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Ecological site AX001X01X415

High Cryic Udic Dry Forest

Last updated: 5/15/2025
Accessed: 05/20/2025

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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 Dry 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 leeward side of the Olympic Mountains where precipitation is relatively low. 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 Dry Forest sites are characterized by a subalpine fir (Abies lasiocarpa) and lodgepole pine (Pinus contorta) canopy, accompanied by an understory shrub and subshrub community of common juniper (Juniperus communis), and Oregon boxleaf (Paxistima myrsinites). The most common herbaceous layer species are broadleaf lupine (Lupinus latifolius), Cascade desertparsley (Lomatium martindalei), sidebells wintergreen (Orthilia secunda).

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

Associated sites

AX001X01X414	High Cryic Udic Moist Forest High Cryic Udic Moist Forest sites may be found downslope of High Cryic Udic Dry 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 Dry 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 Dry 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 Dry Forest sites. Cryic Aquic Subalpine Wet Meadow sites are frequently ponded and lack tree cover.

Similar sites

AX001X01X412	Low Cryic Udic Dry Forest Low Cryic Udic Dry Forest sites are found at lower elevations and lack subalpine fir (Abies lasiocarpa).
AX001X01X413	High Cryic Udic Forest High Cryic Udic Forests are typically located on the windward side of the Olympic mountains and on protected aspects. These sites receive higher effective precipitation and production is significantly higher than on High Cryic Udic Dry Forest sites. High Cryic Udic Forest sites lack lodgepole pine (Pinus contorta) and common juniper (Juniperus communis).

AX001X01X412

Low Cryic Udic Dry Forest

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

AX001X01X413

High Cryic Udic Forest

High Cryic Udic Forests are typically located on the windward side of the Olympic mountains and on protected aspects. These sites receive higher effective precipitation and production is significantly higher than on High Cryic Udic Dry Forest sites. High Cryic Udic Forest sites lack lodgepole pine (Pinus contorta) and common juniper (Juniperus communis).

Table 1. Dominant plant species

Tree	(1) Abies lasiocarpa (2) Pinus contorta
Shrub	(1) Juniperus communis (2) Paxistima myrsinites
Herbaceous	(1) Lupinus latifolius (2) Lomatium martindalei

Legacy ID

F001XA415WA

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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 Dry Forest sites are strongly influenced by high slope gradients. Since these sites are typically found on the least stable forested slopes they lose a significant amount of water to run-off.

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	4,593 – 6,234 ft
Slope	15 – 100%
Water table depth	59 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)	69-98 in

Soil features

The soils that support this ecological site occur in the cryic soil temperature regime and the udic soil moisture regime. They are well-drained, formed from residuum or colluvium from metasedimentary rock, and occur on glacial valley walls, structural benches, and ridges. Mountfromme-cold, dry soils are shallow, Marmotlake is moderately deep, and Grandpass is very deep. Saturated hydraulic conductivity is high or very high throughout, and rock fragment content is 35 percent or more in the control section. These soils occur primarily in the rain shadow of the Olympic Peninsula, so they are drier than their counterparts on the west side. Less available water in these soils is the primary limiting factor to plant growth. 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) Very gravelly loam (3) Loam (4) Gravelly sandy loam
Drainage class	Well drained
Soil depth	20 – 60 in
Surface fragment cover <=3"	5%
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	1.3 – 5.4 in
Soil reaction (1:1 water) (0-10in)	4.5 – 5.5
Subsurface fragment volume <=3" (0-20in)	50%
Subsurface fragment volume >3" (0-20in)	20%

Ecological dynamics

Frequent, small-scale disturbances 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, subalpine fir (Abies lasiocarpa) and lodgepole pine (Pinus contorta) 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 of 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) and whitebark pine (Pinus albicaulis) regeneration is favored by stand-replacing disturbance. In the absence of large-scale disturbance, more slow-growing and shade-tolerant subalpine fir and lodgepole pine will regenerate successfully and gradually succeed Douglas-fir. White pine blister rust (Cronartium ribicola) is a deadly fungal pathogen of whitebark pine and generally causes widespread mortality of whitebark pine trees on these sites before they reach maturity. 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 the establishment of early seral 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.

Community 1.1
Subalpine Fir, Lodgepole Pine, Common Juniper, Oregon Boxleaf, Broadleaf Lupine, and Cascade Desertparsley

Structure: Multistory with small gap dynamics Subalpine fir and lodgepole pine are the dominant overstory species in the reference community. Reference community conifers are shade-tolerant and may regenerate continually in the understory. Common understory species include common juniper, Oregon boxleaf, broadleaf lupine, Cascade desertparsley, sidebells wintergreen (Orthilia secunda), Cascade azalea (Rhododendron albiflorum), and Sitka valerian (Valeriana sitchensis).

Dominant plant species

subalpine fir (Abies lasiocarpa), tree
lodgepole pine (Pinus contorta), tree
Douglas-fir (Pseudotsuga menziesii), tree
whitebark pine (Pinus albicaulis), tree
common juniper (Juniperus communis), shrub
Oregon boxleaf (Paxistima myrsinites), shrub
Cascade azalea (Rhododendron albiflorum), shrub
broadleaf lupine (Lupinus latifolius), other herbaceous
cascade desertparsley (Lomatium martindalei), other herbaceous
broadleaf arnica (Arnica latifolia), other herbaceous
sidebells wintergreen (Orthilia secunda), other herbaceous
Sitka valerian (Valeriana sitchensis), other herbaceous

Community 1.2
Lodgepole Pine, Douglas-fir, Common Juniper, Spreading Phlox, Broadleaf Lupine, and Broadleaf Arnica

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. Douglas-fir may recruit to canopy gaps before subalpine fir can establish. This community may be identified by higher than reference understory productivity.

Community 1.3
Douglas-fir, Whitebark Pine, Broadleaf Lupine, and Broadleaf Arnica

Structure: open forest with shrubby regeneration and snags This early seral 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. Douglas-fir and whitebark pine readily germinate and establish post-disturbance. Shrubs and forbs are often able to outcompete tree saplings for several years post-disturbance. Juvenile whitebark pine will generally be killed by white pine blister rust in this community phase.

Community 1.4
Douglas-fir, Lodgepole Pine, Common Juniper, Spreading Phlox, Broadleaf Lupine, and Jacob's-Ladder

Structure: shrubby meadow with sparse tree establishment With additional time post-disturbance lodgepole pine will recruit to the site. Whitebark pine will be largely removed from the site in this community. Snags of dead trees and a few uninfected trees may be found.

Community 1.5
Lodgepole Pine, Subalpine Fir, Common Juniper, Oregon Boxleaf, Broadleaf Lupine, and Cascade Desertparsley

Structure: single story with diminished understory Additional time without major disturbance allows slow-growing and shade-tolerant tree species to gradually replace Douglas-fir. Lodgepole pine, subalpine fir, and Alaska cedar generally dominate in this community. Understory productivity may be limited by locally 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

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	05/16/2025
Approved by	Grant Petersen
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:

Download reference sheet

Click on box and path labels to scroll to the respective text.

Ecosystem states

1. Reference

State 1 submodel, plant communities

1.1. Subalpine Fir, Lodgepole Pine, Common Juniper, Oregon Boxleaf, Broadleaf Lupine, and Cascade Desertparsley

1.2. Lodgepole Pine, Douglas-fir, Common Juniper, Spreading Phlox, Broadleaf Lupine, and Broadleaf Arnica

1.3. Douglas-fir, Whitebark Pine, Broadleaf Lupine, and Broadleaf Arnica

1.4. Douglas-fir, Lodgepole Pine, Common Juniper, Spreading Phlox, Broadleaf Lupine, and Jacob's-Ladder

1.5. Lodgepole Pine, Subalpine Fir, Common Juniper, Oregon Boxleaf, Broadleaf Lupine, and Cascade Desertparsley

Communities 1 and 5 (additional pathways)

1.1. Subalpine Fir, Lodgepole Pine, Common Juniper, Oregon Boxleaf, Broadleaf Lupine, and Cascade Desertparsley

1.5. Lodgepole Pine, Subalpine Fir, Common Juniper, Oregon Boxleaf, Broadleaf Lupine, and Cascade Desertparsley

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

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Natural ResourcesConservation Service

Ecological site AX001X01X415

High Cryic Udic Dry Forest

Last updated: 5/15/2025 Accessed: 05/20/2025

General information

MLRA notes

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Legacy ID

Ecosystem states

State 1 submodel, plant communities

Communities 1 and 5 (additional pathways)

Natural Resources
Conservation Service

Last updated: 5/15/2025
Accessed: 05/20/2025