Fen Management Handbook - Scottish Natural Heritage

It is good practise to record with each photo the date, weather and any
management carried out in the photographed area, so that this can be used in
evaluation of photographs.
Objectivity in NVC Mapping
The NVC methodology provides a very robust and consistent approach
to plant community identification. It is however primarily a method of
identifying communities, not a mapping and monitoring tool. Quadrat
locations are selected by eye as being representative, but this can
lead to a subjective approach in visually identifying and mapping
communities, which is prone to errors. Visually dominant species that
occur in several communities are a common source of error and can
lead to misidentification of basic habitat type. For example both greater
tussock sedge and common reed are visually dominant in wet woodland,
sand dune, open vegetation, swamp and mire NVC communities,
but greater tussock sedge occurs in 15 communities and 4 habitats,
while common reed occurs in no less than 46 communities and all 5
habitats. Both are constant in several communities, some of which are
differentiated by the presence of much smaller and less frequent plants.
To maintain as much objectivity as possible, surveyors should:
– Read and routinely re-read the introductory chapters for the relevant
habitat types in British Plant Communities, together with the Users’
Handbook (Rodwell J S, 2006).
– Take great care to select quadrat locations that are typical of the
actual surrounding community, not of the predicted or assumed NVC
community.
– Record an absolute minimum of three quadrats (ideally five quadrats
or more) in each community that can provide habitat monitoring
evidence.
– Record each quadrat formally, with a habitat description.
– Be alert for linear communities or small isolated communities
adjoining the principal communities, and take care to record these
separately.
– Whenever a community does not key out easily or there is some
feasible doubt over the basic habitat type, use a programme such as
MATCH, TABLEFIT, or MAVIS to sort the data.
Rodwell J S, 2006: National Vegetation Classification: Users’
Handbook, JNCC 2006
10.3.4 Geo-statistical Vegetation Mapping and similar GIS spatial
analysis techniques
These methods combine the accurate mapping of physical attributes, principally
topography and hydrology, with random sampling of vegetation. Presence or
absence of indicator species is recorded at a large number of very accurately
located (i.e. within 1 m) sample points. Statistically based interpolation methods
(the most commonly used being ‘kriging’) are used to predict the occurrence of a
species, giving a map layer that models the distribution of that species.
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