Does Fire Drive Quaternary Ecosystem Transformation at Lake Tulane, Florida?

Abstract

Ecosystems across the world are experiencing seemingly unprecedented fire activity due to changes in land use and climate. However, disentangling the drivers of fire regime intensification is difficult when climate and land use changes occur simultaneously. Thus, multi-proxy paleoecological records with evidence for climate, vegetation composition, and fire regime changes can provide valuable frameworks in which to interpret modern environmental shifts. Lake Tulane, Florida, offers an iconic record of vegetation responses to Heinrich Events and other climate variations over the last 60,000 years, but its fire history is unknown. Here we present the results of a 60,000-year fire history from Lake Tulane, Florida, based on sedimentary macro charcoal data at ca. 30-year resolution. Charcoal accumulation rates are highest in pre-32,000 year old sediments and decline toward the end of the Pleistocene. Fire activity was lowest during the period directly before the last glacial maximum (32,000 to 23,000 years ago). The end-Pleistocene record indicates on-going oscillations in fire activity from 22,000 to 10,000 years ago, but fire activity does not appear to be closely linked with pine/oak oscillations, thus indicating differential drivers of vegetation and fire change. Ultimately, the fire history at Lake Tulane is best understood in the context of other environmental factors such as millennial-scale climate variability, human influence, and megaherbivory.