Ivan Nijs (research group PLECO) is an expert in ecological interactions between plant species. How do climate, biodiversity loss and invasive species affect these interactions? Ivans research searches the answer through experimental and modelling studies. Ivan has strong experience on "mesocosm"-studies, studies on a small version of a natural ecosystem. These miniatures of reality can be subjected to multiple pressures, as they are predicted in the future. Ivan mainly aims at quantifying the impact of "extreme changes", like drought and heat waves. These extremes will increase as climate change progresses. Ivan was and is a pioneer in translating mesocosm results to natural systems. To achieve this, he performs multiple "open-air" manipulations, where selected plots in a large scale ecosystem are subjected to different pressures, including drought and increased temperature. Within the European AnaEE-consortium, Ivan is involved in the construction of several "ecotrons": true-scale representations of complete ecosystems, where the effect of the climate of the future is tested on functioning and sustainability.