Providing Paleoenvironmental Baselines to Inform Prescribed Fire Application in Central Florida

Abstract

Prescribed fire (Rx-Fire) is widely applied in the United States of America (U.S.A.) as a land management tool to promote ecosystem health and mitigate the risk of wildfires by removing excess fuels from landscapes. Rx-Fire use is particularly pronounced in the southeastern U.S.A. Rx-Fire was first developed in this region to restore ecosystems lost to logging, human land use, and Euro-American colonization. However, owing to the relative lack of tree ring records in the area, there is little empirical constraint for this region's pre-modern, long-term fire regimes. In this research, we leverage a lake sediment record of charcoal deposition to establish the natural and early anthropogenic baselines of fire in central Florida. By measuring macroscopic charcoal accumulation rates and characterizing charcoal morphological and morphometric changes through time, we provide paleoenvironmental context for modern Rx-Fire application in this region. Further, we compare the paleofire record with archeological and historical perspectives to understand the pre-colonization impacts of Indigenous people on the natural fire regimes in the Holocene. This thesis highlights the complex relationships between anthropogenic fire influence, climate, and vegetation. Overall, we found that the modern Rx-Fire application is likely overapplied relative to the Holocene baseline of fire activity. Further, we discovered a high variance between all morphometrics from 6.5 to 5.5 cal kyr BP, which can be indicative of the fuel source change from oak to pine dominance, as supported by neighboring proxies.