Future climate and land-use intensification modify arthropod community structure

Climate change and land-use intensification pose increasing threats to biodiversity, with climate change expected to eventually surpass other global environmental change drivers and become the greatest threat to biodiversity in the future. Understanding the combined ecological impacts of multiple global change drivers is crucial to predict future scenarios of biodiversity change. However, experimental evidence for the impacts of land-use intensification under current and future climate scenarios is lacking, even though this is imperative for understanding future trajectories of biodiversity in agricultural landscapes. We experimentally tested for the simultaneous effects of land-use intensification and climate change on arthropod biodiversity in a field-scale grassland experiment known as the Global Change Experimental Facility (GCEF). Specifically, we tested whether future scenarios of climate change are likely to exacerbate impacts of land-use intensification on arthropod diversity and abundance across different trophic levels by sampling aboveground arthropod communities in low and high land-use intensity grasslands under current and future climatic conditions. We found that climate change reduced total abundances of arthropods and increased evenness of the whole community, while only having trophic level-specific effects on detritivore abundance and evenness. Land-use intensification reduced abundance of the whole community, predators and detritivores, but only eroded species richness of the whole community and herbivores, with the magnitude of declines in predator and detritivore abundance depending on the climate scenario. Additionally, both land-use intensification and climate altered species composition of the whole community and within the predator, herbivore, and detritivore trophic levels. We show that climate change and land use intensification cause simultaneous shifts in arthropod abundance, species richness, and species composition across trophic levels. Changes in arthropod communities as a result of climate change and land-use intensification will likely have profound consequences for ecosystem functioning under future environmental conditions.