The Index of Ecological Continuity (IEC) for beetles was originally developed as a means of producing a simple statistic which could be used in grading a site for its significance to the conservation of saproxylic (wood-decay) beetles based on ecological considerations rather than rarity. Several important sites have been designated as a result of this approach to interpreting site species lists as saproxylic assemblages of ecological significance.
The Index is based on a listing of the species thought likely to be the remnants of the saproxylic beetle assemblage of Britain’s post-glacial wildwood, and which have survived through a history of wood pasture management systems in certain refugia. The list was first published as Harding and Rose 1986. The original list scores 188 of 695 listed British native saproxylic beetles. The list was subsequently updated, see IEC (Revised). Both versions of the IEC are provided within Pantheon, to maintain audit purposes, so that changes in site score can be related back to individual species assessments.
The IEC groups species according to the extent to which they have been consistently recorded from areas of ancient woodlands with continuity of dead-wood habitats, particularly in pasture-woodlands. Note that Pantheon displays and uses the Score number (not the Group number) in order to calculate the IEC.
- Group 1: Species which are known to have occurred in recent times only in areas believed to be ancient woodland, mainly pasture-woodland. Score = 3
- Group 2: Species which occur mainly in areas believed to be ancient woodland with abundant dead-wood habitats, but which also appear to have been recorded from areas that may not be ancient woodland or for which the locality data are imprecise. Score = 2
- Group 3: Species which occur widely in wooded land, but which are collectively characteristic of ancient woodland with dead-wood habitats. Score = 1
The total IEC score is calculated by listing all the qualifying species recorded since 1950 and summing their scores. (Pantheon does not apply any date filtering, so users should exclude pre-1950 records from their analysis.)
For more information see: Harding, P.T., and Rose, F. 1986. Pasture-woodlands in Lowland Britain - A review of their importance for wildlife conservation. Institute of Terrestrial Ecology.