Land use and climate change affects butterfly diversity across northern Austria

Biodiversity is severely decreasing at a global scale since several decades. There are significant changes in species community compositions, reductions of species richness and abundances of arthropods, as well as of arthropod biomass. Land use intensification and climate change are assumed to be main drivers causing biodiversity change and loss. However, proximate effects of land use, landscape configuration, topography and climate on species richness and species community composition were only rarely analysed. We study the effects of current land cover, landscape structures and climate on butterfly and burnet moth species diversity and community composition across northern Austria (i.e. the federal state of Salzburg). We compiled observation data of butterflies and burnet moths for the past 40 years. We divided faunal data, land cover data and data on climate into 5 × 5 km2 grid cells. We classified all lepidopterans assessed into groups according to their distribution, behaviour, ecology and life-history. We found higher species richness and temporal community shifts in higher elevations, and where topographic heterogeneity is high. Habitat connectivity has a positive impact on ecologically specialised, sedentary, and endangered species. Mean temperature and precipitation positively influenced species richness. Both, land-use and climate strongly shape biodiversity structures. In particular, landscape heterogeneity promotes the diversity of ecological niches, which subsequently accelerates species diversity, including specialist species. Agricultural intensification in higher elevations and at steep slopes is more difficult and therefore less attractive, and thus the level of biodiversity is still high. In addition, climate warming might lead to the accumulation of species in higher elevations. Our study further underlines the relevance of habitat conservation at lower elevations, where not all habitat types are conserved sufficiently.