When driving past temperate deciduous forests, walking beneath limbs of a 50-year-old northern red oak or stumbling over hundreds of acorns each autumn, it's easy to be fooled into thinking the oak - a mainstay of hardwood forests in the driftless area - is a picture of health.
But look more closely, says Tom Hill, Department of Natural Resources forester in Iowa County. In truth, oaks are not regenerating themselves because - and many people will find this revelation surprising - deer, invasive plants and diseases are preventing seedlings from becoming replacement trees.
"The problems are many, including invasive species like garlic mustard, diseases like oak wilt and timber sales without professional guidance, but the biggest issue in getting oaks to regenerate an oak forest in southern Wisconsin is white-tailed deer," Hill said. "If the deer were cut back to a normal level, seedlings would have a chance even with these other problems."
Instead of seeing straight, fast-growing red, white and bur oaks, Hill sees shrubby oaks, trees that have been browsed - sometimes mere bushes.
Deer used to spend time browsing oaks during winter, when food was scarce, but now it seems the oaks will put out a flush of growth in spring, get browsed, then grow and get browsed again.
"This wasn't an issue 15 to 20 years ago," said Bill Carlson, DNR forestry team leader for Grant, Iowa and Richland counties. "If ever there was a time to get our deer herd down, it is now."
John Nielson, DNR forestry area leader in southern Wisconsin said oaks seem to be the only dwindling tree group in the area.
"Many people don't make the connection between high deer numbers and lack of oak regeneration," Nielson said. "Right now garlic mustard is a hot topic and is getting a lot of attention, but even if the mustard were removed, the oaks wouldn't have a chance. Good stands of oaks we see were regenerated during low deer years."
In many cases, the oaks won't make it short of fencing the deer out. Area foresters are trying another method, however, but only in fields that are planted in trees.
"High-density plantings have a chance, but still the deer gravitate to the red oaks first, then nibble the white oak, bur oak, white pines and even walnuts," Hill said. "Spruce seem to be the only thing that will survive during this period."
In Pennsylvania, where foresters have studied oak forests, red oaks used to be number one as a hardwood. Now oak is 10th and red maple is first.
"If you take the deer numbers down, oaks and other valuable species will come back," said Jim Finley, a forestry professor at Penn State University.
Foresters know how to get oaks to regenerate during usual conditions, even though they admit oaks are one of the more difficult species to get started.
Hunters who love deer more than trees need to realize that oaks are a life blood of deer, as well as other game species, including turkeys, squirrels and even ruffed grouse in southern Wisconsin. Without oaks, deer will eventually suffer, too.
"Many people are purchasing land for deer first and forestry second, but some have seen the light and are working toward a more balanced ecosystem," Hill said. "If we look closely at a forest understory, that's changed too, due in part to the deer."
Carlson said timing is critical in cutting oak timber.
"When there are good seedlings under mature oaks, that's the time to cut," Carlson said. "But not in July or August, that's oak wilt time, plus you're cutting before the acorns have dropped. You need to remove the overstory when the seedlings are there. If we lose those seedlings, the battle is lost."
Oaks are still the tree most valued by those who want forests. Don't look for many examples of good timber management in state parks, however. Many of those forests are museums, not active, regenerating ecosystems.
"These are the public's playgrounds and there isn't much tree cutting going on there," Nielson said. "Most people wouldn't stand for it."
People used to talk about not being able to see the forest for the trees. Now it's more a case of not being able to see the oak trees for the low quality forests.Wisconsin State Journal
