Invertebrate survey at Gunpowder Park, the former Royal Ordnance Site in the Lee Valley
species which have shown a continuous decline over the last twenty
years.
Regionally Important species which are important in a national context because the county
contains a significance proportion* of the national populations.
species which are important in a national context because they have a
close association with a specific nationally threatened habitat included
in the Biodiversity Action Plan.
species which are important in a national context because they are
dominant in or peculiar to a specific habitat for which the county
contains a large percentage of the national habitat.
*the author has used the following definitions to define a significant
proportion of the national population, using the definitions of RDB
and Notable categories in Shirt (1987), Ball (1986), revised by Falk
(1991):
RDB species - all species not already defined as Essex Endangered or
Essex Vulnerable are included;
Notable A - species with records from 3 or more ten km squares,
representing at least 10% of the known national distribution;
Notable B - species with records from 5 or more post-1980 ten km
squares, representing at least 5% of the known national distribution.
Essex Unknown species for which there is insufficient data available to determine a
reliable threat status but which may be under significant habitat or site
threat.
Species not assigned an Essex Threat status are assumed to be under no direct threat of severe
decline or extinction in Essex at the present time or the county is not known to contain a significant
proportion of the national populations of the species.
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Essex Naturalist (New Series) 21 (2004)