La vegetazione a Juniperus thurifera L. sulle Alpi occidentali

We here present a phytosociological study of the Juniperus thurifera L. phytocoenoses, including the chamaephyte phytocoenoses that are dynamically linked to them, in the western Alps of Italy and France. This study was conducted with the aim of understanding in more detail the significance of the 9560 habitat "Endemic Mediterranean forests of Juniperus spp." in the Italian territory. The Juniperus thurifera vegetation in the two Italian study areas, of Moiola, in Stura Valley (at altitudes between 800 m and 1,000 m), and of Valdieri, in Gesso Valley (at altitudes between 950 m and 1,670 m), have been referred to the new association Juniperetum communis-thuriferae. The vegetation of the French study areas that has already been attributed to the association Juniperetum hemisphaerico-thuriferae, which is widely spread also along the Iberian peninsula, has been recognized as the new subassociation amelanchieretosum embergeri, which distinguishes the French formations of J. thurifera from those Iberian. Both of these juniper wood types are dynamically connected with Mediterraneo-montane chamaephyte formations that have been referred to the new association Hyperico coris-Lavanduletum angustifoliae, which is here seen as the new subassociation tipica lavanduletosum angustifoliae and the thymetosum vulgaris subass. nova of the mainly thermo-xerophilous aspects. At lower altitudes, in chain contact with woods of Quercus pubescens or of Ostrya carpinifolia, the J. thurifera formations are substituted by others of J. phoenicea ssp. phoenicea, attributed to the new association Cytiso sessilifoliae-Juniperetum phoeniceae, to which are also referred the formations indicated as low supraMediterranean (Barbero & Quezel, 1986) that are present in the French Alpes-de-Haute-Provence.