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Natural Resources
Conservation Service
Ecological site R236XY154AK
Subarctic Ericaceous Scrub Loamy Plain Swales
Last updated: 2/13/2024
Accessed: 08/17/2024
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.
![Location map](/images/maps/R236XY154AK.png)
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
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).
Ecological site concept
This site is in linear swales on plains and hills. Site elevation is between 170 and 550 feet above sea level. Slopes are nearly level to gentle (0 – 7 percent). Site hydrology and soil acidity shape the vegetation on this landform. Ponding is occasional and brief and a water table is present from October through April between 13 and 31 inches. Soils are well drained and moderately to extremely acidic, which are excellent conditions for low, ericaceous shrubs.
The reference state supports two communities. The reference plant community is characterized as an ericaceous shrubland (Viereck et al., 1992). It is composed of a mix of low and dwarf ericaceous shrubs with patchy graminoids and moss throughout.. Wetter areas within swales typically support more herbaceous species and less shrubs.
Associated sites
R236XY132AK |
Subarctic Dwarf Scrub Dry Loamy Slopes R236XY132AK describes convex slopes on rolling plains and hills. The vegetation on these slopes strongly clash with the more hydrophytic community associated with the nearby concave swales described by R236XY154AK. |
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R236XY174AK |
Subarctic Mosaic Loamy Steep Bluffs R236XY174AK describes steeply sloped bluffs. Though spatially close, the vegetation and other ecological dynamics of a bluff are very different from that of concave swales. |
Similar sites
R236XY151AK |
Subarctic Open Willow Loamy Plain Swales Both sites are in swales. R236XY151AK describes circular swales. Vegetation at both sites is influenced by site hydrology. Ponding occurs in circular swales but not in the swales described by R236XY154AK. Differences in site and soil hydrology results in different site vegetation. |
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Table 1. Dominant plant species
Tree |
Not specified |
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Shrub |
(1) Empetrum nigrum |
Herbaceous |
(1) Calamagrostis canadensis |
Click on box and path labels to scroll to the respective text.
Ecosystem states
State 1 submodel, plant communities
1.1a | - | Increased hyrologic effects |
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1.2a | - | Decreased hydrologic effects |