The aquatic and wetland vegetation of Lake Doberdò: an analysis for conservation value assessment of a disappearing lake of the Classical Karst (North East Italy)

Lake Doberdò (Classical Karst) is a well-known example of karst lakes, temporary lakes that seasonally fill and empty through springs and swallow holes connected to the underground waters. It is an area of exceptional interest for geological-geomorphological and biodiversity conservation, and is part of the Natura 2000 network. Its peculiar hydro-ecological nature allows an impressive variety of species and habitats. A phytosociological survey was carried out to provide a comprehensive analysis of the vegetation. On the basis of 177 phytosociological relevés and multivariate analysis 43 communities were found, belonging to Platyhypnidio-Fontinalietea antipyreticae, Lemnetea minoris, Potametea pectinati, Bidentetea tripartitae, Isoëto-Nanojuncetea, Phragmito-Magnocaricetea, Agrostietea stoloniferae, Molinio-Arrhenatheretea, Filipendulo ulmariae-Convolvuletea sepium, Alnetea glutinosae, Rhamno catharticae-Prunetea spinosae, Alno glutinosae-Populetea albae. The Leucojo aestivi-Poetum pratensis association including waterside periodically flooded meadows is validated. Compared to the past, various communities show a change in their distribution while some valuable coenoses were not found. 21 communities are attributed to 8 Annex I Habitats of the 92/43/EEC Directive. The study confirms the high value of Lake Doberdò for biodiversity conservation but highlights an ongoing process of environmental change due to both natural and human-related causes including modifications of the hydrological regime and abandonment of traditional agricultural practices. An overview of the features of Lake Doberdò is provided to compare this disappearing lake with the karst groundwater-dependent wetlands found in Ireland called “turloughs”, corresponding to Annex I Habitat 3180*. Also on the basis of the current interpretation and distribution of this habitat type at the EU level, a proposal is presented to recognize and protect this outstanding area of the Natura 2000 network in Italy as the habitat 3180*, modelled on Irish turloughs.