Abstract
Assisted migration is the translocation of species beyond their historical range to more suitable locations given future climate change. This conservation approach poses risks of establishment failure because of uncertainty in decision making, climate, and interactions with the recipient ecological community. To quantify the risks and benefits of assisted migration under different management decisions, we built a stochastic metacommunity model to simulate several species reproducing, dispersing, and competing on a temperature gradient as temperature increases over time. Without assisted migration, species were vulnerable to climate change if they had a low population sizes, short dispersal, and strong poleword competition. When relocating species that exemplified these traits assisted migration increases the long-term persistence of the species most when relocating a fraction of the donor population, even if the remaining population was very small or rapidly declining. Especially when it is difficult to identify a species’ optimal climate, leaving behind a fraction of the population could be a robust approach, allowing managers to repeat assisted migration in case they move the species at the wrong place and wrong time. Assisted migration was most beneficial to species with low dispersal ability and least beneficial to species with narrow thermal tolerances, for which assisted migration increased extinction risk in almost all situations. Relocation did not affect the survival of non-target species, suggesting that competitive interactions alone were unlikely cause invasions from assisted migration.