Brazos Valley trees hit hard by 2011 drought
Published: Thursday, September 27, 2012
Updated: Thursday, September 27, 2012 02:09
According to a survey by the Texas A&M Forest Service released Tuesday, 301 million trees were killed in Texas as a result of the 2011 drought, with Brazos Valley as the region with the highest tree mortality rate at 9.7 percent — almost 25 million trees.
The survey, done by the U.S. Forest Service Inventory and Analysis Program and the Texas A&M University Ecosystem Science and Management Department, used 599 field plots and satellite imagery to determine the tree mortality rate.
“We looked at satellite imagery to identify areas that were green before the drought that weren’t green after,” said Burl Carraway, head of the Department for Texas A&M Forest Service Sustainable Forestry. “Then we focused our efforts there.”
Carraway said the original estimate of tree mortality from December 2011 was 100 to 500 million trees.
“Leaves fall off trees so it’s hard to tell if a tree is alive or dead in the winter,” Carraway said. “That’s why we went back for a more definite study in the spring and summer.”
The three areas hardest hit from the drought were Houston, Juniper-Crocket, and Caldwell-Bastrop.
“Brazos Valley was the hardest hit region across the state,” said Chris Edgar, Texas A&M Forest Service analyst. “As I drive around, I see a lot of dead oak and cedar trees. The land looks pretty stark, so the estimate seems very plausible to me.”
Factors that led to the drought that caused the high tree mortality rate are high temperature, strong winds and lack of rain.
“Last year was hotter than normal, windy and dry,” Carraway said. “These factors dried the trees out.”
Nearly the entire state was in the drought category last year.
“This year was more typical in terms of temperature and rainfall,” Carraway said. “We could still see continued mortality, but not near the amount of last year.”
Although there are large amounts of dead trees across the state, these trees can help regenerate the forests, because tree mortality is a natural process.
“The standing and fallen trees that stay out there are providing services to the forest, so I don’t see them as a problem,” Edgar said. “They provide habitats for insects, birds and wildlife. The trees are a natural part of the forest.”
In rural and remotes areas, these trees are going to remain where they are and begin the decaying process.
“The dead trees hang around for two to three years, maybe even four, to fall and decay,” said Tom Spencer, department head of the Texas A&M University Forestry Services. “They fall to the forest floor and make space for new trees.”
Despite the chance for new tress to grow in place of the old ones, Spencer said dead trees pose a threat to surrounding areas.
“The amount of dead trees increases the difficulty to control wildfires and increases the risk to people and property,” Spencer said. “Wildfires start easier, burn longer and it takes a lot to put them out.”