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Environment

Oak trees are disappearing. The Cincinnati Nature Center wants to help fix the problem

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Ann Thompson
/
WVXU
Cincinnati Nature Center Director of Conservation Cory Christopher looks up at one of very few oaks in this old growth forest.

Oak trees are disappearing here and around the world. The causes are many, but in Greater Cincinnati it may come down to the fact they are not as tolerant of honeysuckle and drought as maple trees.

Cincinnati Nature Center Director of Conservation Cory Christopher walks toward an old growth forest spotting just a few large oak trees and a lot of teenage maples. On the forest floor is just hickory and spicebush.

“This shouldn’t look this way," he says. "What we should see is lots of young oak saplings waiting for those overhead trees to die so they can suddenly reach for the sky."

Oak trees are disappearing here and around the world. The causes are many, but in Greater Cincinnati it may come down to the fact they are not as tolerant of honeysuckle and drought as maple trees.

That’s a problem, because oak trees drop millions of acorns every couple of years and small animals like chipmunks, squirrels, even deer and wild turkey depend on them.

Christopher says carnivores like foxes, coyotes, and birds of prey benefit from fattened small animals. In addition, he says almost every pollinator larva eats oak leaves.

He and his staff began researching the problem two years ago. They surveyed all the trees and shrubs in 24 parts of old growth forests (more than 150 years old) at the Nature Center. They tested the effects of honeysuckle and drought on maple and oak seedlings.

Extracts from honeysuckle leaves are known to inhibit growth. So they planted acorns and maple seeds in color-coded pots with and without drought and with and without the extract.

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Cincinnati Nature Center
At Long Branch Nursery, part of the Nature Center, researchers studied individual seedlings and the effect of honeysuckle and drought.

That’s how they found out maples can tolerate both while oaks cannot. But there are still many questions. Christopher says the next phase will be how to fix the problem instead of more academic pursuits.

“What we didn’t test is, are there any sort of residual impacts of honeysuckle in the soil? So for instance, in this forest in front of us, there aren’t many shrubs right now and there are no honeysuckle shrubs.” Christopher says nobody knows how long the honeysuckle compounds stay in the soil so should the Nature Center plant oak saplings right away or wait?

He says this is the first real effort creating a replicated, publishable, rigorous study for the Nature Center. It’s not that those studies don’t exist, but academic researchers don’t really share the information with forests like his, he says.

Christopher says he wants to be a careful and nimble steward with the land and that’s why he’s conducting studies like these. One thing people can do to help oaks outside of the Nature Center is plant native plants and trees. “Put in oaks, put in your willows, encourage your neighbors to do the same,” Christopher says.