La diversitat de líquens saxícoles de l'avantpaís meridional dels Pirineus orientals

Abstract

This contribution to the knowledge of the saxicolous lichen catalogue from the southern foreland of the eastern Pyrenees has yield a list of 312 taxa. Among them, 14 are newly quoted for Catalonia: Alyxoria variiformis, Caloplaca emilii, Clauzadea chondrodes, Encephalographa elisae, Hymenelia coerulea, Lathagrium dichotomum, Lecidea swartzioidea, Lemmopsis arnoldiana, Lepraria umbricola, Myriolecis prominens, Placidium adami-borosi, Staurothele nantiana, Thalloidima opuntioides, Toninia tristis subsp. asiae-centralis, and Zahlbrucknerella calcarea. In addition, C. emilii is the first record in the Iberian lichen biota. The catalogue has been analysed in terms of available geological substrates and habitat types. Species richness varies markedly between habitats, not between geological substrates, except for a slightly increase in Cretaceous calcareous rocks and dolomites. Species composition is extremely different between sites, independently of habitat or geological substrate. The average value of dissimilarity index reaches the 90 %. This heterogeneity in species composition shows a great variability within the considered factors, but not between those factors. On the other hand, abundance of functional traits holds a large homogeneity between sites, with an average dissimilarity index reaching 27 %. A substantial low variability is found within factors, compared with species composition. The features of the southern Pyrenean foreland affords a large set of geological substrates; however, saxicolous lichen communities do not seem to be related with such diversity. In addition, adaptive responses to ecological factors by lichen community are more steady despite the large specific heterogeneity.