For about 20 years foresters have been following a disturbing trend in Illinois — the gradual decline of oak and hickory.
A 2015 brochure produced by Southern Illinois University and the Illinois Forestry Development Council provides some shocking information.
In 1980 the forest overstory at Trail of Tears State Forest, located in Union County, was 36 percent oak and 11 percent hickory. By 2014, the overstory was comprised of 21 percent oak and 10 percent hickory.
The once dominant oaks are being replaced by shade-resistant species like beech and maple. The Trail of Tears State Forest, as well as other tracts of forest in the state, will change markedly if the situation goes unabated.
“There would be a change in species composition,” said Eric Hozmueller, a professor of forestry at SIU. “You’d have a loss of mast producing species and an increase in American beech and maple. They just don’t have the same wildlife values or timber values as well.
“Basically, the forest wouldn’t be able to support as many deer or turkey.”
One of the major issues at Trail of Tears is that the forest hasn’t been actively managed for quite some time. There are things that can be done to halt the decline. There are obstacles to overcome — all the options carry varying costs and some of the options are not popular with some segments of the populace.
“In order to maintain the oak component, overstory removal with follow-up prescribed burning and mechanical removal of undesirable species,” Holzmueller said. “A lot of people don’t like to see trees harvested. You can make a lot of money cutting trees. For aesthetics or personal values, they don’t like to see the large trees removed.
“As far as prescribed burning, understory removal, that can be costly and there are also time and weather constraints. We’re kind of at that critical state as the trees in the overstory get older. They might still be standing, but they won’t put out as much seed.”
He said black oaks live about 100 years, red oaks maybe 150, and white oaks 200 years or so.
To that end, a substantial portion of Trail of Tears State Forest has been turned into a living laboratory.
Nearly 1,000 acres of the forest have been turned into test plots.
One segment remains untouched. The understory is cluttered with maple and beech. One area is called a “cut-first” area. It has had beech and maple trees removed and will be subjected to prescribed burns later. Another area has been treated with prescribed burns, and another area has had beech and maple removed and has been burned.
The difference among the plots is noticeable, sometimes dramatic … which is the point.
Calvin Beckmann, the Illinois Department of Natural Resources’ site superintendent for Trail of Tears, said landowners with forested land can walk through the demonstration areas and determine how they’d like to manage their property.
The burning and thinning regimen allows more light to reach the forest floor, which promotes the growth of oak and hickory saplings.
“This plan has a lot of support of a lot of environmental groups,” Hozmueller said. “Everybody recognizes that in order to maintain the wildlife habitat and diversity we find in these forests, we are going to need some management.
“You should be able to start seeing regeneration in a couple years.”