Natural Resources
Conservation Service
Ecological site F237XY216AK
Boreal Woodland Loamy Flood Plains
Last updated: 7/23/2020
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): 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 F237XY216AK is on mid to high flood plains of the Izavieknik River valley. The climate, landform, and location create a unique ecological site along this river. The river valley is in the eastern part of the Ahklun Mountains area, and it is prone to the pressure of tree propagule from neighboring MLRA 236. Poplar trees, more common in areas of milder climates to the east, are now a keystone plant species in this river valley. The reference state supports one documented community phase.
The reference plant community is an open broadleaf forest (Viereck et al., 1992) of balsam poplar (Populus balsamifera) and an understory of shrubs, graminoids, and forbs. Understory plants include willow (Salix spp.), squashberry (Viburnum edule), bluejoint (Calamagrostis canadensis), field horsetail (Equisetum arvense), and a mix of less prevalent graminoids and forbs.
Associated sites
R237XY210AK |
Western Alaska Maritime Scrubland Gravelly Flood Plains Ecological site F237XY216AK is differentiated from the associated ecological sites based on position on the landscape, landform, disturbance regime, and vegetative communities. Ecotonal plant communities that have characteristics of more than one ecological site are in areas where these sites abut. |
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R237XY211AK |
Western Alaska Maritime Scrubland Loamy Flood Plains Ecological site F237XY216AK is differentiated from the associated ecological sites based on position on the landscape, landform, disturbance regime, and vegetative communities. Ecotonal plant communities that have characteristics of more than one ecological site are in areas where these sites abut. |
R237XY222AK |
Western Alaska Maritime Scrubland Loamy Hummocks Ecological site F237XY216AK is differentiated from the associated ecological sites based on position on the landscape, landform, disturbance regime, and vegetative communities. Ecotonal plant communities that have characteristics of more than one ecological site are in areas where these sites abut. |
Similar sites
F237XY239AK |
Boreal Forest Loamy Slopes Four ecological sites are on major flood plains in the Ahklun Mountains area. Three of these sites are throughout the area. Site F237XY216AK, however, is restricted to the valley carved by the Izavieknik River (fig. 1). Location, flooding characteristics, and soil features create a unique vegetative community in this ecological site. Site F237XY239AK is a balsam poplar community, but it is associated with discharge slopes, such as fans or seeps, that behave differently than flood plains. The understory vegetation of site F237XY239AK is different from that of site F237XY216AK. |
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Figure 1. Mid to high flood plains along the Izavieknik River support open balsam poplar forests.
Table 1. Dominant plant species
Tree |
(1) Populus balsamifera |
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Shrub |
(1) Viburnum edule |
Herbaceous |
(1) Equisetum arvense |
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