SAPROXYLIC QUALITY INDEX: EVALUATED SITES RANKED BY SQI

(updated 20 Jan 2007)

The Saproxylic Quality Index (Fowles, A.P., Alexander, K.N.A. & Key, R.S. 1999. The Saproxylic Quality Index: evaluating wooded habitats for the conservation of dead-wood Coleoptera. The Coleopterist, 8: 121-141) is a scoring system designed to assist with the evaluation of the conservation significance of wooded habitats in Great Britain for saproxylic Coleoptera. For this purpose saproxylic beetles were defined as species "dependent upon microhabitats associated largely with the processes of damage and decay in the bark and wood of trees and larger woody shrubs and climbers. This includes sap runs, fungal hyphae or fruiting bodies, rot holes, etc.". The Index is calculated against a standard list of 598* saproxylic species (published in Fowles et al., 1999) for which rarity scores, based on their known distribution, have been assigned. [*Note that these calculations exclude Anoplodera livida (Cerambycidae) which was included in the published list in error]. The sum of these rarity scores for a site list gives the Species Quality Score (SQS) and the Index (SQI) is derived by dividing SQS by the number of contributing species. SQI provides a method for reducing the bias of observer effort but is dependent upon surveys recording information on all saproxylic species, not just the rarer elements. A threshold of 40 qualifying species is required before SQI can be calculated to minimise the impact of recording a rare species in a small sample. 

Ideally SQI should be calculated from recent site lists, but an appropriate period for collated inventories is considered to be post-1980. The list below has been compiled from published information and from site lists kindly contributed by many British coleopterists. However, in most cases the site lists do not distinguish between recent and historic data and, in the case of sites with a long history of recording, SQI may have declined below that presented. The IEC (Index of Ecological Continuity - see Harding, P.T. & Alexander, K.N.A. 1994. The use of saproxylic invertebrates in the selection and evaluation of areas of relic forest in pasture-woodlands. British Journal of Entomology and Natural History, 7: 21-26) is also presented for each site list. Links to regional rankings are presented below.