"A lot of the focus has been on what's occurring above ground. We decided to look at what's going on below the ground," Swihart said. "We know pine voles can do a lot of damage in apple orchards, but there is little, except for a few anecdotal accounts, of what they do in their natural environment."
Swihart got the idea for his study from Ron Rathfon, a Purdue Extension forestry specialist in southern Indiana who has studied oak mortality issues. Rathfon found in 2006 that animals, later determined to be pine voles, had been responsible for killing at least 19 percent of the dead oak seedlings observed in his study area. He said the voles, which are common to eastern deciduous forests, were likely responsible for the majority of oak seedling mortality because many seedlings went missing, suggesting the voles had eaten or removed the entire plants.
There is little overall loss of oak forest to date, but Rathfon said that might change if foresters, the timber industry and landowners do not implement practices that better manage long-term oak growth and development.
"We do see some data that more shade-tolerant trees - particularly sugar maples - are becoming more prominent," Rathfon said. "It is a gradual, subtle shift that is taking place."
Swihart said the loss of oaks would have other serious effects besides losses to the hardwood industry.
"Oak mortality could reduce the capacity of hardwood forests to support wildlife populations that rely on oaks for food - everything from deer and turkey down to mice and songbirds," Swihart said.
|Contact: Brian Wallheimer|