Listen to ecologist Dr. Tom DeLuca talk about his research trips to the remote area of northern Sweden and you’ll be treated to an ecological mystery story. Birch forests once filled an open valley in the mountains between Sweden and Norway just north of the Arctic Circle, but sometime around 1000 years ago the trees disappeared. All that remains today is an open vista and the collapse of an ecosystem, says Dr. Tom DeLuca Senior Forest Ecologist with The Wilderness Society. more