Wind dispersal of alpine plant species : a comparison with lowland species

Question: The prominent role of wind dispersal in alpine habitats has been recognized early but has rarely been quantified. The aim of this study is to compare wind dispersal under alpine and lowland conditions and to analyse whether differences are caused by species traits, e. g. terminal velocity of seeds (V-term) or weather conditions. Location and Methods: We characterized wind dispersal potential of < 1100 Central European species using measured V-term. To quantify the habitat effect on wind dispersal, we measured meteorological key-parameters and simulated dispersal distance spectra of nine selected species under typical alpine conditions (foreland of the Scaletta-glacier, Switzerland) and typical lowland conditions (grassland in Bad Lippspringe, Germany). Results: Lowland species had higher V-term compared to alpine species. However, this difference is absent when only species of species of open habitats are concerned. The meteorological measurements showed that the alpine habitat was mainly characterized by higher frequency and strength of updrafts. The simulations showed that under alpine conditions long distance dispersal occurred much more frequent. Conclusions: More than 50 % of the alpine species have a fair chance to be dispersed by wind over long distances, while this proportion is less than 25 % for species from open habitats in the lowland. The more prominent role of wind dispersal in alpine habitats is mainly a result of differences in environmental conditions, namely more intense vertical turbulence in the alpine habitat, and does not result from prominent differences in plant traits, namely V-term, between alpine and lowland species.