Biodiversity and trace element content of epiphytic bryophytes in urban and extraurban sites of southern Italy

In the present study epiphytic bryophytes were employed as a model system in an integrated way both as bioindicators at species, population and community levels and as bioaccumulators of airborne trace elements. Twenty sites with Quercus ilex trees were chosen in a Mediterranean area both in urban and natural locations, with an altitude ranging from 0 to about 500 m a.s.l., in coastal and inland areas (Campania, Italy). Data on the presence of species, cover values and phenology were recorded for each site and the Index of Atmospheric Purity (IAP) was calculated. The data matrix of frequency/cover x species was analysed by multivariate methods. Data obtained clearly show that in urban sites the number of species and IAP values are lower, and that acrocarpous mosses and vegetative reproduction occur more frequently. Contents of trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, Zn) were measured in four species and concentrations were normalised to the soil pattern by calculating the Enrichment Factor (EF). The results show the large contribution of resuspended soil particles to the chemical composition of the analysed bryophytes. All the examined species were enriched in Cd, Cu and Zn, and in some cases showed high EF for Pb. The differences among epiphytic bryophyte vegetation are discussed in order to evaluate suspected alterations due to human impact and/or environmental change.