If you enjoy a glass of bourbon, you also like white oak trees. By law, bourbon must be aged in new, charred white oak barrels. There are no exceptions. But Kentucky’s white oak trees are in trouble, and I bet most bourbon fans don’t know. There’s a strange thing happening. It seems white oak seedlings are sprouting on forest floors, while mature white oaks still tower above them. But the middle-sized trees, or what you could call the teenagers, keep disappearing.