Given the uncertainty of global environmental changes, forest managers need reliable and science-based tools to support planning decisions. To evaluate the state of forests as well as the outcomes of new management practices aimed at fostering the adaptive capacity of forest ecosystems, methods and metrics for practitioners should be self-explanatory, based on easily-available data, and straightforward to use. Here, we present and apply the functional network approach, a trait-based approach that scales-up from species functional traits to community-level functional diversity and from stands to landscape-level functional connectivity, to guide sustainable forest management when faced with global change. In the functional network approach, (1) tree and shrub species are clustered into functional groups based on selected functional traits, (2) forest stands become the nodes of the network, and (3) functional traits can be exchanged between nodes according to species dispersal capacity via functional connectivity. We complemented the functional network approach with an assessment of stand-level vulnerability to natural disturbances. This new approach was applied to a mixed temperate forest landscape in south-eastern Canada to test four management scenarios varying in intensity (5–40% of the landscape area) and silvicultural strategy, including planting tree species from rare functional groups or harvesting tree species from predominant functional groups. Managed stands were ranked according to functional diversity and vulnerability to disturbances, and species were considered for planting based on their contribution to functional diversity and level of vulnerability. We found that a species-rich forest may be a functionally poor ecosystem so its adaptive capacity and resilience may be strongly compromised in the face of high global uncertainty. In addition, both functional diversity and connectivity increased with more intense management, and when functionally rare species were planted. By adopting the functional network approach, forest practitioners have a new simple-to-use tool to evaluate landscape-level functional diversity, vulnerability, and functional connectivity. This tool can be used to inform both plans for mitigating natural disturbances and strategies for enhancing overall ecosystem adaptive capacity to future environmental conditions and societal demands.