Diversity and ecology of the bryophytes in the cave environment: a study on the volcanic and karstic caves of Sicily

The results of a long investigation (20 years) on bryophyte diversity of 28 Sicilian caves are reported; the study regarded both karstic and volcanic caves, located at altitudes ranging from 15 to 2030 m a.s.l. The bryophyte diversity consists of a total of 136 taxa, 20 liverworts, 3 hornworts and 113 mosses. The ecological analysis was performed using the Ellenberg indicator values for moisture, light and soil reaction to the substrate. On the whole, mesophytic and meso-hygrophytic, sciophytic and photo-sciophytic species strongly prevail independently from the geological nature of the caves; the values of the soil reaction to the substrate well reflect the characteristics of the substrate. The phytogeographical analysis shows the prevalence of the Mediterranean species, followed by the temperate and southern-temperate species. It is remarkable the occurrence of boreo-arctic-montane species, which find refuge for their survival in some high-altitude caves. Some typical species well adapted to the cave environment are reported, including Amphidium mougeotii, Isopterygiopsis pulchella, Thamnobryum alopecurum and Rhynchostegiella tenella, showing a troglophilous character. The occurrence of species of phytogeographical significance, as well as of conservation interest, e.g. Ptychostomum cernuum, Tortula bolanderi, Rhabdoweisia fugax, Grimmia torquata, Brachytheciastrum collinum, very rare in Italy, is emphasized too.