British Columbia has begun to allow tree species to be planted toward the northernmost reaches of their natural range and beyond to respond to predictions that because of climate changes, by the time the trees are fully grown, their new habitat will be similar, if not identical, to their original habitat. Plant species are already moving to new or expanded ranges; assisted migration mimics what the trees would do themselves over time, with human help. Although it could reduce the number of species that face extinction, assisted migration could also accidentally introduce an invasive species, diseases the new habitat is unable to resist, or hybrid species that would lower genetic diversity. The process can be costly, and may require regulatory changes if local, state/provincial or national laws forbid moving the species.