La vegetazione dell'Isola di Giannutri (Arcipelago Toscano)

The vegetation of Giannutri island (Tuscan Archipelago, Grosseto, Italy). The phytosociological study of the vegetation of Giannutri is here presented. On the basis of relevés, 12 plant communities have been identified and illustrated. 4 new syntaxa are described: Centaureo melitensis-Asteriscetum aquatici, Ononido mitissimae-Galietum muralis, Erico multiflorae-Euphorbietum dendroidis, Limonio sommieriani-Senecetum cinerariae subass. carduetosum pycnocephali. Two new names are here formalized: Erico multiflorae-Rosmarinetum officinalis subass. rosmarinetosum officinalis and Limonio sommieriani-Senecetum cinerariae subass. senecetosum cinerariae. Dynamic and spatial contacts between different vegetation types are recognized and illustrated. Two different landscapes can be recognized: the coastal landscape and the hilly landscape. The first one is formed by the mosaic of lithophylous and aerohaline Crithmo-Limonieto sommieriani hyposigmetum, and by the halophylous and nitrophilous communities dominated by Frankenia pulverulenta and/or Mesembryanthemum nodiflorum and Frankenia pulverulenta . The coastal xerophilous-calcicolous maquis series belongs to the Teucrio fruticantis-Junipereto turbinatae sigmetum. On the hills, the landscape is dominated by the thermo-xerophilous series formed by the Cyclamino repandi-Querceto ilicis sigmetum. The presence of habitats deserving conservation according to Habitats Directive 92/43 and following revisions, and in conformity with L.R. 56/2000 and following revisions, is pointed out. For some habitats, the main conservation problems are indicated and some management proposals are suggested. The study of spatial distribution of vegetation types recognized on a physiognomical and phytosociological basis has permitted to distinguish typologies at a scale of 1:5000 and to build up the island vegetation map, which file can be downloaded at http://dl.dropbox.com/u/15732686/Carta_VEG_GIANNUTRI.pdf. By the study of the aerial photos of the years 1954, 1968, 1987, 1994 and 2005 the variation of the landscape is here illustrated. The diachronic analysis highlights that the vegetation types with higher biomass have increased their surface while the more simplified ones have tended to vanish in the island.