Trace element content and molecular biodiversity in the epiphytic moss Leptodon smithii: two independent tracers of human disturbance.

This paper focuses on chemical composition of the epiphytic moss Leptodon smithii, gathered on Quercus ilex bark, assessed in seven sites located in urban and extra-urban/remote areas of southern Italy, a poorly surveyed geographic area. The concentrations of Cr, Cu, Pb and Zn in moss tissue are generally more abundant in moss gathered in the urban sites; among extra-urban/remote sites Valle delle Ferriere showed the highest metal concentrations, mostly related to an industrial activity occurred in the past. L. smithii chemistry seems influenced by airborne dust locally enhanced by erosion phenomena, long-range transport of pollutants and marine aerosols. Element content in moss is compared with genetic variability of L. smithii estimated in the same sites. Pearson's correlation coefficient between gene diversity and total element load (r=-0.851; p=0.03) suggests that anthropogenic pressure, determining habitat disturbance and fragmentation, leads both to genetic impoverishment consequent to population shrink, and to a higher accumulation in moss tissues, as a consequence of increased airborne major/trace elements. Thus, the coupled evaluation of chemical composition in mosses and gene diversity may prove a useful tool to highlight environmental disturbance in a gradient of land use.