Illinois oak forests decreasing - WSIL-TV 3 Southern Illinois

Illinois oak forests decreasing

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WSIL -- A growing concern for southern Illinois's predominantly oak and hickory forests.  These native trees, which make up the bulk of the Shawnee National Forest, are being replaced by more shade tolerant trees.

"We could go from oak being a major component in southern Illinois to only being a minor component in a sugar maple, beech forest," said Justin Dodson, Forest Service silviculturist.

For thousands of years, more than twenty oak species have been one of the dominant trees in Illinois forests. Those forest could be the first in the U.S. to completely shift into a shade tolerant species.

"Oaks are not regenerating as well as they used too because they require more sunlight," explained Dr. Charles Ruffner, SIU Forestry professor.

Since 1980, the number of oak trees in the forest overstory has decreased by 50 percent in southern Illinois.


Overcrowding due to less timber harvesting and less fire.

"With those changes in the forest, less disturbance, less burning, less activities in the forest, that allows the forest canopy to close," said Ruffner. "When the canopy closes, the sunlight doesn't reach the forest floor."

The lack of sun allows shade tolerant trees like sugar maple and beech to take over. These trees are native, but they don't produce "hard mass", which benefits countless wildlife.

"With so many wildlife species that depend on the acorns, we're going to lose some of those species as well," explained Ruffner. "And there may be some changing in the types of species we find in our forests."

The forest service has used controlled burns for years and may look at commercial tree harvesting in the future.

"You want trees at a certain space because that's the growing area that they need to grow," said Dodson. "When they become too large, or new trees come up, they're taking that up. They're the weeds of your garden."

For information on how to properly manage privately owned forests, contact an IDNR Forester.

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