Invasive grass species originating from Africa are rampant in Hawaii, wilting in the summer and exacerbating fire spread.
Intense wildfires on the island of Maui, Hawaii, have devastated the tourist town of Lahaina, damaging thousands of structures and claiming at least 110 lives to date. Researchers are still analyzing the causes of the fire, including one factor that has made the flames more deadly: invasive grasses, according to Smithsonian on August 16.
Homes, structures, and the harbor in Lahaina burned on August 10. (Photo: Patrick T. Fallon/ AFP).
For nearly 200 years, Hawaii’s economy relied heavily on sugarcane and pineapple cultivation. However, by the 1990s, cultivation area began to decline as the state shifted towards tourism as its main industry, according to the New York Times. Many vast agricultural areas were abandoned. In 2016, Hawaii’s last sugarcane farm closed.
Without farmers to tend to the land, non-native grasses such as Guinea grass, Guinea sorghum, and buffel grass spread extensively. These species originated from Africa and were brought to Hawaii by European farmers in the late 18th century to provide a stable and drought-resistant food source for livestock. Today, they cover nearly a quarter of Hawaii’s land area. Thriving, aggressive, and opportunistic, they proliferate in areas that were once sugarcane and pineapple farms, encroaching upon both roadways and urban housing.
“These invasive, flammable species will fill any gaps anywhere – on the roadside, among communities, between people’s homes, everywhere,” said Elizabeth Pickett, co-executive director at the Hawaii Wildfire Management Organization.
Cattle grazing on land that was once used for sugarcane in Hawaii. (Photo: Bonnie Jo Mount/The Washington Post).
Invasive grasses spread during the rainy season and wilt during droughts. During dry periods like this summer, their state makes them highly flammable. After a fire sweeps through, many of these species have adapted to recover quickly, becoming the first to thrive again on the burned land, overshadowing native vegetation. This “grass-fire” cycle allows invasive grasses to flourish even more after wildfires, further increasing the flammability of the affected areas.
Scientists have long recognized the flammability of invasive species. In 2018, a fire broke out in West Maui and destroyed 21 homes, partly due to these grasses. Researchers estimate that 85% of the area burned in 2018 consisted of non-native vegetation. Following the disaster, one of Maui’s most renowned wildfire experts, plant ecologist Clay Trauernicht at the University of Hawaii, warned that these grasses could ignite future incidents. In 2021, a report from the Maui government also warned of rampant shrub growth and called for measures to control them.
