Seeking a Hideout: Caves as Refuges for Various Functional Groups of Bryophytes from Terceira Island (Azores, Portugal)

Abstract

Caves represent sites of great geological and biological interest. For most taxonomic groups, caves represent one of the most challenging ecosystems due to their extreme conditions. However, these places are rich in biodiversity, and some groups, such as bryophytes, can take advantage of these conditions. Bryophytes from twelve caves on Terceira Island (Azores archipelago) were sampled and compared in terms of species richness, abundance, and composition. The results revealed a high species richness of bryophytes, with one-fifth of the species being threatened and one-third endemic. Moreover, the dominance of bryophyte species, as determined by different functional groups, varies depending on the sampled cave and, consequently, the environmental variables. This is evident from the high β-diversity values obtained, demonstrating significant dissimilarities in species composition among the surveyed caves. Both macro- and microclimatic variables significantly influenced the richness and abundance of bryophyte species in different ways, depending on the functional group studied. Highlighting bryophyte diversity in cave environments, this study points to the need for effective management strategies to preserve and protect these unique and ecologically significant communities. These places can serve as refuges for some species, even for bryophytes, a taxonomic group with a long-distance dispersal strategy.