Skomer Island supports a diverse and ecologically significant
lichen flora, with 248 recorded species (as of 1995), including numerous
saxicolous (rock-dwelling) species that grow in the island's exposed maritime environment. The
lichen communities on the island shows well-defined zonation patterns, influenced by rock type, exposure to
salt spray, and nutrient enrichment from the island's abundant seabird populations. The lower
littoral zone is dominated by
Hydropunctaria maura and associated species, forming a black crust on wave-exposed rocks. Above this, a striking yellow-orange band is created by
Teloschistaceae-family lichens, such as
Caloplaca marina and
Verrucoplaca verruculifera, while the xeric-
supralittoral zone supports communities dominated by
Ramalina siliquosa and other maritime lichens. In areas with high levels of seabird activity,
nitrogen- and
phosphorus-rich
guano influences the composition of lichen communities, promoting the growth of species such as
Xanthoria parietina and
Candelariella coralliza on bird-perching rocks. Several rare and biogeographically significant lichens occur on Skomer, including
Roccella fuciformis, a Mediterranean-Atlantic species at its northern limit, and
Teloschistes flavicans, a species of conservation concern in Britain. The island's geological diversity, with acid rhyolites, basaltic lavas, and quartz conglomerates, further contributes to the variety of lichen habitats. Monitoring programs have been established to track long-term changes in lichen populations, particularly in response to fluctuations in seabird numbers and environmental disturbances such as oil pollution. The 1996
Sea Empress oil spill raised concerns about potential impacts on Skomer's maritime lichens, highlighting the need for ongoing conservation efforts. ==Access==