Fen Management Handbook - Scottish Natural Heritage

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Consultation with the relevant county or local planning authority
archaeologist is recommended before undertaking any work which
may affect water or land levels on fens. University archaeological,
geographical or biological science departments may be able to help take
and analyse core samples.
7.1.1 Decide on desired or target fen type
Most fens include a range of conditions, and a variety of different types of
vegetation. For example a soligenous fen will have drier areas, discrete seepage
zones, and areas where water collects, whereas on a floodplain (topogenous) fen,
the different types of fen vegetation found will depend on the surface level and
proximity to the flood source. Defining what type of fen is aimed for where, taking
into consideration topography and available water sources, is crucial before any
water management is undertaken. The conservation objectives for a protected site
will help to decide or prescribe the desired fen type, but climate and other potential
changes in the long term availability, sustainability and variability of the required
sources of water will also need to be taken into account.
7.1.2 Define the optimum water sources and regimes for the various fen types over
the different seasons through the year
Fluctuation in water levels is entirely natural, particularly on certain types of
floodplain where water level may be high in winter but relatively low in summer.
Some vegetation, such as that found around water-fringe fens is adapted to these
fluctuations – the vegetation mat rises and falls with the water level. Other types
of vegetation cannot cope with such fluctuations. For example fen types sustained
by groundwater seepage and springs or those in hollows cannot withstand being
overtopped by floodwaters, especially when the surrounding land is intensively
cultivated or bare soil and intense rainfall increases the risk of higher than normal
nutrient loads. Depth of flooding can be as important as frequency. Water quality
also needs to be taken into account. An alkaline fen would require continuous
discharge from alkaline groundwater in all seasons.
7.1.3 Determine whether/how fen hydrology has changed
Various sources of observational evidence should be used to determine how the
hydrology of the fen has changed, including for example:
– observations by an experienced and knowledgeable site manager;
– repeated vegetation sampling (e.g. Common Standards Monitoring);
– assessment of plant community extent from aerial photographs and maps;
– anecdotal evidence;
– research (i.e. results from site specific investigations).
The types of change include water levels, degree/timing of floods, fluctuations and
loss of supply.
7.1.4 Work out why fen hydrology has changed
Determining which factors have influenced the fen and been responsible for the
identified hydrological changes requires consideration of: