PS 2-24 - Holocene peatland fire reconstruction in the Appalachian Mountains of West Virginia, USA.

Abstract: Charcoal records are useful in interpreting and reconstructing fire history, especially in conjunction with pollen records of past vegetation, but records of peatland fires in the Eastern United States are sparse. Here we investigate how local fire regimes have interacted with peatland development and vegetation change as a result of both climate and human impacts during the Holocene. We collected cores from two small peatlands: Big Run Bog (BRB) and a bog in the Dolly Sods Wilderness Area (DS), 25 km apart, and located in the Allegheny Mountain section of the Appalachian Plateaus physiographic province, in West Virginia (WV). The BRB spans the period from 18000 cal yr BP to present, whereas the DS record is younger, spanning at least the last 5000 cal yr BP. We examined macroscopic ( >125 µm) charcoal morphological types (morphotypes) and accumulation rates to understand local fire history and indicators of vegetation burned. Charcoal concentrations at BRB were high from ~18000-15000 cal yr BP. Charcoal morphotypes include fragments of conifer materials and sedges, which agrees with our pollen record, indicating that conifers and sedges were dominant during this time interval, indicating that it started off as a tundra and then a boreal forest dominated by conifers and a few sedges present. Charcoal concentration decreased between 15000 cal yr BP and 12000 cal yr BP, but a few peaks in charcoal accumulation provide evidence of local fire; pollen assemblages show a concurrent decline in conifers. Charcoal morphotypes of deciduous leaves were also recorded, indicating the presence of hardwood species such as Quercus and Betula. Soon after 12000 cal yr BP, charcoal concentrations decreased. In the late Holocene, charcoal concentrations at both BRB and DS increased. A sharp increase in charcoal concentration in the uppermost samples of BRB tracks the increase in Ambrosia in our pollen records, which coincides with the onset of forest clearance by European colonists. DS also recorded this rise in charcoal and a corresponding rise in Ambrosia pollen, but the charcoal abundance here is variable. Historical evidence has indicated extensive logging between 1880 and 1980 CE. The charcoal records from Big Run Bog and Dolly Sods Bog therefore show strong influence of both climate and human impacts driving fire in this region of the Appalachian Mountains.