In the context of an inventory of the FFH site „BentheimerWald“ (Lower Saxony, shire of Bentheim) 16 sites of matured forest stands were studied for the presence of bryophytes and lichens. Overall 78 lichen and 64 bryophyte species could be recorded. A rich lichen flora with large populations of indicators for woodlands with a long environmental continuity („ancient woodland“) was observed. Remarkable is the rediscovery of Porina borreri, a lichen species thought to be extinct in Germany, and the finding of the nationwide rare Agonimia allobata as a new element for the lichen flora of Lower Saxony. Due to a high number of lichen species classified as „threatened to become extinct“ and the only recent locality of Porina borreri within Germany the BentheimerWald has to be rated as an important site for the protection of lichen species. Key words: Flechten, Moose, Niedersachsen, Altholz, historisch alte Wälder, Eichen-Hainbuchenwald, Porina borreri, Agonimia allobata.