A parishwide prevention effort is needed to avert in the future the level of devastation caused by trees knocked down in storms, Southern University and LSU tree experts said.

Fred Fellner, who oversees LSU's landscape services, said just a 10 percent increase in tree cleanup and trimming could save millions of dollars a year in the region.

"I believe it's feasible," Fellner said. "Everybody wants to react to a storm rather than prepare for what we should do ahead of time."

Yadong Qi, Southern urban forestry professor, said people must be very attentive to the health of trees in their neighborhoods.

Trees can be damaged by disease, insects, drought, flood, wind, fire, nearby construction and human harm, she said.

People must keep their eyes out for "basal rot," when there are cavities or fissures near the tree base, or root rot, she said. White rot is another sign of disease, she said.

Mushroom growth at the base of trees also points to disease, Qi said, and the prevalence of carpenter ants is indicative of "intensive decay."

Nearly 75 percent of all felled trees have root rot problems, she said.

Southern's urban forestry department has sonic tomography technology that can produce three-dimensional images of the internal conditions of trees.

Using a large water oak on Southern's bluff as an example, Qi said the tree looked relatively healthy.

But more than 70 percent of it was decayed or completely hollowed on the inside. Other trees may have sound bases and roots, but the limbs are damaged or imbalanced and can threaten roofs and vehicles below.

Qi also cited the 250-year-old Thomas Boyd oak that was felled by Hurricane Gustav in front of the State Capitol. "All the agriculture practices didn't save it from the winds of Gustav," Qi said. "It's Mother Nature. No tree is going to be there forever, just like people," she said.

Professor of urban forestry Yadong Qi, Ph.D., left, explains how the Picus Sonic Tomograph uses sound waves to detect decay in trees, to genetics and statistics professor Sebhatu Gebrelul, right, Thursday during an Urban Forestry seminar at Southern University. In the background, urban forestry undergraduate student Brittany Fost listens to the explanation after helping Qi with a demonstration of the device.

Because of the region's heavy clay subsoil, it is difficult for the roots of trees to anchor deep enough, Fellner said, noting the increased vulnerability.

Fellner said that, sometimes, trees simply must be removed, no matter how much landowners do not want to give them up. Trees must be trimmed, he said, and they cannot be allowed to grow too tall for their own good. Noting about $50 million of parish costs for tree and debris removal after Gustav, Fellner said the 90-mile-per-hour gusts proved devastating to trees, power lines, utility poles and roofs.

LSU lost only one large, live oak tree, he said, which was already diseased.

When Fellner came to LSU in 1994, "The first thing I noticed was the population of older water oak trees," he said.

They looked nice but had to be replaced, he said.

Most trees lost from Gustav were pine and red oak trees, many of which were too old or allowed to grow too large, he said.

Urban forestry doctoral student Yongsheng Li offered some advice on planting new trees to replace those lost. The first step is to remove the sod and dig a planting hole that is at least 2 feet wider than the tree's root system, Li said.

Rocks and debris near the roots must be removed, Li said, and people should water all around trees and not just at the base, especially as trees get older.

Pruning is critical to remove overly dominant branches and to keep the trees balanced, he said. "Pruning is sort of an art," Li said, as well as a science. Extra pruning is needed when roots are harmed to alleviate stress, he said.

If a tree is hurt, it often is helpful to temporarily cover the damaged area with black plastic, Li said.