New AgriLife Research study gives insights on fire management for mesquite control
Fire must be effectively managed to get the best control of mesquite seedlings, according to new research results from Dr. Jim Ansley, Texas A&M AgriLife Research rangeland ecologist.
His study results, published in Rangeland Ecology and Management, indicate both season and intensity are important factors in the mitigation of mesquite seedlings by fire.
“We know adult mesquite trees are fire resistant because they resprout following a fire,” Ansley said. “We have determined that range managers might have a greater success of mesquite control with fire if their efforts are aimed at the seedlings.”
In the study, mesquite seeds were planted in mid-grass and tall-grass plots in the spring and then burned in the winter at 10 or 22 months seedling age or in late summer when they were 17 months old.
He said summer fires were especially effective in the mid-grass fuels and yielded a higher death rate when the seedlings were 17 months old than did earlier winter fires when seedlings were 10 months old.
However, Ansley said, this same advantage of summer over winter fires is not seen in higher fuel load areas, such as those with tall-grass types. In that case, both seasons had a high death rate of trees after fire.
The air temperature was, of course, higher during summer fires, and this greatly increased fireline intensity on the mid-grass plots, but only slightly increased intensity on the tall-grass plots, he said.
Grass fuel amounts were similar for both winter and summer fires in the mid-grass plots, about 1,700 pounds per acre, and slightly higher in summer than winter in the tall-grass plots, 6,900 versus 5,950 pounds per acre.
“One of the most important conclusions was that there was a very close positive relationship between fireline intensity and seedling mortality, especially in winter fires,” Ansley said. “So, conditions that yield high fire intensity such as higher fuel loads or summer burning will have the greatest effect on seedling mortality.”