By JOHN FLESHER
The Associated Press
TRAVERSE CITY — Michigan's forests are under siege from diseases and exotic pests, a problem worsened by unwitting people who ignore pleas not to haul firewood across the state or even across town, officials said Thursday.
In a report on the condition of the state's 19.3 million acres of woodlands, the Department of Natural Resources and Environment said the biggest concern is a relentless march of invasive species that have killed millions of trees in recent years.
"The forest itself will survive but some species are undergoing severe threats," said Bob Heyd, a Marquette-based forest health specialist.
Beech bark disease, emerald ash borer infestation and oak wilt were among the plagues that hammered Michigan trees last year, the report said. The spread of all three has been linked to movement of firewood, which can transport invasive insects and spores in the same way that ballast water aboard cargo ships brings unwanted mussels and fish to the Great Lakes, Hey said.
"The word is getting out and people are more aware of the danger," he said. "The problem is that they're thinking only of ash trees and the emerald ash borer, because they've gotten so much attention. But it really applies to all firewood. If you move oak wilt even a mile, you can establish a whole new disease epicenter."
The Michigan Department of Agriculture has set up a quarantine to limit the ash borer's spread — including a firewood checkpoint at the Mackinac Bridge linking the Upper Peninsula and Lower Peninsula. People caught hauling firewood into the U.P. can be fined or even jailed. Even so, the ash borer has been found in several U.P. locations after killing more than 30 million ash trees in southeastern Michigan.
The DNRE tested ash borer containment methods in three areas of the Upper Peninsula last year, the report said. Meanwhile, the battle continued against other harmful invaders.
Crews planted the first seedlings of a beech tree strain that appears to be resistant to beech bark disease, Heyd said. If so, the trees eventually could offset heavy losses of beeches in northern Michigan.
Meanwhile, teams used a special plow to break apart grafted oak roots and establish a barrier at 38 locations in Menominee and Dickinson counties — a method biologists say can limit the spread of oak wilt.
Scientists continue to watch for outbreaks of invaders such as annosum root rot, which has been spotted in red pines in south-central Michigan, and the dreaded Asian longhorned beetle, which targets deciduous trees including maples, elm, ash and aspen. The beetle wasn't found in the state last year but has infested maples in a 62-acre of Massachusetts, raising concerns elsewhere.
The hemlock wooly adelgids, a tiny but deadly insect discovered in Harbor Springs in 2006, was spotted last year in ornamental hemlock trees in Emmet, Macomb and Ottawa counties.
"Every year, insects and diseases pose a significant threat to our state's woodlands and, in turn, forest-based recreation and timber industries," said Lynne Boyd, chief of the DNRE's forest management division.
The report said some Michigan tree species were suffering from a loss of growth and vigor simply known as "decline," which make them more susceptible to pests and stresses such as drought. Among them were some aspens, maples and white pines.