Forest restoration interventions in temperate oak woodlands benefit epiphyte communities – The effect of gap openings and deadwood enrichment on bryophytes and lichens

The structure and composition of Central European deciduous oak forests have undergone significant homogenisation in recent centuries due to the long-lasting practice of intensive forestry interventions, resulting in decreased biodiversity. Targeted forest restoration strategies may reverse these processes; however, the success of the forest restoration process aiming for a comprehensive biodiversity increase in epiphyte assemblages is less known, especially the initial impact. The present study revealed the early effect of restoration interventions on bryophyte and lichen communities and their drivers on formerly managed and later abandoned Central European Natura 2000 deciduous oak forests. Abundance and species richness differences were seen, presumably by altered light conditions due to the changed stand structure. Nonetheless, community composition was slightly altered due to dispersal limitation. The responses of bryophytes and lichens differed in their pace. Although basal area and tree size were crucial variables for both groups, the age of the forest stand and tree species diversity differed only for lichens and the relative abundance of admixing tree species only for bryophytes, highlighting their different ecological requirements and sensitivity. Our results showed that restoration interventions aiming at increasing structural and compositional naturalness of deciduous oak forests may positively impact their epiphyte community from a conservation point of view on a long-term scale; however, epiphytes need more time to respond to interventions than other organism groups. Maintaining forest continuity, increasing old-growth attributes of forest stands, continuous small gap openings, high tree species diversity, and protecting habitat trees may enhance high epiphyte diversity in oak forests.