Effects of Trampling on Vegetation above the Timberline in the Eastern Alps, Austria

Abstract

The effects of trampling on alpine pasture vegetation were analyzed in four regions of the Austrian Alps: one in the Radstädter Tauern mountains (Central Alps) and one on the Rax plateau near Vienna, on predominantly calcareous substrates, and two in the Central Alps on siliceous substrates. Species composition, vertical and horizontal structure, and biomass were investigated, as well as diaspore communities of heavily disturbed vegetation (on trails) and adjacent undisturbed (natural and seminatural) vegetation. Results show that species resistant to trampling (e.g., Poa supina) are more frequent in disturbed than in seminatural vegetation, and that they reproduce under trampling pressure and can store more than 20,000 germinable seeds/m2 in the uppermost 5 cm of soil. Some species (e.g., Deschampsia cespitosa) show hardly any negative effects on abundance and/or diaspore bank, whereas aboveground biomass and vegetative growth of the single ramet can be reduced by trampling. Because of the presence of species like Poa supina, some trails store a larger diaspore community than the adjacent vegetation. However, most of the species investigated, including some endemic or threatened species of the Eastern Alps, are neither able to germinate nor to establish themselves on trampled sites. There is no evidence that they develop a sufficiently persistent and evenly distributed diaspore bank for a possible regeneration in the future.