Stroking a tiny spruce sapling, Swiss forest ranger Francois Villard fears the tree will not withstand global warming and live to a ripe old age like its ancestors. The Risoud Forest, covering the border between France and Switzerland some 1,200 metres (3,900 feet) up in the Jura mountains, is filled with spruce trees which are hundreds of years old. Their wood is perfect for crafing acoustic guitars, violins and other ...