Controlled fires might help dogwood trees

WEST LAFAYETTE, Ind., June 8 (UPI) -- Forestry experts say planned burning in some Eastern U.S. forests might be helpful in restoring flowering dogwood tree populations.

Purdue University Assistant Professor Michael Jenkins says dogwood trees act as a calcium pump, pulling nutrients from deep in the soil and depositing them on the forest floor with their fallen leaves each autumn. And that, Jenkins said, is an important source of nutrition for a variety of species in a forest ecosystem, such as fungi, insects, songbirds, snails and other organisms.

The problem is a fungus -- Discula destructive -- that's causing a serious decline in dogwood populations by killing foliage and then girdling the tree by creating cankers on the trunk.

"The disease has expanded across much of the flowering dogwood's range in North America," Jenkins said. "In some cases, we have seen more than 90 percent mortality."

Jenkins and his colleagues studied the effect fire has on revitalizing dogwoods. In forests where there have been two fires during a 20-year period, dogwoods have survived the disease, he said.

Jenkins explained the fungus likes cool, moist areas with little air movement. Undisturbed forests provide such an environment, but occasional burning opens forests, increases sunlight and allows greater air movement.

The study by Jenkins, Assistant Professor Eric Holzmueller of Southern Illinois University and Professor Shibu Jose of the University of Missouri appears in the journal Forest Ecology and Management.