Berberido aetnensis-Crataegion laciniatae, new orophilous pre-forestal alliance of the class Rhamno-Prunetea.

In this paper the results of a phytosociological study carried out on some aspects of shrub vegetation of forest margins are presented, investigated in the higher belt of the Madonie Mts. (Northern-Central Sicily), referred to the order Prunetalia spinosae (Rhamno-Prunetea). Through comparison with other known coenoses in the central- southern part of the Italian Peninsula and in Sicily – especially, the associations of Berberidion vulgaris and those of Pruno-Rubion ulmifolii – a coenological and phytogeographical autonomy has been made evident and has resulted in the recognition of a new alliance, described under the name Berberido aetnensis-Crataegion laciniatae Gianguzzi et al., all. nova. This new syntaxon, interpreted as a southern vicariant of Berberidion vulgaris, as well as an eastern vicariant of Lonicero arboreae-Berberidion hispanicae O. Bolòs 1954 (Iberian Peninsula, Betican Province; Rivas-Martìnez et al. 2002), includes formations with orophilous and relict characteristics, currently located in Northern Sicily, characterized by the presence of endemic entities (species or subspecies) or of particular phytogeographic relevance (Berberis aetnensis, Prunus mahaleb subsp. cupaniana, Amelanchier ovalis subsp. cretica, Rhamnus saxatilis subsp. infectorius, Sorbus aria subsp. cretica and Rosa heckeliana), as well as several “geographic differentials” species that are quite rare and exclusive of these coenoses (Cotoneaster nebrodensis, Ribes uva-crispa subsp. austro-europaeum, Crataegus laciniata, Rhamnus catharticus, Lonicera xylosteum, Rubus canescens, Rosa sicula, R. montana, R. micrantha, R. rubiginosa), in addition to “transgressive” elements of the class Querco-Fagetea (Daphne laureola, Lamium fl exuosum and Ilex aquifolium). On the basis of the investigations carried out, two associations can be referred to the new alliance until now: 1) Lonicero xylostei-Prunetum cupanianae Gianguzzi et al., ass. nova; 2) Crataegetum laciniatae Brullo & Marcenò in Brullo, 1984, previously referred to as the alliance Pruno-Rubion ulmifolii.