Floating island in Central Italy: neoformations or ancient bogs?

Lake Posta Fibreno (S Latium , CW Italy), is a site where some outstanding anomalies for the flora and vegetation of the wetlands of peninsular Italy are concentrated. Here the probably extant southernmost Italian populations of Sphagnum palustre occur, along with the southernmost largest lacustrine stands of Carex paniculata. The former are restricted on the surface of a floating island, a cup-formed core of Sphagnum peat and rhizomes of Helophyta, erratically floating on the water-body of a submerged doline, annex to the easternmost edge of the lake. The latter forms impressive palisades of 1-1,5 m high tussocks all around the island and along the S and SE shores of the lake. The assessment of a conservation plan is extremely urgent, owing to the vulnerability of these isolated outposts of boreal plants and to the threat from the explosive increase of a local population of an alien herbivore, Myocastor coypus, which heavily affects the C. paniculata stands. Since the explanation of the origin of this island is still controversial, a consistent descriptive model for the floristic changes along the physical gradients is crucial for the correct management of its plant cover, which is expected to be addressed to the preservation of Sphagnum.