Information Underload: Ecological Complexity, Incomplete Knowledge, and Data Deficits Create Challenges for the Assisted Migration of Forest Trees

Forest managers are considering assisted migration as a strategy to develop climate-resilient forests. Assisted migration (AM) is the translocation of species or genotypes from their current ranges to areas predicted to have a supportive future climate. Although correlations of species ranges with climate are traditionally used to explore AM potential, successful AM strategies will have to consider many other variables. In this article, we review recent research that informs the complexity of AM decisions. Local microenvironment, herbivory, and intraspecific interactions frequently outweigh climate in determining species establishment and survival. Species adopt several strategies to cope with drought, heat, and cold, but translocated genetic material can display cryptic maladaptation when challenged by extreme, out-of-range weather events. Phenology, photoperiod, and climate are related in complex, often provenance-specific ways. We discuss the implications of our findings for forestry AM and make recommendations for incorporating these insights into future research and AM practice.