LiveScience: Around the arrival of Columbus, “it’s said that squirrels could travel from tree to tree from the Northeast to the Mississippi without ever having to touch the ground,” said Chris Roddick, chief arborist at the Brooklyn Botanic Garden in New York. “In the old growth forests in the Northeast, you had hemlock that were six or seven feet in diameter, chestnut trees 200 feet tall.” Although Native Americans used to burn forests to farm, such practices were nowhere close to damaging “as …