Analisys of the bryophytes diversity of mountain ranges in Sicily.

Abstract

The focus of this study was an analysis of the bryophyte flora of the main Sicilian mountain ranges, i.e., Peloritani, Nebrodi and Madonie mountains, located along the northern side of the Island, the Sicani mountains, located in the west-central Sicily and the Etna, the highest and most active volcano of Europe. The overall bryoflora consists of 504 taxa, 400 mosses and 104 liverworts and hornworts. It represent the 85.3% of the whole Sicilian flora; the mosses are referred to 37 families, the liverworts together with hornworts to 31 families. The phytogeographical analysis has shown the prevalence of the Mediterranean species, with the highest value on the Sicani mountains. It is noteworthy the occurrence of a group of arctic-montane and boreo-arctic-montane species which find refuges for their survival on Sicilian mountains, such as Barbilophozia hatcheri, Brachytheciastrum collinum, B. cirrosum, Grimmia alpestris, G. fuscolutea, G. donniana, G. torquata, Hypnum procerrimum, Jungermannia sphaerocarpa, Nardia geoscyphus, and Tortula hoppeana. The relationships of similarity among the moss floras of mountain systems reflects their geographical location and geological features, while the similarity of the hepatic flora the different degree of edaphic and atmospheric humidity. As regards the bryophyte vegetation, 56 syntaxa (associations and subassociations) are reported from the Sicilian mountains; the communities of the alliances Racomitrion acicularis, Distichion capillacei, Pohlion crudae and Andreaeion petrophilae are the most chorologically interesting. The greatest number of communities occurs at altitudes between 800 and 1600 m a.s.l. with higher values between 1000 and 1200 meters; above 1600 meters the community richness decreases, remaining high only on the Etna up to 1800 meters. A marked dissimilarity of the floras was observed between the individual mountain ranges. Their specificity even at low altitudes suggests that they have not undergone a clear decharacterization because of human activity. Some differences are observed in the variations of the values of species richness with the altitudinal gradient. The maximum number of taxa in fact can be found at different altitudes in mountain ranges: at lower altitudes of Etna and especially Peloritani at higher elevations in the Madonie, Nebrodi and Sicani mountains