Everything about Fen totally explained
A
fen is a type of
wetland fed by surface and/or groundwater. Fens are characterized by their water chemistry, which is
neutral or
alkaline. Fens are different from
bogs, which are
acidic, fed primarily by rainwater (
ombrotrophic) and often dominated by
Sphagnum mosses.
Derivation
The word "fen" is derived from
Old English fenn and is considered to have proto-Germanic origins, since it has cognates in
Gothic (
fani),
Old Frisian (
fenne),
Dutch (
veen) and
German (
Fenn(e),
Venn,
Vehn,
Feen).
Fen flora
Fen is a phase in the development of
natural succession from open
lake, through
reedbed, fen and carr, to
woodland, or as the peat develops and its surface rises, to
bog.
Carr is the northern European equivalent of the wooded
swamp of the south-eastern
United States. It is a fen overgrown with generally small trees of species such as
willow (
Salix spp.) or alder (
Alnus spp.). A list of species found in a fen therefore covers a range from those remaining from the earlier stage in the successional development to the pioneers of the succeeding stage.
Fen also merges into freshwater marsh, when it develops more in the direction of grassland. This is most likely to occur where the tree species of carr are systematically removed by man for the development of
pasture (often together with drainage), or by browsing wild animals, including
beavers.
The water in fens is usually from groundwater or flowing sources (
minerotrophic) with a fairly high pH (base-rich, neutral to alkaline). Where the water is from rainwater or other sources with a lower pH (more acidic), fen is replaced by vegetation dominated by
Sphagnum mosses, known as
bog.
Where streams of base-rich water run through bog, these are often lined by strips of fen, separating "islands" of rain-fed bog.
List of fen flora species
The following is a list of plant species to be found in a north European fen with some attempt to distinguish between reed bed relicts and the carr pioneers. However, nature doesn't come in neat compartments so that for example, the odd stalk of common reed will be found in carr.
In pools
In typical fen
Flat sedge; Blysmus compressus
Great fen sedge; Cladium mariscus
Lesser tufted sedge; Carex acuta
Lesser pond sedge; Carex acutiformis
Davall's sedge; Carex davalliana
Dioecious sedge; Carex dioica
Brown sedge; Carex disticha
Tufted sedge; Carex elata
Slender sedge; Carex lasiocarpa
Flea sedge; Carex pulicaris
Greater pond sedge; Carex riparia
Common spike-rush; Eleocharis palustris
Few-flowered spike-rush; Eleocharis quinqueflora
Slender spike-rush; Eleocharis uniglumis
Broad-leaved cotton sedge; Eriophorum latifolium
Reed sweet-grass; Glyceria maxima
Yellow flag iris; Iris pseudacorus
Brown bog [sic] rush; Schoenus ferrugineus
In fen carr
Narrow small-reed; Calamagrostis stricta
Purple small-reed; Calamagrostis canescens
Tussock sedge; Carex paniculata
Cyperus sedge; Carex pseudocyperus
Wood club rush; Scirpus sylvaticusFurther Information
Get more info on 'Fen'.
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