24-10 Late Quaternary Wetland Development and Wildfire Regimes from a Central Appalachian Peat Bog: Bear Meadows, Pennsylvania

Session: Lake Sedimentary Records of Past Climate and Environment (Posters)

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Abstract:

The history of postglacial peatland development, wildfire regimes, and Indigenous land management in the temperate hardwood forests of the central Appalachians remains poorly understood, particularly prior to the Colonial Era. Although Indigenous people have occupied the region since at least the Archaic Period, Holocene fire histories do not exist for this region. Our study reconstructs the ecological development and local wildfire activity at Bear Meadows, a  boreal-like peatland in temperate, central Pennsylvania, using sedimentary charcoal, macrofossil and geochemical indicators from radiocarbon dated peat cores. Additional subsamples are being analyzed for carbon to nitrogen ratios (C:N) and stable carbon and nitrogen isotopes (δ¹³C, δ¹⁵N) to further characterize organic matter sources and peatland hydrology. A preliminary Bayesian age model developed from 5 radiocarbon dates shows continuous sedimentation from 15,000 cal yr BP to present, with the rapid initiation of peat accumulation around 8,500 cal yr BP. Charcoal analysis indicates low but persistent fires during the late Pleistocene. Charcoal abundance increases significantly at horizons dated to approximately 1,116 cal yr BP, indicating elevated fire activity during the late Holocene. Botanical macrofossils record the floristic development of the wetland. Around 13,000 cal yr BP aquatic macrofossils including Chara and Isoetes indicate a marsh or shallow pond prior to the peatland formation in the early Holocene. Thereafter, macrofossils including mosses and seeds increase markedly after approximately 8,500 cal yr BP, consistent with peatland establishment and expansion. This Holocene increase is expressed in stratigraphic changes within the upper peaty portion of the core. Horizons with higher charcoal concentrations are associated with greater abundance of moss remains, decomposed root material, and seeds relative to lower sections. These macrofossils occur within well-developed peat layers and are most common in the upper Holocene portion of the sequence. Charcoal particles in these horizons are predominantly small and angular with void spaces, consistent with herbaceous material, while woody charcoal fragments are present but relatively less abundant.Together, our macrofossil and charcoal study provides new insight into peatland development and Holocene fire dynamics in the central Appalachians.

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