A phytosociological study on the gypsicolous bryophyte communities of Sicily was carried out. The surveyed communities are: Tortuletum revolventis, Trichostomo crispuli-Tortuletum revolventis, Crossidio squamiferi-Aloinetum aloidis of the order Barbuletalia unguiculatae, and Crossidio crassinervis-Tortuletum obtusatae of the order Tortulo brevissimae-Aloinetalia bifrontis. The associations were examined from a synecological, synhierarchical and chorological point of view. A life form and life strategy analysis of all communities reflect the response of plant functional types towards the environmental demands. Only one life strategy dominates the communities; acrocarpous, turf-forming colonists clearly prevail on gypsum outcrops, subject to drought stress. They provide the main functional type within pioneering communities and communities of first successional stages. The keystone characters outlined ensure a successful dispersal, establishment and habitat maintenance of the species and associations.