Bringing rare species into the open: they significantly contribute to
species richness in British lichen biodiversity hot-spots
Ecological science aims for general principles that are transferable,
predictive and widely applicable across different local situations.
However, natural history, in contrast to ecology, is rife with examples
of the particular. In this study, we reject the validity of the general
expectation that diversity hot-spots contribute to overall species
diversity accordingly to their species richness. In eleven 1-hectare
forest plots in four distinct areas across Great Britain, we recorded
550 epiphytic and epixylic lichen species, i.e. 73 % of the presently
known British epiphytic flora. Species richness per site was regionally
stratified and mirrored by functional diversity, but species composition
differed among sites, and was unrelated to the distance between sites.
Rare species and species restricted to a single site consistently
represented a high proportion of the local species richness. This
demonstrated that each site contributed substantially and evenly to the
regional and national biodiversity of epiphytic lichens in Britain.
Several functional attributes are quite specific to rare species, so
further disappearance of rare species would lead to disproportionately
high loss of overall functional diversity.