AbstractThe effectiveness of Protected Areas in conserving forest ecosystems has been examined at the continental scale using area-based habitat parameters, but knowledge of the three-dimensional structure of forest habitats is still lacking. Here, we assess the effectiveness of European Protected Areas in conserving the vertical structure of forests by analysing more than 30 million records from the Global Ecosystem Dynamics Investigation (GEDI), a spaceborne LiDAR (Light Detection And Ranging) mission. We compare a suite of indicators of the vertical structure of forests inside and outside nearly 10,000 protected areas. We find that European forests are on average 2 m taller and vertically more complex in protected areas than in nearby unprotected areas, albeit with some regional differences. At the same time, forests outside protected areas show greater variations in canopy height than inside, probably as a result of past and current forest management operations. Our findings highlight the positive imprint of environmental policies on forest structure across Europe and underscore how spaceborne LiDAR enables the large-scale monitoring of forest vertical structural attributes that are key to conservation and restoration policies.