Analisi distributiva e studio fitosociologico delle comunità a Santolina insularis (Gennari ex Fiori) Arrigoni della Sardegna meridionale (Italia)

Information on the distribution and phytosociological study of communities with Santolina insularis (Gennari ex Fiori) Arrigoni in southern Sardinia (Italy). Santolina insularis is a polyploid endemic distributed mainly in the south and central-eastern parts of Sardinia (Italy). It is found from sea level to the summit of Mt. Gennargentu (1834 m a.s.l.). This paper provides up-to-date information on the distribution of the species and the results of phytosociological study of the communities found in southern Sardinia. Two new associations called Euphorbio cupanii-Santolinetum insularis and Thymelaeo hirsutae-Santolinetum insularis are proposed on the basis of 37 original relevés and two from the literature. The former is linked to glareicolous environments of the Iglesias area and has two subassociations which vicariate in relation to substrate rocks and their physicochemistry, as well as bioclimatic and syndynamic conditions. The second is characteristic of non-stabilised alluvial beds of the Sarrabus-Gerrei and was hitherto regarded as a variant of the association Polygono scoparii-Helichrysetum microphylli. The two associations are related syntaxonomically through the alliance Teucrion mari, which includes chamaephytic vegetation with distribution in Sardinia and Corsica, indifferent to substrate chemistry and capable of establishing on degraded soils in the initial stages of pedogenesis