Fragmentation of Mediterranean oak forests affects the diversity of epiphytic lichens

The present study investigated a fragmented Mediterranean oak forest to evaluate so called edge effect on species richness and composition of epiphytic lichen communities colonizing tree trunks. The results showed that in Mediterranean oak forest patches, epiphytic lichen diversity and communities are significantly influenced by microlimatic variables related to the edge effect. Light influx rather than atmospheric humidity and temperature was the main driving factor affecting lichen diversity along the forest edge-interior gradient, while humidity is the prevailing factor inside the forest. It is concluded that forest fragmentation may have a heavy impact of epiphytic lichens, with the reduction and disappearance of typical forest species and the appearance of ubiquitous tolerant species, with an overall impoverishment and banalization of the lichen flora.