NEW YORK (AP) -
Five prominent species of ash tree in the eastern U.S. have been driven to
the brink of extinction from years of lethal attack by a beetle, a
scientific group says. Tens of millions of trees in the U.S. and Canada have
already succumbed, and the toll may eventually reach more than 8 billion,
the International Union for Conservation of Nature said Thursday.
Ash trees are a
major part of eastern forests and urban streets, providing yellow and
purplish leaves to the bounty of fall colors. Their timber is used for
making furniture and sports equipment like baseball bats and hockey sticks.
The rampage of the
emeraldash borer is traced to the late 1990s, when it arrived from Asia in
wood used in shipping pallets that showed up in Michigan. Asian trees have
evolved defenses against the insect, but the new North American home
presented it with vulnerable trees and no natural predators.
are exploding,” said Murphy Westwood of the Morton Arboretum in Lisle,
Illinois. Infestations have been detected in 30 states.
“It’s a very
efficient killer,” Westwood said. “As the ash borer moves through a forest,
it will completely kill all of the mature ash trees within three or four
She led the
scientific assessment that resulted in classifying the five species as
critically endangered - meaning they are facing an extremely high risk of
extinction in the wild. The change appears on the IUCN’s Red List,
considered by scientists the official index of what animals and plants are
in danger of disappearing. The species are the green, black, white, pumpkin
and blue ash.
A sixth species,
the Carolina ash, was put in the less serious category of “endangered”
because it might find some refuge from the infestation in the southern part
of its range, which includes Florida, Texas and Cuba, Westwood said.
Dan Herms, an
entomologist at Ohio State University who studies the ash borer, called it
“the most devastating insect ever to invade North American forests.” It’s
already the most expensive because it has killed so many urban trees that
had to be removed, disposed of and replaced, which has cost billions of
dollars, he said.
Herms, who was not
involved in the IUCN project, said he’s not sure the ash species will
literally disappear. But he said they could become “functionally extinct,”
with populations too small to play a significant role in the environment for
benefits like providing shelter and filtering water.