Effects of different farming methods and utilisation intensities of alpine pastures on the butterfly fauna in the NP Gesäuse

The biggest cause of risk for butterflies is the loss of suitable habitats due to the intensification of agricultural land or their use task. This process does not stop at alpine pastures either. Unmanaged pastures below the climatic forest boundary are rapidly re-inhabited by shrubs and ultimately by trees. Especially for heliophile animals such as butterflies, this has dramatic negative consequences. An extensive way of farming promotes the diversity of butterflies and increases the number of rare species, according to general opinion. In order to investigate the effects of grazing of pastures on butterflies and day-active moths, 66 sample areas (50 x 50 m) were investigated on 13 different alpine pastures in the Gesäuse National Park (Austria). The alpine pastures covered a gradient from already out-of-use to intensively managed. All sample areas were examined three times during the growing season 2011. In addition to the sightings of representatives of the investigated insect group, environmental parameters were also included. Multivariate models (GLM, GLMM, distLM) were used for the data analysis, and ordination methods were used for the graphical presentation of the results. In total, 95 species of day-active butterflies were observed in 3065 individuals, of which 66 species belonged to 2545 individuals among the real day butterflies (Hesperioidea and Papilionoidea). The grazing intensity generally did not have a significant impact on the diversity and species power of the butterflies, but with a differentiated view, it was shown that with increasing intensity of grazing, the proportion of habitat specialists and species inhabiting the preferred natural/semi-natural habitats decreased. The abundance of the butterflies was also negatively influenced by grazing. The most important predictor for the diversity and number of species of the butterflies was the altitude of the sample area or the average altitude of the examined alpine pasture. In contrast, abundance was mainly influenced by the local resource supply, the Nactar Sources. The moth societies differed quite little between the different grazing intensities. Only the species inventory of abandoned alpine pastures differed significantly from the still managed alpine pastures of various usage intensities. Similar to the diversity and number of species, the altitude had the greatest influence on the species composition of the butterflies; second, predictors of usage intensity followed by nectar availability. In order to keep the abundance of species and the abundance of alpine butterflies high, flower-rich meadows, which can serve as nectar springs, are desirable. The difference in the moth societies of broken land and still managed alpine pastures leads to the conclusion that different succession stages are important for certain groups of moths. For this reason, management measures should aim at a mosaic of different succession stages.