Abstract
78 lichen species, the list of which was given, were found on 42 erratic blocks. There arę a few very rare and becoming extinct on the Polish lowland taxa among them, e.g. Aspicilia gibbosa (Ach.) Koerber, Bacidina inundata (Fr.) Yezda, Micarea syhicola (Flotow) Yezda et V. Wirth, Porina chlorotica (Ach.) Miill. Arg., Rluzocarpon lecanorinum Anders and Xanthoparmelia angustiphylla (Gyelnik) Hale. A tendency to decrease the epilithic flora of erratic blocks was stated. Natural and anthropogenic factors that arę dangerous to epilithic lichens were described. Monitoring of the most valuable boulders is necessary, including frequent and periodical evaluation of the conditions of a given habitat. The protection must include smaller boulders, stones and groups of them.
Keywords
lichens; erratic blocks; nature protection; landscape parks; N. Poland