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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 Betula glandulosa / Carex aquatilis var. dives Wet Shrubland [Provisional]
Dwarf birch / Sitka sedge (Murray 2000: 44; Christy 2004: 39)
G3S2 WC
wetland type image Betula glandulosa / Carex utriculata Wet Shrubland
Dwarf birch / southern beaked sedge (NS)
G4S4 BR, EC, WC
wetland type image Boykinia major Fen [Provisional]
Large boykinia (Murray 2000: 13; Christy 2004: 71)
G4S2 CR, WC
wetland type image Calamagrostis canadensis Western Wet Meadow
Bluejoint reedgrass (Murray 2000: 13; Christy 2004: 73; Crowe et al. 2004: 138; Wells 2006: 146; NS)
G4S4 BM, EC, WC
wetland type image Caltha leptosepala Wet Meadow
White marshmarigold (Murray 2000: 13; Christy 2004: 76; McCain et al. 2014: 70; NS)
G4S4 BM, CR, EC, WC
wetland type image Caltha leptosepala - Carex obnupta Fen [Provisional]
White marshmarigold - slough sedge (Christy 2004: 77)
G3S1 CR
wetland type image Carex aquatilis var. aquatilis Wet Meadow
Water sedge fen (Christy 2004: 82; Crowe et al. 2004: 81; Wells 2006: 125; Christy 2014: 20; NS)
G5S4 BM, BR, EC
wetland type image Carex aquatilis var. dives Fen
Sitka sedge (Murray 2000: 14; Christy 2004: 83; Crowe et al. 2004: 84; Odion et al. 2013: 68; McCain et  al. 2014: 74, 79; NS)
G4S4 EC, KM, WC
wetland type image Carex aquatilis var. dives - Comarum palustre Fen
Sitka sedge - purple marshlocks (Christy 2004: 84; NS)
G2S2 CR
wetland type image Carex buxbaumii Fen
Buxbaum sedge (Christy 2004: 85; Crowe et al. 2004: 89; NS)
G3S2 WC
wetland type image Carex canescens Fen [Provisional]
Gray sedge (Crowe et al. 2004: 90)
G5S2 BM, WC
wetland type image Carex cusickii Fen
Cusick sedge (Murray 2000: 15; Christy 2004: 86; Crowe et al. 2004: 91; NS)
G3S2 BM, CR
wetland type image Carex lasiocarpa Fen
Slender sedge (Christy 2004: 90; Crowe et al. 2004: 96; NS)
G4S2 BM, BR, WC
wetland type image Carex limosa Fen
Mud sedge (Christy 2004: 92; Wells 2006: 135; NS)
G2S2 BM, EC, WC
wetland type image Carex luzulina Fen [Provisional]
Woodrush sedge (Christy 2004: 93; Crowe et al. 2004: 101; Wells 2006: 142; Odion et al. 2013: 72)
G4S3 BM, EC, KM
wetland type image Carex obnupta Wet Meadow
Slough sedge (Murray 2000: 16; Christy 2004: 96; NS)
G4S4 CR, WV
wetland type image Dulichium arundinaceum Shore Fen
Threeway sedge Threeway sedge (Christy 2004: 110; Crowe et al. 2004: 76; NS)
G3S2 CR, EC, WC, WV
wetland type image Eleocharis quinqueflora Fen
Few-flowered spikerush (Murray 2000: 15, 18; Christy 2004: 114; Crowe et al. 2004: 126; Wells 2006: 131; McCain et al. 2014: 110; NS)
G4S2 BM, BR, EC, WC
wetland type image Eleocharis quinqueflora - Carex scopulorum Wet Meadow
Few-flowered spikerush - Mountain sedge
G3S3 BM, EC, WC
wetland type image Eleocharis quinqueflora - Eriophorum criniger Herbaceous Vegetation [Provisional]
Few-flowered spikerush - fringed cottongrass
G2S2 KM
wetland type image Hypericum anagalloides Fen [Provisional]
Bog St. John's wort (Murray 2000: 20)
G5S3 CR, WC
wetland type image Juncus balticus - Bistorta bistortoides Wet Meadow [Provisional]
Baltic rush - American bistort (Murray 2000: 21; Christy 2004: 124)
G4S4 EC, WC
wetland type image Kalmia microphylla / Carex aquatilis var. dives Wet Shrubland [Provisional]
Alpine laurel / Sitka sedge (Christy 2004: 41)
G3S2 WC
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 Menyanthes trifoliata Aquatic Vegetation
Buckbean (Murray 2000: 23; Christy 2004: 130; Crowe et al. 2004: 61; NS)
G5S4 BM, CR, EC, WC, WV
wetland type image Myrica gale / Carex (aquatilis var.dives, utriculata) Fen
Sweet gale / (Sitka sedge, southern beaked sedge) (Murray 2000: 33; Christy 2004: 50; NS)
G3S1 CR
wetland type image Menyanthes trifoliata Herbaceous Vegetation [Provisional]
Buckbean
G5S4 BM, CR, EC, WC, WV
wetland type image Nephrophyllidium crista-galli Fen [Provisional]
Deer cabbage (Murray 2000: 19; Christy 2004: 131)
G4S1 WC
wetland type image Picea engelmannii / Eleocharis quinqueflora Swamp Woodland
Engelmann spruce / small-flowered spikerush (Crowe et al. 2004: 444; NS)
G3S3 WC, EC
wetland type image Rhododendron columbianum / Carex obnupta / Sphagnum spp. Fen
Western Labrador-tea / slough sedge / sphagnum (Christy 2004: 43; NS)
G2S2 CR
wetland type image Rhododendron columbianum / Carex scopulorum Fen [Provisional]
Western Labrador-tea / mountain sedge (Crowe et al. 2004: 267; Wells 2006: 96)
G4S2 BM
wetland type image Rhododendron columbianum / Darlingonia californica / Sphagnum spp. Fen
Western Labrador-tea / darlingtonia / sphagnum (Christy 2004: 45; NS)
G2S2 CR
wetland type image Tsuga heterophylla / Rhododendron columbianum / Carex obnupta - Lysichiton americanus Treed Bog
Western hemlock / western Labrador tea / slough sedge - yellow skunk cabbage (Christy 2004: 35; NS)
G1S1 CR
wetland type image Rhododendron columbianum - Gaultheria shallon / Carex obnupta Fen
Western Labrador tea - salal / slough sedge (Murray 2000: 33; Christy 2004: 42; NS)
G2S2 CR
wetland type image Rhododendron columbianum / Sanguisorba officinalis / Sphagnum spp. Fen
Western Labrador tea / great burnet / sphagnum (Christy 2004: 48; NS)
G1S1 CR
wetland type image Rhododendron (columbianum, groenlandicum) - Myrica gale / Sphagnum spp. Fen
Western Labrador-tea - sweet gale / sphagnum (Christy 2004: 47; NS)
G2S1 CR
wetland type image Sanguisorba officinalis - Carex aquatilis var. dives Fen [Provisional]
Great burnet - Sitka sedge (Murray 2000: 25; Christy 2004: 140)
G2S2 CR, WC
wetland type image Sphagnum (angustifolium, capillifolium, fuscum, mendocinum, miyabeanum, pacificum, palustre) Fen [Provisional]
Sphagnum (Murray 2000: 11, 12)
G3S2 CR, WV, WC
wetland type image Spiraea douglasii / Sphagnum spp. Fen
Douglas spiraea / sphagnum (Christy 2004: 60; NS)
G3S1 WV
wetland type image Spiraea douglasii - Vaccinium uliginosum / Carex (aquatilis var. dives, exsiccata) Fen [Provisional]
Douglas spiraea / sphagnum (Christy 2004: 60; NS)
G3S2 WC
wetland type image Spiraea douglasii - Vaccinium uliginosum / Carex obnupta - Deschampsia cespitosa Fen [Provisional]
Douglas spiraea - bog bilberry / slough sedge - tufted hairgrass (Christy 2004: 59)
G3S2 CR
wetland type image Spiraea douglasii - Vaccinium uliginosum / Carex obnupta - Deschampsia cespitosa Fen [Provisional]
Douglas spiraea - bog bilberry / slough sedge - tufted hairgrass (Christy 2004: 59)
G3S2 CR
wetland type image Spiraea douglasii - Vaccinium uliginosum / Carex obnupta - Deschampsia cespitosa Pacific Fen
Tufted clubrush (Murray 2000: 28; Christy 2004: 147; NS)
G5S1 WC
wetland type image Vaccinium caespitosum / Sanguisorba officinalis Fen
Dwarf huckleberry / great burnet (Christy 2004: 61; NS)
G1S1 CR
wetland type image Vaccinium uliginosum / Carex aquatilis var. dives Wet Shrubland
Bog blueberry / Sitka sedge (Murray 2000: 39; Christy 2004: 65; Crowe et al. 2004: 262; McCain et al. 2014: 125; NS)
G4S4 CR
wetland type image Vaccinium uliginosum / Carex obnupta Wet Shrubland [Provisional]
Bog bilberry / slough sedge (Christy 2004: 63)
G3S3 CR
wetland type image Vaccinium uliginosum / Deschampsia caespitosa Wet Shrubland
Bog blueberry / tufted hairgrass (Christy 2004: 64; NS)
G2S2 EC, WC
wetland type image Vaccinium uliginosum / Eleocharis quinqueflora Wet Shrubland [Provisional]
Bog blueberry / few-flowered spikerush (Crowe et al. 2004: 259)
G4S2 EC, WC
wetland type image Xerophyllum tenax - Sanguisorba officinalis Meadow
Bear-grass - great burnet (Christy 2004: 62; NS)
G1S1 CR, KM
wetland type image Xerophyllum tenax / Sphagnum spp. Meadow
Bear-grass / sphagnum (Murray 2000: 29; NS)
G3S2 CR, WC

Authored by John A. Christy, Wetlands Ecologist, (ORBIC) Oregon Biodiversity Information Center (2012 rev. 2017)

randomness