Biologia 70/7: 879—892, 2015 Section Botany DOI: 10.1515/biolog-2015-0100 The Paliurus spina-christi dominated vegetation in Europe Simona Casavecchia*, Nello Biscotti, Simone Pesaresi & Edoardo Biondi Department of Agricultural, Food and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche I-60131 Ancona Italy; e-mail: s.casavecchia@univpm.it Abstract: The revision of the Paliurus spina-christi dominated vegetation of Europe is presented here. The study area includes the north-eastern part of Iberian Peninsula and Provence to the west, and spreads through the Apennine Peninsula to the Balkan Peninsula and up to Eastern Mediterranean areas. The phytosociological relevés of Paliurus spina-christi dominated vegetation found in the literature for these European territories were gathered together in a phytosociological table. Floristic analysis, cluster analysis, and indirect gradient analysis were performed to determine the similarities and differences between the different Paliurus spina-christi dominated communities and their correlations with the main biocli- matic indices described in the literature. The various analyses highlight the existence of nine different associations (one of which is described here for the first time) that are attributed to different syntaxonomic levels. In the conclusion, a syntaxonomical scheme is proposed that classifies the European vegetation of shrublands in the class Rhamno-Prunetea which includes the class Paliuretea. Currently, we recognized three orders within this class: Prunetalia spinosae for central and south-central Europe; Pyro spinosae-Rubetalia ulmifolii within the Temperate oceanic bioclimate of the sub-Mediterranean variant; Paliuretalia spinae-christi with a central Mediterranean and sub-Mediterranean distribution, that mainly occurs in the central-eastern Mediterranean (Southern Apennine Peninsula) and the Balkans. Finally, a part of the shrub vegetation dominated by Paliurus spina-christi is referred to the class Quercetea ilicis, the order Pistacio lentisci-Rhamnetalia alaterni, the alliance Oleo sylvestris-Ceratonion siliquae and the suballiance Oleo sylvestris- Paliurenion spinae-christi that refers to thermophilous shrub communities that require high edaphic humidity. Key words: Paliurus spina-christi dominated vegetation; cluster analysis; indirect gradient analysis; bioclimatic indices; plant ecology; phytosociology; syntaxonomy. Abbreviations: Io, annual ombrothermic index; Cti, compensated thermicity index; Ic, extended continentality index; SIA, species indicator analysis (SIA); NMDS, non-metric multidimensional scaling ordination. Introduction The aim of the present study is to provide a syntaxo- nomic review of the Paliurus spina-christi Miller dom- inated vegetation within the distribution range of this species. Some results of this study were anticipated in a re- cent short article (Biondi et al. 2014c) in which some new syntaxa were described in order to include them in the Prodrome of Italian vegetation (Biondi et al. 2014b). Paliurus spina-christi belongs to the family of Rhamnaceae, and it is a deciduous shrub species that has a south-European-Pontic distribution, with its focal centre in the Carpathian-Danubian region and around the Black Sea. Its distribution range extends to the west across to north-western Spain and southern France, al- though it is not found in central and northern European countries (Fig. 1). In Italy, Paliurus spina-christi oc- curs throughout the national territory, excluding Valle d’Aosta, although it has been probably spread by hu- mans (Pignatti 1982). In Eastern Europe, it is present in Slovenia (Šilc & Čarni 2012), Croatia, Serbia, Mon- tenegro, Macedonia, Albania, Greece, Cyprus, Bulgaria and Romania; it also occurs in Turkey and Crimea (Tutin et al. 1988). Paliurus spina-christi grows on calcareous-clay soils and occurs from coastal areas up into the hills (to about 500 m a.s.l.), where it grows along the sunny slopes. Scrublands with Paliurus spina-christi grow in different bioclimatic and successional contexts, and therefore they have also been attributed to several as- sociations related to different syntaxa. Distribution of Paliurus spina-christi dominated vege- tation in Europe From the literature that was examined for the Pali- urus spina-christi dominated vegetation at the Euro- pean level, it is evident that it has been interpreted in different ways. In the Balkans, where Paliurus spina- christi dominated formations are called shibljak (orig. šibljak cf. Adamovi´ c 1901), the communities have been * Corresponding author c 2015 Institute of Botany, Slovak Academy of Sciences Brought to you by | University of Sussex Library Authenticated Download Date | 3/1/17 11:37 AM