Something is killing bigleaf maples — Washington's biggest broadleaf tree — and scientists can't stop it. They don't even know what's causing it.
"We've looked for everything we can possibly think of and what people smarter than us can think of," said Amy Ramsey, a forest pathologist with the state Department of Natural Resources.
From British Columbia to California, stands of bigleaf maples are dying, leaving bald patches in the forest canopy or even denuded hillsides. Reports of dying and dead maples first reached the DNR in 2010, Ramsey said. Foresters noticed the trees were producing small, scorched-looking leaves or none at all. Sometimes, the crown — the upper most branches of the tree — would die.
The reports, from forest professionals, were scattered at first. Then the public began to call. "The public had questions, and we didn't have answers," Ramsey said.
When the DNR began to survey state forests, it found the problem was widespread. Since then, the number of trees affected has grown. Several agencies — including the DNR, the U.S. Forest Service and the University of Washington — have been studying the maples but no diseases or insects have been found in significant numbers to be a culprit. "It is still a mystery," Ramsey said.
Acer macrophyllum, the tree's Latin name, translates as "maple large leaf." The leaves are the biggest in the maple world, reaching a foot in width.