Bryophyte flora and vegetation of serpentine sites in the French Massif Central

Abstract

Eight major serpentine sites in the French Massif Central have been bryofloristically surveyed and their specific assemblages studied by performing systematic relevés. Seventy bryophyte taxa are reported from these serpentine areas. Archidium alternifolium, Bryum gemmilucens, Cephaloziella stellulifera, Grimmia dissimulata, Racomitrium fasciculare, R. lanuginosum and Riccia subbifurca are dominant and characteristic species. Soil and rock communities harbour typical combinations of specialized and ubiquitous taxa. The occurrence of saxicolous species (Grimmia) on the ground may be a typical feature of serpentine communities. The scarcity of liverworts is underlined, as is the complexity of the controlling factors. Lack of competition and periodic submergence are probably ecological factors of prime importance. Successional pathways are certainly insufficiently known, especially as far as bryophytes are concerned. The causes of negligible succession on skeletal soils would benefit from renewed studies. Grazing of serpentine grasslands, generally considered the most relevant management tool, should be evaluated further.

Keywords:

• Ultramafic vegetation
• ultramafic flora
• Riccia subbifurca; Grimmia dissimulata
• temporary wet substrates
• low competitors
• temporary inundation
• succession
• grazing

Acknowledgments

Thierry Vergne made the maps illustrating this article. Ron Porley pointed out to my attention several important references. Tom Blockeel offered many insightful comments, valuable suggestions and numerous corrections and his help is greatly acknowledged.