Direct and indirect effects of ski run management on alpine Orthoptera

Abstract

Alpine landscapes are heavily influenced by ski run management, which can have severe impacts on alpine biodiversity. To assess these impacts on alpine Orthoptera, we compared species richness and species abundance in 41 plot pairs on ski runs and adjacent off-slope control plots in three ski resorts in Austria and Germany. A mixed modelling approach was used to assess the impacts of ski run preparation, artificial snow-making and environmental variables such as altitude, cover of dwarf shrubs and the application of fertilizer. Ski run plots showed a significantly lower species richness and number of individuals than control plots. Moreover, artificial snow led to a further decrease in species number. Hierarchical variance partitioning revealed that Orthoptera community composition is best predicted by environmental variables indirectly related to ski run management (fertilization, cover of dwarf shrubs) and to altitude. Only one out of five species significantly decreased in abundance after artificial snow-making. Other species were more sensitive to fertilizing and altitude. Dwarf shrubs were negatively associated with ski run management but positively associated with abundance of three species and species richness. Our data provide evidence for both direct and indirect consequences of ski runs and artificial snow-making on alpine Orthoptera. Overall, Orthoptera communities are suitable indicators for human-induced changes in alpine environments. In particular, a shift towards generalist species such as Chorthippus parallelus along with a decrease in typical alpine species gives cause for concern as this implies a homogenisation of biodiversity owing to ski run management.