Natural Resources
Conservation Service
Ecological site R236XY158AK
Boreal Tall Scrub Gravelly Flood Plains
Last updated: 2/13/2024
Accessed: 04/26/2024
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.
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 ecological site is lowland flood plains. Site elevation is between 20 and 810 feet above sea level. Slopes are nearly level (0 - 2 percent). Soil hydrology, a large volume of soil fragments, and a flood regime shape the vegetation on this landform. Brief, occasional flooding and ponding during the growing season restricts vegetation. However, the high volume of subsurface rock fragments keeps the soil well drained, allowing taller, less hydrophytic species to grow.
The reference state supports one community. The reference plant community is characterized as a closed tall scrubland (Viereck et al., 1992). It is composed of alder and one or more species of willow in the overstory, with an understory of bluejoint and various forbs. This community is very resilient to the flooding events it experiences.
Associated sites
| F236XY111AK |
Boreal Forest Loamy Flood Plains F236XY111AK describes lowland forested flood plains. They are rarely flooded and support a forested reference plant community. It is typically found at higher elevations on the flood plain than the scrubland described by R236XY158AK. |
|---|---|
| R236XY121AK |
Boreal Tall Scrub Loamy Flood Plains Both are lowland flood plains sites. Soils are wetter in R236XY121AK and flooding is more disruptive in R236XY158AK. This site is typically found closer to the flood source. |
Similar sites
| R236XY121AK |
Boreal Tall Scrub Loamy Flood Plains Both sites are on mid flood plains. Vegetation in R236XY121AK is more restricted by soil hydrology (redox concentrations present), while flooding is more intense in R236XY158AK. Differences in soil and disturbance regime result in unique reference plant communities. |
|---|
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Alnus |
| Herbaceous |
(1) Calamagrostis canadensis |
Click on box and path labels to scroll to the respective text.