Important Plant Areas for algae - Natural History Museum

iii) Status
In some cases the sites fell within SACs or SSSIs. Here the status is included but the IPA proposed may
only be a part of the designated area.
iv) Application of IPA criteria for UK IPAs
At the UK level, the qualifying criteria applied were those stated in Box 1 plus an additional criterion D:
Criterion A: Site holds significant populations of one or more species that are of global or European
conservation concern.
Criterion B: Site has an exceptionally rich flora in a European context in relation to its biogeographical
zone.
Criterion C: Site is an outstanding example of a habitat type of global or European plant conservation
and botanical importance.
Criterion D: A nominated site considered to be important but for which further information is required
(‘data deficient’).
At the UK level the criteria were applied as follows:
Criterion A was assigned to a site if there was a species or species:
i) confined to a specific habitat or habitats that are rare or absent elsewhere in Europe in the marine
context, e.g., chalk cliffs, maerl beds;
ii) nationally rare (Table 4.4), possibly declining and, if known, rare in a European context;
iii) confined to only one known site in the UK;
iv) nationally rare and a large proportion of the world’s known population (e.g., Schmitzia hiscockiana -
about 98% of the world’s population occurs in the sea around the UK).
Criterion B was assigned to a site if a large number of species had been recorded from it. If this
information was not directly available, it was ascertained by consensus mapping (see 4.23) which was
also used to confirm sites based on recorded numbers of species. Habitats and species composition
(assemblages) were also taken into account. One site might not be diverse in terms of number of habitats
present or have habitat types which typically have large numbers of species but might be rich in numbers
of species or species assemblages for that particular habitat or geographical location.
Criterion C was assigned to a site if it was an outstanding example for the algae of
habitats which already have UK BAP conservation status: chalk, maerl and eel grass (Zostera), plus
exceptional reef systems supporting rich algal communities, and saltmarsh and gravel sites to which some
algae are confined and these are frequently neglected habitats.
v) Number of species recorded
For many sites it was not possible to provide this information. Where it has been possible, e.g. published
species lists of good quality, an indication of diversity has been given based approximately on 200 = very high
diversity. However, the habitat was also taken into account when assessing the richness of the site, given
that some have inherently higher diversity than others.
vi) Site description
Site descriptions were compiled from a variety of sources including from the nominee, additional
personal knowledge of the authors of this report, literature and web-based sources. Given the enormous
range of sources and the difficulty of assessing the quality of some of these, a comprehensive literature
search was not undertaken, but a list of the main references consulted are given in Appendix 7.1.
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