Pasture communities linked to ovine stock. A synthesis of the Poetea bulbosae class in the western Mediterranean Region

The Poetea bulbosae class encompasses gramineous, leguminous and other plan ts adapted to the continuous treading and fertilisation of sheep stock. The two principal centres of diversity are located in the western Iberian Peni nsula and the Atlas Mountains (Morocco), where they are specially linked to transhumance. Because the livestock routes function as ecological corridor s, different aspects of this vegetation type have originated. Four alliances are included in the Poetea bulbosae class: Trifolio subterra nei-Periballion, Poo-Astragalion sesamei, Plantaginion serrariae and Potent illo maurae-Campanulion filicaulis. Trifolio-Periballion presents two assoc iations: Poo bulbosae-Trifolietum subterranei, which is distributed in the siliceous soils of the Iberian Peninsula and northwestern Morocco; and Trif olio nigrescentis-Poetum bulbosae on the island of Sardinia. Poo bulbosae-A stragalion sesamei includes only the Poo bulbosae-Astragaletum sesamei asso ciation, which is distributed in the calcareous, gypsiferous and salty soil s of the central and western Iberian Peninsula, although it extends to sout hern France. Plantaginion serrariae consists of two associations: Trifolio subterranei-Plantaginetum serrariae, which grows in the vertisols around th e Strait of Gibraltar; and Paronychio echinulatae-Plantaginetum serrariae o f northern Tunisia. Currently, Potentillo maurae-Campanulion filicaulis onl y includes the basophilous association Phleo nodosi-Poetum bulbosae, distri buted in the Atlas Mountains. In addition to the impoverished forms of this class (Poetea bulbosae BC, Po etea bulbosae MC) and other geographical and successional aspects, the foll owing syntaxonomic news is presented: Trifolio nigrescentis-Poetum bulbosae (Ladero et al. 1992) stat. nov., Plantaginion serrariae all. nova, Trifoli o subterranei-Plantaginetum serrariae Martin Osorio & Galan de Mera ass. no va, Trifolio subterranei-Plantaginetum serrariae trifolietosum stellati sub ass. nova, Paronychio echinulatae-Plantaginetum serrariae ass. nova, Phleo nodosi-Poetum bulbosae silenetosum mekinensis (Benabid 1988) comb. nov., Ph leo nodosi-Poetum bulbosae vulpietosum siculae (Benabid 1988) comb. nov., a nd Phleo nodosi-Poetum bulbosae caricetosum jahandiezii (Negre 1961) comb, nov.