The fires of Hawaii don’t follow the rules of their continental counterparts. There are fire risk factors at play in the island chain that states like California or Arizona simply don’t deal with.
Tradewinds move across the Pacific Ocean and strike the windward side of Hawaii’s mountains to create dry conditions, for example. Rain soaks the leeward sides of the mountains as the air cools. That rush of rainfall can feed the rapid growth of the fast-growing non-native grasses and shrubs that now cover a third of the chain’s land—often in areas that were once home to sprawling sugar cane and pineapple plantations.
Rainfall can fluctuate from 10 to 400 inches a year on average in the span of just a few miles, with fire-fueling biomass accumulating in kind. El Nino years exacerbate the extremes.
“Our vegetation types and the variability in our climate is just incredibly diverse when compared to the mainland,” said Clay Trauernicht, University of Hawaii Extension Specialist and Program Lead for the multi-agency Joint Fire Science Program’s Pacific Fire Exchange. “We see fires under conditions you’d never expect to see fires on the mainland.”
Even the dynamics of Hawaii’s Wildland Urban Interface (WUI) are different from the mainland. In California, the WUI is comprised of homes built into fuel-laden, forested areas. In Hawaii, non-native vegetation has crept closer to existing homes, sometimes proliferating on lava flows that had served as fire breaks to create risk where little existed a few years before.
Those grasses fed some of the largest fires ever seen on the island of Maui in 2019, swallowing up around 25,000 acres in a matter of weeks across landscapes in and around a cane plantation retired in 2016.
“We were all just sort of waiting for it to happen,” Trauernicht said.
The peculiar realities of fire risk in Hawaii and Pacific territories like Guam, American Samoa and the Marshall Islands are why the detailed vegetation types embedded in LANDFIRE products are so useful to people like Trauernicht and his fellow island fire scientists.
Trauernicht uses LANDFIRE to define land cover types across broad areas, which feed into locally-useful fire models. The data also helps land managers determine which “knobs we might be able to turn” to reduce risk when planning projects like forest restoration.
“LANDFIRE has been really useful in the sense of understanding the composition of the landscape,” he said. “We want to know what types of vegetation we’re dealing with, and we’ve relied on LANDFIRE to establish baseline models and then develop future scenarios.”
The recently-released LANDFIRE Remap for Hawaii will offer another level of value for researchers working in the Pacific’s U.S. enclaves. The Remap products include all the updates, upgrades and improvements found in the Remap products for the conterminous U.S. (CONUS) released this summer, as well as regionally-specific vegetation type improvements for the islands.
LANDFIRE Hawaii now includes more detail on “ruderal vegetation,” loosely defined as the non-native grasses and shrubs that carry the greatest risk in places like Hawaii. The Remap team worked with stakeholders and reviewers to insure that those vegetation classes lined up more closely to conditions on the ground than previous versions had, according to Daryn Dockter, an Ecologist with the LANDFIRE Technical Services Support Contract (TSSC) at the USGS Earth Resources Observation and Science (EROS) Center near Sioux Falls, SD.
There was an intensive focus on areas where “the types of vegetation growing have been modified so much that it doesn’t resemble a natural ecosystem anymore,” Dockter said. “Part of our updating process was focusing on those classes.”
All LANDFIRE Remap products serve to update the Landsat-derived base maps to reflect 2016 conditions. The base maps are then used to build the periodic updates and higher-level products like capable fuels.
LANDFIRE products, which are freely available at 30-meter resolution at no cost to users, have value beyond fire science in the U.S. and in Hawaii. A 2016 study in the journal Ecological Economics, for example, used LANDFIRE to identify non-native forest areas in a cost-benefit analysis that mapped out the freshwater yields per dollar invested in watershed conservation projects.
“For Hawaii, the use goes beyond wildfire,” Dockter said. “There’s a lot of interest in land management and conservation, and the improvements in Remap will only make that better.”
The next step for LANDFIRE Remap will be the release of data for Alaska and insular areas such as American Samoa, Guam, and the Marshall Islands, according to Joel Connot, a contractor on the LANDFIRE team at EROS. After that, LANDFIRE production staff will turn its attention to updating Remap with new information for disturbances on the landscape.
“Internally, we’re already turning our attention to life after Remap,” Connot said. “The planning in earnest has begun for those updates.”
For more information on LANDFIRE Remap, follow this link.
Use this link to find and download data using the LANDFIRE viewer.