Forest fires may receive more attention, but a recent study shows that grassland fires are actually more prevalent and destructive across the United States. According to the study, almost every year since 1990, grass and shrub fires have burned more land and destroyed more homes than forest fires.
Despite this, many residents are not as aware of the wildfire risk in grasslands and shrublands.
When the Marshall fire swept into the Boulder suburbs in 2021, it caused significant devastation, taking the lives of two people and destroying over 1,000 homes. This resulted in residents being surprised that such a fierce blaze could encroach on their community, which was far from the forests of the Rocky Mountains.
However, this risk was high due to the proximity of many homes to wide expanses of tall, dry grass that were ready to burn. When a grass fire ignited, strong winter winds propelled it towards nearby neighborhoods, resulting in the flames easily spreading from grasses to homes, sometimes using wooden fencing as a means of spreading.
One resident affected by the fire described it as a “wake-up call” to the dangers of grassland fires.
Volker Radeloff, a professor of forest ecology at the University of Wisconsin-Madison, who led the study, highlighted the Marshall fire and the recent Lahaina fire in Hawaii as extreme examples of the risks that wildfires can pose outside of forests. Both fires started with burning grasses and grew into devastating urban infernos.
According to Dr. Radeloff, the risk of wildfires to homes is especially high in areas where the built environment meets wild vegetation, known as the “wildland-urban interface,” or WUI for short.
The study also found that wildfire risk has increased across the United States in recent decades, with the highest risk in WUI areas.
Over the past 30 years, the number of people living in these fire-prone areas has significantly increased due to the demand for more housing, driven by factors such as affordability and second homes. At the same time, climate change and the historical over-suppression of wildfires have heightened the risks of major wildfires across many parts of the country.
The study, published in the journal Science, illustrates how the wildfire problem in the United States extends beyond the West and beyond forests.
Nearly two-thirds of wildfires in the United States between 1990 and 2020 occurred in grasslands and shrublands, the study revealed. Due to their higher frequency, these fires also destroyed many more houses than forest fires.
Grass fires and forest fires have some important differences. Forests tend to burn more intensely and can throw embers that ignite new fires far outside of their original area. On the other hand, grassland fires can spread more quickly when driven by wind, giving communities less time to respond.
Like forest fires, the frequency of grass and shrub fires has increased over time.
Victoria Donovan, a fire researcher at the University of Florida, noted that more research is needed to fully understand the reasons behind the rise in grassland fires, but factors such as a warming climate and the encroachment of woody vegetation and nonnative species have had an impact. Additionally, the suppression of lower-intensity wildfires has increased the risk of larger, more destructive blazes in many grassland ecosystems.
Dr. Donovan emphasized the importance of prescribed burns, a practice used by Indigenous people, as a tool for wildfire management in grasslands, shrublands, and forests which reinforces the ecosystems.
Some states and localities have passed laws focused on new construction in wildfire-prone areas, requiring the use of fire-resistant materials for new homes built in high-risk zones. Additionally, creating a vegetation-free buffer around homes, covering entry points, and retrofitting homes with fire-resistant models are recommended strategies for homeowners in wildfire-prone areas.