In the forests of the American West, there is a tree called the Lodgepole Pine that carries a secret. Its cones are sealed shut by a thick, stubborn resin. They are essentially "locked." They can sit on the forest floor for years, hardened and seemingly dead. To the naked eye, they look like small, gray stones.   The mystery of the Lodgepole Pine is that it requires fire to bring forth life. The very thing that threatens to consume the forest is the only thing hot enough to melt the re...