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Marshes and Fens

Description

Marshes and fens are open, wet habitats dominated by grasses and sedges. They occur in areas where the soil is saturated or slightly submerged in water for most of the year. In summer, the soil can become dry and exposed.

Small sedge meadow near Aleck Meadow Reservoir

Small sedge meadow near Aleck Meadow Reservoir

Fens and marshes are usually distinguished by the presence or absence of peat mosses. Fens have peat mosses growing in them, and they are usually wetter or flooded longer than marshes. Marshes have no peat mosses and, though the soil is always saturated, are usually only flooded for a short time in the spring.

Selected Plants

Herbs

Occurrence

There is a small marsh on the east side of Aleck Meadow Reservoir. There is a large fen, called Beaver Swamp or 'Annichen's Swallow,' between Sphagnum Pond and Continental Road. Smaller stands can be found in wet areas throughout the forest.

Ecology

Beaver Swamp (Annichen's Swallow), actually a grassy fen

Beaver Swamp (Annichen's Swallow), actually a grassy fen

Sedge-dominated marshes occur on sites with organic soils that are saturated throughout the year. Though Sphagnum species are common, there is little accumulation of peat. Grassy fens occur on mineral soils and are often flooded for a longer period.

Marshes and fens are vulnerable to infestation by purple loosestrife (Lythrum salicaria) and reed (Phragmites australis). These invasive weeds can quickly take over a wetland that is disturbed.

History

Marshes and fens are often short-lived. If they do not remain flooded for much of the year, they are often invaded by wetland shrubs. They often form at the sites of old beaver ponds.

Also Called

Selected References

For general references see the reference page.

Photos: Kerry Barringer