Mountain Ash trees. CSIRO

A landmark study of the towering ash trees that grow in the mountains of Victoria, Australia, which was launched in the 1980s, boosted arguments for clearcutting the iconic trees. But when scientists returned to the site years later, they came to a much different conclusion.

Australian conservationists have long contended that clearcutting imperiled koalas and other native wildlife. Foresters, on the other hand, argued that mountain ash trees, which can grow taller than 300 feet and live for more than 400 years, were adapted to catastrophic bushfires that cleared the forest, leaving nothing behind.…