Increased risk of forest wildfire from redcedar invasion of Oklahoma’s oak forests

Tuesday, April 17, 2018

It has more than four letters, but redcedar is almost always considered a bad word.

Oklahomans are well-aware of the encroachment of eastern redcedar into prairie ecosystems and the negative consequences that entails. However, the invasive species also is increasing within the oak-dominated Cross Timbers forests of central Oklahoma.

 “Because the foliage of redcedar is highly flammable, this has the potential to increase the risk of uncontrollable forest fires,” said Rod Will, professor in Oklahoma State University’s Department of Natural Resource Ecology and Management.

In partnership with the Bureau of Indian Affairs, a team of researchers at OSU’s Division of Agricultural Sciences and Natural Resources, led by NREM graduate student Dan Hoff and Will, recently measured the less obvious encroachment of eastern redcedar within the Cross Timbers forests of Pawnee and Payne counties.

The team used winter-time satellite images to identify the coverage of redcedar and then conducted field testing to verify the amount of redcedar and determine the biomass it contained. Results of their study, recently published in Forest Ecology and Management, found approximately 20 percent of the area within the forest interior is covered by eastern redcedar and this redcedar component increased available fuels for wildfire by 38 percent.

“Given the high flammability of its evergreen foliage, redcedar invasion into the Cross Timbers forest has the potential to cause catastrophic wildfires that threaten property and safety,” Hoff said. “Looking at satellite images, there are locations within communities such as Edmond, Stillwater and Sand Springs that are at increased risk.”

The cause of increased redcedar in the forest is the exclusion of frequent, low-intensity fires, which previously killed the small redcedar trees before they could establish.

“The irony is that by eliminating the type of fires that historically occurred, we’ve altered the forest and increased the risk of catastrophic fires” said John Weir, a fire specialist at OSU.

While redcedars have been marching through Oklahoma prairies for more than a century, the forest invasion is relatively recent.

“We measured the ages of the trees and found redcedar began to enter the forest in the mid-1950s, and the rate of establishment increased with each decade since,” said Chris Zou, NREM associate professor.

Without proper management, or at least some management, Oklahoma’s forests will continue to be overtaken and become an increasingly greater risk for devastating wildfires.

“The information from this study is important to land managers so they can make decisions about treatments to reduce redcedar and wildfire risk,” said Nathan Lillie, natural resource specialist with BIA

The time to act is now, according to Will.

“This is yet one more call to action in efforts to combat the increase of redcedar,” he said.

Story by Sean Hubbard