|Basic Information||Biotope classification||Ecology||Habitat preferences and distribution||Species composition||Sensitivity||Importance|
Image Roger Covey - Yellow and grey lichens on supralittoral rock. Image width ca XX m.
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LR.L.YG recorded () and expected () distribution in Britain and Ireland (see below)
Temperature range preferences - Data deficient
Water clarity preferences - Not relevant
Limiting Nutrients - Nitrogen (nitrates)
Other preferences - Hard siliceous rocks
The west shores of Britain and Ireland exhibit more species rich lichen communities than eastern shores. Foliose-terrestrial or sun-loving species are conspicuously absent from eastern shores (Fletcher, 1980). The xeric-supralittoral zone is better represented in south west England and Ireland than in western Scotland, presumably because the lower temperatures and increased rainfall of western Scotland increase leaching from terrestrial habitats and reduced saline influence. The lack of terrestrial (rather than maritime) lichens in south west Britain is probably due to an excess of seawater spray.
Each species of lichen inhabits a very narrow range of environmental conditions and are particularly susceptible to environmental change (Jones et al., 1975). The supralittoral lichen zone probably exhibits its greatest vertical extent on wave and wind exposed shores, although the species richness and cover is probably greatest on sheltered shores. The vertical distribution of supralittoral species is dependent on a number of environmental factors (see 'zonation' under 'habitat complexity', Fletcher, 1980), however, the primary factors appear to be water availability and desiccation, wind abrasion, salt and nutrients, light intensity and the availability of suitable substrata (for details see individual sensitivity assessments and Fletcher, 1980).
This biotope is characteristic of hard siliceous rock substrata. In the supralittoral, the rock chemistry and texture affects the lichen flora so that the lichens become separated by their salinity and nutritional tolerances. Supralittoral quartzites are almost pure silica and bear depaurate lichen floras dominated by Ramalina siliquosa, while sandstones bear species characteristic of soft siliceous rocks (Fletcher, 1980). Calcareous rocks support few exclusively maritime lichen species. Fletcher (1980) suggested that the ready supply of calcium on calcareous substrata satisfied the lichen's nutritional requirements so that the distribution of lichens was affected primarily by salinity. Soft rocks bear specialized lichen communities and the reader should refer to Fletcher (1980) for details or to LR.Chr for the sensitivity of a similar supralittoral soft chalk biotope.
This review can be cited as follows:
Tyler-Walters, H. 2002. Yellow and grey lichens on supralittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 28/11/2014]. Available from: <http://www.marlin.ac.uk/habitatpreferences.php?habitatid=96&code=1997>