Hawai'i conservation alliance

2009 Best Student Poster Presentation

Fuel Loading and Fire Parameters in Nonnative Grasslands on Military and Surrounding Lands on Oah‘u, Hawai‘i

Lisa Ellsworth 1, Creighton Litton 1, Boone Kauffman 2
1 University of Hawai‘i at Mānoa, United States, 2 USDA Forest Service: Institute of Pacific Islands Forestry, United States

Recurring wildland fires in landscapes dominated by the invasive guinea grass (Urochloa maxima) pose a significant threat to surrounding native ecosystems, landowners, and military preparedness. To more effectively manage Hawai‘i’s natural resources while maximizing military training opportunities, the invasive grass-wildfire cycle must be aggressively managed, and ultimately eliminated. Predicting and managing fire behavior is commonly done with fire models (e.g., BehavePlus), but their realistic use requires a better understanding of spatial and temporal changes in the parameters that most drive fires – fuels and climate. This initial study was conducted to quantify the spatial and temporal variability in fuel parameters. We hypothesized that fuel moisture, total aboveground fuel loads, and live:dead biomass ratios would vary with land use history (grazing, fire history), topographical position, and overstory cover. To address this hypothesis, we quantified these variables across military lands and surrounding areas along the Waianae Coast and North Shore areas of O‘ahu. Fuels in guinea grasslands exhibited a wide range of biomass, live:dead ratios, and fuel moistures. Low elevation sites with no tree overstory exhibited the lowest live and detrital fuel moistures at 28% and 9%, respectively. Schofield Barracks sites exhibited the highest live and detrital fuel moistures at >50% and >30%, respectively. Initial results will guide continued sampling efforts to quantify how fuel parameters vary both spatially and temporally. Relating these parameters to climatic data will substantially improve future predictions of the probability of ignition and potential fire behavior, which will be of widespread use to fire managers.