Linking Fine Scale Fuel Heterogeneity with Fire Behavior in a Frequently Burned Pinus palustris Ecosystem

In ecosystems with frequent surface fire regimes, fire and fuel heterogeneity has been largely overlooked. This could be a result of the relatively complete burns that give an impression of homogeneity in fire behavior and fire effects, or due to the difficulty in capturing fine scale variation in fuel characteristics and fire behavior. While there are often few unburned patches in these systems, there is variation in fire intensity and duration that occurs at fine scales (\u3c10 \u3em). The diverse vegetation in these ecosystems also varies at a similar fine scale. This diversity could be driven by the influences of local interactions among patches of fuels, both derived from understory vegetation and canopy supplied fine fuels. We will present the results of a study linking fine-scale fuel heterogeneity and in-situ measures of fire intensity within longleaf pine forests of the southeastern USA. Initially, we developed a novel method to capture fine scale fuel spatial variation and structure and found that fuels occur in discrete patches that occur at a scale of approximately 0.5 m. We referred to these patches as “wildland fuel cells” and present here the results of how they influenced fire behavior. We used infrared thermography to couple fire intensity and residence time with fuel cells in a spatially explicit manner. We found that fire temperatures and residence times varied at similar scales to those observed for wildland fuel cells. The results also showed that fuel cells directly affected maximum temperatures, residence time, and an index of intensity, though there were also complex interactions. We plan to couple these measurements to effects on understory vegetation dynamics. The wildland fuels cell concept shows promise as a means to connect empirical studies with models of fire behavior and fire effects, allowing better predictions of the impact of within burn heterogeneity