Using fossilized charcoal to corroborate the Everglades fire history geodatabase

Fire in the Everglades National Park (ENP) has historically been influential in shaping the Everglades ecosystem. As a result, ENP has been documenting fire events since 1948, and these data have been incorporated into an Esri ArcGIS geodatabase (Smith, T.J. III, and others, 2015). According to this geodatabase, 757,078 hectares of wetlands burned from 1948 to 2011. The main type of vegetation that has burned is comprised of palustrine and estuarine wetlands; however, there are areas in ENP that are comprised of these wetlands but have no documented fire events. Consequently, scientists at the USGS St. Petersburg Coastal and Marine Science Center question the accuracy of the data in this geodatabase. The abundance of fossil charcoal in sediment cores has been used, historically, as a fire proxy so to test the accuracy of this data, USGS scientists examined fossil charcoal in sediment cores taken from six locations in ENP. Two of the cores were taken from areas with well-documented fire events and four cores where taken from areas with no documented fire events. USGS scientists also dated three of the cores using excess Lead-210 (210Pb). Based on charcoal abundance in these cores, USGS scientists were able to verify documented fire events in the geodatabase. Furthermore, the presence of fossil charcoal in cores from areas with no documented fire events indicate that fire events did, in fact, occur in these areas in 1948-1964 and 1950-1980. These findings indicate the presence of fire events that are undocumented in the Esri geodatabase and suggest that 210Pb-dating is a promising method for reconstructing a regional fire history.