MINNESOTA — Brian Palik, a forest ecologist with the USDA’s Forest Service Northern Research Station, stops and points to a newcomer under the red-pine canopy: a broadleaf deciduous tree, bitternut hickory. …It is a promising sign in a project that aims to keep forests growing in a warming world. …Two decades back, these southern seedlings likely would have struggled to flourish here. Today, Palik can see the success of almost all the southern trees they planted. …“The climate typical of southern Minnesota from 20 years ago is now in northern Minnesota,” Palik says. Climatic conditions have moved about 200 miles north in just two decades. …Palik’s project is an experiment in forest assisted migration. …Many forest managers could eventually face a choice: Consider moving southern trees into northern areas, or eventually wind up with fewer productive woodlands for timber and other uses.