Over 350 species of lichens have been recorded on Lundy, which is about one-fifth of the total lichen flora of Great Britain, making Lundy a very important site. The clean air, south-western oceanic location, variety of undisturbed habitats and lack of agricultural or industrial contaminants provide ideal conditions for these symbiotic organisms. A lichen is a partnership between a fungus and an alga and can assume a diverse range of forms. The fungus provides the structure and absorbs moisture and the alga provides the food by photosynthesising. Lichens are very slow growing and can colonise a wide range of substrates. On Lundy they can be found from the intertidal zone to the top of the island, on natural rocks, walls, woody and herbaceous plants, exposed peat and sometimes on metal and other man-made surfaces. Lichens reproduce by means of microscopic spores which develop in “fruiting bodies” on the surface of mature specimens. The use of a hand lens will help in observing these structures.
A noticeable feature of the rocks at sea level is the zonation of lichens just above the high tide line. Bands of black, orange and grey lichens can be easily seen from a distance. Higher up above the high tide line and splash zone some of the largest lichens can be found, including the grey-green Sea Ivory Ramalina siliquosa which produces long flowing strands in exposed sites and may cover whole outcrops. One other noticeable feature of exposed outcrops is the Golden Hair Lichen Teloschistes flavicans, a nationally very rare and fully protected species which thrives on Lundy.
The maritime heathland on top of the island is another good habitat for lichens with several species of “Reindeer Moss” such as Cladonia ciliata var tenuis and C. portentosa being quite widespread. Little spots of bright red are sometimes noticed amongst the grey tufts and these are the tips of the fruiting bodies of Bengal Matchsticks Cladonia floerkeana.
Towards the north end of the island are some noticeable exposures of granite which are gradually being re-colonised after disastrous peat fires in 1933 and 1935 when most of the organic matter was burnt off. Lichens are the first colonisers of these habitats and provide a good example of the recovery of a site after serious damage to the environment.
The granite marker stones, in position along the main track since 1909, provide good habitats for lichens, especially species which thrive where there is some nutrient enrichment, such as from bird droppings. The bright orange Xanthoria candelaria is one species which thrives here, but closer examination will reveal many more species, including the brownish foliose Anaptychia runcinata.
Lundy has many stone walls, almost all made of the island’s granite, and these provide ideal habitats for lichens. Different communities can be found on opposite sides of some of the walls, with some requiring shade and others growing well in full sunlight. As many as 50 species can be found on the south-facing side of Halfway Wall, but the north-facing side has a smaller range of species and fewer individuals.
The cemetery at Beacon Hill provides more habitats for lichens in the form of headstones and memorials, some made of the local granite, but some made from imported rocks such as slate and marble which support different lichen communities.
Trees are scarce on Lundy, and are mostly found on the sheltered east side of the island, but despite the paucity of trees about 120 species of lichens have been found colonising them. Many of the lichens on trees are quite large foliose species which completely cover the twigs and branches they are growing on. There are various species of Usnea which are seen as indicator species of very clean air. Some lichens are host-specific, so a species which grows on Beech, may not also occur on Oak. Oak Moss Evernia prunastri, however, seems to be most at home on Blackthorn.
More information can be found in Lundy Lichens by Ann Allen, published in 2007 by the Lundy Field Society.
Text by Andrew Cleave