The overall research question addresses the effectiveness of incentive mechanisms in poli -cies that enhance private forest owners’ biodiversity protection. In particular, the paper focuses on the link between forest owners’ motivations, incentives, and institutions, and questions the incentives of the current biodiversity protection policies. Our hypothesis is that the purely monetary nature of the incentives can cause a “crowding out effect”, i.e., forest owners may reduce their voluntary contribution to biodiversity protection that is driven by prosocial motivations (altruism, self-image, etc.). With this in mind, as well as the knowledge acquired via this project about forest owners’ motivations, we looked for the most effective combinations of “incentive mechanisms” (monetary and non-monetary) and “institutions” (national and local authorities, NGOs, etc.) to encourage forest owners to adopt biodiversity protection measures in their forests.