Natural Resources
Conservation Service
Ecological site F005XB108CA
Douglas-fir-tanoak/tanoak-California hazelnut,
mountain slopes,
phyllite and schist, loam and very channery loam
Accessed: 08/05/2026
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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
F005XB107CA Douglas-fir-canyon live oak/Pacific poison oak-tanoak/common whipplea, mountain slopes, phyllite and schist, very gravelly loam
F005XB107CA can be found in conjunction with this site and is located on shallow soils and has a significant overstory cover of canyon live oak.
Similar sites
F005XB101CA Douglas-fir/tanoak, mountain slopes, sandstone and mudstone, clay loam
F005XB101CA has similar overstory composition but overlies sandstone and mudstone and has less of a diversity of understory shrub species.
Table 1. Dominant plant species
Tree (1) Pseudotsuga menziesii
(2) Lithocarpus densiflorusShrub (1) Lithocarpus densiflorus
(2) Corylus cornuta var. californicaHerbaceous Not specified
Physiographic features
This ecological site is found in eastern Humboldt County and eastern Hoopa Tribal Nation. It occurs on uniform to convex mountain slopes and ridges, which are gently sloping to steep.
Table 2. Representative physiographic features
Landforms (1) Mountain
(2) Ridge
Flooding frequency None Ponding frequency None Elevation 1000 – 3500 ft Slope 20 – 100 % Aspect S, SW, W Climatic features
The climate on this site is characterized by cold winters and hot, dry summers. The average annual precipitation ranges from 49 to 80 inches with most falling as rain from November to April.
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 hydrological features on this site.
Soil features
These well-drained, deep soils developed from colluvium dervied from phyllite and/or schist. They are strongly to very strongly acidic with a dominantly loamy subsurface texture. Rock content ranges from sparse to very gravelly.
The site is found on the following soil components:
SSA MU Component
CA605 702 Redtop
CA605 702 Bagual
CA605 702 Darkwoods
CA605 702 Redtop
CA605 705 Darkwoods
CA605 706 Darkwoods
CA605 707 DarkwoodsTable 4. Representative soil features
Surface texture (1) Loam
(2) Very channery loam
Family particle size (1) Loamy
Drainage class Well drained Surface fragment cover <=3" 0 – 35 % Surface fragment cover >3" 0 – 10 % Available water capacity
(0-40in)6.3 – 10 in Subsurface fragment volume <=3"
(Depth not specified)0 – 70 % Subsurface fragment volume >3"
(Depth not specified)0 – 10 % Ecological dynamics
State and transition model
Custom diagramStandard diagram
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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
Reference State - Plant Community 1.1Community 1.1
Reference State - Plant Community 1.1kl
Forest overstory.The overstory is dominated by Douglas-fir with tanoak and a lesser amount of madrone in the subcanopy. <br /> <br /> Overstory average canopy cover: <br /> <br /> Douglas-fir 20-70%<br /> tanoak 25-60%<br /> Pacific madrone 10-30%<br /> California black oak 0-20%<br /> giant chinquapin 0-10%<br /> big leaf maple 0-5%
Forest understory. The understory of this ecological site is dominated by shrubs including tanoak, California hazelnut, and Pacific poison oak. <br /> <br /> Understory average canopy cover: <br /> <br /> tanoak 5-25%<br /> California hazelnut 2-10%<br /> Pacific poison oak 2-10%<br /> Douglas-fir 0-5%<br /> California huckleberry 0-5%<br /> salal 0-5%<br /> Pacific madrone 0-5%<br /> brackenfern 0-5%<br /> Pacific dogwood 0-5%<br /> common whipplea 0-5%<br /> little prince's pine 0-5%<br /> Cascade barberry 0-5%<br /> big leaf maple 0-2%<br /> pink honeysuckle 0-2%
State 2
Plant Community 1.2Community 2.1
Plant Community 1.2A shrub plant community will dominate this ecological site following an intensive disturbance such as a stand-replacing wildfire or land clearing. Two ceanothus species, snowbrush and deerbrush, may dominate this phase with poison oak patches in open areas.
State 3
Plant Community 1.3Community 3.1
Plant Community 1.3This community phase is dominated by California black oak and Pacific madrone and arises in areas experiencing frequent disturbance by wildfire or development.
State 4
Plant Community 1.4Community 4.1
Plant Community 1.4This community phase arises after Douglas-fir regenerates onto a previously disturbed landscape. Hardwoods including tanoak, California black oak, and Pacific madrone will continue to dominate the overstory, but Douglas-fir recruits occupy a high percentage of the site.
State 5
Plant Community 1.5Community 5.1
Plant Community 1.5A tanoak dominated community phase may arise following the preferential harvest of Douglas-fir or a light to moderate severity fire which stimulates tanoak sprouting. Tanoak will continue to occupy a majority of the canopy for several decades until Douglas-fir becomes more firmly established.
State 6
Plant Community 1.6Community 6.1
Plant Community 1.6Following hardwood management or several decades of ecological succession, Douglas-fir will dominate the overstory of this plant community phase and tanoak will occupy the subcanopy and understory with California hazelnut and other shrub species.
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
These mixed stands of Douglas-fir, tanoak, Pacific madrone, and California black oak provide both food and cover for a variety of birds and animal species. Acorns of black oak and tanoak are an important dietary component for many birds and mammals.
These sites are utilized by large mammals such as bear, mountain lion, and deer. Smaller mammals include squirrel, rabbit, woodrat, fox, skunk and mice.
Birds that might utilize the site include quail, pheasant, turkey, morning dove, jays, mountain chicadee, and a wide variety of woodpeckers.Hydrological functions
These slopes can be steep and prone to erosion. The soils are very well-drained.
Hydrologic Group--D
Refer to the Soil Survey Manuscript for further information.Recreational uses
These sites can be utilized for recreational uses, but the steep slopes could be challenging for recreational development.
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.
Pacific madrone is not widely used for wood products. It is utilized occasionally for flooring, cabinet making, and veneers. It is frequently used as firewood.Other products
Tannin from tanoak bark is used commercially to cure leather.
Berries from Cascade barberry are edible and are made into jams and pies. The foliage is utilized for decorative purposes. California hazelnuts were gathered by Native peoples for food.
Historically, tanoak acorns provided a dietary staple for native americans throughout the California Coast Ranges.Other information
Site productivity interpretations are based on the following site index curves:
Species Curve Base age
Douglas-fir 790 100 yearsTable 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 120 180 115 191 – – – Supporting information
Inventory data references
Forestry data was collected at soil pedons and along transects in the CA605 Soil Survey Area. Forest plot# Pedon# 09F139 01-340p 09F140 01-332p 09F141 01-624p 09F148 01-307p 09F143 09F147 09F149 09F155 09F157
Type locality
Location 1: Humboldt County, CA Township/Range/Section T8N R5E S4 UTM zone N UTM northing 4549850 UTM easting 447783 General legal description USGS Quadrangle Tish Tang Point 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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