The composition and structure of twenty-first century forests will depend on the seed production needed for tree populations to keep pace with climate change. The dramatic, immediate impacts of climate change include large-scale forest die-backs. But the decade-scale trends will depend on the regeneration that follows tree death. Tree regeneration will determine the capacity of trees to disperse seed to the shifting habitats where they can survive in the future; risks to each species depend not only on the current distribution of fecundity, but also on its trajectory. As with many ecological processes, noisy, spatially-variable recruitment trends are hard to quantify, but this is only the first problem. Attribution of trends to environmental variables is complicated by individual variation as trees interact with others that are also responding to climate change. Conservation efforts must anticipate not just the direct climate effects on this trajectory, but also the indirect effects as climate affects growth and changing size structure. To address these challenges, the Forecasting Biodiversity Change (FORBIC) network of primary data and modeling synthesis has allowed us to quantify direct and indirect effects of climate on the next generation of global forests. Both the novel data network and technical innovations in hierarchical analysis provide evaluate direct and indirect effects. I discuss emerging insights from individual-scale processes such as demographic changes, to community consequences for mast-consuming wildlife, to global climate and soil controls on forest migration and resilience.
