Ecologica Montenegrina, 42, 2021, 62-84 Vegetation of alpine screes on Bjelašnica Mt. — syntaxonomy and ecology SABINA TRAKIĆ 1,* , VELIDA BAKIĆ 1 & SAMIR ĐUG 1 1 Department of Biology, Faculty of Science, University of Sarajevo, Zmaja od Bosne 33-35, 71 000 Sarajevo, Bosnia and Herzegovina. *Correspondence: sabinatrakic@pmf.unsa.ba Received 27 March 2021 │ Accepted by V. Pešić: 7 May 2021 │ Published online 12 May 2021. Abstract We analised vegetation of calcareous screes in the alpine belt of Bjelašnica Mt. (Western Balkan) by the Central European phytosociological method. In total, 69 relevés were submitted to numerical analysis in R ver. 3.5.2. (UPGMA clustering with chord distance). The obtained cluster dendrogram showed differentiation in nine associations, of which Festuco xanthinae—Valerianetum montanae Trakić et al. ass. nov. and Drypido spinosae—Seslerietum wettsteinii Trakić et al. ass. nov. are new ones. In lower section of the alpine belt we described new subassociation Pseudofumarietum leiospermae helictochloetosum Trakić et al. subass. nov. which raises questions about ecological preferences of the alliance Corydalion ochroleucae. We also neotypified the association Drypidi—Heracleetum orsinii Redžić et al. ex Trakić et al. and made correction for Pseudofumarietum leiospermae Lakušić et Redžić 1991 nom. corr. The observed high diversification of the alpine screes on Bjelašnica Mt. is based upon its ecological heterogeneity and tranzitional position in the Dinarides. Key words: New syntaxa, alpine screes, distribution pattern, Dinarides. Introduction The vegetation of screes in the Dinarides occurs azonally, mainly in the alpine and subalpine belt, between 1800 and 2000 m a.s.l. (Strid et al., 2003). Due to extreme temperature fluctuation, the weathering of rocks, which gives rise to rockslides, is more intense at high altitudes. On the other hand, development of screes in the past was favoured by the Periglacial climate (Ružička and Klimeš, 2005), as well as by the occurence of the Pleistocene glaciers which covered numerous mountain tops across the Balkan Peninsula (Cvijić, 1924), and exist even today in the central Dinarides (Gachev et al., 2016; Gachev, 2017). Generally, the glaciation events have played major role when it comes to the evolution of dinaric relief (Roglić, 1959) and local flora (Mucina et al., 1990; Stevanović et al., 2009). The regional orogenesis gave rise to isolated habitats in the alpine belt, because of which the screes represent an island-like ecosystems that support species missing in the surrounding areas (Möseler and Molenda, 1999; Kubát, 2000). The proportion of glacial or Tertiary relics within the vegetation of alpine screes is high (Lakušić, 1975; Redžić et al., 2011a). Because of conservative thermic character, screes are largely independent of the above-ground temperature fluctuations (Ružička and Ecologica Montenegrina 42: 62-84 (2021) This journal is available online at: www.biotaxa.org/em http://dx.doi.org/10.37828/em.202.42.3