According to a recent discovery made by a PhD student from the University of Hawai'i at Mānoa School of Sciences, new species of flammable, invasive grasses have been found across most Hawaiian Islands. The student, Kevin Faccenda, believes that by identifying and locating these "fire-promoting" grass species, measures can be taken to reduce the impacts of future wildfires.
"If we can react to new fire-promoting species of grasses and contain or eradicate them before they become widespread across the landscape, we can reduce ecosystem flammability and therefore the impacts of wildland fire across the islands," said Faccenda. He also emphasized the importance of knowing the names and areas where these species grow in order to effectively manage them.
Faccenda's research, which was shared by the University of Hawai'i at Mānoa on Oct. 13, involved over 50 days of fieldwork across Kauaʻi, Oʻahu, Maui, Molokaʻi, and Hawaiʻi Island in the past year. During this time, Faccenda identified 34 invasive and/or weedy grass species that had not been previously reported in Hawai'i. Six of these species had never been documented outside their native habitats, making Hawai'i the first location globally where they have become naturalized.
Among the newly identified grass species, two were found to be highly flammable and observed in various locations throughout the Hawaiian Islands. The most flammable of these grasses, Enneapogon cenchroides, is originally native to Africa and India. Faccenda and Professor Michael Ross from Kapiʻolani Community College found this species in Mākaha on Oʻahu, where they counted over 500 plants concentrated in less frequently mowed areas along the roadside. Faccenda believes that this grass is likely to spread up the ridge dividing Mākaha and Mākua-Keaʻau valleys, further increasing the area's fire risk.
The second highly flammable species, Bothriochloa macra, was discovered on multiple Hawaiian islands, including Niʻihau, Oʻahu, Molokaʻi, Maui, Kahoʻolawe, and Hawaiʻi Island, at elevations ranging from 15 meters to 1,300 meters. While this species has been in Hawaiʻi since 1936, it was previously misidentified by Hawaiian botanists. Faccenda noted that this Australian grass had only been documented as naturalized in New Zealand. Its weed potential and ecology are not well-documented, but in Australia, it is typically found in grassy woodlands affected by disturbances and thrives in low-fertility soils.
Faccenda emphasizes the importance of identifying, tracking, and managing these grass species to prevent future wildfires. In addition to the invasive grasses, Faccenda's research also uncovered various agricultural weeds that pose threats to crops, natural ecosystems, and human and livestock health. One of the findings is an African crabgrass species, classified as a federal noxious weed. Faccenda has reported his findings to the Hawai'i Department of Agriculture and the invasive species committees on each island.
The University of Hawai'i at Mānoa hopes that Faccenda's research will contribute to efforts in reducing ecosystem flammability and minimizing the impacts of wildfires across the Hawaiian Islands.