Natural Resources
Conservation Service
Ecological site F021XE240CA
Pinus contorta var. murrayana/Achnatherum
Accessed: 08/17/2026
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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 contorta var. murrayana
Shrub Not specified
Herbaceous (1) Achnatherum
Physiographic features
This site occurs on toeslopes of mountains and plateaus. Slopes range from 2 to 15 percent. The mean annual precipitation is approximately 30 to 50 inches and the mean annual temperature is approximately 40 degrees F. The frost-free period is approximately 30 to 60 days.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
Elevation 7000 – 8500 ft Slope 2 – 15 % 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.
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 very deep, well drained soils that formed in glacial outwash and alluvium derived from volcanic rocks and volcanic ash. These soils have high amounts of vitric volcanic ash and glass throughout the profile which enhances the waterholding capacity. These soils are usually moist in winter, spring and early summer and dry out later in the summer and fall. These soils have a mollic epipedon to 32 inches. Rock fragements average between 40 and 60 percent, mainly gravels and cobbles. Soils associated with this site include Longval.
Table 4. Representative soil features
Parent material (1) Alluvium – volcanic breccia
Surface texture (1) Ashy fine sandy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderately rapid Soil depth 60 in Surface fragment cover <=3" 15 – 25 % Surface fragment cover >3" 0 – 5 % Available water capacity
(0-40in)5 – 7 in Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)6 – 6.1 Subsurface fragment volume <=3"
(Depth not specified)20 – 30 % Subsurface fragment volume >3"
(Depth not specified)1 – 20 % Ecological dynamics
Fire return intervals for Sierra lodgepole pine forests range from 35 to 200 years. Shrubby sites on drier aspects with irregular tree distributions probably have a fire return interval closer to 35 years rather than 200 years. Fires may also be larger and more intense.
Small or moderate-intensity fires are thought to favor perpetuation of the lodgepole habitat. The mature lodgepole trees have very thin bark, deep roots, and medium to low foliage flammability and are considered intermediate in fire tolerance. Mature lodgepole trees are most commonly killed by scorching cambium or crowning. Lodgepole seedlings are shade tolerant and but require openings for growth. These seeds germinate best in openings and sterilized mineral seedbeds produced by high-intensity fire. After a stand-replacing fire, it typically establishes from wind-dispersed seed and developments into even-aged stands. Smaller-scale disturbances such as windfall and avalanches are thought to convert Sierra lodgepole pine forests to the uneven-aged structure typical of this variety. The exclusion of fire may allow for the encroachment of white fir.
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 a dense forest of slender trees up to 85 feet tall, often in nearly pure stands of lodgepole pine. The trees in the dense stands are relatively short-lived, and if the stand has not burned for a long time, fallen trees, branches and needles cover the ground. Mountain big sagebrush, currant and snowberry are common understory shrubs. The dominant understory grasses are western and California needlegrasses and Wheeler's bluegrass. Sandworts, lupine and spreading phlox are common perennial forbs. The understory is normally sparse in these dense stands, but shrubs and perennial forbs and grasses occur abundantly in the forest openings. Approximate understory cover (basal and canopy) ranges from 20 to 30 percent. Overstory canopy cover is typically 30 to 40 percent.
Forest overstory.MATURE FORESTLAND: The visual aspect and vegetal structure are dominated by lodgepole pine that have reached or are near maximal heights for the site. Tree canopy cover ranges from 30 to 40 percent. Whitebark pine and white fir may comprise up to 5 percent of the canopy cover. This stage of community development is assumed to be representative of this site in the pristine environment.
Forest understory. Understory vegetation is approximately 55 percent grasses and grasslike plants, 15 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 200 to 500 pounds per acre. Understory production includes the total annual production of all species within 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 110 193 275 Shrub/Vine 50 87 125 Forb 30 53 75 Tree 10 17 25 Total 200 350 500 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 88–200 California needlegrass ACOCC Achnatherum occidentale ssp. californicum 35–84 – western needlegrass ACOCO Achnatherum occidentale ssp. occidentale 35–84 – Wheeler's bluegrass POWH2 Poa wheeleri 18–32 – 2 Secondary Perennial Grasses/Grasslikes 12–54 mountain brome BRMA4 Bromus marginatus 4–18 – Ross' sedge CARO5 Carex rossii 4–18 – big squirreltail ELMU3 Elymus multisetus 4–18 – Forb3 Perennial 22–56 prickly sandwort ARAC2 Arenaria aculeata 4–18 – tailcup lupine LUCAC3 Lupinus caudatus ssp. caudatus 4–18 – spreading phlox PHDI3 Phlox diffusa 4–18 – tuber starwort PSJA2 Pseudostellaria jamesiana 2–4 – woolly mule-ears WYMO Wyethia mollis 2–4 – pale agoseris AGGL Agoseris glauca 2–4 – slender penstemon PEGR4 Penstemon gracilentus 2–4 – Mt. Hood pussypaws CIUMU Cistanthe umbellata var. umbellata 2–4 – Shrub/Vine4 Primary Shrubs 35–84 mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 35–84 – 5 Secondary Shrubs 12–44 wax currant RICE Ribes cereum 4–18 – gooseberry currant RIMO2 Ribes montigenum 4–18 – roundleaf snowberry SYRO Symphoricarpos rotundifolius 2–4 – rabbitbush ERBL2 Ericameria bloomeri 2–4 – Tree6 Evergreen 8–26 Sierra lodgepole pine PICOM Pinus contorta var. murrayana 4–18 – whitebark pine PIAL Pinus albicaulis 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 – 95-100 – 0 whitebark pine PIAL Pinus albicaulis Native – 0-3 – 0 Interpretations
Animal community
Livestock Interpretations:
This site has limited use for livestock grazing due to low production of suitable forage. This site does provide valuable shade during the summer months.
Wildlife Interpretations:
Sierra lodgepole pine forests provide food, cover, and habitat for several species of mammals and birds. Dead or dying trees provide nesting sites for cavity-nesting birds. The fallen branches from these trees provide sites for ground-nesting birds and mammals. Dense stands of Sierra lodgepole pine provide escape and resting cover for elk and mule deer. The seeds are a food source for squirrels, chipmunks, birds, and mice.Recreational uses
This site has value for camping, hiking, birdwatching and hunting.
Wood products
The wood of Sierra lodgepole pine is suited for
common lumber grades, and used for light framing materials, interior paneling, exterior trim, posts, railroad ties, pulp and paper, and has potential for structural particle board. The uniform size of Sierra lodgepole pine makes harvesting efficient.Other information
Sierra lodgepole pine regenerates well on poor soils, rocky slopes, and exposed sites.
Supporting information
Type locality
Location 1: Lassen County, CA Township/Range/Section T38N R16 S28 UTM zone N UTM northing 737663 UTM easting 4557671 Latitude 41° 8′ 8″ Longitude 120° 10′ 6″ General legal description About 2 miles southwest of Lost Lake, Warner Mountains, Modoc National Forest, Lassen County, California Other references
Cope, Amy B. 1993. Pinus contorta var. murrayana. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).
Fire Effects Information System (Online; http://www.fs.fed.us/database/feis/plants/).
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.
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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