Il paesaggio vegetale della Nurra (Sardegna nord-occidentale)

The description of plant typologies that characterise the plant landscape in Nurra – according to phytosociology and sinphytosociology interpretations – is presented. Plant associations found out are here presented from areas closer to the sea towards the inner ones, grouped according to environmental and structural characteristics. The following new associations are described: Crithmo maritimi-Limonietum nymphaei, Evaco pygmaeae-Bellietum bellidioidis, Senecioni leucanthemifolii-Nanantheetum perpusillae, Spergulario salinae-Hordeetum marini, Limonietum laeti-glomerati, Brassico insularis-Seselietum praecocis, Anthyllido vulnerariae-Kundmannietum siculae, Loto cytisoidis-Dactyletum hispanicae, Dactylo hispanicae-Camphorosmetum monspeliacae, Scillo obtusifoliae-Bellidetum sylvestris, Scillo autumnalis-Bellidetum sylvestris, Hypecoo procumbentis-Silenetum nummicae, Bupleuro fontanesii-Scorpiuretum muricati, Rosmarino officinalis-Thymelaeetum tartonrairae, Dorycnio pentaphylli-Cistetum eriocephali, Pyro amygdaliformis-Quercetum ilicis, Euphorbio characiae-Juniperetum turbinatae, Pistacio lentisci-Calicotometum villosae, Crataego monogynae-Pistacietum lentisci. Furthermore, phytosociological and syntaxonomical study of the subnitrophilous hemicryptophyte communities allowed their attribution to the Artemisietea vulgaris class. Within this class the new Brachypodio ramosi-Dactyletalia hispanicae order is described, together with two new alliances, Reichardio maritimae-Dactylion hispanicae and Leontodo tuberosi-Bellidion sylvestris. The order includes the perennial, hemicryptophyte and geophyte, subnitrophilous vegetation of the secondary formations, finding their optimum in the sub-humid and humid mesomediterranean macroclimate, and can also penetrate into the thermomediterranean one for edaphic compensation. Moreover, this study suggests to include in the new Brachypodio ramosi-Dactyletalia hispanicae order, the Bromo-Oryzopsion alliance and the Thero-Brachypodion ramosi alliance. The study of associations and their dynamic relationships also allowed to reconstruct the vegetation series whose integration produces the main plant landscape units present in Nurra. The coastal Tyrrhenian, basophilous, calcicole, thermomediterranean and edaphon-xerophilous series of Juniperus turbinata (Chamaeropo humilis-Junipereto turbinatae sigmetum) was reconstructed on Mesozoic limestone. Different plant associations of comophytic and chasmophytic communities integrating the coastal limestone landscape are connected to this pattern by chain relationships. In contact with the landscape units of the Mesozoic limestone sector and with the Paleozoic metamorphic one, the coastal Tyrrhenian, neutroacidophilous, of sandstone, thermomediterranean and edaphon-xerophilous series of Juniperus turbinata with Arbutus unedo (Chamaeropo humilis-Junipereto turbinatae arbutetosum unedonis sigmetum), representing an edaphic variant of the previous one, linked to the violet quartzose sandstone on which a more clayey soil is generated, was reconstructed. The geosigmetum of Mesozoic limestone is completed by the Tyrrhenian, neutroacidophilous, calcicole, thermomediterranean climatophilous series of Quercus ilex (Pistacio-Querceto ilicis sigmetum). It is present on the inner hills and, of its series-head, only a few examples of Quercus ilex grove remain, which assume a particular characterization for the presence of Chamaerops humilis. The Sardinian coastal, neutroacidophilous, of Paleozoic schist, thermomediterranean and edaphon-xerophilous series of Juniperus turbinata (Euphorbio characiae-Junipereto turbinatae sigmetum) was reconstructed in the metamorphic area. The prevalently chain contact with the subhalophile garigue and the microgeosigmeta of the therophyt