The conservation of Didymodon glaucus Ryan in Britain

Abstract

Didymodon glaucus is listed as Critically Endangered in Britain and it is fully protected under domestic legislation. It is known from a single site in England, discovered in 1961, growing on weathered and shaded chalk in a disused chalk pit which is protected within a Site of Special Scientific Interest. However, neglect of the chalk pit lead to successional changes and the apparent loss of D. glaucus. A recovery programme was initiated involving removal of talus and debris from the chalk pit using a mechanical digger. Within one year D. glaucus was observed on the freshly exposed chalk face, probably originating from persistent moniliform gemmae. A second excavation in 2003 also resulted in similar success. Conservation management for this moss therefore involves regular disturbance and exposure of fresh chalk, exploiting the moss’s ability to produce persistent asexual propagules.