Broom-dominated shrublands of Sicily: revisiting the syntaxonomy of the Cytisetea scopario-striati at the south-eastern margin of their range

Aims : This study focuses on the shrublands growing on siliceous and calcium-poor substrates in the hilly and mountainous regions of northern Sicily. These vegetation types, typically found in abandoned rangelands, forest edges, and clearings, are dominated by several acidophilous shrubs. The aim is to analyze their composition, distribution, and ecological relationships with allied syntaxa. Location : Tyrrhenian mountain ranges of Northern Sicily (Nebrodi and Peloritani mountain ranges), extending from the Strait of Messina in the east to the central-western part of the island, encompassing diverse terrains characterized by nutrient-poor, acidic soils, influenced by a Mediterranean climate. Methods : Vegetation surveys were conducted using the Braun-Blanquet method; vegetation plots were classified using a modified TWINSPAN approach, and the resulting groups were floristically characterized by their diagnostic, constant, and dominant species. Multivariate statistical analyses were employed to classify the vegetation plots and to investigate their ecological relationships, distribution and syntaxonomy, compared with related vegetation described in Sicily and Southern Peninsular Italy (Calabria). Results : The study identified several new associations of shrubland vegetation, such as Carlino globosae-Cytisetum scoparii , Origano viriduli-Cytisetum villosi , Carlino globosae-Telinetum monspessulanae , and Achilleo ligusticae-Spartietum juncei , among others. Comparative analysis revealed many differences from the Siculo-Calabrian supramediterranean broom heath ascribed to the Violo messanensis-Adenocarpion commutati , leading to the description of a new alliance, named Achilleo ligusticae-Telinion monspessulanae , which can be considered a more thermophilic and mesophilous vicariant of the former. Conclusions : Our findings provide new insights into the vegetation classification of the Sicilian acidophilous shrublands. By identifying several new vegetation associations and analyzing their relationships with allied communities in Southern Italy, this study contributes substantially to the knowledge of the class Cytisetea scopario-striati in the south-eastern most limit of its distribution range. Taxonomic reference : Flora d’Italia (Pignatti et al. 2017–2019) for vascular plants. Syntaxonomic reference : Mucina et al. (2016) for alliances, orders and classes, Brullo et al. (2001b) and Guarino et al. (2017) for associations. Abbreviations : ANOVA = analysis of variance; CPO = Calabria-Peloritani Orogen; EIVE = Ecological Indicator Values for Europe 1.0; ICPN = International Code of Phytosociological Nomenclature; NMDS = non-metric multidimensional scaling; TWINSPAN = two-way indicator species analysis.