Ecological site AX003X03F007

AX003X03C004	Glaciated Middle Cascades Frigid Udic Forest Group Lower on the landscape.

AX003X00F005	Western Middle Cascades Low Cryic Udic Forest Group Non-glaciated landforms.

Tree	(1) Abies amabilis
Shrub	Not specified
Herbaceous	Not specified

Elevation	3000 – 4530 ft
Slope	25 – 50 %

Parent material	(1) Colluvium – andesite (2) Volcanic ash (3) Colluvium – basalt
Drainage class	Well drained

Ecological dynamics

This ecological site is found on mountain slopes, at elevations of 3000 to 4530 feet. Slope gradient is usually 21-47 percent. Climate is cold and moist (frost free days average 32-60, mean annual precipitation averages 77-111 inches, mean annual air temperature is 39-44 degrees Fahrenheit). Precipitation occurs mainly during fall, winter, and spring. Summers are dry. Snowpack accumulates during winter and persists through spring or early summer. Soils are usually well drained but, when present, the top of the seasonal water table averages 24-36 inches below the soil surface. Soils are usually greater than 60 inches to a restrictive layer but, when present, root restrictions occur 32-47 inches below the soil surface. Soil temperature regime is cryic, and soil moisture regime is udic. Soil parent material is usually volcanic ash and colluvium derived from andesite or basalt. Soils usually classify as Andisols (Typic Haplocryands) or Inceptisols (Andic Cryochrepts).

The reference plant community has an overstory of Abies amabilis, though seral trees include noble fir, Douglas fir, western redcedar, western hemlock, Sitka spruce and mountain hemlock. The understory includes salal, Pacific rhododendron, thinleaf huckleberry, common beargrass, mountain brome, vine maple, red alder, western swordfern, oval-leaf huckleberry, sweet-after death, red huckleberry, western fescue, Cascade barberry, common snowberry, broadleaf starflower. The fire return interval is generally rare (200-500 years) and is stand replacing, Abies amabilis perishes in fire but quickly restablishes under a canopy of seral trees. Shrubs resprout, and pioneering herbaceous species establish on the site post fire. Shrubs form a post-disturbance phase which may include vine maple, Douglas maple, Scouler willow, pachistima, thinleaf huckleberry, serviceberry, Sitka alder, and snowbrush ceanothus. Fires on the east side of the Cascade Crest are more frequent due to the continental climate factors. Fire is a rare, large-patch disturbance while diseases and insects create frequent, small-patch disturbances that open the tree canopy. Diseases include Annosum and laminated root disease, Indian paint fungus, and mistletoe. Insects include mountain pine beetle (in lodgepole pine) and silver fir beetle.

State and transition model

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Ecosystem states

1. Reference

State 1 submodel, plant communities

1.1. Mature Pacific Silver Fir Forest

1.2. Pioneering Herbaceous

1.3. Mid-Development

1.4. Late-Development

State 1
Reference

Community 1.1
Mature Pacific Silver Fir Forest

This phase has an overstory dominated by Pacific Silver Fir although western hemlock can be co-dominant, with numerous lower tree canopies of seral species including western hemlock, western redcedar, Douglas fir, noble fir, Engelmann spruce, western white pine, an understory of tall shrubs, and cool, moist adapted herbaceous species. The trees are large (average diameter at breast height is 45 inches) and mature (the average age is over 150 years). The understory includes salal, Pacific rhododendron, thinleaf huckleberry, common beargrass, mountain brome, vine maple, red alder, western swordfern, oval-leaf huckleberry, sweet-after death, red huckleberry, western fescue, Cascade barberry, common snowberry, broadleaf starflower.

Community 1.2
Pioneering Herbaceous

Immediately post-fire, windblown tree seeds establish, shrub and herbaceous plants resprout and pioneering herbaceous plants establish on mineral soil interspaces. This is a short duration community phase. Shrub Community. This plant community contains a high diversity of shrubs and herbaceous species including salal, Pacific rhododendron, thinleaf huckleberry, common beargrass, mountain brome, vine maple, red alder, western swordfern, oval-leaf huckleberry, sweet-after death, red huckleberry, western fescue, Cascade barberry, common snowberry, broadleaf starflower. Seedlings mature to saplings within twenty years.

Community 1.3
Mid-Development

This phase is dominated by a mix of Pacific Silver fir and seral tree species that are pole sized and are in either an open or closed canopy depending on the occurrence of mixed severity fire. If mixed severity fire occurs than a open canopy is created and maintained. The lower, secondary tree canopy layer is of Pacific Silver fir.

Community 1.4
Late-Development

This plant community is dominated by larger trees that is a mix of Pacific Silver fir and seral tree species in the overstory in either an open or closed canopy configuration depending on the occurrence of mixed severity fire. Fire would create and maintain an open canopy configuration. The lower tree canopy has Pacific Silver fir. Douglas fir can dominate this stand with mixed severity fire occurrence and adequate seedbank of Douglas fir.

Pathway 1.1A
Community 1.1 to 1.2

Rare, stand-replacement fire that kills significant number of mature trees and top-kills shrubs and herbaceous plants. This disturbance causes a return to the pioneering, herbaceous community with resprouting shrubs.

Pathway 1.1B
Community 1.1 to 1.4

Mixed severity fire returns the reference phase to the late development, open canopy phase which can allow Douglas fir a competitive advantage over Pacific Silver Fir.

Pathway 1.2A
Community 1.2 to 1.3

Saplings of seral tree species and Pacific Silver fir mature to pole-sized trees in either a closed canopy, if mixed severity fire does not occur or an open canopy if it does.

Pathway 1.3A
Community 1.3 to 1.1

With time, the mid development community will grow into the mature reference phase.

Pathway 1.3B
Community 1.3 to 1.4

Mixed severity fire can prefer Douglas fir, which can dominate community phase 1.4.

Pathway 1.4A
Community 1.4 to 1.1

With time, Pacific Silver fir in the lower tree canopy will dominate the overstory and transition the community phase to the reference phase.

Pathway 1.4B
Community 1.4 to 1.2

Stand replacement fire would return this forest to the pioneering herbaceous phase.

Additional community tables

Table 4. Community 1.1 plant community composition

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

Table 5. Community 1.2 plant community composition

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

Table 6. Community 1.3 plant community composition

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

Table 7. Community 1.4 plant community composition

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

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	10/05/2023
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:

Download reference sheet

Natural ResourcesConservation Service

Ecological site AX003X03F007

Glaciated Middle Cascades Cryic Udic Forest Group

Last updated: 1/28/2025 Accessed: 06/29/2026

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General information

MLRA notes

LRU notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Legacy ID

Natural Resources
Conservation Service

Last updated: 1/28/2025
Accessed: 06/29/2026