THE FLOATING ISLAND OF POSTA FIBRENO: AN EXAMPLE OF A RELIC MIRE IN CENTRAL ITALY

The lake of Posta Fibreno (S Latium, C. Italy), is a biotope where some outstanding anomalies in the flora and vegetation of the wetlands of peninsular Italy are concentrated. Here the southernmost Italian populations of Sphagnum palustre occur on the small surface of a floating island, a cup-formed core of Sphagnum peat and rhizomes of Helophytes, erratically floating on the water-body of a submerged doline, annexed to the easternmost edge of the lake, characterised by the extension of a large reed bed. A strong correlation between characteristics of the physical environment and the structure of the vegetation on the island, points out the descriptive ability of the communities recorded in the site to reconstruc the genesis of the biotope.