A&M Says 301 Million Trees Died in 2011 Drought. Dallas Arborist Thinks Real Number is Much Larger.
The record-breaking drought that Texas endured in 2011 wasn't good for much of anything. Farmers and ranchers suffered, as did the people in towns whose water supplies ran dry. And let's not forget the owners of lakefront property whose lots fronted an empty stretches of parched earth.
The lack of rain, though, was particularly hard on plants. Exactly how hard became a bit clearer yesterday when the Texas A&M Forest Service announced that 301 million trees in Texas died as a result of the drought. Forested areas in North and Northeast Texas fared particularly badly, losing more than 8 percent of their trees.
The A&M survey, the product of three months worth of on-the-ground tree health assessments and satellite imagery, focused only on rural areas. A previous survey of cities and suburbs counted 5.6 million dead trees.
Those figures understate the drought's true impact on Texas trees, said Steve Houser, the chair of Dallas' Urban Forest Advisory Committee. He expects the numbers to keep ticking skyward.
"The effects of drought and heat last year won't fully be known for five to 10 years," he said.
Houser recalls a massive aspen die-off he studied several years ago in rural Colorado. Foresters and arborists were puzzled, since the levels of pests and diseases they found weren't high enough to kill healthy trees. When they looked back, they found that a major drought had hit the area about five years before and that its fatal effects were only just becoming clear.
He expects the same thing to happen in Texas, where a couple of factors made the 2011 drought particularly bad. There was the lack of rain, of course, which caused trees' root systems to contract, thus impairing trees' chances of long-term survival, but there was also the heat.
The biological processes in trees and other plants start to shut down when temperatures are in the low 90s. That's a given during the Texas summer, but nighttime temperatures typically drop low enough to allow trees to hang on. This year, with something like 20 straight days in which the temperature never dropped below 85, even irrigated trees had a rough go of it.
Burl Carraway, who heads A&M's sustainable forestry department, was philosophical about the die-off.
"The drought produced traumatic results, especially for individual landowners. But the good news is the forest is resilient. When a dead tree falls over, a young, new tree eventually will grow back in its place," he said. "Tree death is a natural forest process. We just had more last year than previous years."
That's the point of view of a forester, who is primarily concerned with large tracts of commercially grown trees. Houser is an arborist, who cares for individual trees over a long period of time. And he's working to keep the death toll in Dallas as low as possible.