Natural Resources
Conservation Service
Ecological site F005XB102CA
Douglas-fir-tanoak/tanoak,
mountain slopes,
sandstone and mudstone, very gravelly clay loam
Accessed: 07/02/2026
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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
F005XB101CA Douglas-fir/tanoak, mountain slopes, sandstone and mudstone, clay loam
F005XB101CA may be found in conjunction with this ecological site, but F005XB101CA is more productive and overlies fine-loamy soils.
F005XB103CA Douglas-fir-canyon live oak/tanoak, mountain slopes, sandstone and mudstone, very gravelly loam
F005XB103CA can be found adjacent to this ecological site, but F005XB103CA has a large component of canyon live oak and has shallow soils.
Table 1. Dominant plant species
Tree (1) Pseudotsuga menziesii
(2) Lithocarpus densiflorusShrub (1) Lithocarpus densiflorus
Herbaceous Not specified
Physiographic features
This ecological site is found near the Beaver and Pine ridge areas. It occurs on uniform to slightly convex summits of broad ridges and mountain slopes, which are strongly sloping to very steep.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
(2) Ridge
Flooding frequency None Ponding frequency None Elevation 948 – 4042 ft Slope 9 – 100 % Ponding depth 0 in Water table depth 0 in Aspect Aspect is not a significant factor Climatic features
The climate is characterized by dry, warm summers, and cold, moist winters. Summertime temperatures range from 70 to 90 degrees F. The total annual precipitation ranges from 49 to 80 inches and usually falls from October to May. At elevations above 4,000 ft precipitation may fall in the form of snow.
*The climate station data selected may not adequately represent that of the ecological site.Table 3 Representative climatic features
Frost-free period (average) 250 days Freeze-free period (average) 250 days Precipitation total (average) 80 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
There are no influencing water features in this ecological site.
Soil features
These well-drained soils developed from colluvium and residuum derived from sandstone and mudstone. They are strongly to very strongly acidic at 40 inches with a dominantly loamy subsurface rock content ranging from very to extremely gravelly. These soils are primarily moderately deep to lithic contact, with small areas that are very deep.
Soils that have been tentatively correlated to this ecological site include the following.
Soil Survey Area: CA605 - Redwood National and State Park
Mapunit Symbols Soil Components
465 Noisy
462 Noisy
465 SidehillTable 4. Representative soil features
Surface texture (1) Gravelly loam
(2) Very gravelly loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate to moderately rapid Soil depth 40 – 80 in Surface fragment cover <=3" 0 – 55 % Surface fragment cover >3" 5 – 25 % Available water capacity
(0-40in)1 – 6 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)4.5 – 5.5 Subsurface fragment volume <=3"
(Depth not specified)40 – 75 % Subsurface fragment volume >3"
(Depth not specified)Not specified Ecological dynamics
This site has evolved with natural disturbances from lightning-ignited fire and historic ignitions from Native American burning (Agee, 1993).
Generally this site has a low to moderate fire regime with occasional severe fires (Arno, 2002). Fire return intervals fluctuate from 10 to 30 years (Wills, 1994, Agree, 1991). Fire effects and the patterns of stand development in the mixed evergreen forest-type are complex and highly variable (Eyre, 1990). Often, multiple ages and sizes of trees are found on the same site.
Young Douglas-fir (Pseudotsuga menziesii) is has thin bark and will likely be killed by fire, while the thick-barked mature Douglas-fir is more resistant. Tanoak (Lithocarpus densiflorus) and other hardwoods are sensitive to fire but are able to re-sprout and so are able to maintain their presence following fire (Mc Murray, 1989).
Light surface fire will kill young tanoak, while older stands may survive. Moderate fire may kill some Douglas-fir but leave others. Tanoak and other hardwoods will re-sprout and grow rapidly. Severe fire may kill mature Douglas-fir and while enabling the re-sprouting of tanoak, which will then dominate a site for decades (Agee, 1991). Gradually, Douglas-fir will infill from adjacent areas, and eventually overtop tanoak. This process could take many years depending on the size of the burned area.
There are a few potential pathways for stand development following fire (adapted from Agee 1993, Thornburg, 1982):
1) Immediately after a fire, Douglas-fir infills and tanoak will re-sprout. This causes a mixed stand with a mosaic of Douglas-fir in the overstory, and tanoak existing as a co-dominant tree in the sub-canopy. Some areas are dominated by tanoak, while other areas are primarily Douglas-fir (Jimerson, 1990).
2) Douglas-fir does not infill or there are large areas of fire-killed Douglas-fir; tanoak and other sprouting hardwoods may dominate the site for decades. Eventually, Douglas-fir overtops tanoak and dominates the site. Tanoak continues to exist in the sub-canopy.
Disturbance from timber harvesting is likely to mimic fire. Forest management may result in the dominance of hardwoods. The combined effects of fire and harvesting have increased the stocking and density of tanoak and Pacific madrone (Arbutus menziesii), as well as other shrubs.
Tanoak can establish under full shade and maintains itself through periodic diebacks. It sustains a shrub-like form until the canopy is opened, and then may rapidly attain tree status (McDonald and Tappenier, 1987). It may regenerate via seed or vegetatively.
Douglas-fir requires a mineral seedbed or light litter to regenerate. Light shade aids the first year’s survival. Thereafter, Douglas-fir requires full sunlight and will not survive under dense shade (Burns and Honkala, 1990).
State and transition model
Custom diagramStandard diagram
Figure 3. Douglas-fir/tanoak model
More interactive model formats are also available. View Interactive Models
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 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 5 submodel, plant communities
State 6 submodel, plant communities
State 1
Douglas-fir/tanoakCommunity 1.1
Douglas-fir/tanoakPlant Community 1. The presumed historic climax plant community (HCPC) was dominated by Douglas-fir (Pseudotsuga menziesii) and tanoak (Lithocarpus densiflorus). The interpretive plant community is dominated by a mature, multi-storied Douglas-fir stand over a tanoak sub-canopy. Other minor hardwood tree species found on the site may include Pacific madrone (Arbutus menziesii) and canyon live oak (Quercus chrysolepis).
The understory is dominated by tanoak. Other shrubs found may include creeping snowberry (Gaultheria hispidula) and woodrose (Merremia). Common forbs include western brackenfern (Pteridium aquilinum) and western modesty (Whipplea modesta).
1a) In the event of block harvesting with mechanical slash treatment, tanoak and any other hardwood present would sprout. See PC#2.
1b) In the event of a moderate fire, or block harvesting followed by post-harvest burning, seeds buried in the soil may germinate, resulting in significant competition from blueblossom (Ceanothus thyrsiflorus) and other shrubs. Tanoak and Pacific madrone are top-killed by fire but will re-sprout from buds on root burls (McMurray, 1989). Pacific madrone will also seed into burned areas. See PC#3.
1c) Infrequent moderate fires that cause partial stand replacements allow for natural regeneration of Douglas-fir, and maintain the historic climax plant community.
1d) Fire exclusion favors the establishment of tanoak, and may lead to tanoak as the dominant species in the mixed evergreen zone (Atzet, 1979, Franklin and Dyrness, 1973). Partial cutting of Douglas-fir may also favor the establishment and dominance of tanoak. See PC#6.
Forest overstory.The overstory is dominated by Douglas-fir with tanoak in the sub-canopy. The amount of Douglas-fir to tanoak is highly variable and depends on past disturbances. <br /> <br /> Douglas-fir (Pseudotsuga menziesii) 10-60% <br /> Tanoak (Lithocarpus densiflorus) 30-60%<br />
Forest understory. Tanoak forms the shrub layer, but cover is highly variable.
State 2
Tanoak/Pacific madroneCommunity 2.1
Tanoak/Pacific madronePlant Community 2. Following harvest, the plant community is dominated by sprouting tanoak and Pacific madrone. Both species are capable of vigorous height growth following a disturbance. Pacific madrone is an abundant seeder and may form a dense shrub cover capable of providing severe competition for conifer seedlings (Tappenier, 1984).
2a) The site could be returned to a Douglas-fir-dominated community with the use of conifer tree planning, in conjunction with brush management or chemical control. Due to the density of hardwood stems, multiple treatments may be necessary (Jimerson, 1996). See PC#5.
2b) If the community were left to develop, tanoak and Pacific madrone would grow rapidly into the overstory and dominate the site for many years. Conifer seedlings may be able to infill from adjacent seed sources to establish in openings See PC#4.
State 3
Blueblossom/tanoak/Pacific madroneCommunity 3.1
Blueblossom/tanoak/Pacific madronePlant Community 3. The plant community is dominated by shrubs following a moderately severe fire or block harvesting and burning. Blueblossom germinates from seeds stored in the soil for long periods of time. Cover of blueblossom increases significantly on burned sites; it is thought that heat improves germination success (Hobbs, et al, 1992). Seeds are produced at an early age and continue for over 20 years.
Both tanoak and Pacific madrone will sprout following a disturbance; the number of sprouts is dependent on tree age and burl size (Tappeiner, 1984).
3a) Growth of tanoak and Pacific madrone is rapid in the early years following a disturbance. Natural regeneration of Douglas-fir may be delayed by competition from hardwoods for many years. Gradual infill of Douglas-fir will occur, if an adjacent seed source is present. See PC#4.
3b) The community could be maintained as shrubs with periodic moderate fire.
3c) Tree planting or infill of Douglas-fir, in conjunction with chemical control or manual brush management, could reduce competition and accelerate Douglas-fir growth and dominance. See PC#5.
State 4
Tanoak/Pacific madrone/Douglas-firCommunity 4.1
Tanoak/Pacific madrone/Douglas-firPlant Community 4. The overstory of the plant community is dominated by tanoak and Pacific madrone, with Douglas-fir almost equally represented. Tanoak continues to regenerate in the understory.
4a) Douglas-fir establishment and dominance can be accelerated through management practices that include tree planting, partial cutting of tanoak, and the chemical treatment of tanoak. Tanoak continues its presence as a shrub in the sub-canopy. See PC#5.
4b) If fire is excluded from the site there will be a lack of Douglas-fir regeneration. This may allow tanoak to become the climax plant species. (Atzet, 1979, Franklin and Dyrness, 1973). See PC#6.
State 5
Douglas-fir/tanoakCommunity 5.1
Douglas-fir/tanoakPlant Community 5. This plant community develops following partial cutting and hardwood management. The overstory is dominated by Douglas-fir and tanoak with tanoak also in the shrub layer.
5a) In the event of a block harvest, the plant community could be set back to the tanoak/Pacific madrone shrub stage. See PC#2.
5b) In the event of a moderate to severe fire, and if a seed source is present, the community could be set back to PC#3, blueblossom/tanoak/Pacific madrone.
5c) With continued fire exclusion, and on sites where a Douglas-fir seed source is absent, tanoak could become the dominant climax species (Atzet, 1979. Franklin and Dyrness, 1987). See PC#6.
State 6
Tanoak/Douglas-firCommunity 6.1
Tanoak/Douglas-firPlant Community 6. With continued fire exclusion, tanoak could become the dominant climax species over Douglas-fir on some sites (Atzet, 1979. Franklin and Dyrness, 1987).
Additional community tables
Table 5. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 6. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 7. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 4.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 5.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 6.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
A wide variety of bird and animal species use the Douglas-fir/tanoak forest. The diversity of wildlife utilizing the site is influenced by the presence of the mast-producing tanoak and giant chinquapin, as well as berry producing species such as Pacific madrone and Oregon-grape (Mahonia aquifolium).
Bird species that may utilize these upland sites include woodpecker, warbler, nuthatch, finche, and Stellar's jay. Other bird species include numerous hawks. Tanoaks are also used by cavity nesting birds, such as the downy woodpecker, northern flicker, red and white breasted nuthatch, brown creeper and house wren. Tanoak habitats are also food and nesting sites for the northern flying squirrel, Allen's chipmunk, and dusky-footed woodrat.
Mammals such as the black-tailed deer, black bear, Townsend chipmunk, California ground squirrel, and redwood chickaree utilize tanoak for food and cover.
Hydrological functions
Runoff class is high.
The hydrologic groups, hydrologic conditions and runoff curves for each soil series are:
Noisy Sidehill
462--C 462--C
463--B 463--C
473--C 464--C
473--C
Refer to the Soil Survey Manuscript for further information.Recreational uses
This site can support a variety of recreational uses. Slope may affect the recreation potential on some sites.
Wood products
Douglas-fir is employed in residential structures and light commercial timber-frame construction. It is also used for solid-timber heavy-duty construction such as pilings, wharfs, bridge components and warehouse construction.
The manufacturing of tanoak wood products is limited. Upper-grades produce good quality veneers and plywood. Tanoak flooring, paneling and decking have also been produced. Lower-grades are used to make pallets, crossties, mine timbers, baseball bats and tool handles. The wood had also been chipped for pulp and for use in the cogeneration of electricity. It is also widely utilized as firewood.
Other products
Tannin from tanoak bark is used commercially to cure leather.
Berries from Cascade barberry (Mahonia nervosa) are edible and are made into jams and pies. The foliage is utilized for decorative purposes.
Other information
Historically, tanoak acorns provided a dietary staple for Native Americans throughout the California Coast Ranges.
Table 11. 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 Douglas-fir PSME 140 173 145 184 – – – Supporting information
Inventory data references
Forestry data was collected at the following sites. Redwood Soil pits Vegetation plot # 03-53 8 03-64 31 03-77 34
Type locality
Location 1: Humboldt County, CA Township/Range/Section T7N R3E S10 UTM zone N UTM northing 4539349 UTM easting 431454 General legal description USGS Quadrangle Hupa Mountain. Other references
Agee, James, K. 1993 Fire Ecology of Pacific Northwest Forests. 493p.
Atzet, Thomas. 1979. Description and classification of the forests of the upper Illinois River drainage of southwestern Oregon. Corvallis, OR: Oregon State University. 211 p. Dissertation.
Arno, Stephen F., and Allison-Bunnell, S. 2002, Flames in our Forest, Disaster or Renewal? Island Press.
Burns, Russell M., and Honkala, Barbara H. Technical Coordinators. 1990. Silvics of North America, Volume 1, Conifers. U.S. Department of Agriculture, Forest Service, Agriculture Handbook 654.
Eyre, F.H., Editor. 1980. Forest Cover Types of the United States and Canada. Society of American Foresters.
Franklin, Jerry F. and Dyrness, C.T. 1973. Natural Vegetation of Oregon and Washington. Gen. Tech. Rep. PNW-8. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Southwest Range and Experiment Station. 417 p.
Jimerson, T.M., 1996. A Field Guide to the Tanoak and the Douglas-fir Plant Associations in Northwest Caifornia.
McMurray, Nancy E. 1989. Arbutus menziesii. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2001, May 2]
Tappenier, John C., II; Harrington, Timothy B; Walstad, John D. 1984. Predicting recovery of Tanoak (Lithocarpus densiflorus) and Pacific madrone (Arbutus menziesii) seedlings in the forests of southwestern Oregon. New Forests. 1:43-55. [3234]
Tappeiner, John C., II; McDonald, Philip M. 1984 Development of tanoak understories in conifer stands. Canadian Journal of Forest Research. 14: 271-277. [6445]
Thornburg, D.A. 1982. Succession in the mixed evergreen forests of northwest California. In Means,J.E. (ed.) Forest Succession and stand development research in the Northwest. pp.87-91. Corvallis: Oregon State University For. Res. Lab.
Wills, R. D., and Stuart, J.D. 1994. Fire history and stand development of a Douglas-fir/hardwood forest in northern California. Northwest Science 68:205-212.
Contributors
Judy Welles
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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