Invasive Grasses Double And Triple Wildfire Risk Across U.S.

KCBS Radio Morning News
November 07, 2019 - 1:03 pm
sonoma county wildfire

Trevor Hughes/USA Today

(KCBS Radio) — Invasive grass species are doubling and in some cases tripling the risk of wildfires across the country, including in fire-prone California.

A study published Monday in the journal Proceedings of the National Academy of Sciences looked at a dozen grass species not native to the U.S. and found a link between the presence of eight difference species and an increase in wildfires.

The species include a common Mediterranean grass Schismus barbatus, which is common across Southern California and more than tripled the likelihood of wildfires, and cheatgrass Bromus tectorum, which is common across much of the state.

“A non-native invasive grass comes into an eco-system and then basically promotes the fire cycle by creating new fuels for those fires, and then that cycle perpetuates,” said Dr. Bethany Bradley, senior author of the study and an associate professor of environmental conservation at the University of Massachusetts Amherst. “The fires destroy the native vegetation and then the invasive species are able to come in quickly after that disturbance and promote more fires, and the cycle continues.”

The species can be found in a large variety of ecosystems across the U.S., including desert regions, pine forests in the southeast and temperate forests in the northeast, and have introduced fuel and fire risk to California’s deserts.

“In areas of California that are semi-arid, those are all areas that historically wouldn’t have had a lot of stuff that could burn,” said Bradley. “There are a lot of grassland areas that wouldn’t have historically been grasses unless we brought these invasive species in.”

Five of the species entered the U.S. by accident in hay bales and seed transportation, but the other three were deliberately planted and spread to the rest of the eco-system.

While it can be nearly impossible to completely eradicate a species that has proliferated across a large region, Bradley said work can be done to reduce risk in targeted areas. “Whether that thing that you’re trying to protect is a neighborhood, a community or an eco-system, you can take a pretty good look at those areas and work hard to reduce the biomass and the cover of the invasive species in those areas.”

Bradley said that while a lot of attention is given to forest fires, her findings highlight the serious risk presented by grasslands.