New Study Researches Hawai’i Wildfires

Photo of helicopter crew assisting in Kawaihae brush fire effort taken Saturday, Aug. 8, 2015. Photo credit: M. Scott Smith.

Dr. Clay Trauernicht and Dr. Creighton Litton, who both work within the Department of Natural Resources and Environmental Management in the University of Hawai’i College of Tropical Agriculture and Human Resources, recently constructed a 108-year wildfire history in Hawai’i.

The research paper was published in Pacific Science and draws on multiple sources to construct a history that shows more than a fourfold increase in the area burned annually statewide in recent decades.

Over the past decade, Hawai’i has had more than 1,000 fires that have burned over 20,000 acres each year.

“People don’t typically think of wildfires as a frequent disturbance on tropical islands,” said Dr. Trauernicht, an associate specialist. “However, it is a serious threat to communities, watersheds, and other natural resources in Hawai‘i, a fact that has long been known to environmental managers. Now, that threat has been quantified.”

The study indicated that relative to total land area, the percentage of the state that has burned on an annual basis from 2005 to 2011 was comparable to, and in some years even exceeded, that of the western portions of the mainland United States.

Spatial patterns of recent fire incident records were also researched to aid in the understanding of factors that caused the fires.

Developed areas were found to have the highest frequency of ignitions, which researchers say helps point out that over 99 percent of known wildfire causes in Hawai’i are the result of human activities. The researchers also say the information is different than on the mainland, where lightning is one of the major contributing factors.

The authors showed that human activities have also dramatically increased the “flammability” of Hawai’i’s landscapes through land-use practices that have promoted the spread and establishment of fire-prone nonnative grasses, including species introduced for pastures and as ornamental plants.

In addition, the widespread abandonment of agricultural lands have shown to be a factor in wildfires. Historical records and United States Department of Agriculture census data were used to show that the land area under active grazing or cultivation occupies about 2.6 million acres in 1960. It has since declined to 970,000 acres, a reduction of over 60 percent.

Other risk factors include strong rain shadow effects in the leeward areas and episodic droughts, especially those associated with El Niño events, such as is happening now, creating year-round potential for frequent and often destructive wildfires.

The researchers emphasize that since the links between wildfires and human activities are so strong in Hawai‘i, there are far more ways that humans can cut down on the possibility of wildfires by changing those activities. They point to clear pathways to address the issue through public outreach and engagement and landscape-scale approaches to watershed management. Dr. Trauernicht believes that there is another possible benefit.

“Given the increasing threat of wildfires to communities and resources, and its disregard for property lines, wildfire management provides an opportunity to bring together diverse interests and stakeholders to work towards a common goal,” said Dr. Trauernicht.

The Big Island’s most recent wildfire took place in West Hawai’i earlier this week and burned 250 acres of land near Hawai’i Community College Palamanui, as of 1:30 p.m. Thursday.