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Serpentine Fens

Serpentine Fen with Darlingtonia, Josephine County

Serpentine Fen with Darlingtonia Josephine County
(John A. Christy, Oregon Biodiversity Information Center)

Serpentine fens (see also Fens and Forested wetlands)are one of Oregon's rarest wetland types. They form on slopes or in small basins where seepage and springs discharge in soils derived from peridotite and serpentinite bedrock. The soils have very high levels of base metals and very low levels of common nutrients needed by plants. These wetlands are restricted to a small area of Josephine and Curry Counties in southwestern Oregon and several other sites in the Klamath Mountains of northwestern California.

Best known for their stands of cobra lily (Darlingtonia californica) that also occurs in coastal fens without serpentine, they are habitat for several species of plants found nowhere else on the planet. Primary threats to serpentine wetlands are groundwater pumping and diversion of spring water for domestic or agricultural use, and plant succession occurring in the absence of periodic fire. Some of these wetlands are also threatened by mining claims seeking to extract deposits of nickel and chromium from serpentine.

Serpentine Fens Map

Serpentine Fens Map

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

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 Calliscirpus criniger - Eleocharis quinqueflora Fen [Provisional]
Fringed cottongrass - few-flowered spikerush (Titus 1996-1998: 3)
wetland type image Carex mendocinensis Fen [Provisional)
Mendocino sedge (Titus 1996-1998: 2)
wetland type image Chamaecyparis lawsoniana / Rhododendron occidentale / Carex Forest
Port Orford cedar / western azalea / sedge (NS)
wetland type image Darlingtonia californica - Rudbeckia glaucescens Fen [Provisional]
California pitcher plant - California coneflower (Titus 1996-1998: 2)
wetland type image Deschampsia cespitosa - Danthonia californica - Rudbeckia glaucescens Wet Prairie [Provisional]
Seacoast bulrush (Eilers 1975: 225)
wetland type image Hastingsia bracteosa Fen [Provisional]
Purple-flowered rush-lily (Titus 1996-1998: 3)
wetland type image Rhododendron occidentale Shrub Swamp [Provisional]
Western azalea (Titus 1996-1998: 2)

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