Winter 2002

Small is beautiful: rare mosses and liverworts on the Sefton Coast

Jenny Duckworth, Plantlife

Sand dunes are renowned for their rich diversity of wildlife, including some of our more charismatic species such as Natterjack toads and orchids. But they are also play host to a group of less well known plants - the mosses and liverworts, known collectively as bryophytes - that form a fascinating miniature world amongst the sand grains.

The Sefton Coast is probably the most important dune system for bryophytes in Britain, with no less than three of our most threatened species that are listed under the UK Biodiversity Action Plan. Petalwort (Petalophyllum ralfsii) is perhaps the most distinctive of these - a bright green liverwort that resembles a minute lettuce, measuring no more than 5mm across. Long leaved thread-moss (Bryum neodamense) is relatively large as mosses go, forming tufts up to 10cm tall, and has blunt leaves on a red stem. Warne's thread-moss (Bryum warneum) is smaller, but has its fruiting body borne on a disproportionately long stalk. This moss is infamous for being incredibly difficult to identify, success being gained from hours if not months of painstaking examination under the microscope!

All three species are very particular as to where they grow and inhabit similar places - bare areas of damp sand in or on the edges of dune slacks. Once larger vascular plants such as Creeping Willow colonise, the bryophytes are unable to 'keep up' with the competition and are eventually lost from these areas. Ensuring that there is a continual supply of damp bare sand for these species to colonise is a key to their success. Dunes are by their very nature dynamic so areas of bare sand appear from time to time of their own accord. Grazing by rabbits and stock is also important here to keep some of the taller vegetation in check and open up the ground. Even trampling by people can be beneficial so long as it is not too heavy.

These species have been lost from several of their former sites in the past due to a variety of pressures including coastal development and drainage, so particular care is needed to look after those that remain. The spread of Sea Buckthorn is a widely acknowledged problem, with a continual struggle in place to keep it in check, whereas other threats are rather more difficult to pin down such as enrichment by nutrients. But we now know where these species occur and what they need to survive - which is an important first step- and the effective partnership on the Sefton Coast is working hard to ensure that the needs of this special group of species are taken into account in the management of their sites.

A leaflet entitled 'Looking after mosses and liverworts in coastal dune slacks' giving more information on these species is available.
Copies will be available from Plantlife (Tel: 020 7808 0100 Email: