rotundifolius 43–102 – 4 Secondary Shrubs 24–126 pale serviceberry AMPA2 Amelanchier pallida 4–21 – pinemat manzanita ARNE Arctostaphylos nevadensis 4–21 – mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 4–21 – rabbitbush ERBL2 Ericameria bloomeri 4–21 – bitter cherry PREM Prunus emarginata 4–21 – wax currant RICE Ribes cereum 4–21 – Tree5 Evergreen 12–37 western juniper JUOC Juniperus occidentalis 2–4 – Sierra lodgepole pine PICOM Pinus contorta var. murrayana 2–4 – western white pine PIMO3 Pinus monticola 2–4 – 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) TreeSierra lodgepole pine PICOM Pinus contorta var. murrayana Native – 0-2 – 0 western white pine PIMO3 Pinus monticola Native – 0-2 – 0 western juniper JUOC Juniperus occidentalis Native – 0-1 – 0 Interpretations
Animal community
Livestock Interpretations:
This site is suited to cattle and sheep grazing during the summer and fall. Grazing management should be keyed to needlegrass production and the amount of leaf area left for regrowth. Mountain brome is one of the most important forage grasses in the quaking aspen zone. Mountain brome is ranked as excellent forage for both cattle and horses and good for domestic sheep. Domestic sheep will graze mountain brome only when it is fairly succulent. Sedge provides good to fair forage for domestic grazing. Snowberry is readily eaten by all classes of livestock, particularly domestic sheep.
Stocking rates vary over time depending upon season of use, climate variations, site, and previous and current management goals. A safe starting stocking rate is an estimated stocking rate that is fine tuned by the client by adaptive management through the year and from year to year.
Wildlife Interpretations:
Mountain brome seedheads and seeds provide food for many birds and small mammals. Pronghorn antelope will consume mountain brome primarily in the spring. The palatability of mountain brome is excellent for deer, particularly during the late spring and early summer. Sedges have a high to moderate resource value for elk and a medium value for mule deer. Elk consume beaked sedge later in the growing season. Snowberry is an important forage species for deer and elk on high elevation summer ranges. Snowberry is frequently one of the first species to leaf out, making it a highly sought after food in the early spring.Other information
Mountain brome is an excellent native bunchgrass for seeding alone or in mixtures in disturbed areas, including depleted rangelands, burned areas, roadways, mined lands, and degraded riparian zones.
Table 8. Representative site productivity
Common name Symbol Site index low Site index high CMAI low CMAI high Age of CMAI Site index curve code Site index curve basis Citation PIWA 70 85 55 77 – – – Supporting information
Type locality
Location 1: Modoc County, CA Township/Range/Section T39N R16E S34 UTM zone N UTM northing 739769 UTM easting 4564825 Latitude 41° 11′ 57″ Longitude 120° 8′ 26″ General legal description Near Cold Springs, Horse Mountain in the Warner Mts. Modoc National Forest, Modoc Co., California Other references
Fire Effects Information System (Online; http://www.fs.fed.us/database/feis/plants/).
Holland, R.F. 1986. Preliminary descriptions of the terrestrial natural communities of California. Unpublished report. State of California, The Resources Agency, Department of Fish and Game, Natural Heritage Division, Sacramento, CA. Element Code: 85220 - Washoe Pine - Fir Forest
Sawyer, J.O. and T. Keeler-Wolf 1995. A manual of California vegetation. Washoe Pine Series.
Smith, S. and B. Davidson. 2003. User''s Manual Terrestrial Ecological Unit Inventory (TEUI) Land Type Associations, Modoc National Forest. Code: WFmv White Fir-Washoe/Mt. Snowberry/Starwort Association.
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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