The lichen flora of unprotected soft sea cliffs and slopes

Abstract

Soft unprotected sea cliffs and slopes were surveyed at forty localities around the English coast and found to support a restricted lichen flora that was zoned in relation to sea-level. Bed rock composition, structural heterogeneity and high levels of instability largely control the terricolous lichen vegetation, which is predominantly composed of calcicoles typical of early successional stages. Cyanobacterial lichens are well represented. The species encountered can be arranged into three provisional assemblages characteristic of alkaline bed rock, acidic bed rock, and turf edges. Few species with maritime affinities were present but this group included rarely recorded species of Pyrenocollema and abundant Lecanora zosterae. Other rare and unusual lichens were present, often at a low density and in only a few localities. The lichen flora of soft cliffs has links with that found on urban wasteland and, remotely, with that of sand dunes.