0903treesaudArborist Tim Costley talks about how trees are reacting to drought.
Stressed by two severe droughts in less than a decade, a disturbing number of large trees in Northeast Georgia are dead or dying.
You can see these "half-naked" victims all over the region. They are typically barren of leaves on all or most of their branches, instead growing foliage in clusters around the trunk.
"It’s like frostbite (in humans), where the extremities are given up to save the core," said Tim Costley, an arborist with Superior Arbor Management in Gainesville.
Charles Bailey, senior forester with the Georgia Forestry Commission in Gainesville, said the tree is trying desperately to adjust its metabolism.
Growing leaves straight out of the bark is called epicormic sprouting, and it’s the tree’s way of crying for help.
"It’s an indicator of stress," said Bailey. "The hormonal system of the tree is in turmoil."
When some of its roots dry out, the tree tries to compensate by putting out fewer leaves from the crown. If this happens to only a couple of branches, the tree will probably be OK, Bailey said.
"But if you’ve got over 60 percent loss, especially if it’s all over the crown, that’s a pretty bad sign," he said.
Costley advises tree owners not to wait that long. "Trees will shed limbs that are not of use. A lot of that is normal," he said. "But if you lose 20 to 30 percent of the original canopy, it may be in trouble."
And it may have been in trouble for a long time, even if the tree looked healthy.
"Sometimes a tree won’t show it for a while. It’s been living on its reserves," Costley said. "By the time people see these problems, it’s often too late to do anything."
People may assume that the tree is just dialing back on its leaf production because of the drought, and once Georgia finally returns to a normal weather pattern, the foliage will return.
But Bailey said the condition is usually irreversible. "A branch that has no leaves this year probably won’t ever have leaves all the way out to the tips again," he said.
Bailey said he’s noticing more trees with this affliction.
"For the past few years, I’ve seen a good bit of crown dieback in the larger trees," he said. "I think it’s a gradual response to drought conditions."
Georgia is in its third year of the current drought. The previous drought lasted from 1999 through 2002.
Scott Merkle, professor of forestry at the University of Georgia, said the cumulative effect is taking its toll, especially on red oaks. "If you have two droughts, even with a space in between, it can weaken trees," he said.
But the drought is just the latest insult. Bailey said many of these trees were already stressed by human activity.
"It takes two or three years for a large tree to respond to an injury, such as roots being run over by heavy equipment during construction," Bailey said. "Root confinement (by paved surfaces) is a big problem."
Trees located near a road or driveway, or in an area where grading has altered the drainage flow, may have been suffering even before the drought began.
It took a long time for these trees to weaken, and Bailey said it will take a long time for them to recuperate, if they can.
"For a large tree, there aren’t any remedial measures that are going to bring about instant recovery," he said. "They probably need more water than most people can provide (because of statewide watering restrictions)."
Costley said sometimes if a tree is not too far gone, an arborist can help nurse it back to health.
"We try to aerate the roots by plowing up the ground with high-pressure air to loosen the soil. Then we apply mulch on top," he said. "Also, sometimes cutting off dead or dying limbs helps the rest of the tree to survive."
In many cases, though, the property owner has no option other than to cut the tree down before it becomes a safety hazard. Costley said it’s a tough decision to make, because people often have sentimental feelings for a large, old tree. But in a drought, a smaller tree may be a more sensible choice.
"Young trees are more adaptable, and obviously they need less water and nutrients," he said.
Climatologists say there’s a good chance Georgia will pull out of the drought next year. But Merkle said the delayed effects on trees will be evident for some time to come.
"I think we’re going to see trees continue to die," he said.