A new species of Quercus, Q. ichnusae, endemic to Sardinia is described and illustrated. Its distribution and relationships with the other deciduous oaks occurring on the island are examined.
A combined field experiment and modelling approach has been used to provide evidence that ants may be responsible for an observed lower patchiness and higher plant diversity in the neighbourhood of ant nests, within Mediterranean dry grasslands belonging to the phytosociological class Tuberarietea guttatae. The hypothesis was that seeds occurring in clumps may have an higher probability to be harvested than seeds having a scattered distribution. In order to test this hypothesis, four analysis steps have been performed. First, the seed productivity and dispersal pattern was recorded for four plant species found, either more abundant beside the ant nests (Tuberaria guttata, Euphorbia exigua) or away from the ant nests (Bromus scoparius and Plantago bellardi). Second, a stochastic model was developed to simulate the observed dispersal patterns of each studied species. Third, ten seed arranges in accordance to the distribution patterns created by the model were offered to the ants and the positions of the predated seeds was recorded. Finally, the observed pattern of seed predation was matched to models performed by different distributions of probability. Results confirmed the initial hypothesis, showing that the probability of being predated decreases with the increase of the reciprocal distance of seeds. It was concluded that the preference of ants for high concentrations of food items holds down the dominant species sufficiently to allow the subordinates to survive. The observed higher frequency of small-seeded, small-sized, or creeping therophytes close to the ant nests can be therefore seen as an example of indirect mirmecophily
IntroduzioneIl bacino minerario di Montevecchio, conosciuto e sfruttato fin dal tempo dei romani, ha rappresentato per gran parte del XX secolo il maggiore centro di estrazione di piombo e zinco in Italia (Mezzolani & Simoncini, 2001). I duemila anni di sfruttamento di queste colline hanno avuto un impatto ambientale visibilmente devastante lungo tutto lo sviluppo del ricco complesso filoniano, tanto più che la chiusura delle miniere non è stata accompagnata da adeguati interLa flora del distretto minerario di Montevecchio (Sardegna sud-occidentale) Accettato il 4 dicembre 2006The flora of the mining district of Montevecchio (SW-Sardinia) -A contribution to the knowledge of the flora of the mining district of Montevecchio is reported, focussing on the plants colonizing highly polluted substrata, produced or altered by the mining activity. In the present survey, 373 taxonomic units have been recorded, ranking as follows: 332 species, 36 subspecies, 3 varieties, 2 hybrids. On old racking basins and dumps, 192 taxa have been recorded: 170 species, 20 subspecies, 1 variety, 1 hybrid. Further 181 taxa (162 species, 16 subspecies, 2 varieties, and 1 hybrid) are missing on racking basins and dumps, but grow, however, in the nearby areas. The surveyed taxa belong to 73 families and 252 genera, but only 53 families and 146 genera are represented on racking basins and mining dumps. The top three families are: Asteraceae (42 taxa, 11,3% of the total), Fabaceae (36 taxa, 9.7%) and Poaceae (28 taxa, 7.5%). The top three genera are: Trifolium and Ophrys (8 taxa), followed by Euphorbia (6 taxa). The biological spectrum highlights the remarkable Mediterranean connotation of the investigated district, being the therophytes 42,1% of the whole flora, followed by the hemicryptophytes (22,5%). The chorologic spectrum is dominated by the Mediterranean chorotype (56.6%), including circum-Mediterranean (39.4%), W-Mediterranean (8.0%) and endemic taxa (7.2%). Further 22.3% of the surveyed taxa have a wider distribution range, but centered, however, in the Mediterranean region. As concerns the endemics, 26 taxa have been found, of which 21 species and 5 subspecies. Asteraceae and Scrophulariaceae resulted the richest in endemic taxa (3 units each). Most of the recorded endemics have a Tyrrhenian-insular distribution; with reference to the biogeographic units of the Mediterranean region, they belong to the Italo-Tyrrhenian superprovince.Key words: Italy, mining polluted substrata, Sardinia, vascular flora.venti di bonifica e mitigazione degli impatti.L'attività mineraria è, infatti, una tra le attività industriali che maggiormente possono danneggiare, inquinare e modificare più o meno permanentemente il paesaggio, compromettendo anche attività produttive quali agricoltura, pastorizia e pesca.Il distretto minerario di Montevecchio si presenta tuttavia peculiare rispetto alle altre principali aree estrattive della Sardegna. L'attività mineraria è infatti andata a inserirsi in un contesto ambientale e paesaggistico caratterizzato da elevata...
Le profil proanthocyanique (prodelphinidine) de deux spécimens de Juniperus communis ssp. nana récemment récoltés en Sardaigne est identique à celui du taxon corse précédemment défini comme chimiovar «corsicana». Ce taxon constitue donc une endémique corso-sarde, distinct du Juniperus communis ssp. hemisphaerica de Sicile et de Kabylie, mais aussi du Genévrier nain des Apennins.
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