Natural Resources
Conservation Service
Ecological site R236XY203AK
Subarctic Tall Scrub Wet Loamy Mountain Slopes
Last updated: 2/13/2024
Accessed: 11/21/2024
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): 236X–Bristol Bay-Northern Alaska Peninsula Lowlands
The Bristol Bay-Northern Alaska Peninsula Lowland Major Land Resource Area (MLRA 236) is located in Western Alaska. This MLRA covers approximately 19,500 square miles and is defined by an expanse of nearly level to rolling lowlands, uplands and low to moderate hills bordered by long, mountain footslopes. Major rivers include the Egegik, Mulchatna, Naknek, Nushagak, and Wood River. MLRA 236 is in the zone of discontinuous permafrost. It is primarily in areas with finer textured soils on terraces, rolling uplands and footslopes. This MLRA was glaciated during the early to middle Pleistocene. Moraine and glaciofluvial deposits cover around sixty percent of the MLRA. Alluvium and coastal deposits make up a large portion of the remaining area (Kautz et al., 2012; USDA, 2006).
Climate patterns across this MLRA shift as one moves away from the coast. A maritime climate is prominent along the coast, while continental weather, commonly associated with Interior Alaska, is more influential inland. Across the MLRA, summers are general short and warm while winters are long and cold. Mean annual precipitation is 13 to 50 inches, with increased precipitation at higher elevations and areas away from the coast. Mean annual temperatures is between 30 and 36 degrees F (USDA, 2006).
The Bristol Bay-Northern Alaska Peninsula MLRA is principally undeveloped wilderness. Federally managed land includes parts of the Katmai and Aniakchak National Parks, and the Alaska Peninsula, Becharof, Togiak and Alaska Maritime National Wildlife Refuges. The MLRA is sparsely populated. Principal communities include Dillingham, Naknek, and King Salmon. Commercial fishing in Bristol Bay and the Bering Sea comprises a major part of economic activity in the MLRA. Other land uses include subsistence activities (fishing, hunting, and gathering) and sport hunting and fishing (USDA, 2006).
Classification relationships
Alaska Vegetation Classification:
Open tall scrubland (II.B.2 - level III) / Open willow-alder scrubland (II.B.2.d - level IV)
(Viereck et al., 1992)
Circumboreal Vegetation Map – Alaska-Yukon Region:
Southern Alaska Alder-Willow-Dwarf Birch Scrub
(Jorgensen and Meidinger, 2015)
BioPhysical Settings: 7616390 – Arctic Mesic-Wet Willow Shrubland
(LANDFIRE, 2009)
Ecological site concept
This ecological site is on mountain backslopes and footslopes. It is associated with poorly drained soils. Site elevation is between 500 and 1,600 feet above sea level. Slope gradient is strong (5 – 15 percent). Soil hydrology has a major influence on vegetation on this landform. Soils are poorly drained and weakly developed and a water table present during growing season are ideal for hydrophytic shrubs.
The reference state supports one community. The reference plant community is characterized as a tall open scrubland (Viereck et al., 1992). It is composed of a mix of willow and alder with various low shrubs, graminoids and forbs in the understory.
Associated sites
| R236XY104AK |
Alpine Dwarf Scrub Gravelly Slopes R236XY104AK describes subalpine positions that support a mix of alpine and ericaceous shrubs. It is at higher elevations than R236XY203AK and does not support the willow and alder associated with poorly drained soils at lower elevations. |
|---|---|
| R236XY106AK |
Subarctic Dwarf Scrub Dry Loamy Slopes R236XY106AK describes the low ericaceous shrubland found on well drained, convex mountain backslopes and shoulders. It is on steeper slopes than R236XY203AK and does not support tall shrubs. |
| R236XY107AK |
Western Alaska Maritime Scrub Gravelly Drainages R236XY107AK describes drainages and swales on mountain backslopes and footslopes. These swales can be found on the same slopes described by R236XY203AK. |
Similar sites
| F236XY116AK |
Boreal Forest Loamy Wet Slopes R236XY203AK may be misidentified as a burn sere from a forest ecological site. Historic and current data should be reviewed to determine whether a willow-alder site is capable of supporting one or more tree species in the reference plant community. |
|---|---|
| R236XY107AK |
Western Alaska Maritime Scrub Gravelly Drainages R236XY107AK describes willow swales and drainages. Vegetation is similar. However, these landforms can be susceptible to ponding, which typically excludes alder and other less hydrophytic species. |
| R236XY124AK |
Subarctic Tall Scrub Loamy Convex Hillslopes Both sites support tall shrubs in the reference plant community. The soils in R236XY124AK are well drained and it is unlikely that the reference plant community will match one associated with poorly drained soil. Further data are required to fully differentiate these sites. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Salix pulchra |
| Herbaceous |
(1) Carex |
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