Holocene peatland fire reconstruction in the Appalachian Mountains of West Virginia, USA.

Abstract

Pollen and charcoal records are useful in reconstructing past vegetation and fires, but Late-glacial and Holocene records of peatland fires and vegetation in the Eastern United States are sparse. Here we investigate how local fire regimes have interacted with peatland development and vegetation change in response to climate and human impacts during the Holocene. We collected a 2 m core from Big Run Bog (BRB), located in the Appalachian Mountains of West Virginia. The core was analyzed for radiocarbon dates, loss-on-ignition, pollen, plant macrofossils and charcoal. The 2 m BRB core spans the period from 18,000 cal yr BP to present, with a period of low accumulation between 12,000 and 3500 cal yr BP. Macrofossils of herbaceous materials identified from Big Run Bog show that the bog initiated as a rich fen. Pollen records show that the surrounding upland area began as a conifer dominated site, and our analyses of charcoal morphotypes corroborate this. The vegetation shifted from a conifer dominated area to a mixed hardwood forest during the Holocene. A sharp increase in charcoal concentration in the uppermost samples (~300 cal yr BP) of BRB corresponds to the increase in Ambrosia in our pollen records, which indicates the onset of forest clearance by European colonists. Our macrofossil record shows a transition to a Sphagnum-dominated peatland around this time. This suggests that European deforestation may have led to the formation of a bog through decreases in forest transpiration. The paludification is also recorded by increases in organic matter.