La vegetazione delle isole Palmaria e Tino (Golfo della Spezia)

Abstract

The vegetation of the Palmaria and Tino Islands (Gulf of La Spezia). — The vegetation of the Palmaria and Tino islands in the Gulf of La Spezia shows various aspects although they are completely calcareous and do not exceed two hundred meters in height. Along the coast, we have noticed some small beaches with a few psammophytes, and some cliffs vertically overlooking the sea with the endemic Centaurea cineraria var. veneris and with a few shrubs (among which I would like to mention Pinus halepensis) that become bigger and bigger and grow in number with the altitude. On the southern side of Palmaria the Mediterranean « maquis » with Calicotome spinosa, Cistus monspeliensis, Myrtus communis and Pistacia lentiscus is to be noticed. This bush is either compact or rarefied so that it makes a sort of « garigue » on limestone with Euphorbia dendroides, Helichrysum stoechas, Ruta chalepensis, Thymus vulgaris. Owing to the fact that some land strips of Palmaria escaped from fire a thermophilous vegetation is to be found, with a few trees of Pinus halepensis and with a thick undergrowth of Euphorbia dendroides, Cistus incanus, Pistacia lentiscus, Myrtus communis, Smilax aspera. The vegetation of the northern side of Palmaria and Tino is less thermophilous, together with a thick wood of Quercus ilex with some plants of Quercus pubescens and with undergrowth of Viburnum tinus, Smilax aspera, Smilax mauritanica, Coronilla emerus; this wood, especially in the higher part of Palmaria, shows some glades where Erica arborea, Cistus salvifolius, Dorycnium hirsutum grow, with some entities which are distributed quite far from the sea, such as Peucedanum cervaria. Still on the northern side of Palmaria there are some traces of chestnut woods with Castanea sativa, Quercus pubescens, Ostrya carpinifolia, Corylus avellana, Cytisus laburnum and with some plants that usually grow in the cooler areas among the chestnut woods and often in the beech woods like Daphne laureola, Digitalis lutea, Helleborus foetidus and Sesleria autumnalis. A comparison between the biological spectrum of the two islands with the one of Capo Caccia in north western Sardinia and of Marettimo island in western Sicily, clearly shows that in going down southwards, a strong increase of the therophytes (respectively 29,57%, 41,73%, 49,59%), of the chamaephytes and of the nanophanerophytes (13,53%, 16,94%, 18,47%) is to be noticed, while the hemicryptophytes decrease (35,33%, 22,72%, 21,28%). Besides, the vegetation of Capo Caccia although being situated half way between the two Ligurian islands and Marettimo, is much more similar to the latter one; evidently Palmaria and Tino are conditioned by their closeness to the La Spezia coasts while having a climate quite different from them.