By CARIN TUNNEY
Capital News Service
The thick canopies of oak stands can prevent seedling oaks from taking root. Image: Carin Tunney
LANSING — Foresters in Michigan and throughout the Great Lakes region are destroying mighty oaks and other trees to regrow hardwood forests.
That may seem counterproductive, but forestry officials say oaks need special attention to maintain a diverse and healthy forest system. That means cutting down decades-old trees, clearing shrubs and sometimes burning the forest floor to encourage new oaks to grow.
The Department of Natural Resources (DNR) recently launched a multi-year effort to reforest between 2,000 and 2,500 acres in Kalkaska County. The state land has mature oaks that block oak seedlings from taking root. Timber harvesting encourages acorns and stumps with well-established root systems to sprout new trees.
Woodlands that lack human intervention put species diversity at risk, said Dave Lemmien, a DNR forest manager.
Aging oaks create thick canopies that inhibit natural reseeding, he said. Shade-loving trees and plants take over.
“They will grow just to certain size and that’s it,” Lemmien said. “You are not creating canopy gaps and allowing for natural generation for regrowth to occur.”
Lemmien said an even distribution of trees in terms of age and species also helps woodlands survive attacks by invasive species. Older trees are more susceptible to disease and other threats. Many oaks in Kalkaska County died when gypsy moths invaded two years ago, he said.
Michigan is emphasizing oak regeneration as part of its conservation plan, said Mark Mackay, a DNR wildlife ecologist.
“Oak is dominant on state wildlife lands,” he said. “It represents about 25 percent of our lands. However more than 50 percent of those lands don’t have any oak regenerating in the understory and oak is incredibly important from a wildlife perspective, across species.”
Foresters say regeneration benefits the entire ecosystem, since insects, birds and reptiles rely on oak-forest habitats, and deer and squirrels benefit from increased acorns.
The DNR started using a forest simulation program this year that aids in inventory calculations, monitoring and determining best-case scenarios to grow oaks, such as burning, herbicide application, planting or simply thinning the trees, Mackay said.
The department recently used the program to analyze state land in Barry, Ionia and Montcalm counties. The findings showed these areas will benefit from prescribed burns and herbicide treatments before reforestation begins next spring, he said.
DNR officials in Kalkaska County say they will consider a burn if the forest needs extra encouragement to grow.
Prescribed burns are becoming a more common method of reforestation, forestry officials said. Research shows they encourage natural seeding of new plants in oak forests, and result in oak seedlings that are taller and larger in diameter.
People often associate burning with air pollution, but forestry officials say they use techniques to minimize it, such as burning only in suitable weather conditions. They say the long-term benefits to the ecosystem outweigh the minimal, short-term smoke pollution.
Forests were once regenerated by fires set by Native Americans and through extensive logging, said Charles Ruffner, a forestry researcher from Southern Illinois University. But many of today’s forests have gone untouched for more than 80 years, he said.
Research shows some southern Illinois forests lost half their oaks between 1980 and 2014. Shade trees such as sugar maple and beech are taking over.
“When you don’t do anything in the woods for 80 years, forest succession — the change that happens in forests naturally — continues to happen,” Ruffner said. “In a generation or two, the forest has changed drastically, and then you spend your whole career trying to get it right again.”
Conservationists say private landowners play a critical role in oak forest management.
The Michigan DNR provides guidance to private landowners through its Forest Stewardship Program, which connects residents to foresters and wildlife biologists, said Mike Smalligan, DNR’s forest stewardship coordinator.
The U.S. Department of Agriculture and the U.S. Forest Service are also involved in oak reforestation efforts across the Midwest, said Christina Coulon, a public affairs specialist with the Agriculture Department. Efforts include clearing trees, planting new seedlings and often burning parts of the forest floor on federal, state and private lands.
Carin Tunney writes for Great Lakes Echo