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Wetlands

Wet Prairies

Wet Prairie, Willamette Floodplain RNA, Benton County

Wet Prairie
(John A. Christy, Oregon Biodiversity Information Center)

Wet prairies are one of Oregon's rarest wetland types. Most occur at lower elevations on bedrock or clay loam soils that have a seasonally perched water table. These sites usually dry out by late spring but depressions may retain water well into the summer. Shallow soils over bedrock, and rock outcrops are included as part of this habitat because they are often intermixed with clay soil sites and the same vegetation may occur on both substrates (e.g., Isoetes nuttallii, Triteleia hyacinthina). There is also some overlap with vernal pool vegetation. Wet prairie in the Willamette and Umpqua valleys are habitat to several rare species of plants. Although best known for tufted hairgrass (Deschampsia caespitosa), wet prairies contain many other species of grasses, sedges and herbs. Before flood control, wet prairies on the Columbia River bottoms were flooded for one or two months every year during the annual "spring freshet" fueled by snowmelt in the Columbia Basin. Most wet prairies have been drained, farmed, grazed, or overrun by exotic species.

Wet Prairie Map

Wet Prairie Map





 

Habitat: Flats, irregular surfaces, and depressions constrained by bedrock or hardpan
Water regime: Intermittently 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 Camassia cusickii Herbaceous Vegetation
Cusick camas
G2S2 BM
wetland type image Camassia quamash Wet Prairie Herbaceous Vegetation
Common camas
G3S3 KM, WV
wetland type image Carex aperta Herbaceous Vegetation
Columbia sedge
G1S1 WC, WV
wetland type image Carex densa - Deschampsia caespitosa Herbaceous Vegetation [Provisional]
Dense sedge - tufted hairgrass
G2S2 KM, WV
wetland type image Carex densa - Juncus patens Herbaceous Vegetation [Provisional]
Dense sedge - spreading rush
G2S2 KM
wetland type image Carex unilateralis - Hordeum brachyantherum Herbaceous Vegetation
One-sided sedge - meadow barley prairie
G2S2 KM, WV
wetland type image Deschampsia caespitosa - Artemisia lindleyana Herbaceous Vegetation
Tufted hairgrass - Columbia River wormwood
G1S1 WC
wetland type image Deschampsia caespitosa - Danthonia californica Herbaceous Vegetation
Tufted Hairgrass - California Oatgrass
G2S2 WV
wetland type image Eleocharis palustris - Carex unilateralis Herbaceous Vegetation
Creeping spikerush - one-sided sedge
G2S2 WV
wetland type image Eryngium petiolatum - Grindelia nana Herbaceous Vegetation
Coyote-thistle - low gumweed
G1S1 WV
wetland type image Eryngium petiolatum - Lasthenia glaberrima Herbaceous Vegetation
Coyote-thistle - smooth lasthenia
G1S1 WV
wetland type image Isoetes nuttallii Herbaceous Vegetation
Nuttall quillwort
G3S3 WV
wetland type image Juncus bufonius Herbaceous Vegetation [Provisional]
Toad rush
G5S5 CR, WV, KM, WC, EC, CP, BM, BR
wetland type image Rosa nutkana / Deschampsia caespitosa Shrubland [Provisional]
Nootka rose / tufted hairgrass
G2S2 WV
wetland type image Triteleia hyacinthina Herbaceous Vegetation [Provisional]
Hyacinth brodiaea
G2S2 KM, WV

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

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