CHARCOAL EVIDENCE OF FIRE HISTORY FROM KEENER BOG, GEORGIA

Keener Bog is a small headwater wetland in the southern Blue Ridge Mountains of Rabun County, Georgia (elevation ca. 1000 m). Southern Appalachian bogs are highly diverse, yet increasingly endangered habitats that support a mosaic of shrub- and herb-dominated vegetation, including many rare and endangered endemic plants (Weakley and Schafale 1994, Water, Air and Soil Pollution 77: 359–383). Due to their rarity, these habitats remain under-studied and the conditions required for their creation and maintenance are not well understood. Like other mountain wetlands in the region, Keener Bog is being invaded by woody plants, and the Georgia Plant Conservation Alliance and others are working to restore the site by manually removing shrubs. Wetland researchers and managers have speculated that historic fires may have played a role in reducing shrub dominance in mountain wetlands such as Keener Bog (Edwards et al. 2013, The Natural Communities of Georgia). In 2013, we used a Colinvaux-Vohnout locking piston corer to collect cores of bog sediment for paleoenvironmental analysis. We reached depths of ca. 200 to 250 cm in two parallel holes. In Hole 1, dark organic sediment with organic contents of 5 to 27% based on loss on ignition extends to at least 150 cm; in Hole 2, we encountered more mineral-rich sediment beginning at 100 cm depth. AMS radiocarbon analysis of a twig at 152 cm in Hole 1 returned a radiocarbon date of 198 ± 21 yr BP, which calibrates to the period from AD 1669 to AD 1944 (95% confidence range). We quantified macroscopic charcoal (>125 microns) in contiguous 2-cm³ samples treated with sodium hydroxide and hydrogen peroxide. Macroscopic charcoal is relatively sparse in the sediments, but smaller charcoal particles are common on microscope slides prepared for pollen analysis. These microscopic charcoal particles likely indicate fires in surrounding forest, rather than on the surface of Keener bog itself.