The vegetation of the Ranunculo-Nardion in the Southern Apennines (S Italy)

In Italy snow-beds are distributed mostly in the Alps, whereas they become more and more rare as far as one proceeds along the Apennines from North to South. The present contribution aims at: i) filling the gap in the basic knowledge of snow-bed vegetation in the southern Apennines; ii) detecting snow-bed plant species at risk of local extinction, as a consequence of warming induced by climate change. The study is based on 60 phytosociological releves taken on the massifs of Pollino and of Sirino-Papa. The releves were numerically classified by the method of minimum increase of sum of squares agglomeration based on the chord distance. Two main physiognomic vegetation units were detected, corresponding to close grasslands respectively dominated by Nardus stricta or by Crepis aurea subsp. glabrescens and Plantago atrata. These vegetation units were classified into phytosociological syntaxa according to the BRAUN-BLANQUET principle of species fidelity The communities were integrated within the three associations: Nardo-Luzuletum pindicae BONIN 1972 (lectotypus h.l. design.; with three new subass. descr. h.l.), Plantagini serpentinae-Nardetum strictae TOMASELLI, BERNARDO & PASSALACQUA (new ass. descr. h.l.) and Bellidi pusillae-Alopecuretum gerardi TOMASELLI, BERNARDO & PASSALACQUA (new ass. descr. h.l., with two new subass. deser. h.l., one of them with two variants), occurring in different ecological conditions and showing a certain degree of floristic heterogeneity and, therefore, subdivided into subassociations and variants. Floristic differences within associations could be best explained by altitudinal and inclination gradients. Furthermore, the hypothetical risk of local extinction of seven species concentrated in the Bellidi pusillae-Alopecuretum gerardi stands, as consequence of warming induced by climate change, was evaluated.