An invasive grass that has spread across nearly every county in Florida may be giving wildfires more fuel and helping flames spread faster, according to a new University of Florida study.
The study — published in Fire Ecology — examined how cogongrass affects fire behavior under different environmental and seasonal conditions.
WHAT’S THE PROBLEM?
In a release, UF/IFAS researchers said dense patches of the grass can lead to faster fire spread, longer flames and a greater chance that a ground fire will move into the tree canopy.
That transition, known as a “crown fire,” can be harder for firefighters to suppress and may require additional resources, researchers said.
“When you have cogongrass, you have greater fuel loads, so that means there’s more dead vegetation on the landscape that can fuel fires,” said Alan Ivory, a graduate student at UF’s West Florida Research and Education Center and lead author of the study.
WHEN DID COGONGRASS GET HERE?
Cogongrass has spread throughout Florida and the Southeast since it was introduced in the 1930s.
It forms dense stands that can displace native plants, reduce biodiversity and alter ecosystems. The grass is especially widespread in North and Central Florida.
Researchers found the strongest differences in fire behavior during late winter and early spring, when prescribed burns are commonly used across the Southeast. The grass had less of an effect during summer than expected because its moisture during that season helped slow fire spread.
WHAT’S THE IMPACT?
The findings could become more significant as weather patterns change. UF researchers said cogongrass is more sensitive to changes in fuel moisture than native vegetation, meaning longer dry periods and warmer temperatures could increase its effect on fire behavior.
For homeowners and landowners, researchers say controlling cogongrass can help reduce potential fire risks around properties, in addition to protecting native vegetation.
The plant can be difficult to contain because it spreads through an extensive underground root system, and small pieces of roots can produce new plants.
Residents can check citizen-science resources such as EDDMapS for reported cogongrass sightings.