La vegetazione delle aree umide dei substrati ultramafici dell Alta Valtiberina (Arezzo, Italia Centrale)

Abstract

The authors describe the vegetation of some small wet sites on the ultramafic soils of the Upper Tiber Valley in the Arezzo district; the finding of very interesting species, already reported by PICHI SERMOLLI (1948) and environmental modifications occurring during the last 50 years, suggested the present phytosociological study, aimed to location and conservation of vegetational emergencies. The study showed the presence of several vegetation classes: Potametea, Bidentetea, Isoeto-Nanojuncetea, Phragmito-Magnocaricetea and Molinio-Arrhenatheretea. Some of the observed phytocenoses result very interesting because they are quite rare in Italy, as Myriophyllo verticillati-Nupharetum lutei or Epipactido palustris-Schoenetum nigricantis; furthermore a new association it has been described: Cirsio palustris-Eupatorietum cannabini. Then a phytocenosis of Molinia arundinacea has been analysed bearing two variants, one with Schoenus nigricans and one with Cladium mariscus. As some of these areas are subjected to severe environmental stress, some methods for their conservation and protection are suggested.