Science is poised to insert foreign genes into conifers and other trees harvested for cash. Opposition already is stirring. The prospect raises ecological and cultural issues unlike any encountered before. But the promise is big, too, said Claire Williams, a geneticist and visiting professor at Duke University. Designer trees may grow faster and yield products cheaper. That could preserve existing forests while the world’s appetite for wood and paper keeps growing.

Supporters and skeptics, she said, need to talk. »We have a narrow window for constructive dialogue. In five or 10 years it will be too late,« Williams said.