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Conservation Service

Ecological site R246XY004AK

Arctic Shrub Sandy Flood Plains

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 – 17150 – Alaska Arctic Floodplain
(Landfire 2009)

Ecological site concept

-Associated with the vegetated portions of low flood plains and incised drainageways and streams between drained lakes. Landforms include river bars, point bars, natural levees, and meander scroll. Flooding is frequent for brief durations of time.
-Soils formed in sandy and loamy alluvium.
-Soils do not pond. A seasonal water table occurs at very shallow to shallow depth and soils are considered poorly to moderately well drained.
-Frequently flooded soils have no permafrost, while rarely flooded soils have permafrost at shallow and moderate depths.
-The reference plant community is characterized as open low scrub or closed low scrub (Viereck et al. 1992) with feltleaf willow dominant on flood plains and tealeaf willow dominant on incised drainageways. Three plant communities were identified within the reference state related to flood regime and depth to a water table in the soil profile.

Associated sites

R246XY050AK	Arctic Sedge Loamy Tidal Marsh Occurs near the coast in estuaries and tidal marsh with halophytic vegetation.
R246XY002AK	Arctic Sedge Loamy Frozen Terraces Occurs on adjacent stream terraces without a mosaic of vegetation related to polygons. Associated with sedge-Dryas tundra.
R246XY005AK	Arctic Ice-Wedge Polygon Complex Occurs on adjacent stream terraces with a mosaic of vegetation related to both low- and high-center, ice-wedge polygons.
R246XY051AK	Arctic Shrub Loamy Frozen Tidal Marsh Occurs near the coast on backshores and tidal marsh with halophytic vegetation.
R246XY012AK	Arctic Dwarf Scrub Sandy Coastal Plain Occurs upslope on active and stabilized dunes on flood plains and stream terraces.
R246XY014AK	Arctic Sedge Peat Frozen Depressions Occurs on adjacent depressions. Associated with wet sedge meadow tundra.
R246XY009AK	Arctic High-Center Polygon Complex Occurs upslope on plains with a mosaic of vegetation associated with high-center, ice-wedge polygons. Dominant vegetation is tussock tundra.

Similar sites

R246XY008AK	Arctic Sedge Peat Frozen Drainageways Associated with low-gradient drainageways and swales that are not incised. Vegetation supports wet sedge meadow tundra.
R246XY012AK	Arctic Dwarf Scrub Sandy Coastal Plain Active dunes on flood plains have similar open low scrub vegetation with feltleaf willow. These dunes do not flood as frequently and support different reference vegetation.

R246XY008AK

Arctic Sedge Peat Frozen Drainageways

Associated with low-gradient drainageways and swales that are not incised. Vegetation supports wet sedge meadow tundra.

R246XY012AK

Arctic Dwarf Scrub Sandy Coastal Plain

Active dunes on flood plains have similar open low scrub vegetation with feltleaf willow. These dunes do not flood as frequently and support different reference vegetation.

Figure 1. Photo of floodplain, dunes, younger stream terraces, and older stream terraces adjacent to Judy Creek in the National Petroleum Reserve.

Figure 2. Photo of typical vegetation in a low-gradient drainageway in the National Petroleum Reserve.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Salix alaxensis
Herbaceous	(1) Equisetum arvense (2) Tanacetum bipinnatum

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Physiographic features

-Associated with flood plains and incised drainageways and/or streams between drained lakes. Flooding occurs frequently for brief durations of time. Landforms on flood plains include river bars, point bars, and meander scroll. Drainageways and streams between drained lakes are often highly incised from massive flood events. These incised waterbodies commonly have a beaded pattern. Landforms on incised drainageways include the adjacent natural levee.
-Elevation occurs between 10 and 330 feet.
-Slopes are nearly level. Given the low relief, aspect is not relevant for this ecological site concept.
-Soils do not pond. For community 1.1 and 1.2, the water table occurs at shallow depth early in the growing season but drops out of the soil profile later in the year. For community 1.3, the water table remains at very shallow depth throughout much of the growing season.
-Associated with negligible runoff to adjacent, ecological sites.

Figure 3. Photo of a recently drained lake and incised drainageway in the National Petroleum Reserve.

Table 2. Representative physiographic features

Landforms	(1) River valley > Flood plain (2) Alluvial plain > Drainageway (3) Alluvial plain > Stream (4) Alluvial plain > Levee (5) River valley > Point bar (6) River valley > Meander scroll (7) River valley > Bar
Runoff class	Negligible
Flooding duration	Brief (2 to 7 days)
Flooding frequency	Rare to frequent
Ponding frequency	None
Elevation	10 – 330 ft
Slope	2%
Water table depth	20 in
Aspect	Aspect is not a significant factor

Table 3. Representative physiographic features (actual ranges)

Runoff class	Not specified
Flooding duration	Not specified
Flooding frequency	Not specified
Ponding frequency	Not specified
Elevation	820 ft
Slope	4%
Water table depth	Not specified

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

Bar

Line

Figure 4. Monthly precipitation range

Characteristic range

Actual range

Bar

Line

Figure 5. Monthly minimum temperature range

Characteristic range

Actual range

Bar

Line

Figure 6. Monthly maximum temperature range

Bar

Line

Figure 7. Monthly average minimum and maximum temperature

Figure 8. Annual precipitation pattern

Figure 9. 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

This ecological site is classified as a riverine wetland under the Hydrogeomorphic (HGM) classification system (Smith et al. 1995). In the associated flood plains, overbank flow from the channel and subsurface hydraulic connections between the stream and adjacent wetlands are the main sources of water (Smith et al. 1995). Flood plain depressions commonly occur as a mosaic with this ecological site and are represented by the Arctic Sedge Peat Frozen Depressions (R246XY014AK) ecological site.

Depth to the water table may decrease following summer storm events or spring snowmelt and increase during extended dry periods.

Wetland description

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

Soil features

- Soils formed in alluvium. On some flood plains, sandy eolian deposits are also an important parent material.
- Rock fragments do not typically occur on the soil surface.
- Soils that flood more frequently have exposed mineral soils that lack an organic cap. As flooding decreases, organic material can increase to several inches or more thick. The surface mineral horizon textures are sandy loam and loamy fine sand.
- Soils are very deep. Soils that flood frequently have no root restrictions, while rarely flooded soils have permafrost at shallow and moderate depths (16 to 33 inches).
- In the National Petroleum Reserve, rock fragments did not occur in the soil subsurface. On rare occasion elsewhere, rock fragments range between 35 and 55 percent of the soil profile by volume.
- The pH of the soil profile ranges from slightly acidic to neutral.
- Soils are typically somewhat poorly or moderately well drained.

This Arctic Shrub Sandy Flood Plains ecological site is correlated to four soil components: Bodfish, Tuluga, E46-Arctic sedge-herbaceous-loamy frozen flood plains,
and E46-Arctic scrub-gravelly low flood plains. These soils are classified as Entisols and Gelisols. The great groups for Entisols are Udipsamments, Gelorthents, and Gelaquents, while the great group for Gelisols is Aquorthels.

In the National Petroleum Reserve, the Aquorthels were commonly observed on levees of incised streams and similar rarely flooded positions that support Salix pulchra scrubland (communities 1.1), while Udipsamments and Gelorthents occur on flood plain that support Salix alaxensis scrubland (communities 1.1 and 1.2). The Gelaquents support wet herbaceous communities (community 1.3).

Figure 10. Photo of a Bodfish soil (Udipsamments) on a flood plain in the National Petroleum Reserve-Beaufort Coastal Plain soil survey.

Figure 11. Photo of a Tuluga soil (Gelaquents) on a flood plain in the National Petroleum Reserve-Beaufort Coastal Plain soil survey.

Table 5. Representative soil features

Parent material	(1) Alluvium (2) Eolian deposits
Surface texture	(1) Sandy loam (2) Loamy fine sand
Family particle size	(1) Sandy (2) Sandy-skeletal (3) Coarse-loamy
Drainage class	Somewhat poorly drained to moderately well drained
Permeability class	Moderately rapid to rapid
Depth to restrictive layer	16 – 60 in
Soil depth	60 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	1.1 – 4.7 in
Calcium carbonate equivalent (10-40in)	Not specified
Clay content (0-20in)	4 – 6%
Electrical conductivity (10-40in)	1 mmhos/cm
Sodium adsorption ratio (10-40in)	1
Soil reaction (1:1 water) (10-40in)	6.1 – 7.2
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	Poorly drained to moderately well drained
Permeability class	Moderately rapid to very rapid
Depth to restrictive layer	Not specified
Soil depth	Not specified
Surface fragment cover <=3"	10%
Surface fragment cover >3"	10%
Available water capacity (0-40in)	Not specified
Calcium carbonate equivalent (10-40in)	Not specified
Clay content (0-20in)	Not specified
Electrical conductivity (10-40in)	Not specified
Sodium adsorption ratio (10-40in)	3
Soil reaction (1:1 water) (10-40in)	5.8 – 8.4
Subsurface fragment volume <=3" (0-60in)	55%
Subsurface fragment volume >3" (0-60in)	35%

Ecological dynamics

The flood plains and stream terraces of rivers in the Arctic Coastal Plain MLRA have a mosaic of vegetation with multiple ecological sites largely based on differences in flood regime and landform position.

One ecological site is associated with flood plain depressions related to oxbow lakes and other meanders (R246XY014AK) that typically support wet graminoid herbaceous vegetation. This Arctic Shrub Sandy Flood Plains ecological site occurs on nearly level surfaces that are frequently and rarely flooded. Dunes are common on larger rivers (R246XY012AK) and support dwarf scrub and low willow scrub. Stream terraces no longer flood. Younger stream terraces lack mosaics of vegetation related to ice-wedge polygon (R246XY002AK) and support sedge-Dryas tundra (Viereck et al. 1992). Older stream terraces have well developed ice-wedge polygons (R246XY005AK) with a unique mosaic of vegetation related to ice-wedge microtopography. The transition from bare alluvium on flood plains to polygons on stream terraces can take 1500-3000 years (Jorgenson et al. 1998).

Flood Plain Succession

For this arctic shrub loamy flood plain ecological site, bare mineral soil is common directly adjacent to the active channel. Colonizing this bare alluvium are two pioneering plant communities largely composed of sparse shrubs, grasses, and/or forbs (community 1.2 and 1.3). Community 1.2 has moist soils, while community 1.3 has comparatively wetter soils. For this ecological site, these plant communities have the most frequent and longest duration flooding. As flooding becomes less severe, willow shrub cover increases substantially (community 1.1). The reference plant community has open to closed low scrub vegetation (Viereck et al. 1992) with feltleaf willow dominant on flood plains and tealeaf willow dominant on incised drainageways.

Field work indicates incised drainageways primarily support community 1.3 and 1.1. The incised drainageway have very minimal to no bare alluvium. The flat portions adjacent to these waterbodies support community 1.3. The natural levees of the drainageways support community 1.1. Larger rivers with point bars and meander scroll support all three plant communities. Low-gradient drainageways support wet sedge marshes dominated by water sedge, tall cottongrass, and other obligate wetland plants species and is described by the Arctic Sedge Peat Frozen Drainageway ecological site concept.

State and transition model

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Ecosystem states

1. Reference State

State 1 submodel, plant communities

1.1. feltleaf willow / field horsetail - Lake Huron tansy

1.2. feltleaf willow

1.3. water sedge - pendantgrass

1.1a	-	more frequent and longer duration flooding associated with moist soils
1.1b	-	more frequent and longer duration flooding associated with wet soils
1.2a	-	less frequent and shorter duration flooding
1.3a	-	less frequent and shorter duration flooding

State 1
Reference State

Figure 12. Point bar on a large river in the National Petroleum Reserve. This ecological site is associated with high-energy streams that commonly have point bars.

Three plant communities occur within the reference state and the vegetation differs in large part due to flooding and depth of a water table in the soil profile.

Dominant plant species

feltleaf willow (Salix alaxensis), shrub
tealeaf willow (Salix pulchra), shrub
field horsetail (Equisetum arvense), other herbaceous

Community 1.1
feltleaf willow / field horsetail - Lake Huron tansy

Figure 13. Typical vegetation associated with community 1.1.

Figure 14. Willow thickets on a large river flood plain.

Community 1.1 has the least frequent and shortest duration flooding associated with this ecological site. This community is characterized as open to closed scrub (Viereck et al. 1992). Commonly observed species include feltleaf willow, tealeaf willow, Richardson's willow, field horsetail, Lake Huron tansy, arctic aster, and a variety of unknown weedy mosses. The binomial name of these and other less common associated plants can be found in the dominant plant species table below. Medium shrubs (between 3 and 10 feet in height) and to a lesser extent medium forbs (between 4 and 24 inches in height) and moss are the dominant vegetative strata.

Dominant plant species

feltleaf willow (Salix alaxensis), shrub
Richardson's willow (Salix richardsonii), shrub
tealeaf willow (Salix pulchra), shrub
field horsetail (Equisetum arvense), other herbaceous
Lake Huron tansy (Tanacetum bipinnatum ssp. bipinnatum), other herbaceous
arctic aster (Eurybia sibirica), other herbaceous
Moss (Moss), other herbaceous
boreal locoweed (Oxytropis borealis), other herbaceous
marsh grass of Parnassus (Parnassia palustris), other herbaceous
dwarf fireweed (Chamerion latifolium), other herbaceous
arctic lupine (Lupinus arcticus), other herbaceous

Community 1.2
feltleaf willow

Figure 15. Typical vegetation associated with community 1.3.

Community 1.2 is a pioneering flood plain community. This plant community is characterized as open low scrub (Viereck et al. 1992) but vegetation is sparse and ground cover is primarily bare alluvium. The most common and dominant plant is feltleaf willow. The binomial name of these and other less common associated plants can be found in the below dominant plant species table.

Dominant plant species

feltleaf willow (Salix alaxensis), shrub
Pumpelly's brome (Bromus inermis ssp. pumpellianus var. pumpellianus), grass
red fescue (Festuca rubra), grass
Alaska rush (Juncus arcticus ssp. alaskanus), grass
arctic bluegrass (Poa arctica ssp. lanata), grass
Lake Huron tansy (Tanacetum bipinnatum ssp. bipinnatum), other herbaceous
arctic aster (Eurybia sibirica), other herbaceous
dwarf fireweed (Chamerion latifolium), other herbaceous
field horsetail (Equisetum arvense), other herbaceous
Pacific alpine wormwood (Artemisia glomerata), other herbaceous
common yarrow (Achillea millefolium), other herbaceous

Community 1.3
water sedge - pendantgrass

Figure 16. Typical vegetation associated with community 1.3.

Community 1.3 floods frequently and has wet soils throughout the year. This community is characterized as fresh grass marsh (Viereck et al. 1992) with the dominant plants being water sedge and pendantgrass. The binomial name of these and other less common associated plants can be found in the dominant plant species table below.

Dominant plant species

water sedge (Carex aquatilis), grass
pendantgrass (Arctophila fulva), grass
Chamisso's cottongrass (Eriophorum chamissonis), grass
tall cottongrass (Eriophorum angustifolium), grass
arctic bluegrass (Poa arctica), grass
drepanocladus moss (Drepanocladus), other herbaceous
floating marsh marigold (Caltha natans), other herbaceous
arctic cinclidium moss (Cinclidium arcticum), other herbaceous

Pathway 1.1a
Community 1.1 to 1.2

feltleaf willow / field horsetail - Lake Huron tansy

feltleaf willow

More frequent and longer duration flooding. Flooding removes vegetation. This is the community pathway associated with moist soils on flood plain.

Pathway 1.1b
Community 1.1 to 1.3

feltleaf willow / field horsetail - Lake Huron tansy

water sedge - pendantgrass

More frequent and longer duration flooding. Flooding removes vegetation. This is the community pathway associated with wet soils on flood plain.

Pathway 1.2a
Community 1.2 to 1.1

feltleaf willow

feltleaf willow / field horsetail - Lake Huron tansy

Less frequent and shorter duration flooding. Willow continues to establish and grow and becomes dominant in the overstory.

Pathway 1.3a
Community 1.3 to 1.1

water sedge - pendantgrass

feltleaf willow / field horsetail - Lake Huron tansy

Less frequent and shorter duration flooding. Willow continues to establish and grow and becomes dominant in the overstory.

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

Tier 2 sampling plots used to develop the grazing state. Plot numbers as recorded in NASIS with associated community phase.

Community 1.1
2021AK185011, 2021AK185013, 2021AK185027, 2021AK185117, 2021AK185234, 2021AK185429, 2021AK185684

Community 1.2
2021AK185014, 2021AK185204, 2021AK185216

Community 1.3
2021AK185019, 2023AK185426, 2023AK185804

References

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.
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..

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.

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	05/22/2025
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

State 1 submodel, plant communities

1.1. feltleaf willow / field horsetail - Lake Huron tansy

1.2. feltleaf willow

1.3. water sedge - pendantgrass

1.1a	-	more frequent and longer duration flooding associated with moist soils
1.1b	-	more frequent and longer duration flooding associated with wet soils
1.2a	-	less frequent and shorter duration flooding
1.3a	-	less frequent and shorter duration flooding

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Natural ResourcesConservation Service

Ecological site R246XY004AK

Arctic Shrub Sandy Flood Plains

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

General information

MLRA notes

LRU notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Figure 1. Photo of floodplain, dunes, younger stream terraces, and older stream terraces adjacent to Judy Creek in the National Petroleum Reserve.

Figure 2. Photo of typical vegetation in a low-gradient drainageway in the National Petroleum Reserve.

Table 1. Dominant plant species

Ecosystem states

State 1 submodel, plant communities

Natural Resources
Conservation Service

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