Lichen species richness on retained aspens increases with time since clear-cutting

► We made a lichen inventory on 720 retained aspens in two ages of clear-felled areas. ► Retained aspens function as lifeboats and provide habitat for colonizing species. ► The epiphytic lichen flora connected to aspen in boreal forest is very species rich. ► Several successional stages are needed to promote the total lichen diversity.