Natural Resources
Conservation Service
Ecological site R237XY230AK
Western Alaska Maritime Scrubland Silty Plains and Mountain Slopes, Lower
Last updated: 7/23/2020
Accessed: 11/23/2024
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): 237X–Ahklun Mountains
The Ahklun Mountains Major Land Resource Area (MLRA 237) is in western Alaska (fig. 2). This MLRA covers approximately 14,555 square miles, and it includes the mountains, hills, and valleys of the Kilbuck Mountains in the north and the Ahklun Mountains in the south. Except for the Kilbuck Mountains and the highest ridges of the Ahklun Mountains, the MLRA was extensively glaciated during the Pleistocene (Kautz et al., 2004). Today, a few small glaciers persist in mountainous cirques (Gallant et al., 1995). The present-day landscape and landforms reflect this glacial history; glacial moraines and glacial drift cover much of the area (USDA-NRCS, 2006). The landscape of the MLRA is primarily defined by low, steep, rugged mountains cut by narrow-to-broad valleys. Flood plains and terraces of varying sizes are common at the lower elevations in the valley bottoms. Glacially carved valleys host many lakes. Togiak Lake is one of the largest lakes in the region. It is 13 miles long and about 9,500 acres in size. Major rivers include the Goodnews, Togiak, Kanektok, Osviak, Eek, and Arolik Rivers. Where the Goodnews and Togiak Rivers reach the coast, the nearly level to rolling deltas support numerous small lakes.
This MLRA has two distinct climatic zones: subarctic continental and maritime continental (fig. 3). The high-elevation areas are in the subarctic continental zone. The mean annual precipitation is more than 75 inches, and the mean annual air temperature is below about 27 degrees F (-3 degrees C) in extreme locations. The warmer, drier areas at the lower elevations are in the maritime continental zone. The mean annual precipitation is 20 to 50 inches, and the mean annual air temperature is about 30 to 32 degrees F (-0.2 to 1.2 degrees C) (PRISM). This climatic zone is influenced by both maritime and continental factors. The temperatures in summer are moderated by the open waters of the Bering Sea, and the temperatures in winter are more continental due to the presence of ice in the sea (Western Regional Climate Center, 2017). The seasonal ice reaches its southernmost extent off the coast of Alaska in Bristol Bay (Alaska Climate Research Center, 2017). The western coast of Alaska is also influenced by high winds from strong storms and airmasses in the Interior Region of Alaska (Hartmann, 2002).
The Ahklun Mountains MLRA is principally undeveloped wilderness. Federally managed lands include the Togiak and Alaska Maritime National Wildlife Refuges. The MLRA is sparsely populated, but it has several communities, including Togiak, Manokotak, Twin Hills, and Goodnews Bay. Togiak is the largest village. It has a population of approximately 855, most of which are Yup’ik Alaska Natives (U.S. Census Bureau, 2016). Major land uses include subsistence activities (fishing, hunting, and gathering) and wildlife recreation (USDA-NRCS, 2006; Kautz et al., 2004).
Ecological site concept
Ecological site R237XY230AK is on lower mountain slopes and talfs of plains. The soils associated with this site are moderately well drained. Landform, location, slope shape, and soil characteristics differentiate this ecological site. The reference state supports one plant community, which is the reference plant community. No alternate states are in this ecological site.
The reference plant community is a closed tall scrubland (Viereck et al., 1992). This community consists dominantly of Sitka alder (Alnus viridis ssp. sinuata). The understory consists of shade-tolerant forbs and graminoids, including ferns and bluejoint (Calamagrostis canadensis).
Associated sites
R237XY202AK |
Western Alaska Maritime Mosaic Gravelly Slopes
|
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R237XY204AK |
Western Alaska Maritime Scrubland Loamy Slopes |
R237XY208AK |
Western Alaska Maritime Scrubland Peat Depressions |
R237XY211AK |
Western Alaska Maritime Scrubland Loamy Flood Plains |
R237XY217AK |
Western Alaska Maritime Dwarf Scrubland Gravelly Slopes, High Elevation |
R237XY201AK |
Western Alaska Maritime Scrubland Gravelly Slopes Site R237XY230AK is on lower mountain slopes and plains. The most common associated ecological sites on or adjacent to these landforms are R237XY201AK, R237XY202AK, R237XY204AK, R237XY208AK, R237XY211AK, and R237XY217AK. These ecological sites typically are differentiated by one or more criteria, including landform, landform position, associated soils, associated disturbance regimes, and the type and amount of plants. Ecotonal plant communities that have characteristics from more than one ecological site are in areas where these sites abut. |
Similar sites
R237XY202AK |
Western Alaska Maritime Mosaic Gravelly Slopes Site R237XY202AK supports a reference community of alder, ferns, and bluejoint similar to that of site R237XY230AK. However, site R237XY202AK is associated with well drained soils, is on backslopes of mountains, and supports a unique mosaic of two communities. These differences require the use of separate ecological sites. |
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R237XY203AK |
Western Alaska Maritime Scrubland Gravelly Drainage, Escarpment The reference plant community of site R237XY230AK is similar to that of site R237XY203AK; however, these sites are on different landforms, support different overstory and understory vegetation, and are associated with different soils. These differences require the use of separate ecological sites. |
Figure 1. Alders are dominant in the plant community. Shade-tolerant forbs and graminoids typically are in the dense understory.
Table 1. Dominant plant species
Tree |
Not specified |
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Shrub |
(1) Alnus viridis subsp. sinuata |
Herbaceous |
(1) Dryopteris expansa |
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