Current status
Calicium corynellum is a black pin-head lichen which, in its natural habitat, grows on siliceous rock underhangs in very humid conditions. However, at its only known British site it occurs both on sandstone and mortar on the sheltered, slightly damp, north-facing wall of a church tower. It may possibly grow or live on Lepraria species.
This species is restricted to one site in Northumberland, where it was discovered in 1972. It has been closely monitored since it was found and is thought to have decreased in extent by 90%. It is now restricted to only four stones and apothecia are scarce. It is otherwise known from central and northern Europe and also from Canada.
This species is Critically Endangered in Great Britain. It receives general protection under the Wildlife and Countryside Act 1981.
Current factors causing loss or decline
The dwindling size of the only known population of this species is thought to be due to the replacement of a stone slab, at the base of the tower on which it grows, with gravel. This has meant that rain water cascading down from a pipe above no longer splashes high up the wall, and consequently a drier microclimate has developed, which appears to be unsuitable for this species.
Building work, such as repointing and restoration of the church walls is threat to this species.
Botanical collection is a possible threat because of the small size of the only known population.
Current action
Periodic monitoring of the only known site is being carried out.
Relevant officials at the church where this species occurs are aware of the presence of this species.
Action plan objectives and targets
Maintain all known populations
If biologically feasible, restore Bywell population to former extent
Proposed actions with lead agencies
Policy and legislation
Consider this species for inclusion on Schedule 8 of the Wildlife and Countryside Act, 1981 if it meets relevant criteria. (ACTION: DETR, JNCC)
Site safeguard and management
Ensure that any repair work to the tower is carried out in a sensitive manner, using the appropriate materials. (see 5.4.1) (ACTION: NE)
Re-establish the moist conditions in which this species originally thrived. This may best be achieved by replacing the stone slab which was previously removed from the base of the tower (see 2.1). (ACTION: NE)
Species management and protection
None proposed.
Advisory
Advise the officials of the church site of the presence and importance of Calicium corynellum, specific management for its conservation (including the need to reinstate moist conditions), and any potentially damaging actions (particularly building works). The church officials should have access to specialist advice, if needed. (ACTION: NE)
Future Research and Monitoring
Continue with regular monitoring at the only known extant C. corynellum site. (ACTION: NE)
Undertake an autecological assessment of this species in order to refine management for its conservation. (ACTION: NE)
Communications and Publicity
Publicity for this species is not recommended because of the small size of the population and the threat from botanical collecting.
Links with other action plans
None given.
Publication details
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume III: Plants and fungi (February 1999, Tranche 2, Vol III, p89)
Related links
ARKive Visit the ARKive website to view images and further information relating to this species
Plantlife Read the Plantlife species dossier relating to this species