Gourmets or gourmands? - Diet selection by large ungulates in high-alpine plant communities and possible impacts on plant propagation

Megaherbivores have a considerable impact on species composition and structure of natural plant assemblages at the alpine/nival ecotone of the Alps, but their role as dispersal vectors has scarcely been investigated. This study examined the diet selection of free-ranging ungulates on high-alpine swards with special focus on their potential for endozoochoric dispersal. Grazed areas and fenced control plots were investigated by a point-framing method. Results show that the foraging behaviour of ungulates in high-alpine swards is selective. Flowers and fruits are preferred to leaves. Accordingly, an increase in longdistance dispersal events of alpine vascular plants by grazing ungulates can be predicted. Preferential feeding on the conspicuous flowers of herbs rather than on graminoid inflorescences causes a more pronounced reduction of seed numbers in herbs. We therefore suppose the enhancement of long-distance dispersal to be higher for graminoids. The impact of herbivores on plant migration processes must therefore be considered when changes in alpine plant assemblages are to be assessed. & 2004 Elsevier GmbH. All rights reserved.