Detecting the drivers of functional diversity in a local lichen flora: a case study on the extinct volcano of Roccamonfina (southern Italy)

Current strategies for conservation reportedly suffer from an inadequate awareness of the drivers affecting lichen diversity, pointing to the need to fully develop a functional approach to lichen ecology. This study is an attempt to detect the drivers affecting functional diversity in the lichen flora of a volcanic Mediterranean area. Data on epiphytic lichen distribution were correlated with information coming from a GIS analysis. Species richness, functional diversity and indicator values of lichens species were analyzed as a function of altitude, bioclimatic patterns and land use patterns. Both taxonomic and functional diversity were found to increase with altitude, peaking at 600 m a.s.l. and slightly decreasing at higher elevations. A filtering effect of altitude on lichen growth-forms was detected at increasing altitude, with foliose isidiate lichens replacing crustose lichens with sexual reproduction, cyanobacteria replacing Trentepohlia as photobiont, and oligotrophic species linked to partially shaded environments gradually replacing species indicating eutrophic conditions. Forest stations impacted by low impact traditional agriculture tended to express higher lichen diversity compared to either undisturbed broadleaved forests or intensive orchards. These data demonstrate the need to integrate traditional low-impact agricultural practices in protected areas. Moreover, they provide the evidence that reanalyzing past and recent lichenological censuses with the proposed analytical tools may help previewing and driving the evolution of endangered ecosystems.