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Ecological site AX001X01X413

High Cryic Udic Forest

Last updated: 5/15/2025
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): 001X–Northern Pacific Coast Range, Foothills, and Valleys

This area consists of a long and narrow range of mountains with associated foothills and valleys that parallels the Pacific Ocean. This area is entirely within the Pacific Border Province of the Pacific Mountain System in Oregon and Washington. MLRA 1 is bounded on the north by the highest elevations of the Olympic Mountains and the strait of Juan de Fuca, and by the Klamath Mountains on the south. The Washington portion of this MLRA is primarily composed of young Tertiary sedimentary rocks (siltstone and sandstone) mixed with some volcanic rocks of the same age. Glacial till and outwash deposits are also found in the northern half of this area in Washington. Much of this area is accreted terrane formed by tectonic processes. The average annual precipitation ranges from 60 to 200 inches (1,525 to 5,580 millimeters), increasing with elevation. Most of the precipitation in this area occurs during low-intensity, Pacific frontal storms and is evenly distributed throughout fall, winter, and spring.

The dominant soil orders in this MLRA are Andisols, Inceptisols, and Ultisols. Soil depths broadly range from shallow to very deep. Soils are primarily well drained, however poorly drained soils may be found in depressional areas and on alluvial floodplains. Surface textures are typically medial and loamy or clayey. Soils in this area dominantly have a mesic or frigid temperature regime and a udic moisture regime. Soils with aquic moisture regimes and cryic temperature regimes also occur.

Ecological site concept

High Cryic Udic Forest sites occur on less stable landscape positions on valley walls, bedrock benches, bedrock knobs, fluve basins, and slides in high elevation areas within the cryic temperature zone. These sites are typically located on the windward side of the Olympic mountains where precipitation is abundant. Relatively high slope gradients limit water infiltration on these sites, generating runoff to more stable High Cryic Udic Moist Forests, Wet Subalpine Meadows, and Cryic Aquic Shrublands.

High Cryic Udic Forest sites are characterized by a dense overstory of mountain hemlock (Tsuga mertensiana) and subalpine fir (Abies lasiocarpa), accompanied by an understory shrub community of thinleaf huckleberry (Vaccinium membranaceum), locally known as black huckleberry, and pink mountainheath (Phyllodoce empetriformis). The most common herbaceous layer species are white avalanche-lily (Erythronium montanum), roughfruit berry (Rubus lasiococcus), and western moss heather (Cassiope mertensiana).

High Cryic Udic Forest sites are readily differentiated from Low Cryic Udic Forest sites by presence of subalpine fir (Abies lasiocarpa).

Associated sites

AX001X01X306	Cryic Aquic Subalpine Wet Meadow Cryic Aquic Subalpine Wet Meadows may be found in depressions and seeps adjacent to or surrounded by High Cryic Udic Forest sites. Cryic Aquic Subalpine Wet Meadow sites are frequently ponded and lack tree cover.
AX001X01X414	High Cryic Udic Moist Forest High Cryic Udic Moist Forest sites may be found downslope of High Cryic Udic Forest sites. High Cryic Udic Moist Forest sites may capture run-on water and have higher productivity.

AX001X01X306

Cryic Aquic Subalpine Wet Meadow

Cryic Aquic Subalpine Wet Meadows may be found in depressions and seeps adjacent to or surrounded by High Cryic Udic Forest sites. Cryic Aquic Subalpine Wet Meadow sites are frequently ponded and lack tree cover.

AX001X01X414

High Cryic Udic Moist Forest

High Cryic Udic Moist Forest sites may be found downslope of High Cryic Udic Forest sites. High Cryic Udic Moist Forest sites may capture run-on water and have higher productivity.

Similar sites

AX001X01X415	High Cryic Udic Dry Forest High Cryic Udic Dry Forest sites primarily occur in the rain shadow of the Olympic mountains and on steep or exposed aspects. High Cryic Udic Dry Forests can be distinguished by the presence of lodgepole pine (Pinus contorta) and common juniper (Juniperus communis).
AX001X01X410	Low Cryic Udic Forest Low Cryic Udic Forest sites occur at lower elevations and lack subalpine fir (Abies lasiocarpa).

AX001X01X415

High Cryic Udic Dry Forest

High Cryic Udic Dry Forest sites primarily occur in the rain shadow of the Olympic mountains and on steep or exposed aspects. High Cryic Udic Dry Forests can be distinguished by the presence of lodgepole pine (Pinus contorta) and common juniper (Juniperus communis).

AX001X01X410

Low Cryic Udic Forest

Low Cryic Udic Forest sites occur at lower elevations and lack subalpine fir (Abies lasiocarpa).

Table 1. Dominant plant species

Tree	(1) Tsuga mertensiana (2) Abies lasiocarpa
Shrub	(1) Vaccinium membranaceum (2) Phyllodoce empetriformis
Herbaceous	(1) Erythronium montanum (2) Rubus lasiococcus

Legacy ID

F001XA413WA

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Physiographic features

This site primarily occurs on valley walls, bedrock benches, bedrock knobs, fluve basins, and slides on mountains. High Cryic Udic Forest sites are found on less stable slope positions and generate run-off that is collected by more stable sites downslope.

Table 2. Representative physiographic features

Landforms	(1) Mountains (2) Glacial-valley wall (3) Bench (4) Knob (5) Slide
Flooding frequency	None
Ponding frequency	None
Elevation	4265 – 5906 ft
Slope	0 – 100 %
Water table depth	59 – 0 in
Aspect	W, NW, N, NE, E, SE, S, SW

Climatic features

This site occurs in a cryic temperature and udic moisture regime. Precipitation arrives mostly via low-intensity, Pacific frontal storms. Precipitation is unevenly distributed, with the lowest amounts on the leeward side of the Coast Range mountains. Precipitation falls largely as snow in higher elevations. Precipitation is evenly distributed throughout the fall, winter, and spring, while summers are dry. Air temperatures vary significantly along the elevation gradient.

Table 3 Representative climatic features

Frost-free period (characteristic range)	30-60 days
Freeze-free period (characteristic range)
Precipitation total (characteristic range)	120-160 in

Soil features

The soils that support this ecological site occur in the cryic soil temperature regime and udic soil moisture regime. Mountfromme-cold soils are shallow, and Hungrycreek soils are very deep. They are well drained, formed from residuum or colluvium from metasedimentary rock, and occur on structural benches and glacial valley walls. Saturated hydraulic conductivity is high or very high throughout. These soils have a rock fragment content of 35 percent or greater in the control section. Although representative of this site, these soils may exist across multiple ecological sites because of naturally variable slope, texture, rock fragments, and pH. An on-site soil pit and the most current ecological site key are necessary to classify a site.

Table 4. Representative soil features

Parent material	(1) Residuum (2) Colluvium – metasedimentary rock
Surface texture	(1) Silt loam (2) Gravelly silt loam (3) Gravelly loam
Drainage class	Well drained
Soil depth	10 – 60 in
Surface fragment cover <=3"	0 – 5 %
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	1.3 – 5.7 in
Soil reaction (1:1 water) (0-10in)	4.5 – 5.5
Subsurface fragment volume <=3" (0-20in)	10 – 50 %
Subsurface fragment volume >3" (0-20in)	0 – 20 %

Ecological dynamics

Frequent, small-scale disturbance from windthrow events create a mosaic fabric of early-seral patches within late-seral communities. Windthrow events create small canopy gaps that provide favorable conditions for limited Douglas-fir regeneration and increased understory productivity. Eventually, mountain hemlock (Tsuga mertensiana) and subalpine fir (Abies lasiocarpa) will regenerate and become dominant.

Infrequent, large-scale disturbances may occur in the form of stand-replacing wildfires, cataclysmic wind events, or large mass movement events. The fire regime of the western half of the Olympic peninsula is characterized by high-intensity, stand replacing fires with a long return interval – greater than 100 years (Agee, 1987). Strong coastal winds produce intense blow-down disturbance events more frequently than fires occur. Wildfires and severe blowdown create conditions favorable for the establishment of early seral tree species. Douglas-fir (Pseudotsuga menziesii) regeneration is favored by stand-replacing disturbance. In the absence of large-scale disturbance, more slow-growing and shade-tolerant subalpine fir and mountain hemlock will regenerate successfully and gradually succeed Douglas-fir. The longevity of Douglas-fir may preserve evidence of historical high-intensity disturbance events.

Large mass-movement events also provide conditions for the initiation of primary succession. Landslides are a significant source of disturbance, owing to the steep terrain and sedimentary geology of the park. (Gavin, 2014). As with stand-replacing wildfires, bare patches created by landslides favor establishment of shade intolerant Douglas-fir recruits (Geertsema and Pojar, 2007).

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 text

1.1B	-	Minor disturbance
1.1A	-	High-intensity disturbance
1.2A	-	Time without disturbance
1.2B	-	High-intensity disturbance
1.3A	-	Time without disturbance
1.4B	-	High-intensity disturbance
1.4A	-	Time without disturbance
1.5A	-	Time without disturbance
1.5B	-	High-intensity disturbance

State 1
Reference

The reference state is comprised of five communities in varying stages of regeneration following either small-scale or large-scale disturbance.

Dominant plant species

mountain hemlock (Tsuga mertensiana), tree
subalpine fir (Abies lasiocarpa), tree
Douglas-fir (Pseudotsuga menziesii), tree
Alaska cedar (Callitropsis nootkatensis), tree
thinleaf huckleberry (Vaccinium membranaceum), shrub
pink mountainheath (Phyllodoce empetriformis), shrub
Cascade bilberry (Vaccinium deliciosum), shrub
white avalanche-lily (Erythronium montanum), other herbaceous
roughfruit berry (Rubus lasiococcus), other herbaceous
common beargrass (Xerophyllum tenax), other herbaceous

Community 1.1
Mountain Hemlock, Subalpine Fir, Thinleaf Huckleberry, Pink Mountainheath, White Avalanche-Lily, and Roughfruit Berry

Structure: Multistory woodland with small gap dynamics
Mountain hemlock and subalpine fir are the dominant overstory species in the reference community. Reference community conifers are shade-tolerant and may regenerate continually. Common understory species include thinleaf huckleberry, pink mountainheath, white avalanche-lily, roughfruit berry, and Cascade bilberry.

Community 1.2
Mountain Hemlock, Alaska Cedar, Pink Mountainheath, Thinleaf Huckleberry, Common Beargrass, and White Avalanche-Lily

Structure: Mosaic of overstory and openings in varying states of regeneration
This community is initiated in the wake of small-scale disturbance which creates small canopy openings. Alaska cedar may recruit to small canopy gaps before mountain hemlock and subalpine fir are able to establish. This community may be identified by higher understory productivity. In the localized absence of a dense tree canopy, understory species are released from sunlight limitation.

Community 1.3
Douglas-fir, Pink Mountainheath, Thinleaf Huckleberry, and White Avalanche-Lily

Structure: open forest with shrubby regeneration and snags
This early seral-stage community occurs in the aftermath of a stand-replacing disturbance. Nearly all trees are removed from the site. In the case of high-intensity fire, few large fire-resistant trees may remain. Shade intolerant Douglas-fir readily germinates and establishes in the absence of canopy cover post-disturbance. Shrubs and forbs are often able to outcompete tree saplings for several years post-disturbance.

Community 1.4
Mountain Hemlock, Douglas-fir, Pink Mountainheath, Thinleaf Huckleberry, Common Beargrass, and White Avalanche-Lily

Structure: shrubby meadow with sparse tree establishment
As a discrete canopy layer is formed by maturing Douglas-fir, mountain hemlock begins to establish on the site. Shade-tolerant conifers readily germinate under the dense canopy.

Community 1.5
Mountain Hemlock, Alaska Cedar, Thinleaf Huckleberry, Pink Mountainheath, White Avalanche-Lily, and Roughfruit Berry

Structure: single story with diminished understory
Additional time without major disturbance allows shade tolerant tree species to gradually replace Douglas-fir. Mountain hemlock, Alaska cedar, and subalpine fir generally dominate in this community phase. Alaska cedar is likely to be subdominant in this phase and will gradually be replaced by subalpine fir. Understory diversity increases as additional time passes. Understory productivity is limited by high canopy density. Individual tree mortality and small-scale disturbance events will promote vertical stratification and create canopy gaps that favor increased understory productivity.

Pathway 1.1B
Community 1.1 to 1.2

Minor disturbances, often caused by individual tree mortality, create small gaps in the forest canopy.

Pathway 1.1A
Community 1.1 to 1.3

Stand-replacing disturbances such as high-intensity fires, catastrophic windstorms, and mass-movement events open the forest and lead to the stand initiation phase of development.

Pathway 1.2A
Community 1.2 to 1.1

Time without disturbance allows regeneration, growth, and progression to a later seral stage.

Pathway 1.2B
Community 1.2 to 1.3

Stand-replacing disturbances such as high-intensity fires, catastrophic windstorms, and mass-movement events open the forest and lead to the stand initiation phase of development.

Pathway 1.3A
Community 1.3 to 1.4

Time without disturbance allows regeneration, growth, and progression to a later seral stage.

Pathway 1.4B
Community 1.4 to 1.3

Stand-replacing disturbances such as high-intensity fires, catastrophic windstorms, and mass-movement events open the forest and lead to the stand initiation phase of development.

Pathway 1.4A
Community 1.4 to 1.5

Time without disturbance allows regeneration, growth, and progression to a later seral stage.

Pathway 1.5A
Community 1.5 to 1.1

Time without disturbance allows continued tree regeneration and growth.

Pathway 1.5B
Community 1.5 to 1.3

Stand-replacing disturbances such as high-intensity fires, catastrophic windstorms, and mass-movement events open the forest and lead to the stand initiation phase of development.

Additional community tables

Table 5. Community 1.1 plant community composition

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

Table 6. Community 1.2 plant community composition

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

Table 7. Community 1.3 plant community composition

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

Table 8. Community 1.4 plant community composition

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

Table 9. Community 1.5 plant community composition

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

Supporting information

Other references

Breemen, Nico van. “How Sphagnum Bogs down Other Plants.” Trends in Ecology & Evolution 10, no. 7 (July 1, 1995): 270–75. 90007-1.

Dwire, K. and Kauffman, J. 2003. Fire and Riparian Ecosystems in Landscapes in the Western United States. Forest Ecology and Management, Vol. 178 pg. 61-74.

Franklin, Jerry F.; Cromack, Kermit, Jr.; Denison, William; [and others]. 1981. Ecological characteristics of old-growth Douglas-fir forests. Gen. Tech. Rep. PNW-118. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 48 p. [7551]

Gavin, D., Brubaker, L. (2015). The Modern Landscape of the Olympic Peninsula. In: Late Pleistocene and Holocene Environmental Change on the Olympic Peninsula, Washington. Ecological Studies, vol 222. Springer, Cham. https://doi.org/10.1007/978-3-319-11014-1_1

Geertsema, Marten & Pojar, James. (2007). Influence of landslides on biophysical diversity — A perspective from British Columbia. Geomorphology. 89. 55-69. 10.1016/j.geomorph.2006.07.019.

Goheen, E.M. and Willhite, E.A. 2006. Field Guide to Common Diseases and Inspect Pests of Oregon and Washington Conifers. Portland, Oregon: USDA 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 Extension Publishing. 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. USDA Forest Service Pacific Northwest Research Station, Research Note PNW-RN-533.

Hemstrom, M., Franklin, J. 1982. Fire and Other Disturbances of the Forests in Mount Rainier National Park. Quaternary Research, Vol 18 pp 32-61.

James K. Agee and Mark H. Huff. 1987. Fuel succession in a western hemlock/Douglas-fir forest. Canadian Journal of Forest Research. 17(7): 697-704. https://doi.org/10.1139/x87-112

Nielsen, E. M., R. L. Brunner, C. Copass and L. K. Wise, 2021. Olympic National Park map class descriptions. National Park Service, Fort Collins.

Pojar J., and MacKinnon. 1994. Plants of the Pacific Northwest Coast. Lone Pine, Vancouver, British Columbia. 528 pages.

PRISM Climate Group, Oregon State University, http://prism.orgeonstate.edu, visited October 2023.

Reed Wendel, Darlene Zabowskl "Fire History within the Lower Elwha River Watershed, Olympic National Park, Washington," Northwest Science, 84(1), 88-97, (1 January 2010)

Rochefort, R.M. and Peterson, D.L. 1996. Temporal and Spatial Distribution of Trees in Subalpine Meadows of Mount Rainier National Park. Arctic and Alpine Research, Vol. 28, No. 1 pp 52-59.

Seastedt, T.R., Adams, G.A. 2001. Effects of Mobile Tree Islands on Alpine Tundra Soils. Ecology, Vol 82 pp 8-17.

Smith, K., G. Kuhn, and L. Townsend. 2008. Culmination of Mean Annual Increment for Indicator Tree Species in the State of Washington. USDA-NRCS Technical Note Forestry-9.

United States Department of Agriculture, Forest Service, 2015. Silvics Manual Vol 1. http://na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/vol1_Table_of_contents.htm, visited December 2015.

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.

United States Department of Agriculture, Natural Resources Conservation Service, and United States Department of the Interior, National Park Service. Ecological Site Descriptions for Mount Rainier National Park, Washington.

Van Pelt, R. 2007. Identifying Mature and Old Forests in Western Washington. Washington State Department of Natural Resources, Olympia, WA. 104 p

Washington Department of Natural Resources, Natural Heritage Program. 2015. Ecological Systems of Washington State. A Guide to Identification.

Wood, David, and Moral, Roger del. “Mechanisms of Early Primary Succession in Subalpine Habitats on Mount St. Helens.” Ecology 68, no. 4 (1987).

Zhao, Yunpeng, Chengzhu Liu, Simin Wang, Yiyun Wang, Xiaoqing Liu, Wanqing Luo, and Xiaojuan Feng. “‘Triple Locks’ on Soil Organic Carbon Exerted by Sphagnum Acid in Wetlands.” Geochimica et Cosmochimica Acta 315 (December 2021): 24–37. https://doi.org/10.1016/j.gca.2021.09.028.

Contributors

Alec Haulotte
Erin Kreutz
Abigail Field
Max Ross
Erik Dahlke

Approval

Grant Petersen, 5/15/2025

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	08/31/2026
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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Natural ResourcesConservation Service

Ecological site AX001X01X413

High Cryic Udic Forest

Last updated: 5/15/2025 Accessed: 08/31/2026

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General information

MLRA notes

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Legacy ID

Natural Resources
Conservation Service

Last updated: 5/15/2025
Accessed: 08/31/2026