This new census catalogue of Irish lichens, based on vice-county distribution, has been produced with the generous support of the National Parks and Wildlife Service of the Department of the Environment, Heritage and Local Government, Dublin, and the Northern Ireland Environment Agency, Belfast. Through LichenIreland, a project championed over several years by National Museums Northern Ireland, there has been a 43% increase in the average number of records per vice-county. Many members of the British Lichen Society participated in surveys.

There has been a 78% increase in post-1960 records since the 2nd edition was published in 1994, this despite the removal of numerous taxa on the basis of re-examination of reference collections and doubt cast on records not supported by voucher material. The catalogue enumerates 1,165 lichen taxa (1,134 species, 5 subspecies, 20 varieties and 6 forms) and 205 taxa of lichenicolous fungi and non-lichenized fungi.

An analysis of post-1960 records on a 10 × 10 km basis, as determined from the BLS's Distribution Maps Scheme database at Bradford University reveals that almost a third of them (327 of the 1010 squares) have fewer than 50 taxa recorded, indicating that Ireland still offers considerable scope for lichenological fieldwork.