A forest in Staffordshire, UK, where an experiment is testing how trees respond to higher levels of carbon dioxide in the airShomari Healy, used by kind permissionTucked away down a quiet country lane in the UKs West Midlands region lies one of the most studied patches of forest in the world.This fragment of woodland, populated mainly by 180-year-old English oak trees (Quercus robur), is at the heart of a major global project to understand how the worlds forests will cope as levels of carbon dioxide rise in the atmosphere.