Fen Management Handbook - Scottish Natural Heritage

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Summary of ecological survey requirements
– Map wetland types and relate to the hydrological regime of the fen;
– Survey and map NVC plant communities;
– Record limits on the validity of mapping the NVC communities;
– Compare on-site NVC examples with generic descriptions;
– Note presence, quantity and location of important plant species
(including invasive nonnative species);
– Survey, map and describe fen fauna (birds, invertebrates, mammals) as
well as flora;
– Similarly map and describe features important for non-plant species.
More detailed guidance on NVC and other ecological survey techniques is included
in Section 10: Monitoring to Inform Fen Management.
The hydrological situations commonly recurring in fens are described in The
Wetland Framework (Wheeler, Shaw and Tanner, 2009). The Wetland Framework
presents water supply as a series of different mechanisms (WETMECs), considers
how these are linked to particular fen NVC plant communities and how they might
be affected by various management actions or other interventions.
5.4.2 Geological and soil survey
Information about the geology (deeper rock and soil layers) and surface (drift)
layers is essential to understanding the hydro-geological functioning of a fen. Good
geological maps (solid and drift) are available from the British Geological Society
(BGS). The surface layers (or drift) might be available as soil maps (contact BGS).
Information about the original wetland lies within its layers of peat and silt.
Specialists or informed amateurs can identify the plants in the sediments from
fragments (macrofossils) and from spores and pollen (microfossils). The succession
from one type of fen to another is evident from the sequence of the plant remains
in these deposits. For example, it is possible to see if the site once supported rich
fen (a highly valued type of fen because of its ecological diversity) even though it is
currently covered by reed canary grass (often a less valued type of fen).
Section 9: Creating Fen Habitat goes into more detail about soil and geological
assessment.
5.5 Hydrological and nutrient assessment
Section 3: Understanding Fen Hydrology and Section 4: Understanding Fen
Nutrients described how the quantity and quality of water reaching the fen is of
fundamental importance in determining fen type and features. Detailed hydrological
studies can become very complicated but they may be essential when assessing
the potential impact of plans and projects such as abstractions and discharges.
However, a simplified approach may provide sufficient understanding to inform
decisions on management objectives, for example whether the fens or their subunits
are fed by rainwater, groundwater or surface water. The next step is to work
out the current hydrological regime i.e. sources of water inflow and outflow, their