Natural Resources
Conservation Service
Ecological site R003XN640WA
Southern Washington Cascades Low Cryic Bog or Fen
Last updated: 5/10/2024
Accessed: 12/21/2024
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): 003X–Olympic and Cascade Mountains
Steep mountains and narrow to broad, gently sloping valleys characterize this MLRA. A triple junction of two oceanic plates and one continental plate is directly offshore from Puget Sound. Subduction of the oceanic plates under the westerly and northwesterly moving continental plate contributes to volcanic activity in the Cascade Mountains. Movement among these plates has resulted in major earthquakes and the formation of large stratovolcanoes. The Cascade Mountains consist primarily of volcanic crystalline rock and some associated metasedimentary rock. The mean annual precipitation is dominantly 60 to 100 inches, but it is 30 to 60 inches on the east side of the Cascade Mountains.
The soil orders in this MLRA are dominantly Andisols, Spodosols, and Inceptisols and minor areas of Entisols and Histosols. The soils are dominantly in the frigid or cryic temperature regime and the udic moisture regime. The soils generally are shallow to very deep, well drained, ashy to medial, and loamy or sandy. They are on mountain slopes and ridges.
Ecological site concept
This ecological site is in nonforested bogs and fens at low to middle elevations (2,100 to 4,600 feet) of the Southern Washington Cascade Mountains. Because of the scale of mapping, this site concept includes both bogs and fens and they are not distinguished differently. The site is influenced by the pH of the soils, availability of nutrients, physiography, and hydrologic dynamics. The summers are cool and dry, and the winters are cold and wet.
The soils that support this ecological site are in the cryic soil temperature regime and the aquic soil moisture regime. The site typically is in poorly drained areas that are subject to residual ponding from overbank flooding, groundwater discharge from nearby slopes, or a seasonal high water table associated with meltwater. The water table commonly is at or near the surface during much of the growing season, and the rate of organic material decomposition is slow because of the anaerobic and acidic conditions. These conditions result in a nutrient-poor environment. The soils are mucky and formed in organic material and bands of volcanic ash.
The site supports vegetation that is tolerant of frequent ponding and periodic saturation. Common plants include mannagrass (Glyceria spp.), American skunkcabbage (Lysichiton americanus), water sedge (Carex aquatilis), bluejoint reedgrass (Calamagrostis canadensis), white marsh marigold (Caltha leptosepala), black alpine sedge (Carex nigricans), rush (Juncus), bog Labrador tea (Ledum groenlandicum), and water parsley (Oenanthe sarmentosa).
Associated sites
R003XN641WA |
Southern Washington Cascades High Cryic Bog or Fen Ecological site R003XN640WA, Southern Washington Cascades Low Cryic Bog or Fen, has features that are associated to those of site R003XN641WA, Southern Washington High Cryic Bog or Fen. Both sites are influenced by ponding and similar disturbance patterns; however, elevation and the duration of ponding distinguish these ecosystems. Ecological site R003XN640WA is at an elevation of 2,100 to 4,600 feet, and site R003XN641WA is at an elevation of 3,600 to 6,500 feet. Both sites support similar plant species, but site R003XN640WA has a longer growing season and higher plant production. |
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Similar sites
R003XN641WA |
Southern Washington Cascades High Cryic Bog or Fen Ecological site R003XN640WA, Southern Washington Cascades Low Cryic Bog or Fen, has features that are associated to those of site R003XN641WA, Southern Washington High Cryic Bog or Fen. Both sites are influenced by ponding and similar disturbance patterns; however, elevation and the duration of ponding distinguish these ecosystems. Ecological site R003XN640WA is at an elevation of 2,100 to 4,600 feet, and site R003XN641WA is at an elevation of 3,600 to 6,500 feet. Both sites support similar plant species, but site R003XN640WA has a longer growing season and higher plant production. |
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Table 1. Dominant plant species
Tree |
Not specified |
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Shrub |
Not specified |
Herbaceous |
(1) Glyceria |
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