Potential natural vegetation units and fire frequency in Ponza island (central Italy)

Aims of the paper are the classification of the landscape of Ponza island using physical features and vegetation series distribution, and the evaluation of the fire frequency and the relative effects on vegetation recover for each land unit. A land units map was realised in GIS environment, following the hierarchical land classification approach: 3 land systems, 4 land facets and 6 land units inside the Mediterrean bioclimatic region were singled out. 75 phytosociological relevés were carried out and 6 main potential natural vegetation types were identified: Quercenion virgilianae series, Erico-Quercetum ilicis series, Fraxino-Ulmenion minoris series, and the phytotoposequences of coastal cliffs, screes, and sand dunes. Fire frequency was calculated for each potential natural vegetation unit (period 1978-2001) and the highest percentage of fires was recorded in northern slopes of hills, mainly during the period August- October. Furthermore, the current research has pointed out that woods currently cover very small surfaces because of the high incidence of fires and that the terraces could play an important role to preserve soil and make easier the vegetation recover.