Natural Resources
Conservation Service
Ecological site R241XY117AK
Alpine Dwarf Scrub Gravelly Summits
Last updated: 5/29/2025
Accessed: 12/20/2025
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): 241X–Seward Peninsula Highlands
The Seward Peninsula Highlands (MLRA 241X) occurs in Western Alaska, along the southernmost reaches of Land Resource Region Y, which describes the zone of continuous permafrost. This MLRA is approximately 13,700 square miles across the central Seward Peninsula. The terrain is defined by broad. extensive rolling hills and plains and solitary groups of rugged mountains expanding from sea level to a high point of 4,714 feet on Mount Osborn. Flood plains systems are common but generally narrow. This watershed drains into Kotzebue Sound and the Chukchi Sea to the north and the Bering Sea to the West. Major rivers include the Buckland, Kiwalik, Serpentine, Agiapuk-American, Kougarok, and Kuzitrin Rivers. The area is mostly undeveloped wild land that is sparsely populated. Residents use this remote area primarily for subsistence hunting, fishing, and gathering. Reindeer herding is a profitable enterprise and many areas of this MRLA are used for reindeer graze and subsistence activities. Parts of this MLRA were mined for gold during the Nome gold rush. Several mines still operate within this boundary (USDA, 2022). The largest communities in this predominantly inland MLRA are along the coast and include Teller and Brevig Mission. Federally managed lands in this MLRA include parts of the Selawik National Wildlife Refuge and parts of Bering Land Bridge National Preserve.
Geology and Soils
MLRA 241X was mostly unglaciated during the late Pleistocene. Glaciers were present during the middle and early Pleistocene in scattered areas such as the York Mountains in the west, the Kiglauik in the south, and the Upper Kiwalik River drainage. The present-day landscape is mantled with loess, colluvium, and slope alluvium (USDA, 2022). Modified glacial moraines are evident in areas of past glacial activity. Bedrock material is a mix of rock types, with areas of sedimentary, volcanic and igneous throughout the MLRA. Bedrock is at or near the surface in most upland areas of this MLRA, which is reflected in soil development and vegetative patterns.
This MLRA is in the zone of continuous permafrost. Frozen soils are common across the landscape, though may be absent from high energy systems on floodplains and around lakes. Permafrost is generally shallow to moderately deep (10 to 40 inches) and constitutes a restrictive layer that perches water and creates poorly drained or poorly drained soils. Alongside permafrost-supporting Gelisols, other common soil orders include soils with little to no development in the Entisol and Inceptisol orders. Periglacial features are common and include solifluction lobes, polygonal ground, and thermokarst pits (USDA, 2022). Non-soil areas (rock outcrop, riverwash, and surface water) make up approximated five percent of the MLRA surface.
Climate
Climate is predominantly continental arctic, with brief, cool summers and long, cold winters. Maritime conditions persist through the summer along the Bering Sea coast. Mean annual precipitation is 10 to 15 inches in the north and west, increasing to 20 to 40 inches in the mountainous areas in the south and east (USDA, 2022). Mean annual temperatures ranges from 20 to 26 degrees Fahrenheit (PRISM, 2018; SNAP, 2014).
Vegetation
Vegetation is mainly influence by site and soil characteristics such as temperature-degree days, exposure, soil depth, and soil hydrology. Dwarf scrublands are present across most of the upland, with vegetation further restricted on shallow soils. Lower elevations generally support more developed soils, and host willow-sedge scrublands, mixed ericaceous shrub scrublands, and herbaceous graminoid meadows. Tussock tundra is ubiquitous across much of the poorly drained, low-sloped landforms across the MRLA. Wetland communities dominate in closed depressions and drainages (USDA, 2022).
LRU notes
There are currently no Land Resource Areas (LRUs) delineated or described in MLRA 241X. There is potential for two or more LRUs along a climatic break between the lowlands and low-elevation hills of the north and west, and the higher, mountainous regions more prevalent in the south and east. However, vegetation and land management may not differ between these areas, as soils and vegetation are already restricted by cold annual temperatures even at low elevations.
Classification relationships
Alaska Vegetation Classification:
Dryas dwarf scrub (II.D.2 - level III) / Dryas-Lichen tundra (II.D.2.b – level IV)
(Viereck et al., 1992)
BioPhysical Settings: 6816850 – Alaska Arctic Acidic Sparse Tundra
(LANDFIRE, 2009)
Seward Rangesites
70 – Lichen Granitic Slope
(SCS, 1984; Swanson et al., 1985)
Ecological site concept
Ecological Site characteristics:
• Describes an alpine Dryas dwarf scrubland on mountain summits and shoulders
• There is no major disturbance affecting vegetation recorded for this ecological site
• The reference plant community is comprised primarily of alpine species and typically excludes ericaceous species
• Soils are gravelly, minimally developed Inceptisols
Associated sites
| R241XY118AK |
Arctic Tall Scrub Loamy Slopes R241XY118AK is on lower mountain slopes. Temperatures are warmer and soils are more developed. Site conditions support a taller mixed willow and alder scrubland. |
|---|---|
| R241XY119AK |
Alpine Scrub-Tussock Frozen Silty Slopes R241XY119AK describes a tussock scrubland on permafrost soil. Site hydrology and annual mean temperature support a different vegetative community on the associated here. |
| R241XY111AK |
Alpine Sedge-Scrub Frozen Loamy Slopes This ecological site is typically downslope of R241XY117AK. It supports a closed, low shrubland on moderate to shallowly steep backslopes. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Dryas octopetala |
| Herbaceous |
(1) Carex bigelowii |
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