Contribution to the knowledge of lichen flora of inland sand dunes in the western Po Plain (N Italy)

This paper describes the lichen flora surveyed in inland sand dunes, called dossi, in the western Po Plain (Lombardy region, Italy). Here, lichens were marginally known in comparison with the epigaeous component, but they were never studied before in relation to the epiphytic, epixylic and epilithic components. The floristic list includes 50 species; ecological and chorological analyses were carried out. Thirteen lichen species observed on various substrata were not reported in the lichen list of the Ticino Natural Park, which distances only few kilometres from our study area. Nine species are new for the Po phytoclimatic region and one species, Cladonia portentosa, is new for Lombardy. Particularly interesting are some species related to the Corynephorus grasslands, such as Cladonia sp. pl. and Stereocauloncondensatum, and three species usually absent, at our latitudes, beneath the montane belt: Cladonia digitata, Hypocenomyce scalaris and Parmeliopsis ambigua. These data confirm the importance of inland sand dunes for lichen diversity of the Po Plain. Some preliminary remarks concerning the management of the habitats hosting lichens are given, with particular emphasis to their conservation. Suggested actions include the possibility to keep woody coarse debris, to favour epixylic species, and mechanical disturbance, dispersal of lichen fragments and sheep grazing, to favour epigaeous species.