Invertebrate survey at Gunpowder Park, the former Royal Ordnance Site in the Lee Valley
Appendix 1
National status explanation
Nationally Rare species arc those falling within the Status categories defined in the British Red
Data Books (Bratton. 1991; Shirt, 1987). These are internationally recognised species listed in the
various Red Data Books published by or under the auspices of, the International Union for the
Conservation of Nature (IUCN). Species included may not be informally removed or transferred
between categories. There are four main categories; RDB 1 (Endangered) species are taxa in
danger of extinction and whose survival is unlikely if the causal factors continue operating. These
include: species known from only a single locality since 1970; species restricted to habitats which
arc especially vulnerable; species which have shown a rapid and continuous decline in the last
twenty years and are now estimated to exist in five or fewer localities; species believed extinct but
which would need protection if re-discovered. RDB 2 (Vulnerable) species are taxa believed
likely to move into the Endangered category in the near future if the causal factors continue operating.
These factors include: species declining throughout their range; species in vulnerable habitats;
species whose populations are low. RDB 3 (Rare) species are taxa with small populations, which
are not at present endangered or vulnerable but that are at risk. These include species that are
estimated to occur in fifteen or fewer localities. RDB K (Insufficiently Known) species arc taxa
suspected to fall within the RDB categories but which are at present insufficiently known to enable
placement. A review of statuses is taking place using new IUCN criteria, but this has not yet been
applied to the majority of invertebrate groups. A national spider review is currently in progress.
Nationally Scarce species are those falling within the Nationally Notable categories introduced by
Ball (1986). They are species that are estimated to occur within the range of 16 to 100 ten-kilometre
squares of the British National Grid system since 1970. These have subsequently been revised for
a number of taxa; those affected in the results for the Royal Ordnance site are Araneae (spiders),
revised by Merrett (1990), aculeate Hymenoptera, revised by Falk (1991a), Coleoptera, revised by
Hyman & Parsons (1992, 1994), Diptera, revised by Falk (1991b) and Hemiptera revised by Kirby
(1992). Nationally Notable species are subdivided as follows: Na (Notable A) species estimated to
occur within the range of 16 to 30 10-kilometre squares of the National Grid System. Nb (Notable
B) species estimated to occur within the range 31 to 100 10-kilometre squares of the National Grid
System. N (Notable) Diptera (flics) and some Coleoptera (beetles) arc not separated, falling into
either category Na or Nb.
Nationally Local species are those that do not qualify as Nationally Notable but are less widespread
and restricted than species considered common. Remaining species are either considered 'Common7
or, where insufficient information is available, 'Unknown'. These designations have been obtained
from the JNCC Recorder 3 software.
Regional (Essex) status explanation
Essex Red Data species are those included in the provisional Essex Red Data list produced by the
Field Club's County Recorders and other Essex naturalists on behalf of English Nature. The list is
currently available at www.essexfieldclub.org.uk. At present some taxonomic groups remain to be
done, and Diptera (flics) is incomplete, covering only those taxonomic groups covered by Falk's
1991 status review (Falk 1991b). The remaining Diptera families are awaiting the availability of
forthcoming national status reviews.
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Essex Naturalist (New Series) 21 (2004)