Vascular flora of calcareous outcrops in North-Western Sardinia (Italy)

Calcareous outcrops in North-Western Sardinia cover a large area (about 380 Km2) known as "Sassarese". In this study the vascular flora of this area is investigated. The actual flora is checked and, when possible, older references, synonyms and critical notes are given. The floristic list includes 840 entities. Among them, 18 have been cultivated (cultae), 11 are considered erroneously reported and so they are excluded from this area (excludendae) and 81 are in various ways considered not confirmed and to enquiry (inquirendae). The current floristic contingent is therefore reduced to 730 entities, divided into 98 families and 385 genera, many of them here documented for the first time in this area. Among them the more relevant are the Sardinian-Corsican endemic Silene nodulosa Viv. and the Sardinian endemic Hieracium gallurense Arrigoni, previously reported only for granite substrata in North-Eastern Sardinia. The biological spectrum shows a clear dominance of therophytes (41%). The chorological spectrum highlights the dominance of the Tethydic element, in which the dominance of more strictly Mediterranean element emerges. Four entities have in this area their locus classicus: Centaurea corensis Valsecchi et Filigheddu, Limonium racemosum (Lojac.) Diana and Scrophularia morisii Valsecchi, exclusive of the region object of this study, and Ophrys sphegodes Mill. subsp. praecox Corrias. Some entities, though not endemic, have a limited or fragmentary distribution in Sardinia, e.g. Capparis spinosa L. subsp. rupestris (Sm.) Nyman, Coridothymus capitatus (L.) Reichenb. f. and Erica multiflora L., whereas Viola arborescens L. Borago pygmaea (DC.) Chater et Greuter and Carex panormitana Guss. are included in the Red Book of Italian Plants. Although the area is strongly urbanised and subjected since long time ago to agricultural and pastoral uses, its flora is still rather diversified. The presence of species depending on the existence of hedges, dry-stone walls and other smaller structures belonging to traditional agricultural activities still present, is also substantial, even though their dilapidated state is often high. Finally the presence of floristic elements of great interest together with small residuals of spontaneous vegetation are of very high value. Indeed, several natural elements from traditionally agricultural activities are present within an area of intense anthropic impact. The indiscriminate building development of the valleys, the reckless exploitation of the water sources and the diffusion of dumps, threaten increasingly some habitats of the region. The improvement of the natural resources could be done through an adequate ecological net starting from a basic knowledge of the floristic biodiversity, that is the main aim of this work.

Gli affioramenti calcarei miocenici della Sardegna Nord-Occidentale occupano una superficie di circa 380 kmq, conosciuta come "Sassarese". Con questa ricerca si è voluto dare un contributo alle conoscenze della flora di questo territorio. L'elenco floristico, che comprende 840 taxa, include: entità rinvenute nel corso di questa ricerca; entità rinvenute nello stesso territorio da altri autori in tempi recenti; entità rinvenute precedentemente e non più ritrovate (inquirendae); entità indicate per il territorio per le quali si esclude la presenza (excludendae);entità coltivate in tipi di vegetazione seminaturali o che conferiscono un impronta caratteristica al paesaggio (cultae); entità introdotte e, a vari livelli, ritenute spontaneizzate...