Il Paesaggio vegetale della Nurra (Sardegna nord-occidentale)

The description of vegetation typologies that characterise the plant landscape in Nurra - according to phytosociological and sinphytosociological 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-Seselictum 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 theArtemisietea vulgarisc1ass. Within this class the newBrachypodio ramosi-Dactyletalia hispanicaeorder is described, together with two new alliances,Reichardio maritimae-Dactylion hispanicaeandLeontodo 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 newBrachypodio ramosi-Dactyletalia hispanicaeorder, theBromo-Oryzopsionand theThero-Brachypodion ramosialliances.The study of associations and their dynamic relationships also allowed to reconstruct the vegetation series which integration produces the main plant landscape units present in Nurra. The coastal Tyrrhenian, basophilous, calcicole, thermomediterranean and edaphon-xerophilous series ofJuniperus turbinata (Chamaeropo humilis-Junipereto turbinataesigmetum) was reconstructed on Mesozoic limestone. Different plant associations of comophytic and chasmophytic communities integrating the coastallimestone landscape are connected to this pattern by chain relationships.Between the landscape units of the Mesozoic limestone sector and the Paleozoic metamorphic one, the coastal Tyrrhenian, neutroacidophilous, of sandstone, thermomediterranean and edaphon-xerophilous series ofJuniperus turbinatawithArbutus unedo (Chamaeropo humilis-Junipereto turbinatae arbutetosum unedonissigmetum), 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 c1imatophilous series ofQuercus ilex (Pistacio-Querceto i1icissigmetum). It is present on the inner hills and, of its series-head, only a few examples ofQuercus ilexgrove remain, which assume a particular characterisation for the presence ofChamaerops humilis.The Sardinian coastal, neutroacidophilous, of Paleozoic schist, thermomediterranean, climatophilous and edaphon-xerophilous series ofJuniperetus turbinata (Euphorbio characiae-Junipereto turbinataesigmetum) was reconstructed in the metamorphic area. The prevalently chain contact with the subhalophile garigue and the microgeosigmeta of the therophytic and chamaephytic halophile communities occurs in the coastal girdle close to the c1iff. The landscape unit of the coastal metamorphic section is completed by the Tyrrhenian, neutroacidophilous, mesomediterranean, of schist, climatophilous series ofQuercus ilex (Erico arboreae-Querceto ilicissigmetum).In the alluvial plain of Nurra, on strong clayey substrata with a mixed calcicole-silicic matrix, always in thermomediterranean climate but under a marked edaphic compensation, the Sardinian, neutroacidophilous, of plain, edaphon-mesophilous series ofQuercus ilexandQuercus suber (Pyro amygdaliformis-Querceto i1icissigmetum) is found. The geosigmetum of the alluvial plain is completed by the edaphon-hydric series of the alluvial soils in the north-western Sardinia (Allio triquetri-Ulmeto minorissigmetum).Finally, some indications about land management are given in order to maintain the high biodiversity that currently is still present.