Common (Translated Scientific) Name: Columbian Sedge Lowland Wet Meadow

Colloquial Name: Columbian Sedge Lowland Wet Meadow

Hierarchy Level:  Association

Type Concept: This plant association occupies lakeshores, river floodplains, and wet meadows in western and south-central Montana, and western Washington. It occurs in low-lying areas with prolonged seasonal flooding. The association is characterized by nearly pure stands of Carex aperta with lesser amounts of Poa palustris, Argentina anserina, Bidens cernua, Bidens frondosa, Ludwigia palustris, Polygonum amphibium, and Erysimum cheiranthoides. Habitat in northwestern Oregon is mostly low-elevation floodplains, but one site is known from a montane fen. Stands are seasonally flooded but are dry by mid to late summer. This association is thought to have been more widespread historically before diking and farming of the Columbia River lowlands and the advent of exotic cultivars of Phalaris arundinacea. The few known stands that remain are either nearly monotypic Carex aperta in depressions too wet for Phalaris arundinacea, or in mixed stands dominated by Phalaris arundinacea. Elsewhere, it has been completely displaced by Phalaris arundinacea. The sedge itself is not rare but it is never plentiful. Most of the ten plots sampled here represent the monotypic expression because these have the fewest exotic species present. They may represent only the wettest end of the historic moisture gradient occupied by the association. Trees are absent or peripheral but would include Salix lucida ssp. lasiandra and Fraxinus latifolia. Shrubs reported include Spiraea douglasii, Sambucus racemosa, and the exotic Rubus armeniacus, but all have low constancy and cover. Ten species are reported from the herb layer, Carex aperta being the most abundant with average cover of 88% and ranging from 62-98%. Phalaris arundinacea is the second most abundant species and would be more abundant if more mixed stands were sampled. Other species observed but not recorded in plots are Polygonum amphibium, Bidens cernua, Bidens frondosa, and Ludwigia palustris. Carex aperta once formed "extensive meadows on overflow bottomlands in the valley of the Columbia and its tributaries...largely cut for hay and regarded by farmers as the best forage sedge," and it was "common about Columbia Slough etc." (Gorman 1926). Piper and Beattie (1915) said it was "the common hay sedge of the Columbia River bottoms." It probably extended from Longview to Skamania and into the Willamette Valley as well. Like Willamette Valley prairie and savanna that have suffered so many losses, the original species composition of this association will probably never be known with certainty.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Classification is based on field data collected in Washington and Montana as recently as 1998. Limited data are available to determine if stands in Washington and Oregon represent the same plant association reported in Montana.

Similar NVC Types: No Data Available

note: No Data Available