1,721,217 research outputs found
La biodiversità vegetale associata ai fontanili della Foresta Demaniale di Anela (Sardegna, Italia)
No full text
Effetti a scala quinquennale dell’esclusione del pascolamento sull’habitat prioritario 6220*-“Percorsi substeppici di graminacee e piante annue dei Thero-Brachypodietea” in Sardegna
No full textQuesto studio analizza gli effetti della cessazione del pascolamento su un pascolo ovino mediterraneo durante un periodo di 5 anni. Il pascolamento è stato escluso sperimentalmente recintando dieci quadrati permanenti di 10 x 10 mq in cui sono stati monitorati i parametri vegetazionali e pedologici durante tre tempi dal 2000 (prima dell’esclusione) al 2005. La cessazione del pascolamento ha alterato notevolmente la composizione floristica della comunità vegetale, con una dissomiglianza media del 96,7% tra il 2000 e il 2005. Le specie d’interesse conservazionistico hanno teso a scomparire e ad essere sostituite da specie ad ampia distribuzione. La cessazione del pascolamento ha coinciso con l’aumento del pH del suolo e la diminuzione della sostanza organica, del carbonio e dell’azoto. Il risultato più significativo di questa ricerca è di aver evidenziato come i cambiamenti nelle comunità pascolive possono avvenire rapidamente dopo la cessazione del pascoloThis study analyzes the consequences of grazing abandonment on a Mediterranean sheep pasture, over a 5-years period. Plant and soil physicochemical parameters were monitored within ten 10 x 10 m permanent plots and ten unfenced control plots, during three sampling times from 2000 (before the fencing) to 2005. Grazing abandonment altered the composition of plant communities, with an average dissimilarity of 96.7% over five years. Species of conservational interest tended to disappear with pasture abandonment and were substituted by more widespread species. Pasture abandonment caused also an increase of soil pH and a decrease in soil organic matter and nitrogen. Remarkably, the results from this study reveal that changes in pastureland communities can occur rapidly following abandonmen
Gestione della flora e vegetazione in sistemi alofili costieri (stagni e lagune) – caso studio
No full textGestione della flora e vegetazione in sistemi sabbiosi costieri – esperienza del Parco Naturale Regionale di Porto Conte
No full textBiodiversity of shrub communities in northern Sardinia: ecological and chorological aspects
No full textEffects of browsing in relation to vegetation cover on common yew (Taxus baccata L.) recruitment in Mediterranean environments
No full textCommon yew (Taxus baccata L.) stands are recognized as prioritary habitats for biodiversity conservation within the European Union. The effects of browsing on the regeneration capacity and spatial dispersal of T. baccata recruits at the European southern limit of the species in the Mediterranean Basin have been herein studied. The efficacy of T. baccata recruitment has been evaluated at six localities in the Northern Sardinia mountains, which have similar altitude, climate, soil, and vegetation but have different types of uses (three were grazed by livestock and three were not). At each site, five habitats have been identified for T. baccata seed dispersal: reproductive female T. baccata canopy, reproductive female Ilex aquifolium canopy, non-fleshy-fruited tree canopy, fleshy-fruited shrubs, and open areas. The density of seedlings was found to be greater under fleshy-fruited trees (reproductive female T. baccata and I. aquifolium) than under shrubs, whereas the sapling density was higher in shrubby habitats, especially at grazed sites due to the mechanical protection afforded by the spiny shrubs against herbivores. Land use (LU) has been found to be the most important factor in determining the spatial distribution of seedlings and saplings in relation to forest habitats. Although browsers had an ephemeral but positive effect on seed germination through their trampling and the resultant scarification, this process eventually became ineffective as was shown by the occurrence of the lowest density of saplings in those habitats where the density of seedlings was the highest. The ultimate and most important effect of browsing was the sharp decrease in the density of saplings, and their almost complete extinction, in non-shrubby habitats. This study highlights the result that, in Mediterranean ecosystems, browsing constitutes the main negative factor on T. baccata seedling-sapling transition and furthermore confirms the necessity to preserve shrubby patches in the vicinity of reproductive female T. baccata and I. aquifolium to permit the regeneration of T. baccata in the presence of livestock. Moreover, at ungrazed sites, T. baccata is able to colonize non-shrubby shady habitats. The application of different management strategies to ungrazed and grazed sites should therefore be the main direction in the management and preservation of T. baccata stands in the Mediterranean regio
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