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Ecological site YX244X00A112

Arctic Shallow Tundra Mountain Slopes

Last updated: 5/28/2025
Accessed: 10/18/2025

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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): 244X–Northern Brooks Range Mountains

Major Land Resource Area (MLRA) 244X includes the steep, rugged, high mountains and narrow valleys on the northern side of the Brooks Range. This remote wildland is sparsely populated and is approximately 14,525 square miles (37,615 square kilometers). The transition to the Arctic climate is the break into MLRA 244X from the surrounding subartic MLRAs. Elevation ranges from about 1,969 feet (600 meters) to 8,570 feet (2,613 meters) at the summit of Mount Igikpak. The major rivers are the Kongakut, Aichilik, Jago, Canning, Ivishak, Ribdon, Atigun, Anaktuvuk, and Killik Rivers. They drain to the Colville River and Arctic Ocean.

Except for the highest peaks, the steep upper ridges, and some unglaciated valleys, glacial ice during the Early and Middle Pleistocene covered the MLRA. By the Late Pleistocene, only the highest valleys and mountains remained glaciated. Periglacial features (gelifluction lobes, polygons, and stripes) and fluvial deposits are common on terraces and gentle slopes. Glacial deposits overlay stratified sedimentary bedrock. This area is in the zone of continuous permafrost. Inclusions of volcanic and igneous rocks occur in the eastern part of the MLRA.

The Brooks Range is characterized by continental arctic climate. The average annual precipitation ranges from 7 to 40 inches (180 to 1,015 millimeters) with an average annual snowfall of 50 to 100 inches (125 to 255 centimeters). The average annual temperature ranges from 8 to 16 degrees Fahrenheit (-13 to -9 degrees C), with freezing temperatures possible any month of the year. Summer temperatures reach 90 to 100 degrees Fahrenheit (32 to 38 degrees Celsius), and winter temperatures drop as low as -75 degrees Fahrenheit (-60 degrees Celsius). The position of this MLRA above the Arctic Circle lends to several days of 24-hour sunlight in June and several sunless days in December.

Freshwater is very limited due to frozen or low flow through long winters. Most domestic use water is from private wells. Aquifers are highly susceptible to contamination from surface activities (septic systems, landfills, and leaking fuel storage tanks).

The dominant soil order in this MLRA is Gelisols. The main soils are Aquiturbels, Histoturbels, Molliturbels, and Haploturbels. These are shallow or moderately deep to permafrost, poorly- to very poorly- drained, and formed in colluvium, slope alluvium, and residuum. Fibristels are shallow or moderately deep to permafrost, very poorly drained, and formed in thick deposits of organic material; in depressions, drainageways, and basins. Miscellaneous areas make up about 75 percent of this MLRA primarily composed of rubble, chutes, rock outcrops, and small glaciers. Lakes make up less than two percent of the area

Low willow, ericaceous shrub scrub, and tussocks are most dominant at lower elevations, with wet sites supporting wet meadows and willow scrub. Dwarf scrub communities (black crowberry, ericaceous shrubs, Dryas, and dwarf willow) are prominent on mountain slopes and ridges with exposed areas dominated by lichens, forbs, sedges, and mosses. As elevation and exposure increase, vegetation disappears and is replaced by rubble, talus, and other miscellaneous areas. This elevational transition is highly variable but roughly occurs at 6,500 feet (Zou et al. 2023) where glaciers also commonly prevail.

Villages use this remote area primarily for subsistence. Mining and prospecting of mineral resources historically occurred. Current disturbance relates to the pipeline and construction of Dalton highway. This disturbance of the fragile permafrost-affected soils is of increasing concern.

LRU notes

No LRUs are developed for this Major Land Resource Area (MLRA). Soils that are within this area are maintained as arctic. Soils corresponding to boreal communities are correlated to the appropriate adjacent MLRA.

Classification relationships

The Brooks Range is the most northerly extension of the Rocky Mountains occurring within the Arctic Mountains province of the Rocky Mountain System.

Description of the Ecoregions of the United States (Bailey 1983)
100 Polar Domain
120 Tundra Division
M120 Tundra Division - Mountain Provinces
M121 Brooks Range Tundra--Polar Desert Province

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
M173. Feltleaf Willow - Eight-petal Mountain-avens - Tussock Cottongrass
Tundra Macrogroup
G896. Arctic Dwarf-shrub Tundra Group

LandFire BpS Model/Description Version: Nov. 2024
- 16850 North American Arctic Sparse Tundra
- 16870 North American Arctic Lichen Tundra

Ecological site concept

- This arctic ecological site occurs on the summits, shoulders, and backslopes of mountains. These mountains are not associated with limestone geology.
- Soils formed in silty eolian deposits and gravelly colluvium.
- Soils are moderately deep to very deep, controlled by bedrock (33 to 60+ inches). These gravelly soils lack permafrost.
- Soils do not flood or pond. These well drained soils do not have a growing season water table.
- Associated vegetation is sparse acidic tundra characterized by dwarf scrubs like eightpetal mountain-avens and crowberry and various lichen.

Associated sites

YX244X00A113	Arctic Tussock Tundra Mountain Slopes Occurs on adjacent slopes with wet soils, permafrost, and abundant tussock cover.

YX244X00A113

Arctic Tussock Tundra Mountain Slopes

Occurs on adjacent slopes with wet soils, permafrost, and abundant tussock cover.

Similar sites

YX244X00A103	Calcareous, Dry Arctic Mountain Slopes Slope appearances are similar. However, there is a shift in shrub cover from Labrador tea to rosebay, and a transition to a more forb-dominated community on less acidic soils. Calcareous soils support different mosses and lichens.

YX244X00A103

Calcareous, Dry Arctic Mountain Slopes

Slope appearances are similar. However, there is a shift in shrub cover from Labrador tea to rosebay, and a transition to a more forb-dominated community on less acidic soils. Calcareous soils support different mosses and lichens.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Dryas octopetala ssp. octopetala (2) Empetrum nigrum
Herbaceous	(1) Flavocetraria (2) Anthoxanthum monticola

Legacy ID

R244XY112AK

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Physiographic features

- Occurs on the summits, shoulders, and backslopes of rounded mountains.
- Elevation ranges from 1975 feet along the edge of the Arctic Foothills to 6,500 feet which provisionally marks the upper threshold of vegetation in this area.
- Slopes range from 15 to 60 percent and occur on all aspects.
- Soils do not pond or flood. During the growing season, a water table does not occur in the soil profile.

Table 2. Representative physiographic features

Slope shape up-down	(1) Convex
Slope shape across	(1) Linear
Hillslope profile	(1) Summit (2) Shoulder (3) Backslope
Landforms	(1) Mountains > Mountain slope
Runoff class	Medium to high
Flooding frequency	None
Ponding frequency	None
Elevation	1,975 – 6,500 ft
Slope	15 – 60%
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 frequency	Not specified
Elevation	1,975 – 8,570 ft
Slope	Not specified

Climatic features

Brief, cool summers and long, very cold winters characterize the continental arctic climate. The average annual precipitation throughout most of this area ranges from 15 to 40 inches (380 to 1,015 millimeters). The average annual snowfall is about 50 to 100 inches (125 to 255 centimeters). The average annual temperature ranges from about 8 to 16 degrees F (-13 to -9 degrees C). Freezing temperatures can occur in any month of the year. The Chandalar Shelf DOT climate station is the only station near this MLRA (Major Land Resource Area) and has incomplete data. The station is on the border of the MLRA and is not representative of the climate within MLRA 244X.

Table 4. Representative climatic features

Frost-free period (characteristic range)	20-60 days
Freeze-free period (characteristic range)	5-45 days
Precipitation total (characteristic range)	15-34 in
Frost-free period (actual range)
Freeze-free period (actual range)
Precipitation total (actual range)	7-40 in
Frost-free period (average)	40 days
Freeze-free period (average)
Precipitation total (average)

Characteristic range

Actual range

Bar

Line

Figure 1. Monthly precipitation range

Characteristic range

Actual range

Bar

Line

Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

Bar

Line

Figure 3. Monthly maximum temperature range

Bar

Line

Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) CHANDALAR SHELF DOT [USC00501497], Southerly North Slope Bo, AK

Soil features

- Soils formed in silty eolian deposits and gravelly colluvium.
- Rock fragments cover 5 to 35 percent of the soil surface.
- These mineral soils are capped with up to one inch of organic material. The surface mineral horizon is silt loam.
- Subsurface rock fragments range between 15 and 60 percent or more of the soil profile by volume.
- Soils are moderately deep to very deep, which is controlled by bedrock (33 to 60+ inches). Strongly contrasting textural stratification is a restriction that occurs at very shallow depth (1 to 6 inches inches).
- Soils are acidic (non-calcareous) with the pH of the soil profile ranging from very strongly acidic to slightly acidic.
- Soils are considered well drained with very rapid permeability.

Components correlated to this ecological site include the Arctic dwarf scrub-gravelly colluvial slopes. These soils are classified as Inceptisols in the great group Haplogelepts.

This Major Land Resource Area (MLRA) is remote and difficult to reach and has not had soil verification completed. The information was obtained using the STATSGO soils information, a class 5 soils product. When opportunity presents to collect data in this MLRA, this Provisional Ecological Site will be updated.

Table 5. Representative soil features

Parent material	(1) Organic material (2) Eolian deposits (3) Colluvium
Surface texture	(1) Silt loam
Family particle size	(1) Loamy-skeletal
Drainage class	Well drained
Permeability class	Very rapid
Depth to restrictive layer	1 – 6 in
Soil depth	33 – 60 in
Surface fragment cover <=3"	5 – 35%
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	4.6 – 6.7 in
Soil reaction (1:1 water) (0-10in)	4 – 5.7
Subsurface fragment volume <=3" (0-60in)	15 – 35%
Subsurface fragment volume >3" (0-60in)	15 – 60%

Table 6. Representative soil features (actual values)

Drainage class	Not specified
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) (0-10in)	4 – 8.4
Subsurface fragment volume <=3" (0-60in)	Not specified
Subsurface fragment volume >3" (0-60in)	Not specified

Ecological dynamics

The Arctic Shallow Tundra Mountain Slopes ecological site described a dwarf-shrub tundra. Total vegetative cover is 10 to 25 percent. Lichen cover is less than 25 percent across the ecological site. Frost scars, solifluction lobes and stripes are common. Scars and stripes have sparse vegetation primarily composed of lichens and pincushion plants.

This ecological site is stable in current conditions. The harsh winds, exposed positions and bedrock controlled soils, limit vegetative potential. These characteristics also provide resiliency to disturbance.

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

State 1 submodel, plant communities

1.1. Eightpetal mountain-avens - black crowberry / alpine sweetgrass / reindeer lichen - Flavocetraria lichen

1.2. Lichen Tundra

CP1.1A	-	Frost action

State 1
Reference State

The ecological site has plant communities representative of the native or natural conditions. Minimal impact from human influence is seen. Fire is rare, and generally not possible due to the lack of fuels. The acidic substrates of the mountain summits, shoulders and exposed side slopes of arctic Alaska mountains are sparsely populated and highly impacted by frost action. This ecological site has exposed to harsh environment and a mesic climate.

Dominant plant species

eightpetal mountain-avens (Dryas octopetala), shrub
black crowberry (Empetrum nigrum), shrub
alpine sweetgrass (Anthoxanthum monticola), grass
northern singlespike sedge (Carex scirpoidea), grass
Altai fescue (Festuca altaica), grass
alpine pussytoes (Antennaria alpina), other herbaceous
twinflower sandwort (Minuartia obtusiloba), other herbaceous
reindeer lichen (Cladina), other herbaceous

Community 1.1
Eightpetal mountain-avens - black crowberry / alpine sweetgrass / reindeer lichen - Flavocetraria lichen

The wind-swept harsh environment limits plant cover and vigor due to the lack of snow cover. Vascular plants are equally dominant with lichens. Lichens account for 25 percent or less of total cover. Vascular cover is between 10 and 25 percent ground cover. Various low and dwarf shrubs are present, including eightpetal mountain-avens (Dryas octopetala), black crowberry (Empetrum nigrum), bog blueberry (Vaccinium uliginosum), entireleaf mountain avens (Dryas integrifolia), alpine azalea (Loiseleuria procumbens), and skeletonleaf willow (Salix phlebophylla). Alpine pussytoes (Antennaria alpina), alpine sweetgrass (Anthoxanthum monticola ssp. alpina), twinflower starwort (Minuartia obtusiloba), northern singlespike sedge (Carex scirpoidea), shortstalk sedge (Carex podocarpa), smallawned sedge (Carex microchaeta), and altai fescue (Festuca altaica) are common herbaceous species within this community. Lichens include Cladina spp., Sphaerophorus globosus, Nephroma arcticum, Flavocetraria spp., and Alectoria ochroleuca.

Dominant plant species

eightpetal mountain-avens (Dryas octopetala), shrub
black crowberry (Empetrum nigrum), shrub
bog blueberry (Vaccinium uliginosum), shrub
alpine sweetgrass (Anthoxanthum monticola), grass
northern singlespike sedge (Carex scirpoidea), grass
Altai fescue (Festuca altaica), grass
reindeer lichen (Cladina), other herbaceous
(Flavocetraria cucullata), other herbaceous
twinflower sandwort (Minuartia obtusiloba), other herbaceous
alpine pussytoes (Antennaria alpina), other herbaceous

Figure 7. Annual production by plant type (representative values) or group (midpoint values)

Community 1.2
Lichen Tundra

Frost scars, extreme exposed faces, and areas with high frost action are uninhabitable by most vascular plants. In these locations, lichens dominate the community. Ground cover is still sparse with less than 25 percent vascular plant cover, but lichens provide added cover with greater than 25 percent. The dominant lichens include navel lichen (Umbilicaria spp.), world map lichen (Rhizocarpon geographicum), star reindeer lichen (Cladina stellaris), racomitrium moss (Racomitrium lanuginosum), snow cup moss (Flavocetraria spp.), and witch's hair lichen (Alectoria ochroleuca). The vascular plants that are common in the community are alpine azalea (Loiseleuria procumbens), dwarf birch (Betula nana), marsh labrador tea (Ledum palustre ssp. decumbens), black crowberry (empetrum nigrum), and bog blueberry (Vaccinium uliginosum).

Dominant plant species

alpine azalea (Loiseleuria procumbens), shrub
dwarf birch (Betula nana), shrub
marsh Labrador tea (Ledum palustre ssp. decumbens), shrub
navel lichen (Umbilicaria), other herbaceous
world map lichen (Rhizocarpon geographicum), other herbaceous
star reindeer lichen (Cladina stellaris), other herbaceous

Figure 8. Annual production by plant type (representative values) or group (midpoint values)

Pathway CP1.1A
Community 1.1 to 1.2

Frost action and soil sorting create a vegetative mosaic in the reference state. Once disrupted or vegetation is shifted, no known resolve has been documented.

Additional community tables

Table 7. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Shrub/Vine
1				–
	eightpetal mountain-avens	DROC	Dryas octopetala	–	–
	black crowberry	EMNI	Empetrum nigrum	–	–
	bog blueberry	VAUL	Vaccinium uliginosum	–	–
	entireleaf mountain-avens	DRIN4	Dryas integrifolia	–	–
	alpine azalea	LOPR	Loiseleuria procumbens	–	–
	skeletonleaf willow	SAPH	Salix phlebophylla	–	–
Forb
2				–
	alpine pussytoes	ANAL4	Antennaria alpina	–	–
	twinflower sandwort	MIOB2	Minuartia obtusiloba	–	–
	saxifrage	SAXIF	Saxifraga	–	–
Grass/Grasslike
3				–
	alpine sweetgrass	ANMO7	Anthoxanthum monticola	–	–
	northern singlespike sedge	CASC10	Carex scirpoidea	–	–
	shortstalk sedge	CAPO	Carex podocarpa	–	–
	smallawned sedge	CAMI4	Carex microchaeta	–	–
	Altai fescue	FEAL	Festuca altaica	–	–
Lichen
4				–
	reindeer lichen	CLADI3	Cladina	–	–
	cup lichen	CLADO3	Cladonia	–	–
	globe ball lichen	SPGL60	Sphaerophorus globosus	–	–
	arctic kidney lichen	NEAR60	Nephroma arcticum	–	–
		FLAVO3	Flavocetraria	–	–

Table 8. Community 1.2 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (lb/acre)	Foliar cover (%)
Lichen
1				–
	navel lichen	UMBIL2	Umbilicaria	–	–
	world map lichen	RHGE60	Rhizocarpon geographicum	–	–
	star reindeer lichen	CLST60	Cladina stellaris	–	–
	racomitrium moss	RALA70	Racomitrium lanuginosum	–	–
		FLAVO3	Flavocetraria	–	–
	witch's hair lichen	ALOC60	Alectoria ochroleuca	–	–
Shrub/Vine
2				–
	alpine azalea	LOPR	Loiseleuria procumbens	–	–
	dwarf birch	BENA	Betula nana	–	–
	marsh Labrador tea	LEPAD	Ledum palustre ssp. decumbens	–	–
	black crowberry	EMNI	Empetrum nigrum	–	–
	bog blueberry	VAUL	Vaccinium uliginosum	–	–

Interpretations

Animal community

The Brooks Range is an important big-game area in Alaska. Mammals common to the area include brown bear, black bear, wolf, caribou, and Dall sheep. The smaller mammals include marmot, red fox, Arctic fox, wolverine, ground squirrel, lemming, and pika. The Brooks Range is an important resting area for migrating waterfowl and songbirds during summer. Raptors prominent in many areas include golden eagles, marsh hawks, gyrfalcons, and snowy and other open country owls.

Hydrological functions

There is no active connection to ground water or channel hydraulics.

Recreational uses

This remote area is used for sport hunting and other kinds of wildland recreation. Visitors use air taxi, guiding, and outfitting companies operating out of the major Alaska communities.

Wood products

Wooded areas reside just outside of the Major Land Resource Area.

Other products

This remote area is primarily used for subsistence hunting, fishing, and gathering.

Supporting information

Inventory data references

No on-site data is available. 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

C. Racine, R. Jandt, C. Meyers, and J. G. Dennis. 2004. Tundra fire and vegetation change along a hillslope on the Seward Peninsula, Alaska, USA. Arctic, Antarctic, and Alpine Research. Environmental Science, Online. 1–10.
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..
Zou, L. and et al. 2023. Assessing the upper elevational limits of vegetation growth in global high-mountains.

Other references

Chapin, F.S., L.A. Viereck, P.C. Adams, K.V. Cleve, C.L. Fastie, R.A. Ott, D. Mann, and J.F. Johnstone. 2006. Successional processes in the Alaskan boreal forest. Page 100 in Alaska’s changing boreal forest. Oxford University Press.

Hinzman, L.D., L.A. Viereck, P.C. Adams, V.E. Romanovsky, and K. Yoshikawa. 2006. Climate and permafrost dynamics of the Alaskan boreal forest. Alaska’s changing boreal forest 39–61.

Johnstone, J.F. 2008. A key for predicting postfire successional trajectories in black spruce stands of interior Alaska. US Department of Agriculture, Forest Service, Pacific Northwest Research Station.

LANDFIRE. 2009. Western North American Boreal Alpine Dwarf-Shrub Summit. In: LANDFIRE National Vegetation Dynamics Models. USDA Forest Service and US Department of Interior. Washington, DC.

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

United States Department of Agriculture. 2022. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin.

Wells, Aaron F., Christopher S. Swingley, Susan L. Ives, Robert W. McNown, and Dorte Dissing; Vegetation classification for northwestern Arctic Alaska using an EcoVeg approach: tussock tundra and low and tall willow groups and alliances; Pages 87–117 in Changcheng Liu, editors. Vegetation Classification and Survey, International Association for Vegetation Science, Online, 2022

Contributors

Marji Patz
Blaine Spellman
Phil Barber

Approval

Blaine Spellman, 5/28/2025

Acknowledgments

Nathan Roe, Ecological Site Specialist in California (Southwest Region) provided the R script and analysis process to summarize data within the NASIS database.
Matthew Mayer, Ecological Site Specialist in Wasilla Alaska provided the R script to summarize geospatial data for climate information.

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	05/30/2025
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: