Impact of dairy farming on butterfly diversity in Alpine summer pastures

The practice of transhumance of livestock herds to Alpine summer pasture has experienced pronounced changes over recent decades due to the general process of agricultural intensification in productive areas and abandonment of farming in marginal areas. Instead of moving lactating cows to summer pastures raising replacement heifers recently gained much importance. Here, we analysed the impact of these changes in dairy farming on butterfly diversity inhabiting Alpine summer pastures in the eastern Italian Alps. We sampled butterflies (Lepidoptera) in 16 Alpine summer pastures that were either grazed by lactating cows (n = 11) or replacement heifers (n = 5) at two distances from the farm building. Butterflies were classified according to their mobility. Our results showed a distance effect on total butterfly species richness only in pastures grazed by lactating cows indicating a stronger impact on vegetation structure and composition nearby the farm building. Abundance of butterflies was higher with increasing distance from the farm building. In contrast to mobile butterflies, sedentary species reacted more strongly to disturbance induced by grazing livestock. Moreover, butterfly composition differed slightly between pastures grazed by lactating cows and heifers. Our results indicate that the widespread adoption of heifer grazing induces a shift in butterfly diversity and composition likely caused by the different behaviour of grazing livestock. In order to benefit butterfly diversity in Alpine summer pastures, we suggest that future agri-environment schemes should provide extra support for summer farming of lactating cows.