Saproxylic Quality Index: Evaluated sites ranked by SQI

The Saproxylic Quality Index (Fowles, Alexander & Key, 1999) 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, 598 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 list of 605 saproxylic species for which rarity scores, based on their known status and distribution, have been assigned (Anoplodera livida was included in the published list in error and Anaspis septentrionalis has been synonymised with A. thoracica). The IEC (Index of Ecological Continuity) is also calculated for each site list: the species and grades used are taken from the latest revision (Alexander, 2024).

There have been considerable advances in our understanding of the ecology and status of saproxylic Coleoptera in Britain over the 25 years since the SQI Index was developed; new species have been added to the British list, several have extended their range such that their conservation status needs revising, and others have been shown not to be as strongly associated with saproxylic habitats as once thought. Almost half of the SQI species have now been assessed in Species Status Reviews under IUCN Red List criteria. The revised statuses have been utilised in the accompanying calculations.

Scores have been assigned to IUCN statuses as follows: CE, CR, EN & RE = 32; VU = 24; DD = 2. Near Threatened (NT) species that are also Nationally Rare score 24, otherwise they score 16. Least Concern (LC) species are scored according to their original GB distribution: species previously classed as Common score 1; Local score 2; others score 4.

Calculating indices: To calculate SQI and IEC values for site inventories, click on the 'Submit New List' button in the top toolbar and enter relevant data.
Rankings: All sites with at least 40 qualifying saproxylic species are displayed by clicking on the Rankings button
Search: This allows you to look for sites with data already entered or to see which sites a particular species has been reported from


Alexander, K.N.A. 2024. Updating the Index of Ecological Continuity as used in site quality assessment for saproxylic beetles. British Journal of Entomology and Natural History, 37: 33-45.

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