We study the processes that shape the strucure, composition and function of the world's forests to better understand how these ecosystems are responding to rapid environmental change. We do this using a range of different approaches, including manipulative experiments, large-scale datasets, remote sensing and modelling. Our goal is to get a more accurate picture of what forests will look like in the future and what consequences this will have for climate, biodiversity and the billion or so people whose livelihoods depend on these ecosystems.