Trees are adapted to specific combinations of environmental and climatic conditions that allow them to grow, thrive, and reproduce. Climate change is already altering conditions across the planet, and changes are expected to continue in the decades to come. The rapid pace of climate change may exceed the ability of many species to adapt in place or migrate to suitable habitats, and this fundamental mismatch raises the possibility of extinction or local extirpation. Assisted migration, human-assisted movement of species in response to climate change, is one management option that is available to address this challenge. This topic page will examine some of the scientific background and management considerations related to assisted migration, focused primarily on tree species.
Definitions Assisted migration, human-assisted movement of species in response to climate change, is a general term that encompasses a variety of different potential actions, which have substantial differences in terms of risk, ecological implications, and policy considerations. Here are some of the commonly used terms that distinguish between different forms of assisted migration [11]:
- Assisted population migration (also assisted genetic migration or assisted gene flow) – moving seed sources or populations to new locations within the historical species range
- Assisted range expansion – moving seed sources or populations from their current range to suitable areas just beyond the historical species range, facilitating or mimicking natural dispersal
- Assisted species migration (also species rescue, managed relocation, or assisted long-distance migration) – moving seed sources or populations to a location far outside the historical species range , beyond locations accessible by natural dispersal
Handler, S.; Pike, C.; St. Clair, B.; 2018. Assisted Migration. USDA Forest Service Climate Change Resource Center. https://www.fs.usda.gov/ccrc/topics/assisted-migration
