One of the main ecological challenges of our time is understanding how ecosystems deal with the various threats of global change. For many species, the effects of global change – either climate warming, land use changes or any other - result in significant changes in their distribution. To obtain reliable predictions of plant species range changes under global change, however, environmental conditions and species interactions at the local scale are key, and both are so far poorly studied. With this proposal, I aim to unravel the role of climate and land use change on range changes with the help of a set of local observations and experiments, building on a longterm global observational study on plant species distributions in mountains (hosted by MIREN, the Mountain Invasion Research Network). First, I will quantify the relative importance of local land use change (exemplified by mountain roads and trails) and microclimate on regional species distributions. Next, I will use local measurements to fully disentangle the mechanisms at work, ending with a field experiment to validate the observations and models. Altogether, this will help answering timely questions on the importance of local-scale mechanisms in defining species distributions, as well as on the impact of global change on mountain biodiversity.