Fen Management Handbook - Scottish Natural Heritage

9.3 What type of fen?
New fens can be located in lowland situations or at high altitude, and range in size
from tens of square metres of flush or spring-head fen, to several hundred hectares
of flood-plain fen and reed-beds. The type of fen can vary as much as the size, from
a base-rich fen receiving ground-water rich in calcium and other base cations from
petrifying springs, to a poor-fen receiving ground-water with low concentrations of
base cations, such as the valley mires of the New Forest. The specific hydrological
requirements of many fen types (see Section 3: Understanding Fen Hydrology) limit
the potential for the creation of some types of fen.
The Wetland Vision launched in 2008 provides a lot of useful information
and maps on the types of fen that can potentially be created across
England as well as some of the constraints on the creation of wetlands
in general.
Reedbeds are a type of fen that may, with appropriate management, develop
into more diverse herbaceous fen vegetation as litter, silt and peat build up. The
creation of reedbeds on various sites may eventually increase the extent of other
types of fen vegetation if natural success is allowed. The length of time over which
this may occur is difficult to determine because of the relatively limited experience
nationwide of wetland habitat creation.
Leighton Moss in Lancashire was one of the first modern examples of
fen creation where arable fields allowed to flood shortly after the First
World War rapidly developed into reedswamp. Around the margins
greater tussock sedge fen has already developed. Many parts of the
reed swamp might have developed into drier herbaceous fen without
regular mowing.
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