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Ecological site R246XY014AK

Arctic Sedge Peat Frozen Depressions

Last updated: 5/22/2025
Accessed: 10/19/2025

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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): 246X–Arctic Coastal Plain

The Arctic Coastal Plain MLRA (MLRA 246X) consists of level to gently rolling plains along the coast of the Arctic Ocean. This area makes up 22,235 square miles. It is mostly remote, sparsely populated wildland. Numerous rivers, mostly originating in the Brooks Range, drain to the Arctic Ocean. The largest being the Canning, Colville, Jago, Kongakut, Kuk, Utukok, and Sagavanirktok Rivers. Narrow, nearly level flood plains and stream terraces parallel the many rivers. The area is dotted by thousands of small and medium-size lakes and interconnecting wetlands. Many of the lakes are elongated thaw lakes, which are consistently oriented from north to northwest. Small sand dunes occur along the coastline, rivers, and plains. Elevation ranges from sea level to about 655 feet.

Permanent settlements include Point Lay, Wainwright, Utqiagvik, Nuigsut, and Kaktovik. The Prudhoe Bay oil fields and the northern terminus of the Trans-Alaska Pipeline are in the central part of the MLRA. The Dalton Highway and the Trans-Alaska Pipeline bisect the area west of the Sagavanirktok River, terminating at Deadhorse. The community of Deadhorse provides much of the industrial infrastructure and many of the residential facilities associated with the oil fields and pipeline. Parts of the National Petroleum Reserve and Arctic National Wildlife Refuge are in this MLRA.

Geology and Soils

This area was never glaciated (NRCS 2022). The bedrock geology consists of Cretaceous and Tertiary stratified sedimentary rocks and uplifted continental deposits. The modern landscape is mantled with Quaternary deposits of alluvial, eolian, or glaciofluvial origin.

This MLRA is in the zone of continuous permafrost. Areas without permafrost in the soil profile are limited to tidal flats, large sand dunes, and soils directly adjacent to large rivers. Thick layers of permafrost occur in both fine textured and coarse textured deposits across the area. Depth to the base of the permafrost layer ranges between 500 and 2000 feet. Periglacial features, such as beaded drainages, patterned ground (ice-wedge polygons, thaw gullies, pingos, and frost boils) occur throughout the MLRA.

The dominant soil order in this MLRA is Gelisols. Most have an aquic soil moisture regime. The Gelisols are shallow or moderately deep to permafrost, occur on fine and coarse textured sediments, and are generally poorly drained or very poorly drained. Common Gelisol suborders are Histels, Orthels, and Turbels. The Histels have a glacic layer and/or thick accumulations of surface organic material and are associated with ice-wedge troughs of polygons, vegetated lake basins, swales, and low-gradient drainageways. The Orthels and Turbels have comparably thinner surface organic material and occur on flood plains, stream terraces, plains, and the centers of low- and high-center polygons. Miscellaneous (non-soil) areas make up about 20 percent of this MLRA. The most common are water, riverwash, and beaches.

Climate
The average annual precipitation in this area is 4 to 8 inches. Brief, cool summers and long, very cold winters characterize the arctic climate. The average annual snowfall is about 20 to 40 inches. The average annual temperature ranges from 11 to 14 degrees Fahrenheit. The average freeze-free period is between 43 and 76 days but freezing temperatures can occur in any month.

Vegetation
The wet soils prevalent across this MLRA support extensive swaths of tussock tundra and wet sedge meadow tundra (Viereck et al. 1992). The drier sites and low uplands support dwarf scrub dominated by various ericaceous shrubs and dwarf willow. On shallow, rocky soils and exposed sites, lichens and scattered herbs dominate the ground layer. Flood plains support a mixture of low willow scrub and scattered herbs. Fire is not common in this MLRA (AICC 2022).

LRU notes

The bulk of the MLRA is associated with the Circumpolar Arctic Vegetation Mapping (CAVM) subzone D with a small portion of the Northern most lands falling into subzone C (CAVM 2022). Arctic subzone D is associated with vegetation that have herbaceous and dwarf shrub communities that are commonly 4 to 15 inches tall, while subzone C has an herbaceous and dwarf shrub layer that are typically less than 6 inches tall (CAVM 2022). At this time, these differences in community structure are recognized with large differences in annual production expected; but unique ecological sites for each CAVM bioclimate subzone were not developed.

Classification relationships

Landfire BPS – 17050 – Alaska Arctic Sedge Freshwater Marsh
(Landfire 2009)

Ecological site concept

-Associated with freshwater depression across the Arctic Coastal Plains MLRA. Two alternate states were developed for recently drained lakes and depressions with string bogs.
-Soils formed in organic material and eolian deposits and/or alluvium.
-Reference state soils pond frequently, have a water table at the soil surface throughout the growing season, and are considered very poorly drained. Soils on elevated ridges in string bogs and in recently drained lakebeds do not pond, have a water table at shallow depth, and are considered poorly drained.
-Reference state soils are considered very deep but typically have permafrost at shallow to moderate depth. Permafrost does not occur in recently drained lakes or in vegetated areas adjacent to open water.
-The reference plant community is wet sedge meadow tundra (Viereck et al. 1992) with the dominant plant being water sedge, tall cottongrass, and various circumneutral moss.

Associated sites

R246XY002AK	Arctic Sedge Loamy Frozen Terraces Occurs on stream terraces with sedge-willow tundra.
R246XY004AK	Arctic Shrub Sandy Flood Plains Occurs on flood plains that support open and closed willow thickets.
R246XY005AK	Arctic Ice-Wedge Polygon Complex Occurs on adjacent stream terraces and depressions with prominent ice-wedge polygons. This ecological site complex also represents older drained lakebeds.
R246XY009AK	Arctic High-Center Polygon Complex Occurs upslope on plains with tussock tundra and high-center polygons.
R246XY012AK	Arctic Dwarf Scrub Sandy Coastal Plain Occurs upslope on inland dunes with dwarf scrub vegetation.

Similar sites

R246XY005AK	Arctic Ice-Wedge Polygon Complex Ecological site complex 005 models the soil and vegetation associated with ice-wedge polygons. While both ecological sites share similar plant communities, degradation of ice-wedges cause unique state transitions and disturbance pathways.
R246XY008AK	Arctic Sedge Peat Frozen Drainageways Ecological site 008 has similar reference state vegetation but does not have alternate states related to lake drainage and string bogs.
R246XY050AK	Arctic Sedge Loamy Tidal Marsh Occurs in tidal marsh and estuaries with halophytic wet sedge communities.

R246XY005AK

Arctic Ice-Wedge Polygon Complex

Ecological site complex 005 models the soil and vegetation associated with ice-wedge polygons. While both ecological sites share similar plant communities, degradation of ice-wedges cause unique state transitions and disturbance pathways.

R246XY008AK

Arctic Sedge Peat Frozen Drainageways

Ecological site 008 has similar reference state vegetation but does not have alternate states related to lake drainage and string bogs.

R246XY050AK

Arctic Sedge Loamy Tidal Marsh

Occurs in tidal marsh and estuaries with halophytic wet sedge communities.

Figure 1. A relict lakebed with ice-wedge polygons and associated with ecological site complex 005.

Figure 2. A low-gradient drainageways associated with ecological site 008.

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	(1) Carex aquatilis (2) Eriophorum angustifolium

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Physiographic features

-Associated with depressions on floodplains, depressions on stream terraces, and drained relict lakebeds that commonly have string bogs.
-Occurs on nearly level slopes. Given the low relief, aspect is not relevant for this ecological site concept.
-Elevation occurs between 10 and 330 feet.
-Soils flood occasionally for long durations. Relict lakebeds commonly have drainageway inlets and outlets, which are thought to occasionally flood the lake basin.

Reference State:
-Soils pond frequently for very long durations. A water table occurs at the soil surface throughout the growing season.

String Bog State:
-String bogs have two microtopographic positions being the raised string and the flat saturated soils between termed the flark. In the National Petroleum Reserve, strings were 3 to 6 feet wide, raised up to 3 feet, and 300 or more feet long.
-The flark ponds frequently for very long durations of time. A water table occurs at the soil surface throughout the growing season. Flark and reference state vegetation are very similar.
-Ponding varies with the height of the string. The largest string no longer flood or pond. A water table occurs at very shallow depth throughout the growing season.

Recent Drained Lake State:
-This state is associated with recently drained lakes with abundant exposed mineral soils. Pioneering plants invade the exposed soils.
-Soils do not pond. A water table occurs at very shallow to shallow depth throughout the growing season. Water table depth depends on lakebed microtopography with slight rises having comparably drier soils compared to nearly level surfaces.

Figure 3. A breached lake on the Arctic Coastal Plain. An encroaching drainageway caused thermal erosion of ice and thawing of soils, which breached the closed lake system.

Figure 4. String bog in a relict lakebed are common in the National Petroleum Reserve.

Table 2. Representative physiographic features

Landforms	(1) River valley > Depression (2) River valley > Flood plain (3) River valley > Stream terrace (4) Coastal plain > Lakebed (relict) (5) Coastal plain > String bog
Runoff class	Negligible
Flooding duration	Long (7 to 30 days)
Flooding frequency	Occasional
Ponding duration	Very long (more than 30 days)
Ponding frequency	Frequent
Elevation	10 – 330 ft
Slope	Not specified
Ponding depth	2 – 8 in
Water table depth	Not specified
Aspect	Aspect is not a significant factor

Table 3. Representative physiographic features (actual ranges)

Runoff class	Not specified
Flooding duration	Long (7 to 30 days)
Flooding frequency	None to occasional
Ponding duration	Very long (more than 30 days)
Ponding frequency	None to frequent
Elevation	10 – 820 ft
Slope	4%
Ponding depth	12 in
Water table depth	6 in

Climatic features

Very short, cool summers and long, very cold winters characterize the arctic climate associated with this ecological site. Given its far North latitude, this Arctic Coastal Plains MLRA experiences long-periods of continuous light in the summer (85 days in Utqiagvik) and continuous darkness in the winter (65 days in Utqiagvik). Mean annual temperature for the Arctic Coastal Plains MLRA typically ranges from 11 to 14 degrees Fahrenheit. The warmest months span June through August with mean normal temperatures ranging from 40 to 47 degrees Fahrenheit (PRISM 2008). The coldest months span December through March with mean normal temperatures ranging from -19 to -9 degrees Fahrenheit (PRISM 2008). This MLRA is arid with mean annual precipitation ranging from 4 to 8 inches. Approximately half of the annual precipitation occurs during the months of July through September. The average annual snowfall ranges from 20 to 40 inches (USDA 2022). The ground is consistently covered with snow from October through May March.

Table 4. Representative climatic features

Frost-free period (characteristic range)	10-28 days
Freeze-free period (characteristic range)	43-76 days
Precipitation total (characteristic range)	4-8 in
Frost-free period (actual range)	3-48 days
Freeze-free period (actual range)	23-94 days
Precipitation total (actual range)	3-9 in
Frost-free period (average)	17 days
Freeze-free period (average)	61 days
Precipitation total (average)	6 in

Characteristic range

Actual range

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Figure 5. Monthly precipitation range

Characteristic range

Actual range

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Figure 6. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 7. Monthly maximum temperature range

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Figure 8. Monthly average minimum and maximum temperature

Figure 9. Annual precipitation pattern

Figure 10. Annual average temperature pattern

Climate stations used

(1) BARROW POST ROGERS AP [USW00027502], Barrow, AK
(2) KUPARUK [USC00505136], Prudhoe Bay, AK
(3) PRUDHOE BAY [USC00507780], Prudhoe Bay, AK

Influencing water features

Depressional wetlands occur in topographic depressions. Dominant water sources are precipitation, ground water discharge, and both interflow and overland flow from adjacent uplands.

Wetland description

This ecological site is classified as a depressional wetland under the Hydrogeomorphic (HGM) classification system (Smith et al. 1995; USDA-NRCS 2008).

Soil features

-Soils formed in organic material and eolian deposits and/or alluvium that are often cryoturbated.
-Rock fragments do not occur on the soil surface or in the soil profile.
-The surface organic cap is highly variable and changes with state and microtopography. The surface mineral horizon textures are silt loam and fine sandy loam.
-The pH of the soil profile ranges from very strongly acidic to slightly alkaline.
- While soils are considered very deep, permafrost is a restriction that typically occurs at shallow and moderate depth (15 to 22 inches). Near open bodies of water and in recently drained lakes, soils have no permafrost in the soil profile.

Reference State:
-Relict lakebeds commonly have mineral soils capped with 20 or more inches of peat and mucky peat.
-Soils are considered very poorly drained.

String Bog State:
-Relict lakebeds commonly have mineral soils capped with 20 or more inches of peat and mucky peat.
-The raised strings are considered poorly drained while the adjacent flarks are considered very poorly drained.

Recent Drained Lake State:
-Recently drained lakes have exposed mineral and/or mineral soils capped with up to two inches of peat.
-Soils are considered poorly drained.

This Arctic Peat Frozen Depressions ecological site is correlated to four soil components: Inigok (strings), Poleakoon, Tuluga (depressions), and E46-Arctic wet meadow-organic depressions. Tuluga (depressions) occurs in recently drained lakes and flood plain and classifies as an Entisol in the great group Gelaquents; Poleakoon occurs in stream terrace depressions, relict lakebeds, and string bogs and classifies as a Gelisol in the great group Historthels; Inigok (strings) occurs in string bogs and classifies as a Gelisol in the great group Histoturbel; E46-Arctic wet meadow-organic depressions occurs near open bodies of water and classifies as a Histosol in the great group Cryofibrists.

Figure 11. Photo of a Poleakoon soil that was mapped in relict lakebeds in the National Petroleum Reserve-Beaufort Coastal Plain soil survey.

Figure 12. Photo of a Tuluga (depressions) soil mapped in a recently drained lakebed in the National Petroleum Reserve-Beaufort Coastal Plain soil survey.

Figure 13. Photo of a Tuluga (depressions) soil mapped in a flood plain depression in the National Petroleum Reserve-Beaufort Coastal Plain soil survey.

Table 5. Representative soil features

Parent material	(1) Organic material (2) Eolian deposits (3) Alluvium
Surface texture	(1) Peat (2) Fine sandy loam (3) Silt loam
Family particle size	(1) Coarse-loamy (2) Sandy
Drainage class	Very poorly drained
Permeability class	Moderately rapid
Depth to restrictive layer	15 – 22 in
Soil depth	60 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	9.7 – 16.5 in
Calcium carbonate equivalent (10-40in)	Not specified
Clay content (0-20in)	5%
Electrical conductivity (10-40in)	1 mmhos/cm
Sodium adsorption ratio (10-40in)	1
Soil reaction (1:1 water) (10-40in)	5.2 – 7.8
Subsurface fragment volume <=3" (0-60in)	Not specified
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	Moderate to rapid
Depth to restrictive layer	15 in
Soil depth	Not specified
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	1.9 – 16.5 in
Calcium carbonate equivalent (10-40in)	1%
Clay content (0-20in)	Not specified
Electrical conductivity (10-40in)	2 mmhos/cm
Sodium adsorption ratio (10-40in)	3
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

Drained Lake State

While this ecological site concept covers many types of freshwater depressions, a unique state was developed for drained lakes. Across the Arctic Coastal Plain MLRA, lakes are a dominant landform. On the eolian plains in the National Petroleum Reserve, these lakes are believed to have an origin dating back to the last Ice Age (Jorgenson and Shur 2007). In this MLRA, there is a mixture of water filled lake basin and relict lakebeds. At some point in the past, water filled lakes were breached and drained. This occurs when streams, drainageways, and flood plain approach lake basins and thermal erosion of ice and thaw of permafrost create exit pathways for water. Lakes can be partially or catastrophically drained.

Lakes that are catastrophically drained have a mixture of bare soil and pioneering vegetation (community 3.1 and 3.2). These two plant communities relate to lakebed microtopography. Plant community 3.1 occurs on nearly level surfaces, while plant community 3.2 occurs on slight rises. In the National Petroleum Reserve - Beaufort Coastal Plain soil survey, no permafrost was found in the soil profile for either of these plant communities. As organic material increases on the soil surface, permafrost aggradation occurs within the soil profile. This permafrost perches the water table and soils become substantially wetter. This marks the shift to the wet sedge meadow tundra associated with the reference state.

In the National Petroleum Reserve, lake basins follow a chronosequence with 5 distinct stages related to genesis and microtopography of ice-wedge polygons (Jorgenson and Shur 2007). The first stage lacks microtopography related to polygons; the second stage has disjunct low rims of low-center polygons; the third stage has low-density, low-centered polygons; the fourth stage has high density, low-center polygons; and the fifth stage has mixed high- and low-center polygons. The first two stages in this chronosequence relate to this Arctic Sedge Peat Frozen Depressions ecological site. Analysis of ice-wedge formation on the Colville River floodplain indicate this chronosequence can take 1500–3000 years (Jorgenson et al. 1998).

Due to this extended timescale and differences in response to disturbance, drained lakebeds were divided into two ecological site concepts. Younger relict lakebeds without abundant ice-wedge polygons belong to this Arctic Sedge Peat Frozen Depressions ecological site. Older relict lakebeds with abundant ice-wedge polygons belong to the Arctic Ice-Wedge Polygon Complex.

String Bog State

String bogs are a type of patterned ground with slightly elevated strings and adjacent flats called flark. The strings form perpendicular to the direction of drainage. In the National Petroleum Reserve, string bogs were commonly observed in lake basin without abundant ice-wedge polygons (chronosequence stages 1 and 2). The most elevated strings commonly support Dryas-sedge tundra and the flark support wet sedge meadow tundra (Viereck et al. 1992). String bogs are also known as appa moors and strangmoor.

State and transition model

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Ecosystem states

1. Reference State

2. String Bog State

3. Recent Drained Lake State

T1	-	Soil creep results in the formation of string bogs.
T2	-	catastrophic lake drainage leads to improved soil drainage
T3	-	perched water table increases ponding frequency and duration

State 1 submodel, plant communities

1.1. water sedge / meesia moss - limprichtia moss

1.2. water sedge - pendantgrass

1.1a	-	soils ponded more frequently and for longer durations of time
1.2a	-	soils ponded less frequently and for shorter durations of time

State 2 submodel, plant communities

2.1. water sedge - tall cottongrass

2.2. entireleaf mountain-avens - tealeaf willow / water sedge / Sphagnum moss - Tomentypnum moss

2.1a	-	soil creep creates strings in the string bog

State 3 submodel, plant communities

3.1. water sedge / Sphagnum moss

3.2. entireleaf mountain-avens - polar willow / dwarf scouringrush

State 1
Reference State

Figure 14. A relict lakebed without microtopography related to ice-wedge polygons.

This state covers all fresh water depressions in this MLRA that do not have a mosaic of vegetation related to low- and high-center ice-wedge polygons. Two plant community were identified within the reference state related to ponding depth and duration. Community 1.1 has a soil profile with permafrost, while community 1.2 has a soil profile without permafrost.

Dominant plant species

water sedge (Carex aquatilis), grass
tall cottongrass (Eriophorum angustifolium), grass

Community 1.1
water sedge / meesia moss - limprichtia moss

Figure 15. Typical vegetation associated with community 1.1.

Community 1.1 is characterized as wet sedge meadow tundra (Viereck et al. 1992) with the dominant plants being water sedge, tall cottongrass, and various circumneutral moss. The binomial name of these and other less common associated plants can be found in the below dominant plant species table. Medium graminoids (between 4 and 24 inches) and moss are the vegetative strata that characterize this plant community. The peaty soils are typically covered with several inches of ponded water.

Dominant plant species

tealeaf willow (Salix pulchra), shrub
Richardson's willow (Salix richardsonii), shrub
water sedge (Carex aquatilis), grass
tall cottongrass (Eriophorum angustifolium), grass
meesia moss (Meesia triquetra), other herbaceous
limprichtia moss (Limprichtia revolvens), other herbaceous
turgid aulacomnium moss (Aulacomnium turgidum), other herbaceous
aulacomnium moss (Aulacomnium palustre), other herbaceous
arctic cinclidium moss (Cinclidium arcticum), other herbaceous
cloudberry (Rubus chamaemorus), other herbaceous
sphagnum (Sphagnum), other herbaceous
tomentypnum moss (Tomentypnum nitens), other herbaceous

Community 1.2
water sedge - pendantgrass

Figure 16. Typical vegetation associated with community 1.2.

This community is characterized as fresh grass marsh (Viereck et al. 1992) with the dominant plants being water sedge and pendantgrass. The soil surface is covered with deep ponded water. The binomial name of these and other provisionally associated plants can be found in the below dominant plant species table. Medium graminoids (between 4 and 24 inches) and moss are the vegetative strata that characterize this plant community. The peaty soils are typically covered with several inches of ponded water.

Dominant plant species

water sedge (Carex aquatilis), grass
pendantgrass (Arctophila fulva), grass
Moss (Moss), other herbaceous
common mare's-tail (Hippuris vulgaris), other herbaceous
buckbean (Menyanthes trifoliata), other herbaceous
tufted loosestrife (Lysimachia thyrsiflora), other herbaceous
water horsetail (Equisetum fluviatile), other herbaceous

Pathway 1.1a
Community 1.1 to 1.2

water sedge / meesia moss - limprichtia moss

water sedge - pendantgrass

The water table rises resulting in soils being ponded more frequently and for longer durations of time. This could result from flooding or short term changes to annual precipitation in the area.

Pathway 1.2a
Community 1.2 to 1.1

water sedge - pendantgrass

water sedge / meesia moss - limprichtia moss

The water table lowers resulting in soils being ponded less frequently and for shorter durations of time. This could result from infilling of depressions or short term changes to annual precipitation in the area.

State 2
String Bog State

Figure 17. Satellite image of string bogs in a breached lake adjacent to Judy Creek on the Arctic Coastal Plain.

Figure 18. Aerial image of a string bog in the same breached lake.

This alternate state covers depressions with string bogs. Two plant communities were identified. Community 2.1 occurs on nearly level surfaces termed flarks, while community 2.2 occurs on the elevated ridge termed strings. In the National Petroleum Reserve, strings were 3 to 6 feet wide, raised up to 3 feet, and 300 or more feet long.

Dominant plant species

entireleaf mountain-avens (Dryas integrifolia), shrub
water sedge (Carex aquatilis), grass
Bigelow's sedge (Carex bigelowii), grass
sphagnum (Sphagnum), other herbaceous

Community 2.1
water sedge - tall cottongrass

Figure 19. Typical vegetation associated with community 2.1.

Community 2.1 is characterized as wet sedge meadow tundra (Viereck et al. 1992) with the dominant plants being water sedge and tall cottongrass. The binomial name of these and other less common associated plants can be found in the below dominant plant species table. Medium graminoids (between 4 and 24 inches in height) and moss characterize this plant community. The peaty soils are typically covered with several inches of ponded water.

Dominant plant species

water sedge (Carex aquatilis), grass
tall cottongrass (Eriophorum angustifolium), grass
rock sedge (Carex saxatilis), grass
round sedge (Carex rotundata), grass
sphagnum (Sphagnum), other herbaceous
tomentypnum moss (Tomentypnum nitens), other herbaceous
yellow marsh saxifrage (Saxifraga hirculus), other herbaceous
sudetic lousewort (Pedicularis sudetica), other herbaceous

Community 2.2
entireleaf mountain-avens - tealeaf willow / water sedge / Sphagnum moss - Tomentypnum moss

Figure 20. Typical vegetation associated with community 2.2.

Figure 21. The string of a string bog.

Community 2.2 is characterized as Dryas-sedge tundra (Viereck et al. 1992) that is highly diverse. Dominant plants are entireleaf mountain-avens, netleaf willow, water sedge, Sphagnum, and various circumneutral moss. The binomial name of these and other less common associated plants can be found in the below dominant plant species table. Medium graminoids (between 4 and 24 inches in height), moss, and dwarf scrub (less than 8 inches in height) characterize this plant community.

Dominant plant species

entireleaf mountain-avens (Dryas integrifolia), shrub
tealeaf willow (Salix pulchra), shrub
netleaf willow (Salix reticulata), shrub
dwarf birch (Betula nana), shrub
white arctic mountain heather (Cassiope tetragona), shrub
marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
water sedge (Carex aquatilis), grass
Bigelow's sedge (Carex bigelowii), grass
sphagnum (Sphagnum), other herbaceous
tomentypnum moss (Tomentypnum nitens), other herbaceous
dicranum moss (Dicranum), other herbaceous
splendid feather moss (Hylocomium splendens), other herbaceous

Pathway 2.1a
Community 2.1 to 2.2

water sedge - tall cottongrass

entireleaf mountain-avens - tealeaf willow / water sedge / Sphagnum moss - Tomentypnum moss

Strings form perpendicular to the direction of drainage and result from the process of soils creep.

State 3
Recent Drained Lake State

Figure 22. A recent and catastrophically breached lake on the Arctic Coastal Plain MLRA. This lake has a mixture of bare ground and pioneering vegetation.

This alternate state covers lakes that are catastrophically drained. Two plant communities were identified within this state related to lakebed microtopography. Community 3.1 occurs on nearly level surfaces while community 3.2 occurs on slight rises. Both communities have very deep soils without restrictions like permafrost. Community 3.1 has a water table at very shallow depth, while community 3.2 has a water table at shallow depth.

Dominant plant species

entireleaf mountain-avens (Dryas integrifolia), shrub
water sedge (Carex aquatilis), grass
dwarf scouringrush (Equisetum scirpoides), other herbaceous

Community 3.1
water sedge / Sphagnum moss

Figure 23. Typical vegetation associated with community 3.1

The community is characterized as wet sedge meadow tundra (Viereck et al. 1992) with the dominant plants being water sedge, Sphagnum, circumneutral moss, and field horsetail. The binomial name of these and other less common associated plants can be found in the below dominant plant species table. Medium graminoids (between 4 and 24 inches) and moss are the vegetative strata that characterize this plant community.

Dominant plant species

red fruit bearberry (Arctostaphylos rubra), shrub
entireleaf mountain-avens (Dryas integrifolia), shrub
water sedge (Carex aquatilis), grass
tall cottongrass (Eriophorum angustifolium), grass
Bigelow's sedge (Carex bigelowii), grass
sphagnum (Sphagnum), other herbaceous
Moss (Moss), other herbaceous
field horsetail (Equisetum arvense), other herbaceous
tofieldia (Tofieldia), other herbaceous

Community 3.2
entireleaf mountain-avens - polar willow / dwarf scouringrush

Figure 24. Typical vegetation associated with community 1.3.

The community is characterized as dwarf scrub (Viereck et al. 1992) with common plants being entireleaf mountain-avens, polar willow, netleaf willow, red fruit bearberry, dwarf scouringrush, and various circumneutral moss. The binomial name of these and other less common associated plants can be found in the below dominant plant species table. Dwarf shrubs (less than 8 inches in height), dwarf forbs (less than 4 inches in height), and moss characterize this plant community.

Dominant plant species

entireleaf mountain-avens (Dryas integrifolia), shrub
polar willow (Salix polaris), shrub
netleaf willow (Salix reticulata), shrub
red fruit bearberry (Arctostaphylos rubra), shrub
white arctic mountain heather (Cassiope tetragona), shrub
water sedge (Carex aquatilis), grass
Bigelow's sedge (Carex bigelowii), grass
northern singlespike sedge (Carex scirpoidea), grass
Krause's sedge (Carex krausei), grass
dwarf scouringrush (Equisetum scirpoides), other herbaceous
Moss (Moss), other herbaceous
(Flavocetraria cucullata), other herbaceous
(Flavocetraria nivalis), other herbaceous
northern asphodel (Tofieldia coccinea), other herbaceous
whiteworm lichen (Thamnolia vermicularis), other herbaceous

Transition T1
State 1 to 2

Reference State

String Bog State

Soil creep results in the formation of string bogs.

Transition T2
State 1 to 3

Reference State

Recent Drained Lake State

A stream, drainageway, or flood plain approaches the lake basin and thermal erosion of ice and thaw of permafrost create exit pathways for water. The lake is catastrophically drained. Bare soils is exposed, permafrost drops out of the soil profile, and soil drainage improves.

Transition T3
State 3 to 1

Recent Drained Lake State

Reference State

Relict lakebed is colonized by sedges and organic matter increases. Permafrost aggradations occurs within the soil profile and soils pond for longer durations of time. The vegetation shifts back to reference conditions.

Additional community tables

Interpretations

Animal community

Not available

Hydrological functions

Not available

Recreational uses

Not available

Wood products

Not available

Other information

Not available

Supporting information

Inventory data references

The vegetation modeled for this site has limited data coverage across the MLRA and is considered provisional. The associated model was largely developed from literature review, NRCS staff with working knowledge of the area, and sample plots from the National Petroleum Reserve – Beaufort Coastal Plain soil survey (AK760). Tier 2 sampling plots used to develop the reference and alternate states are below:

Community 1.1
2021AK185120, 2023AK185103, 2023AK185118, 2023AK185418, 2023AK185803, 2023AK185815

Community 1.2
2021AK185406

Community 2.1
2021AK185109, 2021AK185130, 2021AK185141, 2021AK185142, 2021AK185143, 2021AK185306, 2021AK185696, 2023AK185419, 2023AK185424, 2023AK185813

Community 2.2
2021AK185129, 2021AK185145, 2021AK185697, 2023AK185420, 2023AK185423, 2023AK185814

Community 3.1
2021AK185303, 2021AK185302

Community 3.2
2021AK185121

References

United States Department of Agriculture Staff. 2008. Hydrogeomorphic Wetland Classification System: An Overview and Modification to Better Meet the Needs of the Natural Resources Conservation Service.
Viereck, L.A., C. T. Dyrness, A. R. Batten, and K. J. Wenzlick. 1992. The Alaska vegetation classification. U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station General Technical Report PNW-GTR-286..
Smith, R.D., A.P. Ammann, C.C. Bartoldus, and M.M. Brinson. 1995. An approach for assessing wetland functions using hydrogeomorphic classification, reference wetlands, and functional indices.

Other references

Alaska Interagency Coordination Center (AICC). 2022. http://fire.ak.blm.gov/.

CAVM Team. 2003. Circumpolar Arctic Vegetation Map. (1:7,500,000 scale), Conservation of Arctic Flora and Fauna (CAFF) Map No. 1. U.S. Fish and Wildlife Service, Anchorage, Alaska.

Jorgenson M.T., Shur Y., and Walker H.J. 1998., Factors affecting evolution of a permafrost-dominated landscape on the Colville River Delta, northern Alaska, Collect. Nord., 57, 523–530.

Jorgenson M.T, and Shur Y. 2007. Evolution of lakes and basins in northern Alaska and discussion of the thaw lake cycle J. Geophys. Res., 112 (F2).

LANDFIRE. 2009. LANDFIRE National Vegetation Dynamics Models. USDA Forest Service and US Department of Interior. Washington, DC.

Macander, M.J. Well, A.F., McNown R.W., Christopherson T. 2020. Land cover mapping, north slope of the arctic national wildlife refuge, Alaska, 2019. ABR, Inc. – Environmental Research and Services, Fairbanks, AK.

Schoeneberger, P.J. and D.A. Wysocki. 2012. Geomorphic Description System. Natural Resources Conservation Service, 4.2 edition. National Soil Survey Center, Lincoln, NE.

PRISM Climate Group. 2018. Alaska – average monthly and annual precipitation and minimum, maximum, and mean temperature for the period 1981-2010. Oregon State University, Corvallis, Oregon. https://prism.oregonstate.edu/projects/alaska.php. (Accessed 4 September 2019).

Scenarios network for Alaska and arctic planning (SNAP). Historical Monthly Temperature – 1km, 1901-2009. http://ckan.snap.uaf.edu/dataset/. (Accessed 5 May 2021).

SNAP. Historical monthly and derived precipitation products downscaled from CRU TS data via the delta methods – 2km, 1901-2009. http://ckan.snap.uaf.edu/dataset/. (Accessed 5 May 2021).

Contributors

Blaine Spellman
Gabriel Benitez
Tyler Annetts

Approval

Blaine Spellman, 5/22/2025

Acknowledgments

Marji Patz provided quality control review of these provisional ecological sites.

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	05/26/2025
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:

Download reference sheet

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Ecosystem states

1. Reference State

2. String Bog State

3. Recent Drained Lake State

T1	-	Soil creep results in the formation of string bogs.
T2	-	catastrophic lake drainage leads to improved soil drainage
T3	-	perched water table increases ponding frequency and duration