The Adiantetea class on the cliffs of SW Portugal and of the Azores
Neto, Carlos; Capelo, Jorge; Sérgio, Cecília; Costa, José Carlos
Communities in the Adiantetea class are characterized by the way in which they present a double synusial structure whereby vascular plants usually depend upon the macro and regional climate, while the bryophytes do not. On the sea cliffs of SW Portugal this vegetation seems to be fairly independent of rainfall and temperature and, on the other hand, more conditioned by a particular geomorphological evolution which allows for rainwater to circulate. Water supplies are therefore continuous throughout the year. Owing to the proximity of the sea, the water has also a high saline content. These communities are mainly composed of Adiantum capillus-veneris and Samolus valerandi as well as two relatively abundant bryophytes (Didymodon spadiceus and Eurhynchium speciosum). The fact that this seems to be an original community, when compared with the rest of the Adiantetea communities, allows a new association to be proposed: Didymodon spadicei-Adiantetum capilli-veneris. ass. nov, which is endemic to SW Portugal.On the basalt cliffs of the Azores islands, strongly influenced by a marine microclimate, a second new association was singled out: Dicrano scottiani-Adiantetum capilli-veneris. ass. nov, which is endemic to this area.