The acidophilous taxa of thefestuca varia group in the alps: New studies on taxonomy and phytosociology

The acidophilous taxa of theFestuca varia group appearing in the Alps (F. varia Haenke s.str.,F. scabriculmis (Hack.)K. Richt. subsp.scabriculmis, F. scabriculmis subsp.luedii Markgr.-Dann., andF. acuminata Gaudin) have been investigated with regard to their taxonomy, phytosociology and ecology. Morphometrical analyses of the different taxa confirm that the division of the species group is justified. Moreover three varieties ofFestuca varia s.str. can clearly be distinguished. Apart from the already knownF. varia var.varia and var.handel-mazzettii Krajina a newF. varia var.winnebachensis Wallossek etMarkgr.-Dann. is described. The ploidy levels of 30 samples from all taxa have been determined by means of flow cytometry.Festuca acuminata is diploid (2n=14), although this taxon occurs in ecologically different habitats within an altitudinal range between 200 and 3100 m.Festuca varia var.varia is tetraploid whereas the other varieties occur in hexaploid populations, which can be associated with inter- or post-glacial migration stages. Hexaploidy was also determined for both subspecies ofF. scabriculmis. The phylogenesis of these taxa by allopolyploidy seems possible, as they show a morphologically intermediate position betweenF. acuminata and the basiphilousF. quadriflora Honck. The spatial distribution and separation of the taxa is shown by means of precise area maps. As a result of a numerical classification of 534 relevés, the Alpine variegated fescue grasslands can be subdivided into six independent phytosociological associations of theFestucion variae: the East AlpinePulsatillo albae-Festucetum variae, Gentianello anisodontae-Festucetum variae ass. nov. andSeslerio-Festucetum variae ass. nov. as well as the West AlpineFestucetum scabriculmis, Euphorbio cyparissiae-Festucetum luedii ass. nov. andFestuco scabriculmis-Potentilletum valderiae. The mixture of basiphilous and acidophilous species in theSeslerio-Festucetum variae can be explained by soil heterogeneity with acid and alkaline conditions alternating within a very small space.Festuca acuminata can rather be regarded as a rock plant as it preferably occurs in associations of the allianceAndrosacion multiflorae.