The expected benefits and potential risks of non-native trees (NNT) to European geographic regions have polarised the opinions of experts and citizens. Benefits include adaptation to climate change (CC), contributions to bioeconomy, urban&peri-urban green infrastructure and mitigation of natural hazards by NNT, while risks involve NNT invasiveness and effects on native biodiversity. In critical and vulnerable ecosystems such as the Alpine Space (AS), such risks and benefits must be carefully considered before management decisions are made. Experiences in the management of NNT in urban areas, peri-urban, rural terreories and forests are often country-/city-specific and thus rarely shared. Given the challenges in NNT management with respect to both benefits and risks, a transnational approach is needed to qualify the role of NNT in future AS ecosystems. The objective is to provide a transnational strategy for a Decision Support System on responsible use and management of NNT in the AS. The project fits within the context of national and regional site-derived policy aiming to protect & enhance biodiversity to ensure ecological connectivity and cultural resources while maintaining a high level of resilience and ecosystem services (ES) across AS. Implementations include:developing a comprehensive database on NNT; predicting the current and potential distribution of NNT in AS under CC scenarios; determining their invasive potential; analysing the different ES provided by NNT to assess the tradeoffs between risks and benefits. ALPTREES will formulate management recommendations for NNT under different climate and economic scenarios through stakeholder meetings, policy briefs, a handbook of lessons learned and transnational pilot actions for best management practices. An innovative output of the project is the Open ALPTREES Knowledge Hub, that will support the transnational and interdisciplinary knowledge transfer.The overall planned budget is € 2.348.664,64