Treeline ecosystems are important indicators of environmental change, because they are heavily impacted by environmental drivers, in particular changed climate and land use, resulting in land abandonment and reforestation of formerly treeless areas. With a focus on treeline ecosystems, this Action aims at integrating scientific methods and results related to the biodiversity conservation and sustainable use of natural resources under climate and land use change. The Action will investigate the drivers and extent of contemporary and future environmental changes in European mountain forests, developing methods for estimating their resilience and define consequences for society. This knowledge provides the scientific basis necessarily to develop and adjust management strategies together with local and regional stakeholders as well as policy recommendations for national and European policy makers. Applying the DPSIR (Drivers, Pressures, State, Impact, Response) framework, the joint actions of the SENSFOR network will contribute to the development of strategies for preserving ecosystem services and biodiversity conservation in sensitive mountain areas in Europe.