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Wetlands

Fens

Coastal fen with Darlingtonia, Curry County

Coastal fen with Darlingtonia, Curry County
(John A. Christy, Oregon Biodiversity Information Center)

Fens (see also Serpentine fens) Most wetlands in Oregon that have been called "bogs" are actually fens, because they are hydrated by mineral-rich surface or groundwater, lack a domed peat profile, and have a pH generally higher than 5.5. Many fens, however, contain localized hummocks or lawns of Sphagnum with a pH as low as 4, and these are classified as "poor fens." Oregon's fens occur in depressions and on slopes hydrated by springs and seeps, particularly in interdunal troughs, headwall basins, and floodplains. Fens may also occur around the edges or over the surface of midslope slump or sag ponds in landslide topography. They are usually perennially saturated but local areas of surface drying are not uncommon. Fens may include patches of shrub swamp and forested wetland occurring on peat soils. Drainage, filling, peat mining, conversion to commercial cranberry or blueberry production, and plant succession have destroyed many fens, and losses continue to occur despite wetland regulations that were designed to protect them.

Map of Fens in Oregon

Map of Fens in Oregon

Habitat: Slopes, basins, and flats
Water regime: Perennially to seasonally flooded
Water chemistry: Fresh

Ecoregion*: BM = Blue Mountains, BR = Northern Basin and Range, CB = Columbia Basin, CR = Coast Range, EC = East Cascades, KM = Klamath Mountains, WC = West Cascades, WV = Willamette Valley  
Scientific & Common Name Global & State Rank Ecoregion*
wetland type image Calamagrostis canadensis Western Herbaceous Vegetation
Bluejoint reedgrass
G4S4 BM, EC, WC
wetland type image Caltha leptosepala Herbaceous Vegetation
White marshmarigold
G4S4 BM, CR, EC, WC
wetland type image Carex aquatilis var. aquatilis Herbaceous Vegetation
Water sedge fen
G5S4 BM, BR, EC
wetland type image Carex aquatilis var. dives Herbaceous Vegetation
Sitka sedge
G4S4 EC, WC
wetland type image Carex aquatilis var. dives - Comarum palustre Herbaceous Vegetation
Sitka sedge - purple marshlocks
G2S2 CR
wetland type image Carex buxbaumii Herbaceous Vegetation
Buxbaum sedge
G3S2 WC
wetland type image Carex canescens Herbaceous Vegetation [Provisional]
Gray sedge
G5S2 BM, WC
wetland type image Carex cusickii Herbaceous Vegetation
Cusick sedge
G3S2 BM, CR
wetland type image Carex lasiocarpa Herbaceous Vegetation
Slender sedge
G4S2 BM, BR, WC
wetland type image Carex limosa Herbaceous Vegetation
Mud sedge
G2S2 Mud sedge
wetland type image Carex obnupta - Carex aquatilis dives Herbaceous Vegetation [Provisional]
Slough sedge - Sitka sedge
G4S3 BM
wetland type image Dulichium arundinaceum Seasonally Flooded Herbaceous Vegetation
Threeway sedge
G3S2 CR, EC, WC, WV
wetland type image Eleocharis quinqueflora Herbaceous Vegetation
Few-flowered spikerush
G4S2 BM, BR, EC, WC
wetland type image Eleocharis quinqueflora - Carex scopulorum Herbaceous Vegetation
Few-flowered spikerush - Holm sedge
G3S2 BM, EC
wetland type image Eleocharis quinqueflora - Eriophorum criniger Herbaceous Vegetation [Provisional]
Few-flowered spikerush - fringed cottongrass
G2S2 KM
wetland type image Ledum glandulosum / Carex obnupta / Sphagnum spp. Shrubland
Western Labrador-tea / slough sedge / sphagnum
G2S2 CR
wetland type image Ledum glandulosum / Darlingonia californica / Sphagnum spp. Shrubland
Western Labrador-tea / darlingtonia / sphagnum
G2S2 CR
wetland type image Ledum glandulosum - Gaultheria shallon / Carex obnupta Shrubland
Western Labrador tea - salal / slough sedge
G2S2 CR
wetland type image Ledum glandulosum - Myrica gale / Sphagnum spp. Shrubland
Western Labrador-tea - sweet gale / sphagnum
G2S1 CR
wetland type image Myrica gale / Carex (aquatilis var.dives, utriculata) Shrubland
Sweet gale / (Sitka sedge, inflated sedge)
G3S1 CR
wetland type image Menyanthes trifoliata Herbaceous Vegetation [Provisional]
Buckbean
G5S4 BM, CR, EC, WC, WV
wetland type image Nephrophyllidium crista-galli Herbaceous Vegetation [Provisional]
Deer cabbage
G4S1 WC
wetland type image Picea engelmannii / Eleocharis quinqueflora Woodland
Engelmann spruce / small-flowered spikerush
G3S3 WC, EC
wetland type image Tsuga heterophylla / Ledum glandulosum / Carex obnupta - Lysichiton americanus Forest
Western hemlock / western Labrador tea / slough sedge - yellow skunk cabbage
G1S1 CR
wetland type image Vaccinium caespitosum / Sanguisorba officinalis Dwarf-shrubland
Dwarf huckleberry / great burnet
G1S1 CR
wetland type image Vaccinium uliginosum / Carex aquatilis var. dives Dwarf-shrubland
Bog blueberry / Sitka sedge
G4S4 EC, WC
wetland type image Vaccinium uliginosum / Deschampsia caespitosa Dwarf-shrubland
Bog blueberry / tufted hairgrass
G2S2 EC, WC
wetland type image Vaccinium uliginosum / Eleocharis quinqueflora Dwarf-shrubland [Provisional]
Bog blueberry / few-flowered spikerush
G4S2 EC, WC

Authored by John A. Christy, Wetlands Ecologist, (ORBIC) Oregon Biodiversity Information Center (2012)

randomness