Phytolith types and type-frequencies in subalpine-alpine plant species of the European Alps

Biogenic silica extracted from 21 species commonly occurring in subalpine and alpine plant communities in the central Swiss Alps were examined using light and SEM microscopes; 19 species being screened here for the first time. An inventory of phytolith types is provided and type-frequencies are assessed. Light microscope photographs and SEM micrographs provided illustrations of the types described. The monocotyledons analysed belonged to the genera Calamagrostis, Festuca, Nardus, Poa and Carex. Monocotyledons yielded mainly types of epidermal origin (short cells, rods, cork cells, silicified stomata and trichomes). Dicotyledons analysed were from five genera of the Ericaceae family (Arctostaphylos, Calluna, Loiseleuria, Rhododendron, Vaccinium) and from one genus of the Betulaceae (Alnus). In dicotyledons, silicified epidermal jigsaw cells, stomata complexes and vessels were recovered. Conifer species of the genera Abies, Juniperus, Picea, Pinus and Larix were studied. Distinctive conifer cells were mainly silicified endodermids and transfusion tissues. Phytolith taxonomic diagnostic potential was tested by cluster analysis and principal component analysis (PCA). It was shown that grass and sedge species could be easily differentiated on the basis of phytolith types. In general, Ericaceae and conifers could also be distinguished on the basis of phytoliths; however, some species yielding mainly redundant types were not unequivocally identifiable. The aim of the present work is to provide a framework for phytolith-based plaeoecological studies at the treeline in the European Alps. (C) 2004 Elsevier B.V All rights reserved.