Fen Management Handbook - Scottish Natural Heritage

for Ornithology, the Bat Conservation Trust and similar organisations are good
sources of advice. National conservation bodies publish manuals for work with
species groups, such as The herpetofauna workers manual (Gent & Gibson, 2003).
Breeding success may be the most dependable indicator of habitat quality. For
example, bird species that are broad spectrum insectivores with highly visible
young are in effect testing the habitat diversity over several weeks and providing
quantifiable data, but expertise is required to develop this approach to avoid
misinterpretation. For example, a low return of migrants will allow bigger territories
and cause less stress on the adults, but if the population is high the marginal
territories will be occupied by weaker or less experienced birds, so inner territories
should be observed.
10.6 Assembling an overall biological monitoring plan
The principal biological monitoring system for a fen will almost always be a
botanical method tied to mapped physical habitat data. Geo-statistical vegetation
mapping methods are highly attractive for their objectivity and integration with other
GIS based data, but they are resource demanding and dependent on specialised
skills. Community mapping is an alternative, if rigorously applied, and uses more
widely available skills. Precise questions about changes to the plant community
resulting from changes in one identified physical factor can be answered by the
use of fixed quadrats and transects and fixed point photography. None of these
methods are reliable for particularly rare species, for which the traditional walk-over
count may be best.
NVC community mapping is the usual starting point for hydro-ecological studies of
a site, and can provide the basis for several techniques. Care over position fixing
and boundary mapping at this stage can add a great deal of reliability and simplify
future work.
All monitoring methods have advantages and drawbacks; there is a continuum
between techniques which are easy to carry out and interpret, and those which are
very demanding but more objective. A dual approach is therefore recommended,
using one very refined method and one simpler method that allow a sweep-up
check over most of the site. Combining an indicator species survey with a standard
walking route taking in the perimeter of the fen and an internal circuit can formalise
the most traditional but informal of monitoring tools, the manager’s walkabout.
Long-term standardised practice can provide a very accessible record and a broad
interpretation of changes. Formal developments such as Natural England’s SSSI
woodland monitoring methodology and the River Habitat Survey, offer suggestions
for adding value to a walkabout.
The frequency of monitoring surveys has to be chosen with some care, since the
most rigorous and objective methods are also the most demanding. Community
change may not be apparent over one or two years, so annual full site community
mapping would not be a good use of resources. However, a long period between
surveys capable of providing strong evidence of change may result in habitat
decline becoming well-established before it is detected. Counts of rare herb
species should be annual, to allow confidence in series of results that show a long
term trend. Community mapping at three to five year intervals will provide useful
results.
10.7 Hydrological monitoring of soil water and groundwater levels
Soil water level is an important, and often defining, parameter in relation to
ecological distribution within a fen because wetland plants and habitats often have
precise requirements in terms of the absolute and seasonally fluctuating elevation of
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