Characteristics, vulnerability and conservation value of active tufa-forming springs on coastal cliffs in the NW Iberian Peninsula

Abstract Tufa-forming hard water springs are classified as a priority natural habitat of community interest and described in Annex I of Community Directive 92/43/EEC as “ (Natura, 2000 habitat type 7220* Petrifying springs with tufa formation [Cratoneurion])”. This type of habitat is scarce along the European Atlantic coast. In this study, petrifying springs in 36 coastal locations in the NW Iberian Peninsula were described on the basis of their physiographical characteristics, geomorphologic context, water chemistry, floristic composition and the types of disturbance endangering their conservation. The springs under study differed from other coastal and inland examples of this type of habitat in relation to the abiotic factors controlling their distribution and also some botanical traits. They are the southernmost petrifying springs reported to date on the Atlantic coast of Europe. Unfortunately, one third of the study sites lie outside of the protected areas delimited in the European Natura 2000 Network. This suggests that the network should be extended in order to conserve biodiversity and natural heritage in Atlantic Europe.