The ArcBurn project uses controlled laboratory experiments and instrumentation on prescribed burns and wildfires to determine critical damage thresholds for cultural resources including archaeological sites, artifacts, and heritage resources. Data and observations on fire effects and effectiveness of fuels treatments are then used to develop guidelines for best treatment practices and protection of archaeological resources.
ArcBurn is designed to help forest and fire managers in the southwestern U.S. use the best available science to make decisions about how to protect cultural resources during fuel treatments, prescribed fire, wildfire suppression, and post-fire rehabilitation. ArcBurn is funded by the Joint Fire Science Program, and is a collaborative effort among fire scientists, forest ecologists, earth scientists, archaeologists, tribal members, and fire managers. Information generated is especially critical as the changing climate is altering wildfire patterns and fire behavior.
ArcBurn project highlights in the past year include: deployment of instrumentation on archaeological sites within a large prescribed fire, laboratory experiments, and outreach.
At the Missoula Fire Science Laboratory, experiments have included an outdoor ‘crib’ burn that measured fire effects and heat exposure on ancient architectural stone, a muffle furnace pilot study on ceramics and obsidian, and a kiln test on ceramics. The crib burn measured the effects of both radiant and convective heating, while the muffle furnace and kiln measure the effects of radiant heat alone. Our preliminary results suggest that there is a wide range of fire sensitivity among artifact types, and that ground and surface fires are more damaging than crown fires.
The ArcBurn team has developed a multi-agency advisory team of 13 experts who identify gaps in current understanding of fire effects on cultural resources. In all, the researchers have interviewed 17 fire and cultural resource managers about best practices and research needs for protecting cultural resources from fire and fire-related activities in the southwestern U.S. ArcBurn is also collaborating with FRAMES to create a new web portal for fire and cultural resources which will house useful reports and papers on fire effects on cultural resources, increasing public access.
While researchers have been active in the lab, field-based crews have also collected data for the ArcBurn project. The team has made giant strides in the past year in fire instrumentation. The team developed protocols for monitoring fire behavior, heat flux, and the resulting fire effects on archaeological sites during both wildland and prescribed fires. These protocols were applied in two fires in north-central New Mexico: the San Juan prescribed fire (7,300 acres, October 2013) and the Pino wildland fire (4,300 acres, September 2014). Tribal members were actively involved in data collection during and after these fires.
RMRS researchers instrumented a total of eight archaeological sites with fire behavior packages and in situ camera boxes to monitor fire behavior and effects on a wide range of artifacts, including field houses and pueblos as well as stone, obsidian, and ceramic lithics. The sites varied in fuel load, slope, aspect, and weather. Ignition patterns were varied to alter the overall fire behavior at individual cultural sites, resulting in a wide range of fire intensity. Post-fire analysis revealed that previous fuel treatments had varying levels of effectiveness in protecting artifacts.
Results from this study suggest that treatments such as larger ignition buffers around archaeological sites, tailored ignition patterns, offsite removal of slash and heavy fuels, and minimal treatment of live fuels can protect archaeological sites from damage resulting from heat, direct flame, and smoldering.