When Mount St. Helens blew in 1980, it flattened about 135 square miles of forest and buried the ground under ash thick enough to bury a car. A couple of years later, scientists tried an odd experiment. They carried a few pocket gophers by helicopter onto the barren pumice and let them loose for about a day. The gophers did what gophers do. They dug, and in digging they churned up the old, rich soil and the helpful fungi buried far below the ash. Then the scientists took them away. Six years later, the fenced plots where the gophers had been were covered with about 40,000 plants, while the patches nearby were still bare.
