Poor fen

A poor fen (or poor-fen, sedge or sedge mire) is a natural wetland habitat, consisting of dense low growth of small sedges and other plants. It develops on wet ground where the water is fairly acidic and has very few plant nutrients.

Poor fen is intermediate between the taller vegetation of fen, which occurs where the water is much less acidic, and the short, mossy vegetation of bog, which is even more acidic.

Ecology

Poor fen is often found as the vegetation of flushes (marshy springs on slopes) where the underlying rock is acidic, and also on flood-meadows, particularly in rarely-flooded, flatter areas where much of the water is ombrotrophic (derived directly from rainfall). Poor fen is usually grazed by wild animals or livestock, preventing ecological succession into wet woodland.

Vegetation

In north-western Europe, characteristic plant species of poor fen communities include common sedge ("Carex nigra"), carnation sedge ("Carex panicea"), star sedge ("Carex echinata"), white beak-sedge ("Rhynchospora alba") and many other small sedges, as well as other plants such as jointed rush ("Juncus articulatus"), marsh cinquefoil ("Potentilla palustris"), bog-bean ("Menyanthes trifoliata"), bog pimpernel ("Anagallis tenella"), lesser skullcap ("Scutellaria minor") and marsh valerian ("Valeriana dioica"). "Sphagnum" mosses also occur, but are not dominant as they would be in bog vegetation. There may also be some grasses, but these are usually inconspicuous amongst the sedges and rushes.

ee also

* Bog
* Fen
* Marsh
* British National Vegetation Classification
* Mires in the British National Vegetation Classification system (see especially M5 to M14, and M31 to M38)