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Ecological site F003XN948WA

Southern Washington Cascades Low Cryic Deciduous Forest

Last updated: 1/30/2025
Accessed: 08/31/2026

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General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

MLRA notes

Major Land Resource Area (MLRA): 003X–Olympic and Cascade Mountains

Steep mountains and narrow to broad, gently sloping valleys characterize this MLRA. A triple junction of two oceanic plates and one continental plate is directly offshore from Puget Sound. Subduction of the oceanic plates under the westerly and northwesterly moving continental plate contributes to volcanic activity in the Cascade Mountains. Movement among these plates has resulted in major earthquakes and the formation of large stratovolcanoes. The Cascade Mountains consist primarily of volcanic crystalline rock and some associated metasedimentary rock. The mean annual precipitation is dominantly 60 to 100 inches, but it is 30 to 60 inches on the east side of the Cascade Mountains.
The soil orders in this MLRA are dominantly Andisols, Spodosols, and Inceptisols and minor areas of Entisols and Histosols. The soils are dominantly in the frigid or cryic temperature regime and the udic moisture regime. The soils generally are shallow to very deep, well drained, ashy to medial, and loamy or sandy. They are on mountain slopes and ridges.

Ecological site concept

This ecological site is in cold, moist areas at an elevation of 2,100 to 6,600 feet. It is in active avalanche chutes of debris cones on glacial-valley walls. The most common disturbances are avalanches, rockfalls, and debris flows. Wildfires are not common; however, the steep slopes facilitate rapid upslope movement of wildfires.
The soils that support this ecological site are in the cryic soil temperature regime and the udic soil moisture regime. They are formed in mixed colluvium and volcanic ash. The soils are well drained and very deep. They are not subject to flooding or ponding. Soil moisture is not a limiting factor for forest growth because of the abundance of precipitation and the inherent water-holding properties of soils influenced by volcanic ash. A thin organic horizon consisting of decomposing twigs, needles, and litter is on the soil surface. This horizon helps to protect the soil from wind and water erosion.
As a result of the frequent disturbances, this site primarily supports early seral species such as Sitka alder (Alnus viridis ssp. sinuata) and vine maple (Acer circinatum). Common understory shrubs include red elderberry (Sambucus racemosa), thimbleberry (Rubus parviflorus), salmonberry (Rubus spectabilis), and devilsclub (Oplopanax horridus).

Associated sites

F003XN952WA	Southern Washington Cascades High Cryic Deciduous Forest Ecological site F003XN948WA, Southern Washington Cascades Low Cryic Deciduous Forest, is located at lower elevations compared to site F003XN952WA, Southern Washington Cascades High Cryic Deciduous Forest. Both sites are in active avalanche chutes. Ecological site F003XN948WA dominantly supports tree species such as Pacific silver fir and western hemlock. Site F003XN952WA dominantly supports species such as subalpine fir, mountain hemlock, and Alaska cedar.

F003XN952WA

Southern Washington Cascades High Cryic Deciduous Forest

Ecological site F003XN948WA, Southern Washington Cascades Low Cryic Deciduous Forest, is located at lower elevations compared to site F003XN952WA, Southern Washington Cascades High Cryic Deciduous Forest. Both sites are in active avalanche chutes. Ecological site F003XN948WA dominantly supports tree species such as Pacific silver fir and western hemlock. Site F003XN952WA dominantly supports species such as subalpine fir, mountain hemlock, and Alaska cedar.

Similar sites

F003XN952WA	Southern Washington Cascades High Cryic Deciduous Forest Ecological site F003XN948WA, Southern Washington Cascades Low Cryic Deciduous Forest, is located at lower elevations compared to site F003XN952WA, Southern Washington Cascades High Cryic Deciduous Forest. Both sites are in active avalanche chutes. Ecological site F003XN948WA dominantly supports tree species such as Pacific silver fir and western hemlock. Site F003XN952WA dominantly supports species such as subalpine fir, mountain hemlock, and Alaska cedar.

F003XN952WA

Southern Washington Cascades High Cryic Deciduous Forest

Table 1. Dominant plant species

Tree	(1) Alnus viridis ssp. sinuata (2) Acer circinatum
Shrub	(1) Sambucus racemosa (2) Rubus parviflorus
Herbaceous	Not specified

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Physiographic features

This ecological site typically is in avalanche chutes of debris cones at middle to high elevations (2,100 to 6,600 feet) in Mount Rainier National Park. Although the site typically is confined to avalanche paths and runout areas, but it may be in similar areas that are frequently disturbed, such as talus slopes or areas of debris torrent deposits. The site is on most slopes, but it commonly is on slopes of 35 to 80 percent.

Table 2. Representative physiographic features

Landforms	(1) Mountains > Avalanche chute
Flooding frequency	None
Ponding frequency	None
Elevation	2100 – 6600 ft
Slope	15 – 100 %
Water table depth	70 in
Aspect	W, NW, N, NE, E, SE, S, SW

Climatic features

Most of the annual precipitation is received as snow in October through March. The snow commonly persists until late in spring or early in summer. The mean annual precipitation is 63 to 110 inches, and the mean annual air temperature is 36 to 45 degrees F. Generally, the summers are cool and dry and the winters are cold and wet.

Table 3 Representative climatic features

Frost-free period (characteristic range)	30-90 days
Freeze-free period (characteristic range)
Precipitation total (characteristic range)	60-110 in

Bar

Line

Figure 1. Monthly precipitation range

Bar

Line

Figure 2. Monthly minimum temperature range

Soil features

Applicable soils: Summerland

Applicable soil map units: 8130, 9101

The soils that support this plant community are in the cryic soil temperature regime and the udic soil moisture regime. They are well drained and very deep. They are dominantly on debris cones of glacial-valley walls. The soils formed in mixed colluvium and volcanic ash. They are not subject to flooding or ponding. They have more than 35 percent rock fragments in the particle-size control section. The fine-earth fraction is coarse textured and primarily ashy loamy sand and ashy sandy loam. Podsolization is not evident in the profile because of the active landscape positions, frequent avalanches, and rockfalls. The soils have an umbric epipedon and a cambic horizon.

Table 4. Representative soil features

Parent material	(1) Colluvium (2) Volcanic ash
Surface texture	(1) Extremely stony, ashy sandy loam (2) Very gravelly, ashy sandy loam (3) Very cobbly, ashy sandy loam
Drainage class	Well drained
Soil depth	60 in
Surface fragment cover <=3"	20 – 65 %
Surface fragment cover >3"	5 – 65 %
Available water capacity (Depth not specified)	3.5 – 6 in
Soil reaction (1:1 water) (Depth not specified)	1 – 7
Subsurface fragment volume <=3" (Depth not specified)	20 – 65 %
Subsurface fragment volume >3" (Depth not specified)	5 – 65 %

Ecological dynamics

This ecological site is in cold, moist areas at an elevation of 2,100 to 6,600 feet. It is in active avalanche chutes. Because of the frequent disturbance, the site primarily supports early seral species such as Sitka alder (Alnus viridis ssp. sinuata) and vine maple (Acer circinatum). These species are well adapted to colonizing talus slopes and avalanche chutes. The seeds of Sitka alder are particularly adapted to soils exposed by recent avalanches (Uchytil, 1989). Sitka alder and vine maple have resilient wood, and they grow nearly prostrate in response to the snow load and recurring avalanches.
Frequent avalanches do not allow for the establishment of forest overstory, but seedlings of species such as Pacific silver fir (Abies amabilis), noble fir (Abies procera), western hemlock (Tsuga heterophylla), and western redcedar (Thuja plicata) may encroach from the forested edges. Over time, the majority of the rigid-trunked trees will be snapped off by the avalanches. Common understory shrubs include red elderberry (Sambucus racemosa), thimbleberry (Rubus parviflorus), salmonberry (Rubus spectabilis), and devilsclub (Oplopanax horridus). Common forbs include fireweed (Chamerion angustifolium), ladyfern (Athyrium filix-femina), claspleaf twistedstalk (Streptopus amplexifolius), and common beargrass (Xerophyllum tenax).
Wildfires may occur on this site. Because of the rapid movement of fire on the steep slopes, the damage commonly is not severe and recovery is relatively quick. Early seral species such as Sitka alder and vine maple regenerate post fire. Sitka alder is resistant to damage from wildfires because of its nonflammable bark and non-resinous leaves. Vine maple is able to resprout from the roots very quickly after a fire (Uchytil, 1989).

State and transition model

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Ecosystem states

1. Reference

State 1 submodel, plant communities

1.1. Sitka Alder, Vine Maple, Red Elderberry, and Thimbleberry

1.2. Pacific Silver Fir, Western Hemlock, Sitka Alder, and Common Ladyfern

State 1
Reference

Community 1.1
Sitka Alder, Vine Maple, Red Elderberry, and Thimbleberry

Structure: Mosaic of shrubs and forbs

The reference community represents a lack of major disturbance for at least 10 years. Large areas of continuous canopy cover of Sitka alder develop, especially at the lower, less sloping end of the avalanche chutes. These areas generally have less diverse shrubs, but they have more forbs and ferns, such as fireweed, ladyfern, and common beargrass. Tall shrubs, such as red elderberry, salmonberry, and devilsclub, are in areas where the Sitka alder canopy is patchy. All of these species readily sprout from the root crown; therefore, they persist in avalanche chutes.

Forest overstory.Pacific silver fir, western hemlock, and noble fir are along the outer edges of the reference community. The canopy cover is 2 to 5 percent, and the canopy height is 25 to 130 feet.

Forest understory. The composition of the understory varies depending on the extent of the disturbance and competition for moisture. Overall cover of shrubs such as Sitka alder and vine maple is as much as 80 percent in the reference community. Overall cover of thimbleberry is as much as 40 percent.

Dominant plant species

Sitka alder (Alnus viridis ssp. sinuata), shrub
vine maple (Acer circinatum), shrub
red elderberry (Sambucus racemosa), shrub
thimbleberry (Rubus parviflorus), shrub
devilsclub (Oplopanax horridus), shrub
fireweed (Chamerion angustifolium), other herbaceous
common ladyfern (Athyrium filix-femina), other herbaceous
common beargrass (Xerophyllum tenax), other herbaceous

Community 1.2
Pacific Silver Fir, Western Hemlock, Sitka Alder, and Common Ladyfern

Structure: Sparse overstory encroaching avalanche paths from forested edges, and shrubby understory

Community phase 1.2 represents the forest encroaching on the avalanche chutes. The forest surrounding the avalanche chutes provides a seed source for the plant community. Typically, the rigid-stemmed species in the main snow path do not survive repeated avalanches. They may slowly encroach from the forested edges in areas where mature trees provide some protection against snow movement. Over time and under certain conditions, this can lead to a narrowing of the original chute.

Dominant plant species

Pacific silver fir (Abies amabilis), tree
western hemlock (Tsuga heterophylla), tree
noble fir (Abies procera), tree
Sitka alder (Alnus viridis ssp. sinuata), shrub
common ladyfern (Athyrium filix-femina), other herbaceous

Pathway 1.1A
Community 1.1 to 1.2

Sitka Alder, Vine Maple, Red Elderberry, and Thimbleberry

Pacific Silver Fir, Western Hemlock, Sitka Alder, and Common Ladyfern

This pathway represents an extended time with no disturbance from avalanches, which allows trees to become established.

Pathway 1.2A
Community 1.2 to 1.1

Pacific Silver Fir, Western Hemlock, Sitka Alder, and Common Ladyfern

Sitka Alder, Vine Maple, Red Elderberry, and Thimbleberry

This pathway represents a disturbance such as a wildfire or a major avalanche or series of avalanches that reclaims the original extent of the avalanche chute.

Additional community tables

Table 5. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Table 6. Community 1.1 forest overstory composition

Common name	Symbol	Scientific name	Nativity	Height ft	Canopy cover (%)	Diameter in	Basal area (square ft/acre)
Tree
Pacific silver fir	ABAM	Abies amabilis	Native	–	–	–	0
noble fir	ABPR	Abies procera	Native	–	–	–	0
western hemlock	TSHE	Tsuga heterophylla	Native	–	–	–	0

Table 7. Community 1.1 forest understory composition

Common name	Symbol	Scientific name	Nativity	Height (ft)	Canopy cover (%)
Forb/Herb
common beargrass	XETE	Xerophyllum tenax	Native	12–36	0–20
Pacific trillium	TROV2	Trillium ovatum	Native	1–12	0–5
Fern/fern ally
western oakfern	GYDR	Gymnocarpium dryopteris	Native	2–12	0–1
common ladyfern	ATFI	Athyrium filix-femina	Native	6–24	0–1
Shrub/Subshrub
Sitka alder	ALVIS	Alnus viridis ssp. sinuata	Native	6–180	0–80
vine maple	ACCI	Acer circinatum	Native	24–300	0–80
thimbleberry	RUPA	Rubus parviflorus	Native	12–48	0–40
salmonberry	RUSP	Rubus spectabilis	Native	12–72	0–25
red elderberry	SARA2	Sambucus racemosa	Native	24–120	0–20
devilsclub	OPHO	Oplopanax horridus	Native	12–60	0–20

Table 8. Community 1.2 plant community composition

Group	Common name	Symbol	Scientific name	Annual production ()	Foliar cover (%)

Interpretations

Table 9. 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
western hemlock	TSHE	100	–	142	–	60	–	–

Supporting information

Inventory data references

Other Established Classifications National vegetation classification group: Vancouverian Flooded and Swamp Forest, North Pacific Lowland-Montane Riparian and Wet Slope Shrubland U.S. Department of the Interior, National Park Service, plant association: • ALNVIR • ALNVIR-ACECIR

Type locality

Location 1: Pierce County, WA
Township/Range/Section	T18N R7E S23
Latitude	46° 46′ 36″
Longitude	121° 53′ 2″

Other references

Barnes, George H. 1962. Yield of even-aged stands of western hemlock. U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station Technical Bulletin 1273.
Crawford, R.C., C.B. Chappell, C.C. Thompson, and F.J. Rocchio. 2009. Vegetation classification of Mount Rainier, North Cascades, and Olympic National Parks. Natural Resource Technical Report NPS/NCCN/NRTR-2009/211. National Park Service, Fort Collins, Colorado.
Czuba, J., C. Magirl, C. Czuba, C. Curran, K. Johnson, T. Olsen, H. Kimball, and C. Gish. 2012. Geomorphic analysis of the river response to sedimentation downstream of Mount Rainier, Washington. U.S. Geological Survey Open-file Report 2012-1242. Reston, Virginia.
Dwire, K., and J. Kauffman. 2003. Fire and riparian ecosystems in landscapes in the western United States. Forest Ecology and Management. Volume 178, pages 61-74.
Goheen, E.M., and E.A. Willhite. 2006. Field guide to common diseases and insect pests of Oregon and Washington conifers. U.S. Department of Agriculture, Forest Service, Pacific Northwest Region R6-NR-FID-PR-01-06.
Hanley, D.P., and D.M. Baumgartner. 2002. Forest ecology in Washington. Washington State University Cooperative Extension Technical Report EB 1943.
Hanson, E.J., D.L. Azuma, and B.A. Hiserote. 2002. Site index equations and mean annual increment equations for Pacific Northwest Research Station forest inventory and analysis inventories, 1985-2001. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station Research Note PNW-RN-533.
Hemstrom, M., and J. Franklin. 1982. Fire and other disturbances of the forests in Mount Rainier National Park. Quaternary Research. Volume 18, pages 32-61.
Henderson, J.A., R.D. Lesher, D.H. Peter, and D.C. Shaw. 1992. Field guide to the forested plant associations of the Mt. Baker-Snoqualmie National Forest. U.S. Department of Agriculture, Forest Service, Pacific Northwest Region Technical Paper R6-ECOL-TP-028-91.
King, James E. 1966. Site index curves for Douglas-fir in the Pacific Northwest. Weyerhaeuser Company, Forestry Research Center Forestry Paper 8.
Kittel, G., D. Meidinger, and D. Faber-Langendoen. 2015. G240 Pseudotsuga menziesii-Tsuga heterophylla/Gaultheria shallon forest group. United States National Vegetation Classification. Federal Geographic Data Committee, Vegetation Subcommittee, Washington, D.C.
Means, J.E. 1990. Tsuga mertensiana. In Silvics of North America: Volume 1. Conifers. U.S. Department of Agriculture, Forest Service, Agriculture Handbook 654. Pages 623-634. https://www.srs.fs.usda.gov/pubs/misc/ag_654_vol1.pdf
Naiman, R., S. Bechtold, T. Beechie, J. Latterell, and R. Van Pelt. 2009. A process-based view of floodplain forest patterns in coastal river valleys of the Pacific Northwest. Ecosystems. Volume 13, pages 1-31.
Nierenberg, T., and D. Hibbs. 2000. A characterization of unmanaged riparian areas in the central Coast Range of western Oregon. Forest Ecology and Management. Volume 129, pages 195-206.
Packee, E.C. 1990. Tsuga heterophylla. In Silvics of North America: Volume 1. Conifers. U.S. Department of Agriculture, Forest Service, Agriculture Handbook 654. Pages 613-622. https://www.srs.fs.usda.gov/pubs/misc/ag_654_vol1.pdf
Pojar, J., and A. MacKinnon. 1994. Plants of the Pacific Northwest Coast. Lone Pine, Vancouver, British Columbia.
PRISM Climate Group. Oregon State University. Accessed February 2015. http://prism.oregonstate.edu
Rochefort, R.M., and D.L. Peterson. 1996. Temporal and spatial distribution of trees in subalpine meadows of Mount Rainier National Park. Arctic and Alpine Research. Volume 28, number 1, pages 52-59.
Rot, B., R. Naiman, and E. Bilby. 1999. Stream channel configuration, landform, and riparian forest structure in the Cascade Mountains, Washington. Canadian Journal of Fish and Aquatic Science. Volume 57, pages 699-707.
Seastedt, T.R., and G.A. Adams. 2001. Effects of mobile tree islands on alpine tundra soils. Ecology. Volume 82, pages 8-17. Scientia Silvica. 1997. Regeneration patterns in the mountain hemlock zone. Extension Series, Number 6.
Smith, K., G. Kuhn, and L. Townsend. 2008. Culmination of mean annual increment for indicator tree species in the State of Washington. U.S. Department of Agriculture, Natural Resources Conservation Service, Technical Note Forestry-9.
Tesky, J.L. 1992. Tsuga mertensiana. In Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.fed.us/database/feis/plants/tree/tsumer/all.html
Topik, C., N.M. Halverson, and D.G. Brockway. 1986. Plant associations and management guide for the western hemlock zone, Gifford Pinchot National Forest. U.S. Department of Agriculture, Forest Service, Pacific Northwest Region Technical Paper R6-ECOL-230A-1986.
Uchytil, R. 1989. Acer circinatum. In Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.fed.us/database/feis/plants/shrub/acecir/all.html
Uchytil, R. 1989. Alnus viridis subsp. sinuata. In Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.fed.us/database/feis/plants/shrub/alnvirs/all.html United States Department of Agriculture, Forest Service. 1990. Silvics of North America. Agriculture Handbook 654. https://www.fs.usda.gov/naspf/
United States Department of Agriculture, Natural Resources Conservation Service, and United States Department of the Interior, National Park Service. 2014. Ecological site descriptions for North Cascades National Park Complex, Washington.
Villarin, L., D. Chapin, and J. Jones. 2009. Riparian forest structure and succession in second-growth stands of the central Cascade Mountains, Washington, USA. Forest Ecology and Management. Volume 257, pages 1375-1385.

Contributors

Erin Kreutz
Erik Dahlke
Philip Roberts

Approval

Kirt Walstad, 1/30/2025

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	05/10/2024
Approved by
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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:
Perennial plant reproductive capability:

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