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Ecological site VX226X00A115

Aleutian Organic Wet Depressions

Last updated: 6/14/2025
Accessed: 10/21/2025

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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): 226X–Aleutian Islands-Western Alaska Peninsula

MLRA 226X is the only MLRA in the Aleutian Alaska Region. It makes up about 5,190 square miles (13,450 square kilometers). The chain of islands includes west of Unimak Island to Attu Island, the Pribilof Islands, and the Sanak Islands. Characteristics and weather patterns of the far western end of the Alaska Peninsula is being included in this MLRA. It is bordered on the south by the Pacific Ocean and on the north by the Bering Sea (the Pribilof Islands are bordered on all sides by the Bering Sea). The coastline is complex, with many prominent headlands, sea cliffs, and narrow, steep-walled bays. Elevation ranges from sea level to more than 4,000 feet (1,220 meters) on many of the islands. Islands drain into the North Pacific and the Bering Sea by numerous short, steep-gradient rivers and streams. Lakes make up less than 2 percent of the area.

Geology
This MLRA includes more than 50 volcanoes, with an estimated 27 with activity since the 1950s. Volcanic rocks and unconsolidated deposits from the Quaternary and Tertiary period overlie a submarine ridge of Tertiary sedimentary rocks. Glacial ice once covered the eastern part of the area to approximately Umnak Island. West of Umnak, only the upper elevations were glaciated. Glaciers account for only 1.5 percent, occurring on the highest volcanoes. Volcanic activity has mantled most of the area with thick deposits of silty volcanic ash, sandy and gravelly cinders, and volcanic rubble. Lower elevations have areas of glacial influenced landforms. Recent coastal and fluvial deposits occur in scattered areas along the coast and on flood plains.

Water
Precipitation is adequate for crops generally. Permanent mountain streams feed most of the MLRA. The surface water generally is suitable for all uses. The ground water used in this MLRA is primarily from unconsolidated river valley sediments and bedrock aquifers. Iron is commonly high in the ground water, causing staining and precipitate in pipes. Wells are shallow with constant recharge by freshwater (rainfall and runoff); and are highly susceptible to contamination from runoff. The intrusion of seawater can be a problem along the coast.

Soils
The dominant soil orders in this MLRA are Andisols and Histosols. Miscellaneous areas (cinder land, rock outcrop, water, riverwash, and beaches) make up about 45 percent of this MLRA. The main soils are: Cryofibrists are poorly drained or very poorly drained and formed in thick deposits of organic material, along the margins of streams and lakeshores.
Tsammana series, Andic Dystrocryepts, Aquandic Dystrocryepts and Vitrandic Dystrocryepts are coarse marine sediments underlain by volcanic deposits. Zolotoi series and other Haplocryands are shallow to deep, well drained to excessively drained, and formed in moderately thick or thick deposits of silty to sandy volcanic ash and coarse sandy to gravelly cinders over basalt bedrock. Polovina series and other Vitricryands are shallow to deep, well drained to excessively drained, and formed in moderately thick or thick deposits of silty to sandy volcanic ash and coarse sandy to gravelly cinders over basalt bedrock.

Biological Resources
Higher elevation vegetation consists of a mosaic of dwarf shrub scrub and lower elevations are wet and dry grasslands. Peatland vegetation consists of low ericaceous shrub scrub. No naturally occurring forests occur on the islands. Aleutian shield fern, Steller sea lion, and the Aleutian Canada goose are currently listed as threatened or endangered. The area is an important winter habitat and nesting habitat for waterfowl and a variety of other birds. Some of the eastern islands support small herds of caribou.

Land Use
Commercial fishing is the primary enterprise, with fur seal harvesting for pelts and meat, Reindeer herding, and small cattle herds. Subsistence hunting, fishing, and gathering are critical for local residents. The major resource concerns are water erosion and mass wasting of soils. Overgrazing by reindeer has impacted vegetation and introduction of rats, dogs, cats, and foxes has severely impacted the nesting bird populations.

LRU notes

MLRA 226X, although very size-limited, contains a very complex and dynamic of weather patterns driven by the Pacific air currents on the southern exposure of the islands, and the Bering Sea to the north. The mixing or colliding of these two systems, creates very dramatic and intense storm systems that batter the islands. Weather variables from the Pacific to the Bering Sea, extent from west to east, as well as the extreme elevational gradient moving from sea level to Alpine life zone lends to a community diversity that is difficult to describe across an MLRA extent. Land Resource Units (LRUs) will need to be developed for this MLRA, as more extensive soils survey mapping is completed.

Classification relationships

Alaska-Aleutian province of the Pacific Mountain System.

USFS Description of Ecoregions of the United States
100 Polar Domain
120 Tundra Division
126 Bering Tundra (Southern) Province
M120 Tundra Division - Mountain Province
M127 Aleutian Oceanic Meadow--Heath Province
(USFS, 1994)

United States National Vegetation Classification
C04. Polar & High Montane Scrub, Grassland & Barrens Class
S12. Temperate to Polar Alpine & Tundra Vegetation Subclass
F031. Polar Tundra & Barrens Formation
D044. Arctic Tundra & Barrens Division
(USNVC, 2019)

LandFire BpS Model/Description Version: Nov. 2024
16610 - Alaskan Pacific - Aleutian Fen and Wet Meadow

Ecological site concept

- Soils are Histosols with thick accumulations of organic matter and associated with depressions and fens.
- Soils are deep to very deep to bedrock or very deep without bedrock in the upper 60 inches.
- These are very poorly drained soils with a water table at or near the soil surface throughout the growing season.
- Site is a sedge/rush and forb dominated community but may have a Wet Low Shrub community around the drier edges of the depressions.

Associated sites

VX226X00A113	Aleutian Shrub Meadow Ashy Slopes The Tephra Dip Slopes ecological site, which includes basalt soils, is commonly associated with the Ashy Organic Slopes ecological site. Tephra slopes trend to shorter, more scrub dominated communities with a more tundra/heath community appearance, where the organic ashy trend to a slightly taller, low shrub scrub and meadow cover type.

VX226X00A113

Aleutian Shrub Meadow Ashy Slopes

The Tephra Dip Slopes ecological site, which includes basalt soils, is commonly associated with the Ashy Organic Slopes ecological site. Tephra slopes trend to shorter, more scrub dominated communities with a more tundra/heath community appearance, where the organic ashy trend to a slightly taller, low shrub scrub and meadow cover type.

Similar sites

VX226X00A104	Aleutian Riparian and Lake Shore Complex The organic depressions are reactive to the water table and ponding more than flooding, supporting an herbaceous, sedge dominated community.

VX226X00A104

Aleutian Riparian and Lake Shore Complex

The organic depressions are reactive to the water table and ponding more than flooding, supporting an herbaceous, sedge dominated community.

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	(1) Carex aquatilis var. dives (2) Eriophorum russeolum

Legacy ID

R226XY115AK

Download full description

Physiographic features

- Landforms are depressions on plains, terraces, dip slopes, and foot slopes.
- Elevation ranges from 0 to 2000 feet elevation.
- Slopes range from 0 to 8 percent, however, steeper higher elevation channels are included.
- Soils do not flood but ponding is common. A water table occurs at the soil surface throughout the growing season.
- Few long-term water bodies occur.

Table 2. Representative physiographic features

Landforms	(1) Island > Depression (2) Plain (3) Terrace (4) Dip slope
Runoff class	Low to high
Flooding frequency	None
Ponding duration	Very long (more than 30 days)
Ponding frequency	None to frequent
Elevation	20 – 2,000 ft
Slope	8%
Ponding depth	1 – 12 in
Water table depth	10 in
Aspect	W, NW, N, NE, E, SE, S, SW

Table 3. Representative physiographic features (actual ranges)

Runoff class	Not specified
Flooding frequency	Not specified
Ponding duration	Not specified
Ponding frequency	Not specified
Elevation	20 – 7,040 ft
Slope	25%
Ponding depth	18 in
Water table depth	Not specified

Climatic features

The climate is similar to that on the arctic coastal plain, except Islands are impacted by the tides, air movement, and storms influenced by the Pacific Ocean and Bering Sea, and really no inland influence. Winters are less severe than those on the coastal plain, with temperature ranges of 18 to 27 degrees F (10 to 15C), as compared to a 54 degrees F (30C) range on the coastal plain. The climate is characterized by fog and rain, with the amount of precipitation varying little from month to month. Annual precipitation varies from 21 in (530 mm) to more than 78 in (2,000 mm) across all islands. The higher elevations average 46 to 58 inches per year, with smaller islands receiving less precipitation than larger islands. Winds are often severe on the islands. Pacific Ocean water moving northward through the straits between the islands produces complex mixing with Bering Sea water, including upwelling. The Pribilof Islands in the Bering Sea are the southern limit of the arctic ice pack in winter (USDA-NRCS 2022). Weather information below is captured by climate stations located at Dutch Harbor and Cold Bay. The location of these stations represents only a small segment of the dynamic climate across this chain of islands.

Table 4. Representative climatic features

Frost-free period (characteristic range)	78-92 days
Freeze-free period (characteristic range)	122-136 days
Precipitation total (characteristic range)	46-58 in
Frost-free period (actual range)	75-95 days
Freeze-free period (actual range)	119-139 days
Precipitation total (actual range)	43-61 in
Frost-free period (average)	85 days
Freeze-free period (average)	129 days
Precipitation total (average)	52 in

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

Bar

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

Bar

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) DUTCH HARBOR [USC00502587], Unalaska, AK
(2) COLD BAY AP [USW00025624], Cold Bay, AK

Influencing water features

Connectivity to ground water and overland flow, subsurface seep, and precipitation is key to this ecological site.

Wetland description

A variety of wetland types are included in this concept, but at this time, documented classifications are not researched.

Soil features

- Soils formed in organic material over volcanic ash, drift or lacustrine deposits. The mineral soils are capped with up to 28 inches of peat and mucky peat.
- Soils are deep to very deep to bedrock or very deep without bedrock in the upper 60 inches.
- Soil permeability is moderately rapid.
- Soil drainage is very poorly drained.
- Surface fragments do not occur.
- Subsurface rock fragments will range from 0 to 40 percent.
The soils correlate to Histosols in the Cryohemist great group. The soil components corelated to this ecological site include the Maritime scrub/sedge-organic depressions and Maritime wet meadow-organic depressions.

Table 5. Representative soil features

Parent material	(1) Organic material – scoria (2) Volcanic ash (3) Drift
Surface texture	(1) Peat (2) Mucky peat
Drainage class	Very poorly drained
Permeability class	Moderately rapid
Depth to restrictive layer	60 – 72 in
Soil depth	60 – 72 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	9.9 – 17.6 in
Soil reaction (1:1 water) (10-40in)	5 – 6.1
Subsurface fragment volume <=3" (0-60in)	40%
Subsurface fragment volume >3" (0-60in)	Not specified

Table 6. Representative soil features (actual values)

Drainage class	Very poorly drained to poorly drained
Permeability class	Not specified
Depth to restrictive layer	Not specified
Soil depth	Not specified
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	Not specified
Soil reaction (1:1 water) (10-40in)	Not specified
Subsurface fragment volume <=3" (0-60in)	Not specified
Subsurface fragment volume >3" (0-60in)	Not specified

Ecological dynamics

The vegetation within the Aleutian Organic Depression ecological site is driven by the hydrologic dynamics. The response of vegetation to the ponding and fluctuating groundwater or sub-surface seepage creates a gradient of vegetation from the wettest center to the driest outer reaches of the depressional landform.

Vegetation pattern has the characteristic sedge-grass community. Low shrubs and willows will persist on the outer reaches of the sedge community as the soils begin to dry out. Sphagnum, as well as a variety of mosses and other bryophytes are a strong component of the undercover of these communities.

This system will maintain stability for a long duration of time, if the hydrologic function is not interrupted or disturbed. Resilience to the natural disturbance regimes support communities that can sustain fluctuating water levels and minor animal impacts.

However, with increasing human pressures on the system, changes in storm patterns and intensities, receding glaciers, increased temperatures and changes in seasonal patterns is having impacts on the type and vigor of vegetative cover. Changes in vegetation and soil cover is impacting soil stability, increasing erosion, and altering hydrology. This further degrades the hydrologic function and ecological site stability.

Specific research to further this discussion has not been completed to any extent across the Island chains and further ecologic dynamic data is needed within the Aleutian Islands.

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

Ecosystem states

1. Reference State

2. Disturbed State

T1A	-	Catastrophic event, major disturbance
R2a	-	Time following end of disturbance

State 1 submodel, plant communities

1.1. Sedge-dominated Meadow

1.2. Mixed Sedge and Forb Meadow

CP1a	-	Build-up of peat, organic matter, sediment, frost heave or changes in hydrology.
CP1b	-	Time with ground cover disturbance, hydrologic recovery

State 2 submodel, plant communities

2.1. Low Shrub/Sphagnum

State 1
Reference State

The Reference State encompasses the hydrogeochemistry driven plant community that creates a mosaic of diverse communities, that transition from the wettest inner portions of the depressions to the drier outer edges of the depression. The organic layer is mainly a sedge peat or of a more decomposed mix of organic material. Cover includes sphagnum, sedges, rushes, cottongrasses, wood rushes, and other wet-obligate plants.

Dominant plant species

willow (Salix), shrub
Sitka alder (Alnus viridis ssp. sinuata), shrub
bog blueberry (Vaccinium uliginosum), shrub
sedge (Carex), grass
cottongrass (Eriophorum), grass
woodrush (Luzula), grass
bulrush (Trichophorum), grass
darkthroat shootingstar (Dodecatheon pulchellum), other herbaceous
fringed grass of Parnassus (Parnassia fimbriata), other herbaceous
buckbean (Menyanthes trifoliata), other herbaceous

Community 1.1
Sedge-dominated Meadow

Vegetation is responding to the hydrologic levels and chemistry of the water table and elevation changes within this ecological site. The Sedge-dominated Meadow community is primarily sedges, rushes, and grasses comprising over 25 percent of the cover with forbs scattered through the community. The open water or ponded areas will support a few subaqueous species. The community will vary depending on the chemistry of the site, with few shrubs occurring outside of potentially diamond leaf willow. But in less chemistry driven, slightly drier areas, dwarf shrubs will occur (less than 25 percent cover). The dominant herbacous species are Sitka sedge (Carex aquatilis var. dives), (Carex saxatilis), red cottongrass (Eriophorum russeolum), darkthroat shootingstar (Dodecatheon pulchellum), fringed grass of Parnissia (Parnassia fimbriata), buckbean (Menyanthes trifoliata) and purple marshlocks(Comarum palustre). Diamondleaf willow (Salix planifolia) is the only common shrub, other ericaceous shrubs will vary between fens and bogs. Sphagnum species comprise a significant portion of ground cover in the understory.

Dominant plant species

diamondleaf willow (Salix planifolia), shrub
dwarf birch (Betula nana), shrub
marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
cloudberry (Rubus chamaemorus), shrub
Sitka sedge (Carex aquatilis var. dives), grass
red cottongrass (Eriophorum russeolum), grass
rock sedge (Carex saxatilis), grass
tufted bulrush (Trichophorum cespitosum), grass
tall cottongrass (Eriophorum angustifolium), grass
white cottongrass (Eriophorum scheuchzeri), grass
grassyslope arctic sedge (Carex anthoxanthea), grass
Mertens' rush (Juncus mertensianus), grass
black alpine sedge (Carex nigricans), grass
manyflower sedge (Carex pluriflora), grass
northern green rush (Juncus alpinoarticulatus ssp. nodulosus), grass
three-hulled rush (Juncus triglumis), grass
bluejoint (Calamagrostis canadensis), grass
northern reedgrass (Calamagrostis stricta ssp. inexpansa), grass
darkthroat shootingstar (Dodecatheon pulchellum), other herbaceous
fringed grass of Parnassus (Parnassia fimbriata), other herbaceous
buckbean (Menyanthes trifoliata), other herbaceous
purple marshlocks (Comarum palustre), other herbaceous
deercabbage (Nephrophyllidium crista-galli), other herbaceous
sundew (Drosera), other herbaceous
yellow marsh saxifrage (Saxifraga hirculus), other herbaceous
Aleutian avens (Geum pentapetalum), other herbaceous
yellow marsh marigold (Caltha palustris), other herbaceous
sphagnum (Sphagnum), other herbaceous

Community 1.2
Mixed Sedge and Forb Meadow

As peat or other sources of organic matter or sediment builds in this ecologoical site, or water levels are reduced, sedges will shift and more grasses, and forbs will become prevelant in the community. Shrubs will still remain as a minor component but are more common in the overstory. The dominant herbacous species are still Sitka sedge (Carex aquatilis var. dives), rock sedge (Carex saxatilis), and red cottongrass (Eriophorum russeolum). However, bluejoint (Calamagrostis canadensis), northern reedgrass (Calamagrostis stricta spp. inexpansa), Bering's tufted hairgrass (Deschampsia beringensis) will increase in composition. Darkthroat shootingstar (Dodecatheon pulchellum) and buckbean (Menyanthes trifoliata) are still present, and other forbs such as buttercups (Ranunculaceae spp.), horestails (Equisetum spp.), monkeyflower (mimulus spp.), Canadian burnet (Sanguisorba canadensis), felwort (Swertia perennis), and scentbottle (Platanthera dilatata) increase in the community. Other common herbaceous species are tall cottongrass (Eriophorum angustifolium), white cottongrass (Eriophorum scheuchzeri), grassyslope arctic sedge (Carex anthoxanthea), Merten's rush (Juncus mertensianus), and three-hulled rush (Juncus triglumis).

Dominant plant species

diamondleaf willow (Salix planifolia), shrub
cloudberry (Rubus chamaemorus), shrub
netleaf willow (Salix reticulata), shrub
Sitka sedge (Carex aquatilis var. dives), grass
rock sedge (Carex saxatilis), grass
red cottongrass (Eriophorum russeolum), grass
Bering's tufted hairgrass (Deschampsia beringensis), grass
bluejoint (Calamagrostis canadensis), grass
northern reedgrass (Calamagrostis stricta ssp. inexpansa), grass
northern green rush (Juncus alpinoarticulatus ssp. nodulosus), grass
three-hulled rush (Juncus triglumis), grass
tall cottongrass (Eriophorum angustifolium), grass
white cottongrass (Eriophorum scheuchzeri), grass
darkthroat shootingstar (Dodecatheon pulchellum), other herbaceous
fringed grass of Parnassus (Parnassia fimbriata), other herbaceous
buckbean (Menyanthes trifoliata), other herbaceous
buttercup (Ranunculus), other herbaceous
monkeyflower (Mimulus), other herbaceous
saxifrage (Saxifraga), other herbaceous
yellow marsh marigold (Caltha palustris), other herbaceous
Siberian springbeauty (Claytonia sibirica), other herbaceous
Canadian burnet (Sanguisorba canadensis), other herbaceous
sphagnum (Sphagnum), other herbaceous

Pathway CP1a
Community 1.1 to 1.2

Increasing peat, shifts in the hydrology, increased sedimentation over time, or stints of increased or decreased frost heave will affect the stability and health of the overall community. This change in vigor will start to shift the community to a mixed sedge and forb community.

Pathway CP1b
Community 1.2 to 1.1

Potential fire, ground surface disturbance or alteration in the hydrologic cycle back to normal conditions will shift this community.

State 2
Disturbed State

Frost action within the soils, human degradation, catastrophic events such as avalanches, landslides, glacial events, or other extreme events will alter the hydrologic function, soil stability, and shift the vegetation within the variable communities. There is currently a minimal data set on wide-extent responses to disturbances. Data presented is an inference of LandFire Biophysical models.

Dominant plant species

tealeaf willow (Salix pulchra), shrub
dwarf birch (Betula nana), shrub
bog blueberry (Vaccinium uliginosum), shrub
cottongrass (Eriophorum), grass
sedge (Carex), grass
sphagnum (Sphagnum), other herbaceous
water horsetail (Equisetum fluviatile), other herbaceous

Community 2.1
Low Shrub/Sphagnum

The Low Shrub/Sphagnum Plant Community 2.1 is early- and mid-seral community that will occur following a catastrophic natural event or disturbances. In newly deposited wet or saturated soils sedges and sphagnum will be the first to colonize. Following further events or settling, dry or high zones uplifted above the water influence will maintain the low shrub and scrub cover with the herbaceous species dwindling. Lichen and mosses may be abundant in the understory or as a primary soil cover. Common low shrub/scrub species are tealeaf willow (Salix pulchra) and Grayleaf willow (Salix glauca) with dwarf birch (Betula nana), black crowberry (Empetrum nigrum), and marsh labrador tea (Ledum palustre ssp. decumbens). Cottongrass (Eriophorum spp.), Sedges (Carex spp.) Sphagnum species, and water horsetail (Equisetum fluviatile) are the herbaceous colonizers that will initially settle in the community. Other primary and secondary forbs will establish depending on the water connectivity and position of the community.

Dominant plant species

tealeaf willow (Salix pulchra), shrub
grayleaf willow (Salix glauca), shrub
black crowberry (Empetrum nigrum), shrub
marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
dwarf birch (Betula nana), shrub
Sitka sedge (Carex aquatilis var. dives), grass
tall cottongrass (Eriophorum angustifolium), grass
sphagnum (Sphagnum), other herbaceous
water horsetail (Equisetum fluviatile), other herbaceous
splendid feather moss (Hylocomium splendens), other herbaceous
Schreber's big red stem moss (Pleurozium schreberi), other herbaceous

Transition T1A
State 1 to 2

Catastrophic event, human disturbance, and frost heave.

Restoration pathway R2a
State 2 to 1

Time for successional recover following removal of the disturbance, or completion of catastrophic event impact. Time is a vague term that is undefined.

Additional community tables

Interpretations

Animal community

Sedges provide high value reindeer forage during winter when covered by snow. Wide leaf polargrass maintains its forage value well into the winter and provides excellent early spring forage.
Excellent winter range because of succulent green sedge shoots and roots covered by snow that may be available to foraging reindeer. Areas that are ponded during spring are poor for spring grazing. During periods of heavy rain or high tide the site may be severely flooded.
The area is an important winter habitat for emperor geese and other waterfowl. It provides nesting habitat for a variety of birds, including green-winged teal, rock sandpiper, whiskered auklet, rock ptarmigan, song sparrow, rosy finch, and winter wren. The introduction of dogs, cats, and foxes has severely reduced the population of ground-nesting birds. Rats, coming from ships, also are a danger to these birds. Some of the eastern islands support small herds of caribou. Overgrazing by reindeer is a local concern. Control of animal numbers and proper herd management help to prevent overgrazing and allow natural restoration of depleted range.

Recreational uses

Tourism and wildland recreation are becoming increasingly important. Subsistence hunting and gathering provide food and a variety of other resources to local residents and are a major component of the local economy.

Wood products

None - limited to small willows or dwarf shrubs.

Supporting information

Inventory data references

Very limited data is available and resides more on the coastal zone than the higher volcanics. Information used to build this ecological site was obtained from existing land cover and vegetation maps, literature review, and vegetative summaries from partnering agencies.

References

Hansford T. Shacklette, L. W. Durrell, James A. Erdman, John R. Keith, William M. Klein, Hildur Krog, Herman Persson, H. Skuja, and William A. Weber. 1969. Vegetation of Amchitka Island, Aleutian Islands, Alaska. Geological Survey Professional Paper 648. United States Geological Survey, United States Government Printing Office, Washington : 1969.

Other references

Landfire National Vegetation Dynamics Models; USGS; http://www.LANDFIRE.gov/index.php, 2009 (Date accessed)

USDA PLANTS Database; http://plants.usda.gov, 2021

USNVC [United States National Vegetation Classification]. 2019. United States National Vegetation Classification Database, V2.03. Federal Geographic Data Committee, Vegetation Subcommittee, Washington DC. USNVC: http://usnvc.org/

AMUNDSEN, C.C. 1972. Amchitka Bioenvironmental Program: Plant ecology of Amchitka Island, Final Report. Batelle, Columbus Laboratories, under AEC Prime, Contract No. AT(26-l)-171. 27 p.

AMUNDSEN, c.c. and E.E.C. CLEBSCH. 1971. Dynamics of the terrestrial ecosystem vegetation of Amchitka Island, Alaska. Bioscience 21:619-623.

AMUNDSEN, C.C. 1977. Terrestrial plant ecology. Pages 203-226 in M.L. Merritt and R.G. Fuller, eds. The environment of Amchitka Island, Alaska. ERDA TID-26712.

Bailey, R.G. [in prep.] Description of the ecoregions of the United States. 2d ed. Misc. Publ. No. 1391 [rev.]. Washington, DC: U.S. Department of Agriculture, Forest Service. Bailey, Robert G.; Avers, Peter E.; King, Thomas; McNab, W. Henry, eds. 1994. Ecoregions and subregions of the United States (map). Washington, DC: U.S. Geological Survey. Scale 1: 7,500,000; colored. Accompanied by a supplementary table of map unit descriptions compiled and edited by McNab, W. Henry, and Bailey, Robert G. Prepared for the U.S. Department of Agriculture, Forest Service.

BANK, T.B. II. 1951. Botanical and ethnobotanical studies in the Aleutian Islands. I. Aleutian vegetation and Aleut culture. Mich. Acad. Sci., Arts, and Lett. 37:13-30 + 6 plates.

BYRD, G.V. 1984. Vascular vegetation of Buldir Island, Aleutian Islands, Alaska compared to another Aleutian Island. Arctic 37(1):37-48.

Fosberg, Francis Raymond. "Succession and condition of ecosystems." (1967).

Hultén, Eric (1937) Flora of the Aleutian Islands and westernmost Alaska Peninsula with notes on the flora of Commander islands. Stockholm, Thule. 397 pp. 2nd ed. 1960 (series: Flora et vegetation mundi, vol. 1) Weinheim, Cramer. 376 pp.

SHACKLETTE, H.T., L.W. ERDMAN-J.R. KEITH, W.M. KLEIN, H. KROG, H. PERSSON, H. SKUJA, and W.A. WEBER. 1969. Vegetation of Amchitka Island, Aleutian Islands, Alaska. U.S. Geol. Surv. Prof. Pap. 648. 66p.

Swanson, D.J., Lehner, D., Zimmerman, J., and Pauling, D. Range survey of Nunivak Island, Alaska, 1986.

TATEWAKI. M. 1963. Phytogeography of. the islands of the north Pacific Ocean. Pages 23-27 in J.L. Gressitt, ed. Pacific Basin Biogeography. lOth Pacific Science Congress. Bishop Museum Press, Honolulu.

TALBOT, S.S., S.L. TALBOT, and L.R. Walker. 2010. Post-eruption legacy effects and their implications for long-term recovery of the vegetation on Kasatochi Island, Alaska. Arctic, Antarctic, and Alpine Research, Vol. 42, No. 3, pp. 285-296

WALKER., H. 1945. Plants of the Aleutian Islands. Pages 63-;71 in Collins, H.B., Jr., A.H. Clark, and E.H. Walker, eds. The Aleutian Islands: Their people and natural history. Smithsonian Inst. War Background Studies 21, Publ. 3775.

Contributors

Marji Patz
Tyler Annetts

Approval

Blaine Spellman, 6/14/2025

Acknowledgments

Blaine Spellman, Ecological Site Data Quality Specialist and Phil Barber, Ecological Site Specialist within Alaska, for your review and guidance of the PES development. Matt Mayer for assisting with R Scripts on weather, as well as Nathan Roe for assistance with R scripts on site data summaries.

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	06/14/2025
Approved by	Blaine Spellman
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: