As native trees in the Pacific Northwest die off due to climate changes, the U.S. Forest Service, Portland, Oregon and citizen groups around Puget Sound are turning to a deceptively simple climate adaptation strategy called “assisted migration.” As the world’s climate warms, tree growing ranges in the Northern Hemisphere are predicted to move farther north and higher in elevation. Trees, of course, can’t get up and walk to their new climatic homes. This is where assisted migration is supposed to lend a hand. The idea is that humans can help trees keep up with climate change by moving them to more favorable ecosystems faster than the trees could migrate on their own. Yet not everyone agrees on what type of assisted migration the region needs — or that it’s always a good thing.