Tree inventory data typically are confined to national boundaries and differ in formats and objectives, thus limiting their use for studying species wide ranges. Northern Research Station scientists collaborated with their colleagues in Canada to overcome this barrier to predict current and future habitat quality and calculate colonization likelihoods. Scientists mapped combinations of habitat quality and colonization likelihoods to evaluate management options, including assisted migration.

A two-decade collaboration between Northern Research Station scientists and Canadian scientists resolved differences in inventory formats, allowing the combination of USDA Forest Service’s Forest Inventory and Analysis (FIA) data with gridded estimates of Canada’s National Forest Inventory (NFI) for 25 tree species that span the two countries. Meshing tree inventory data in the two countries allowed scientists to map the future climatic outcomes for 25 iconic northern tree species based on habitat quality and colonization likelihood. For the species examined, habitat losses were primarily experienced along southern range limits, while habitat gains were associated with northern range limits. Leading edge habitats are projected to expand due to greater warming at these latitudes, while trailing edge populations may remain viable, but subject to greater climatic stress. Even though large parts of Canada and Alaska are poised to gain climatically suitable habitat for many tree species, the models predict that only a small portion of the climatic habitat generated by climate change will be colonized naturally by the end of the current century, even with optimistic tree migration rates. Variation among species points to the need for significant management efforts, including assisted migration of populations and species, in order to conserve and promote important tree species. This work highlights the need for increased cross-border cooperation for addressing the common threat of climate change.